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关于水稻的专业英语1. What is the scientific name for rice? - Oryza sativa.2. How is rice cultivated? - Rice is cultivated through the transplantation of seedlings or direct sowing.3. What are the major types of rice? - The major types of rice include long-grain rice, medium-grain rice, and short-grain rice.4. What is the ideal climate for rice cultivation? - Rice thrives in tropical and subtropical climates with abundant rainfall.5. What is the average yield of rice per hectare? - The average yield of rice per hectare can vary but is generally around 4-6 tons.6. What are the common pests and diseases affecting rice plants? - Common pests and diseases affecting rice plants include stem borers, leaf folders, and rice blast.7. What is the purpose of paddy fields in rice cultivation? - Paddy fields provide a flooded environment for rice plants, which helps control weeds and pests and allows for better nutrient uptake.8. How is rice harvested? - Rice is typically harvested by cutting the stalks and then threshing to separate the grain from the husk.9. What is the typical cooking time for rice? - The cooking time for rice depends on the type, but it usually takes around 15-20 minutes for white rice and 40-45 minutes for brown rice.10. What are some popular rice dishes around the world? - Some popular rice dishes around the world include fried rice, risotto, paella, and biryani.11. What are the nutritional benefits of rice? - Rice isa good source of carbohydrates, providing energy for the body. It also contains essential amino acids, vitamins, and minerals.12. How is rice processed before it is consumed? - Rice undergoes processes such as milling, polishing, and packaging before it is ready for consumption.13. What is the role of rice in global food security? - Rice is a staple food for a large portion of the world's population, especially in Asia, and plays a crucial role in ensuring food security.14. How is rice stored to maintain its quality? - Rice should be stored in cool, dry conditions to prevent moisture and pest damage.15. What are the main export countries for rice? - The main export countries for rice include India, Thailand, Vietnam, and the United States.16. How is rice used in the production of other products beyond food? - Rice is used in the production of various products such as rice bran oil, bioplastics, and cosmetics.17. What are some traditional cultivation practices for rice? - Traditional cultivation practices for rice include the use of water buffalo for plowing, manual transplanting, and hand-pounding of rice grains.18. What is the importance of rice in cultural celebrations and rituals? - Rice holds significant cultural importance in various traditions and is often used in ceremonies, festivals, and religious rituals.19. How does rice contribute to the economy of rice-producing countries? - Rice production and export contribute significantly to the economies of rice-producing countries, creating jobs and generating revenue.20. What are the challenges faced in rice farming? - Challenges in rice farming can include water scarcity, pests and diseases, climate change, and market fluctuations.21. What is the role of genetic improvement in rice breeding? - Genetic improvement plays a crucial role in developing rice varieties with enhanced yield, resistance to pests and diseases, and tolerance to environmental stresses.22. Can rice be grown in non-traditional environments such as hydroponics or aeroponics? - Rice cultivation in non-traditional environments like hydroponics or aeroponics is challenging but being explored as a potential solution for land-scarce areas.。
2024学年山西省太原市山西大学附属中学高考考前提分英语仿真卷注意事项：1．答卷前，考生务必将自己的姓名、准考证号、考场号和座位号填写在试题卷和答题卡上。
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第一部分（共20小题，每小题1.5分，满分30分）1．New ideas sometimes have to wait for years before _____.A．being fully accepting B．fully accepting C．having fully accepted D．fully accepted2．Large quantities of time ______ for practising guided writings.A．was needed B．are needed C．needs D．is needed3．To fetch water before breakfast seemed to me a rule ______.A．to never break B．never to have brokenC．never to be broken D．never to be breaking4．The enquiry________ new facts, the judge had to postpone the trial again.A．to develop B．developedC．having developed D．being developed5．Take the note as a reminder ______ you forgot to buy some sweets for the kids while shopping there.A．how B．thatC．in case D．even if6．—Steve, the vacation is coming soon．Have you found a summer job yet？—I suppose I can work at the boy’s camp _____ I worked last summer．A．that B．where C．which D．what7．Premier Li Keqiang officially ______ the plan to develop the Bay Area in his government work report delivered at the start of the National People’s Congress session in March.A．laid out B．laid offC．laid down D．laid up8．She is such an irritating woman, I don’t know how you can ______ her.A．put up B．stand with C．stand up to D．put up with9．—What has made him in such high spirits recently?—_____ by his teacher for succeeding passing the exam.A．Being praised B．PraisedC．Having praised D．To praise10．—Do you know how I can ____ him?—On his mobile phone．A．learn B．reach C．seek D．touch11．_____ his homework in time, he had to stay up late into the night.A．Finishing B．Having finished C．To finish D．To have finished12．To tell the truth, I didn’t expect that there were so many people ______ the idea.A．supported B．supporting C．to support D．having supported13．Bathing crabs are raised in the Yangcheng Lake for at least six months，which is what makes them authentic and _____a high price．A．estimate B．fetchC．occupy D．predict14．—Your car should be ready next Tuesday．—We were ________ hoping you'd be able to do it by this Friday．A．still B．rather C．always D．even15．It was in that small house ________ was built with stones by his father ________ he spent his childhood. A．that; where B．which; thatC．which; which D．that; which16．The use of computers has made ______ possible for more people to work at home.A．it B．that C．which D．what17．My mobile phone is missing. Who it?A．must have taken B．must takeC．could have taken D．could take18．Thanks to Mr. Smith, the father and the son eventually ________after ten years' cold relationship between them. A．took up B．made upC．looked up D．turned up19．What actually ______ the accident has not yet been determined.A．brought out B．brought on C．brought about D．brought up20．My sister ______ the baby while I’m at yoga.A．arranges B．minds C．assesses第二部分阅读理解（满分40分）阅读下列短文，从每题所给的A、B、C、D四个选项中，选出最佳选项。
小学上册英语第四单元真题(含答案)英语试题一、综合题(本题有100小题，每小题1分，共100分.每小题不选、错误，均不给分)1.What do you call the main character in a story?A. AntagonistB. ProtagonistC. Supporting CharacterD. Narrator答案: B2.The ______ (生态) plays a role in the survival of many species.3.I enjoy crafting gifts for my friends and family, such as __________.4.My favorite color is ______ (蓝色). It reminds me of the clear ______ (天空).5.The ______ is a measure of how much matter is in an object.6.Which season is known for blooming flowers?A. WinterB. SpringC. SummerD. Autumn答案: B7.We can find many ________ (植物) in the rainforest.8.The doctor, ______ (医生), gives advice on staying healthy.9.小猴子) eats bananas all day. The ___10.__________ are used to represent elements in the periodic table.11.I call my neighbor ______ when I see him. (我见到我的邻居时称他为)12.What is the capital of the United States?A. New YorkB. Washington, D.C. C. Los AngelesD. Chicago答案:b13.The capital of Barbados is __________.14.n Tea Party was a protest against _____. The Bost15. A gazelle is known for its speed and ______ (优雅).16.What is the name of the famous river that runs through Egypt?A. AmazonB. MississippiC. NileD. Yangtze答案: C. Nile17.The __________ (历史的教训) is invaluable.18.The Earth's magnetic field protects us from ______.19.The sky is _______ (非常晴朗).20.The __________ is a famous city known for its historic buildings. (伊斯坦布尔)21.The _____ (ancient) Romans built roads that connected their empire.22.My sister is a ______. She enjoys singing.23.What is the process of taking in oxygen called?A. InhalationB. ExhalationC. RespirationD. Digestion答案: A24.The puppy is very ________.25.Listen and number.(听录音标号.)26.Enzymes are biological ______ that speed up reactions.27.The __________ is famous for its cherry blossoms.28.The dog is ______ with a ball. (playing)29.What do you call a place where animals are kept for public display?A. FarmB. ZooC. ParkD. Aquarium答案: B30.The __________ is a region known for its deserts.31.We will go ______ for a picnic tomorrow. (outside)32.We like to listen to ___. (music)33.I enjoy painting ________ (水彩画) in art class.34.What do we call the act of keeping something safe from harm?A. ProtectionB. PreservationC. ConservationD. Safeguarding答案: A35.The chemical symbol for neon is _______.36.I like to ________ my friends.37.My sister is _______ (在画画).38.We have English class _____ (on/in) Tuesday.39.The _____ (狐狸) is clever and quick on its feet.40.Elements are organized in the periodic ______.41.The rabbit’s ears help it hear _______ (声音).42.My favorite dish is ______ (意大利面).43.Fish come in many _________. (颜色)44. A __________ is a mixture that can be separated by centrifugation.45.在历史上，________ (battles) 常常改变了国家的命运。
超级水稻四级英语作文Super Rice。
Super rice, also known as hybrid rice, is a type ofrice that has been genetically modified to produce higher yields and be more resistant to pests and diseases. It is a major breakthrough in agricultural technology and has the potential to greatly increase food production and alleviate hunger in many parts of the world.The development of super rice began in the 1960s, when Chinese scientist Yuan Longping successfully developed the first high-yielding hybrid rice variety. Since then, super rice has been widely adopted in many countries, especially in Asia, where rice is a staple food. The benefits of super rice are numerous. It has the potential to increase rice yields by up to 30%, which is a significant improvement over traditional rice varieties. This means that more food can be produced on the same amount of land, which iscrucial for feeding the growing global population.In addition to higher yields, super rice is also more resistant to pests and diseases, which can help reduce the need for chemical pesticides and herbicides. This is not only better for the environment, but also for the health of farmers and consumers. Furthermore, super rice has the potential to grow in a wider range of environmental conditions, including areas with poor soil quality or limited water resources. This means that it can be grown in more places around the world, increasing food security for many communities.Despite these benefits, super rice has also faced some challenges. One of the main concerns is the potential impact on biodiversity, as the widespread adoption of super rice could lead to a loss of traditional rice varieties. There are also concerns about the long-term effects of genetically modified organisms (GMOs) on the environment and human health. These concerns have led to debates and regulations about the use of super rice in many countries.In conclusion, super rice is a promising technologythat has the potential to greatly increase food production and alleviate hunger in many parts of the world. However, it is important to carefully consider the potential risks and benefits of this technology, and to ensure that it is used in a responsible and sustainable manner. With proper regulation and oversight, super rice could be a valuable tool in the fight against global hunger.。
水稻主题四级英语作文这篇作文将从水稻的种植、重要性、文化象征以及面临的挑战等方面展开，力求仿写高质量的范文。
让我们开始吧：---。
The Significance and Cultivation of Rice。
Rice, known scientifically as Oryza sativa, is one of the most important cereal crops globally. Its cultivation dates back thousands of years and plays a crucial role in the food security and cultural heritage of many countries, especially in Asia. In this essay, we will explore the significance of rice cultivation, its cultural symbolism, and the challenges it faces.Cultivation of Rice:Rice cultivation involves a series of intricate processes, starting from land preparation to harvesting. Itrequires specific soil conditions, water management, and diligent care throughout its growth cycle. Farmers meticulously plant rice seedlings in flooded fields,allowing them to grow in submerged conditions. This method, known as paddy cultivation, is essential for the optimal growth of rice plants.The cultivation of rice is not merely an agricultural practice but also a way of life for millions of people worldwide. It provides employment opportunities, sustenance, and economic stability for rural communities. Moreover,rice cultivation promotes environmental sustainability by maintaining wetland ecosystems and preserving biodiversity.The Importance of Rice:Rice is a staple food for more than half of the world's population, particularly in Asia, where it serves as a primary source of carbohydrates and nutrients. Itsnutritional value, coupled with its versatility in cooking, makes it indispensable in cuisines worldwide. From steamed rice to sushi, rice-based dishes are enjoyed by people ofdiverse cultures.Beyond its nutritional value, rice holds significant cultural and symbolic importance in many societies. InAsian cultures, rice is often associated with prosperity, fertility, and abundance. It features prominently in religious rituals, festivals, and ceremonies, symbolizing unity and community. The cultural significance of rice transcends its role as a food staple, shaping traditionsand social customs for generations.Challenges Facing Rice Cultivation:Despite its importance, rice cultivation faces numerous challenges, including climate change, water scarcity, pests and diseases, and socioeconomic factors. Climatevariability, characterized by erratic rainfall patterns and rising temperatures, poses a significant threat to rice production. Extreme weather events such as floods, droughts, and typhoons can devastate rice crops, leading to food shortages and economic losses.Water scarcity is another pressing issue affecting rice cultivation, especially in regions reliant on irrigation. The unsustainable use of water resources and competitionfor water among various sectors exacerbate this challenge. Furthermore, pests and diseases pose a constant threat to rice yields, requiring innovative pest managementstrategies and resilient crop varieties.Socioeconomic factors such as land tenure systems, access to credit, and market dynamics also influence rice production. Smallholder farmers, who comprise a significant portion of rice producers, often face barriers to accessing resources and technology, limiting their productivity and income. Addressing these challenges requires a holistic approach, integrating sustainable agricultural practices, technological innovations, and supportive policies.Conclusion:In conclusion, rice cultivation is not just about growing a crop; it is a cornerstone of food security, cultural heritage, and rural livelihoods. As we confrontthe challenges of a changing climate and growing population, ensuring the sustainability of rice production is imperative. By adopting resilient farming practices, promoting biodiversity conservation, and empowering smallholder farmers, we can safeguard this essential cropfor future generations.--。
广东省深圳大学附属实验中学2023-2024学年高一上学期期中考试英语试卷学校:___________姓名：___________班级：___________考号：___________一、单项选择A．状语B．表语C．间接宾语D．宾语补足语A．indoor B．unhappy C．inexpensive D．impossibleA．pick up B．take up C．pack up D．put up 4．Unfortunately I wasn't________ of the importance of learning English well when I was in high school.A．proud B．aware C．guilty D．worthy5．He did a lot to __________ conditions for factory.A．approve B．imagine C．improve D．supportA．temporary B．reasonable C．impossible D．informal 7．— Can you lend me the book Gone with the Wind?— Sorry. I returned it to the library just now. Maybe it is still ____.A．available B．affordable C．acceptable D．valuable 8．Thanks for your directions to the house; we wouldn’t have found it ________.A．nowhere B．howeverC．otherwise D．instead9．When the group discussion is nearing its end, make sure to ______it with important points.A．conclude B．leadC．avoid D．hold10．As the world’s population continues to grow, the ___of food becomes more and more of a concern.A．worth B．supplyC．package D．list11．People were left________ when they saw the flood water rising so fast.A．in particular B．in panic C．in sight D．in order 12．It can be difficult to develop a new habit ________you know the habit is positive and useful.A．now that B．even if C．until D．unlesspotential.A．accelerate B．investigate C．perform D．develop 14．The Forbidden City attracts a _____ stream of visitors every day, especially during national holidays.A．constant B．main C．powerful D．shallow 15．What was so ________ about Jasmine Westland’s victory was that she came first in the marathon bare-footed.A．awful B．essential C．impressive D．obvious 16．The reporter said that the UFO ________ east to west when he saw it.A．traveled B．was traveling C．have traveled D．was to travel 17．That is the reason ________ he gave us for carrying out the plan.A．because B．why C．when D．which 18．It is the first time that we________ Festival in New York, so we will have a special experience.A．will observe B．observed C．are observing D．have observed 19．Although I was embarrassed, his words made me a lot more________.A．relaxing B．being relaxed C．relaxed D．to relaxinternationally renowned.A．which B．where C．whose D．as二、阅读选择We are King’s College London (KCL) Students’ Union!We have a huge range of events!21．What is special about Anatomy Museum Tour?A．It will be held in the afternoon.B．It is only for students of certain majors.C．There is no limit to the number of participants.D．Students from other schools should pay to attend it.22．How much will you pay if you donate 2 shirts and take 2 coats at Clothes Exchange?A．£4.B．£2.C．£1.D．£0. 23．Which event is open to every student free of charge?A．Shiny Stocking.B．Anatomy Museum Tour.C．Clothes Exchange.D．Shab-E Yalda Games Night.An international group of electronic music composers is taking beats from the dance club to jungles and forests and back, all to help save nature’s greatest singers. A Guide to the Birdsong of Mexico, Central America and the Caribbean is a new album that includes thedirectly towards efforts to save birds.The whole project was born out of this idea of trying to combine birdsong, electronic music and conservation. A Guide to the Birdsong of Mexico, Central America and the Caribbean was organized by activist, music producer, Robin Perkins. He invited artists from each of the endangered birds ‘homelands to build their own songs around the birds’ songs. There are contributions from ten artists in eight different countries.First single Black Catbird was created by The Garifuna Collective, from Belize. Al Obando, guitarist and producer of the group, always took in national parks and viewed birds when on the road with the band. “There are no trails, and there are no signs there to tell you about what you’re seeing,” Obando says. “So we’re trying to do something for the birds and nature tourism.”Another musician who responded to Robin’s call is Tamara Montenegro, an artist from Nicaragua. She was shocked to hear of the serious situation of the Guardabarranco after being approached: “This beautiful creature I grew up adoring also faced the influence of the systematic human activities”. In response, she created a song inspired by this bird and the challenges it faces to live naturally.The new album is the second edition, following on from A Guide to the Birdsong of South America, produced by Robin in 2015. That first album has raised, to date, over $15,000 benefitting conservation projects in South America. As with the first album, all of the money from the sales of the new album will support specific organizations, including Birds Caribbean.24．What does the underlined word “proceeds” in Paragraph 1 refer to?A．Profits.B．Budgets.C．Challenges.D．Effects. 25．What do we know about Al Obando?A．He created a hit single himself.B．He was fond of observing birds.C．He was the organizer of the new album.D．He did a lot for birds in South America.26．Why was Tamara astonished to learn of the Guardabarranco?A．It was friendly to humans.B．It was living in bad conditions.C．It was beautiful in appearance.D．It was facing challenges from other birds.27．What is the author’s purpose in writing the text?A．To collect money for a project.B．To popularize electronic music.C．To recommend some famous artists.D．To introduce a new album of electronic music.The San Diego County Water Authority has an unusual plan to use the city’s San Vicente Reservoir(水库)to store solar power. The project could help unlock America’s clean energy future.Perhaps ten years from now, large underground pipes will connect the lake to a new reservoir built about 1100 feet higher. When the sun is high in the sky, California’s rich solar power will pump (泵水) water into that upper reservoir. When the sun goes down, the force of water would produce 500 megawatts (百万千瓦)of electricity for up to eight hours. “It’s a water battery!” says Neena Kuzmich, director of engineering for the water authority.The technology that San Diego puts forward is already in use at more than 40 sites in the US. Some of them were built during the 1970s to store electricity produced by nuclear power plants. Now, the need to store power from renewable sources is bringing this old technology back.Water batteries have many competitors, when it comes to storing energy. However, they have their own advantages. Water batteries are a proven way to store large amounts of power. The San Vicente project would store about as much electricity as the batteries in 50, 000 of Tesla’s Model 3 cars. They also don’t require hard-to-find battery materials. The biggest problem with them is that it is hard to find places to build them. They need a great deal of water, land to build two reservoirs and permission to damage the landscape.Kelly Catlett, director of an environmental organization, says, “We won’t support projects that build new damns on rivers and damage ecosystems. But San Diego’s plan looks like something different, because it uses an existing reservoir and doesn’t damage any streams.”28．What’s the main idea of Paragraph 2?A．What a water battery is.B．How the project will work.C．Why reservoirs are needed.D．What the clean energy future is.29．What is the advantage of water batteries over their competitors?A．They can power Tesla’s cars.B．They can store renewable sources.C．The battery materials are easy to get.D．The technology applied is a new breakthrough.30．What is the biggest challenge for water batteries?A．Damage caused to nature.B．The shortage of solar power.C．Limited ability to store energy.D．Proper places for construction. 31．What is Kelly Catlett’s attitude towards the project?A．Unconcerned.B．Worried.C．Supportive.D．Doubtful.The Ebro Delta, in Spain, famous as a battleground during the Spanish Civil War, is now the setting for a different contest, one that is making rice farmers fight against two enemies: the rice-eating giant apple snail, and rising sea levels. What happens here will have a bearing on the future of European rice production and the overall health of southern European wetlands.Located on the Mediterranean, just two hours south of Barcelona, the Ebro Delta produces 120 million kilograms of rice a year, making it one of the continent’s most important rice-growing areas. As the sea creeps into these fresh-water marshes, however, rising salinity (盐度) is hurting rice production. At the same time, this sea-water also kills off the greedy giant apple snail, an introduced pest that feeds on young rice plants. The most promising strategy has become to play one enemy off against the other.The battle is currently being waged on land, in greenhouses at the University of Barcelona. Scientists working under the banner “Project Neurice” are seeking varieties of rice that can withstand the increasing salinity without losing the absorbency that makes European rice ideal for traditional Spanish and Italian dishes.“The project has two sides,” says Xavier Serrat, Neurice project manager and researcher at the University of Barcelona, “the short-term fight against the snail, and a mid- to long-term fight against climate change. But the snail has given the project greater urgency.”Originally from South America, the snails were accidentally introduced into the Ebro Delta by Global Aquatic Technologies, a company that raised the snails for fresh-water aquariums (水族馆) but failed to prevent their escape. For now, the giant apple snail’spresence in Europe is limited to the Ebro Delta. But the snail continues its march to new territory, says Serrat. “The question is not whether it will reach other rice-growing areas of Europe, but when.”Over the next year and a half investigators will test the various strains of salt tolerant rice they’ve bred. In 2018, farmers will plant the varieties with the most promise in the Ebro Delta and Europe’s other two main rice-growing regions along the Po in Italy, and France’s Rhone. A season in the field will help determine which, if any, of the varieties are ready for commercialization.As an EU-funded effort, the search for salt-tolerant varieties of rice is taking place in all three countries. Each team is crossbreeding a local European short-grain rice with a long-grain Asian variety that carries the salt resistant gene. The scientists are breeding successive generations to arrive at varieties that incorporate salt tolerance but retain about 97 percent of the European rice genome (基因组).32．Why does the author mention the Spanish Civil War at the beginning of the passage?A．It has great impact on the lives of Spanish rice farmers.B．It is of great significance in the records of Spanish history.C．Rice farmers there are engaged in another kind of battle of similar importance.D．Rice farmers there are experiencing the hardships of wartime.33．What may be the most effective strategy for rice farmers to employ in fighting their enemies?A．Striking the weaker enemy first.B．Killing two birds with one stone.C．Eliminating the enemy one by one.D．Using one evil to fight against the other. 34．What does Neurice project manager say about the giant apple snail?A．It can survive only on southern European wetlands.B．It will invade other rice-growing regions of Europe.C．It multiplies at a speed beyond human imagination.D．It was introduced into the rice fields on purpose.35．What is the ultimate goal of the EU-funded program?A．Cultivating ideal salt-resistant rice varieties.B．Increasing the absorbency of the Spanish rice.C．Introducing Spanish rice to the rest of Europe.D．Popularizing the rice crossbreeding technology.For making contact and communicating with a person, effective eye contact is essential to our everyday interaction with people, and also to those who want to be effective communicators in public places. 36 .Generally in Western societies and many other cultures, eye contact with a person is expected to be regular but not overly persistent. 37 , causing the person who’s the object of a person’s stare to feel overly studied and uncomfortable.38 . The New Zealand Medical Journal reported that one reason so many young children fall victim to attacks by pet dogs is their overly-lasting eye contact with pets, which causes them to feel threatened and defensive.Overly lasting eye contact is also a sign of a person’s over-awareness of the messages they are giving. In the case of people who try to lie to someone, they may maintain their eye contact so that their lies would not be noticed. 39 . But on the contrary, evasive (逃避的) eye contact is a sign of discomfort. Why do we avoid looking at a person? It may be because we feel ashamed to be looking at them if we’re being dishonest of trying to take them in. Evasive eye contact may also a sign of dishonesty.However, Scotland’s University of Stirling found that, in a question-and-answer study among children, those who maintained eye contact were less likely to come up with the correct answer to a question than those who looked away to consider their response.40 , when this energy could be spent on deep thinking.A．This is a widely recognized indicator of lyingB．Constant eye contact is often considered to be rudeC．Eye contact is the act of looking into someone’s eyesD．But there’s something you may not know about eye contactE．Overpowering eye contact can make the other person excitedF．Even between humans and non-humans, lasting eye contact is sometimes unadvisable G．Eye contact, as a socializing device, can take a surprising amount of effort to maintain三、完形填空A stranger helped a Jamaican athlete Hansle Parchment get to his Olympic race. He wongold and tracked down the stranger. As a star athlete, he is familiar with overcoming barriersOlympic race.He 42 a video this weekend on social media explaining how 43 turned to hope after he met a “good Samaritan (善良之人),” a(n) 44 working at the Games who helped him to reach his final destination. In the video, Parchment said that he had been enjoying music while traveling to his race and was not 45 paying attention to what was happening around him.“By the time I looked up, I realized this bus was going the 46 way,” he said. He got to what he believed was a centre for water sports 47 the athletics events. Officials on-site 48 him to take another bus back to the sports field-an action he knew could have resulted in his 49 the race. He then met Stojkovic, who was volunteering at the Olympics. She helped him find transport and 50 his cost.Parchment 51 on time to warm up and run, finally coming in first place and achieving his season’s best time at 13.04 seconds.In the video, Parchment revisited the area where he had first met Stojkovic days ago, telling her, “You were 52 in my getting to the final that day.” He showed her his gold medal. Jamaican officials 53 Stojkovic as a good Samaritan and said an “official invitation” to 54 Jamaica had been offered to her.Delighted with his win and his reunion with Stojkovic, Parchment gave her a yellow Jamaican Olympic polo shirt as a gift and left his fans with a message: “Be 55 always.”41．A．curious B．unprepared C．skilled D．confident 42．A．selected B．posted C．downloaded D．replaced 43．A．eagerness B．guilt C．sorrow D．anxiety 44．A．cleaner B．officer C．volunteer D．player 45．A．gently B．fully C．energetically D．significantly 46．A．unique B．remote C．usual D．wrong 47．A．instead of B．as well as C．together with D．in addition to 48．A．allowed B．ordered C．advised D．scared 49．A．missing B．removing C．organizing D．attending 50．A．claimed B．charged C．increased D．covered51．A．recovered B．arrived C．contacted D．reflected 52．A．confused B．thoughtful C．passive D．helpful 53．A．selected B．praised C．appointed D．assumed 54．A．admire B．join C．visit D．catch 55．A．thankful B．positive C．passionate D．logical四、语法填空五、根据所给汉语提示填空71．The mobile phone sellers became eager to their (发财)with the new technology. (根据汉语提示完成句子)72．They (应该，应当) have arrived at lunchtime but the flight was delayed. (根据汉语提示完成句子)73．He missed the appointed time and finally (终于出现) three hours late. (根据汉语提示完成句子)74．Traditional publishers have to start (期待，盼望) to a digital future if they want to survive. (根据汉语提示完成句子)75．Unfortunately, I (不了解……的情况，不了解……的) of my college roommate, so I have no idea how she’s doing now. (根据汉语提示完成句子)六、书信写作76．假定你是李华，你的爱尔兰笔友Chris 发邮件说对你们学校刚刚结束的运动会非常感兴趣，想具体了解你们是怎样举行运动会的，请给他写一封邮件，内容包括：1. 介绍运动会过程；2. 分享个人收获；3. 希望得到Chris 的反馈。
水稻主题四级英语作文范文标题，Rice The Staple Food in China。
Rice, as a staple food, plays an indispensable role in the daily life of Chinese people. It is not only a source of nutrition but also deeply rooted in the cultural heritage of China.First and foremost, rice serves as the primary source of energy for the Chinese population. With its rich carbohydrates, it provides the necessary fuel for daily activities and sustains the physical health of individuals. Whether it's steamed, fried, or made into porridge, rice is a versatile ingredient that can be adapted to various cooking methods, catering to different tastes and preferences. Its importance in the Chinese diet cannot be overstated, as it forms the foundation of countless meals consumed across the country on a daily basis.Moreover, rice cultivation has been a tradition inChina for thousands of years, dating back to ancient times. The meticulous process of planting, nurturing, and harvesting rice has been passed down through generations, embodying the wisdom and diligence of Chinese farmers. From the fertile fields of southern China to the terraced landscapes of the southwest, rice paddies dot the countryside, symbolizing both the agricultural prowess and cultural heritage of the nation. The annual harvest season, marked by celebrations and rituals, is a testament to the significance of rice in Chinese culture, highlighting its role not just as a food source but as a symbol of abundance and prosperity.Furthermore, rice holds a special place in Chinese customs and traditions. It is often featured prominently in ceremonies and festivals, signifying good fortune,fertility, and unity. During weddings, for example, newlyweds are traditionally showered with rice as a symbol of blessings for a fruitful union. Similarly, during the Mid-Autumn Festival, mooncakes, a traditional delicacy made with rice flour, are exchanged among family members and friends as a token of reunion and harmony. These customsreflect the deeply ingrained cultural beliefs surrounding rice and its significance in fostering social bonds and familial ties.In addition to its cultural and culinary importance, rice cultivation also plays a vital role in China's economy and environmental sustainability. As one of the world's largest producers and consumers of rice, China's agricultural sector relies heavily on rice cultivation for employment, income, and food security. However, the cultivation of rice also poses challenges in terms of water usage, land management, and environmental impact. Efforts to promote sustainable farming practices, such as water-saving techniques and organic cultivation methods, are thus crucial in ensuring the long-term viability of rice production while mitigating its environmental footprint.In conclusion, rice holds a multifaceted significancein Chinese society, encompassing nutritional, cultural, economic, and environmental dimensions. As a staple food,it sustains the health and well-being of millions of people across the country. As a cultural icon, it embodies thetraditions and values passed down through generations. As an economic resource, it drives agricultural development and food security. And as an environmental asset, it poses both challenges and opportunities for sustainable growth. Thus, the importance of rice in China extends far beyond the dinner table, shaping the fabric of society and enriching the lives of its people in myriad ways.。
Plant Science 203–204 (2013) 33–40Contents lists available at SciVerse ScienceDirectPlantSciencej o u r n a l h o m e p a g e :w w w.e l s e v i e r.c o m /l o c a t e /p l a n t s ciA rice stress-responsive NAC gene enhances tolerance of transgenic wheat to drought and salt stressesAbu Sefyan I.Saad a ,1,Xu Li a ,1,He-Ping Li a ,b ,Tao Huang a ,Chun-Sheng Gao a ,c ,Mao-Wei Guo a ,Wei Cheng a ,Guang-Yao Zhao d ,Yu-Cai Liao a ,c ,∗aMolecular Biotechnology Laboratory of Triticeae Crops,Huazhong Agricultural University,Wuhan 430070,Hubei,PR China bCollege of Life Science and Technology,Huazhong Agricultural University,Wuhan 430070,Hubei,PR China cCollege of Plant Science and Technology,Huazhong Agricultural University,Wuhan 430070,Hubei,PR China dKey Laboratory of Crop Germplasm Resources and Utilization,Ministry of Agriculture,The National Key Facility for Crop Gene Resources and Genetic Improvement,Institute of Crop Science,Chinese Academy of Agricultural Sciences,Beijing 100081,PR Chinaa r t i c l ei n f oArticle history:Received 30September 2012Received in revised form 24December 2012Accepted 26December 2012Available online 3 January 2013Keywords:Abscisic acid sensitivity Drought tolerance Salinity assayTransgenic wheatStress responsive NAC Triticum aestivuma b s t r a c tDrought and salinity are the primary factors limiting wheat production worldwide.It has been shown that a rice stress-responsive transcription factor encoded by the rice NAC1gene (SNAC1)plays an important role in drought stress tolerance.Therefore,we introduced the SNAC1gene under the control of a maize ubiquitin promoter into an elite Chinese wheat variety Yangmai12.Plants expressing SNAC1displayed significantly enhanced tolerance to drought and salinity in multiple generations,and contained higher levels of water and chlorophyll in their leaves,as compared to wild type.In addition,the fresh and dry weights of the roots of these plants were also increased,and the plants had increased sensitivities to abscisic acid (ABA),which inhibited root and shoot growth.Furthermore,quantitative real-time poly-merase chain reactions revealed that the expressions of genes involved in abiotic stress/ABA signaling,such as wheat 1-phosphatidylinositol-3-phosphate-5-kinase,sucrose phosphate synthase,type 2C pro-tein phosphatases and regulatory components of ABA receptor,were effectively regulated by the alien SNAC1gene.These results indicated high and functional expression of the rice SNAC1gene in wheat.And our study provided a promising approach to improve the tolerances of wheat cultivars to drought and salinity through genetic engineering.© 2013 Elsevier Ireland Ltd. All rights reserved.1.IntroductionBread wheat (Triticum aestivum L.)provides daily sustenance for a large proportion of world population.It is produced in a wide range of climates and different regions with frequent and various stresses.Drought and salt are the major abiotic stresses and primary causes of yield reduction in crops.It has been estimated that they cause an average loss of yield of more than 50%for major crops [1,2].Limited water resources and soil salinity are also among the key fac-tors affecting the global production of wheat.Studies on drought tolerance of plants have indicated that tolerance to abiotic stress is an inherent and multigenic trait in nature [3],and that it is a difficult task to genetically manipulate a multigene-controlled agronom-ical character through breeding.Thus,introduction of an alien gene into elite wheat cultivar provides an alternative approach∗Corresponding author at:College of Plant Science and Technology,Huazhong Agricultural University,Wuhan 430070,Hubei,PR China.Tel.:+862787283008;fax:+862787283008.E-mail address:yucailiao@ (Y.-C.Liao).1These authors contributed equally to this work.to facilitate the development of wheat varieties with improved drought tolerance and good agronomical characteristics for sus-tainable agriculture.Progresses have been made toward identifying potential stress-related genes that could enhance the tolerance of plants to abiotic stresses.Three groups of proteins,NAM (no apical meristem),ATAF1-2and CUC2(cup-shaped cotyledon)[4,5],constitute a large family of transcription factors (NAC)that contain both highly conserved N-terminal DNA-binding domains and diversified C-terminal domains.A genome-wide analysis of 117Arabidopsis and 151rice NAC genes has revealed that many of them are in the SNAC (stress responsive NAC)group [6,7].SNACs are plant-specific transcription factors that have been shown to play roles in plant development,as well as biotic and abiotic stress tolerance [8–11].Many candidate NAC genes regulate the number of tillers,cell wall development [12],root enlargement [8],and crop senescence [12–14].Several Arabidopsis NAC genes,ANAC019,ANAC055and ANAC072that are induced by drought,salinity,and/or low temper-ature,respectively,are involved in plant abiotic stress tolerance [3,15].Overexpression of another stress-related NAC gene,AtNAC2,results in enhanced salt tolerance and sensitivity to abscisic acid (ABA)in Arabidopsis [16].OsNAC52,a rice NAC,has been shown34 A.S.I.Saad et al./Plant Science 203–204 (2013) 33–40Fig.1.Structure of pUbiSNAC1used for transformation.Ubi-P,ubiquitin promoter;SNAC1,SNAC1coding sequence;Bar,phosphinothricin-acetyltransferase gene.not only to improve abiotic stress tolerance of rice,but also to acti-vate ABA-regulated gene expressions [17].OsNAC6and OsNAC5are both transcriptional activators involved in the response of rice to abiotic stresses such as drought,high salinity and cold [18–21].Overexpression of OsNAC6in rice results in retarded plant growth and reduced grain yield;however,OsNAC5overexpression has no effect on the growth of rice [19,21].An improved tolerance to both drought and salinity in transgenic rice plants overexpressing OsNAC5or OsNAC6has been reported [19,21].The wheat NAC gene NAM-B1controls nutrition remobilization from leaves to devel-oping grains [13].Another wheat gene TaNAC69is up-regulated under stresses [22],and transgenic wheat expressing TaNAC69has increased drought tolerance [11].In addition,wheat gene TaNAC2has been shown to enhance tolerance of Arabidopsis to abiotic stresses [23].Recently,two stress-responsive NAC genes SNAC1and SNAC2/OsNAC6have been characterized in rice [24,25].These two genes encode two typical and homologous NAC transcription factors.They have similar expression patterns in response to drought,salt,cold and ABA treatment [25,26].The overexpres-sions of SNAC1and OsSNAC10genes have resulted in the genetic improvement of the existing elite rice varieties and the production of new germplasms with high grain yield and stress tolerance,and thereby have opened up numerous important opportunities for sustainable agriculture [8,24].Yield enhancement in wheat production is one of the essential strategies to meet the food demands for the growing population,yet both drought and salinity has adversely limited productivity in wheat growing areas.To address this problem,a recent review has proposed that the overexpression of NAC genes might be useful for improving stress tolerance in transgenic wheat plants [7].However,it is not known whether the expression of alien SNAC1genes can improve drought tolerance of wheat.In this study,a stress-responsive NAC gene SNAC1from rice was introduced into an elite wheat cultivar,and the transgenic wheat plants were characterized under various stress conditions.Wheat plants expressing SNAC1gene displayed a clearly increased ABA sensitivity and significantly improved tolerance to drought and salinity,suggesting that SNAC1was a potential candidate for enhancing drought tolerance in bread wheat.2.Materials and methods2.1.Vector constructionSNAC1was amplified from a rice cDNA clone [24]using two primers SNAnde1and SNAsac1(Table 1).The PCR product was cloned into pAHC25[27]to generate a recombinant plasmid pUbiSNAC1for wheat transformation (Fig.1).2.2.Transformation and tissue cultureAn elite Chinese wheat cultivar (cv.)Yangmai12was planted in an experimental field in the fall of 2008.The spikes were tagged at anthesis in April 2009,and immature seeds at 14–16days post medium (MS supplemented with 2mg/L 2,4-D)with the embryo scutellum side facing up,and cultured for 5days [28].Calluses were sub-cultured and used for bombardment with a biolistic gun (PDS-1000He,Bio-Rad,Hercules,CA,USA)[28].Subsequent cultures and selection of transgenic calli were performed as previously described [29].The surviving plantlets with strong roots and shoots were vernalized at 4◦C for 14days and then cultured in a growth cham-ber under 16/8h day/night at 18–20◦C.Leaves from each surviving plant were analyzed by PCR with primers S-SNA and NOSR for iden-tification (Table 1).The selected transgenic plants were harvested at physiological maturity,and T1,T2and T3generations were used for drought and salinity tolerance assays.2.3.DNA and RNA extractionGenomic DNA was extracted from young leaves of wheat as described [28].Total RNA was extracted from leaves using TRIzol reagent (Invitrogen,Carlsbad,CA,USA)according to manufacturer’s instructions.To eliminate genomic DNA contamination,purified RNA was treated with RNase-free DNase I (Takara,Dalian,China)before precipitation.2.4.PCR,reverse-transcription PCR (RT-PCR)and quantitative real-time PCR (qRT-PCR)For PCR analysis of transgenic plants,primers S-SNA and NOSR were used to amplify a 392-bp DNA segment spanning SNAC1gene and NOS-terminator.The PCR products were separated on 1.2%agarose gels.For RT-PCR analyses of a target gene,5g total RNA purified from wheat leaves were reversely transcribed into cDNA with reverse transcriptase (Invitrogen,Carlsbad,CA,USA)and an oligo-dT 20primer.PCR amplifications were performed with a thermal cycler (MyCycler TM ;Bio-Rad,Richmond,CA,USA)using primers S-SNA and NOSR.PCR consisted of 35cycles of denaturation (94◦C,30s),annealing (60◦C,30s)and extension (72◦C,30s).Wheat actin gene was co-amplified as control with primers PwactF1and PwactR1(Table 1).For qRT-PCR,total RNA was extracted from four-week-old leaves.Subsequently,5g of total RNA was reversely transcribed into cDNA.qRT-PCR was performed in a 25-L reaction containing SYBR Green I PCR Master Mix (Toyobo;Osaka,Japan),10pmol each of forward and reverse gene-specific primers,and 10L of diluted cDNA (1:100).Gene-specific primers (Table 1)were designed using Primer Premier5software (Premier Biosoft International,Palo Alto,CA,USA).Wheat actin gene was selected as an internal control and co-amplified with primers ActinF and ActinR (Table 1)to normalize the total amounts of cDNA present in each reaction.PCR amplifica-tion was performed in Lightcycler ®480(Roche,Basel,Switzerland)according to the manufacturer’s instructions.Briefly,following a denaturation step at 95◦C for 4min,the amplification was car-ried out with 40cycles at 94◦C for 15s,60◦C for 20s and 72◦C for 20s.The fluorescent signals were recorded at 72◦C for 30s.A melting curve was performed to determine the specificity of each PCR primer by maintaining the reaction at 95◦C for 20s,cooling to 55◦C for 10s and heating to 95◦C at a rate of 0.5◦C per 10s.The experiments were performed in triplicates.2.5.Southern blot analysisA total of 15g DNA from each sample was digested with 60units of Sac I (TaKaRa,Dalian,China)overnight,and the digested DNA was electrophoresed on 0.8%agarose gels.DNA fragments were transferred onto a nylon membrane (Hybond-N +,Amersham,A.S.I.Saad et al./Plant Science203–204 (2013) 33–4035 Table1Primer sequences used for PCR,RT-PCR and qRT-PCR analyses in this study.Name Annealing site Sequence(5 –3 )DNA fragment(bp)SNA nde1SNAC1ACTAGACCATATGAGAAGCAAGCAAGAAGCG1050SNACsac1SNAC1ATACGAGCTCACCCGAGCCATCTCTTGACS-SNA SNAC1CCACCATCCCCAGGAACAAC392NOSR Nos-terminator GATAATCATCGCAAGACCGGCAACActinF Actin GCTGTTCCAGCCATCTCATGT156ActinR Actin CGATCAGCAATTCCAGGAAACPwactF1Actin CCAACAGAGAGAAAATGACCCAG201PwactR1Actin CAAGGTCCAAACGAAGGATAGCASPSF SPS GCTACGGGGAGCCAACAG144SPSR SPS GGAGGTAAGGCCACAGGGAPI3KF PI3K GGCACCAGAGGCCCATGT156PI3KR PI3K GGAGGGAGCCCTTTATCGPP2C3F PP2C TGGGCTGCCAAGGGCTGTA82PP2C3R PP2C CCCACGCCATCAGGAAACATRCAR1F RCAR TGAGGGATATGGGACTGCCG120RCAR1R RCAR GCCGCTTAGAACCACCCTGTUbiP5Ubiquitin promoter CATCTCTGTATATGCATCAG495UbiP6Ubiquitin promoter CGGTAGTTCTACTTCTGTTC(Table1)[30].Autoradiograph was recorded and analyzed with an imaging analysis system(BAS1800-II,Fuji Film,Tokyo,Japan).2.6.Drought and salt tolerance assaysFor drought and salt stress assays,transgenic wheat plants from T2and T3generations of two independent transgenic lines A2and A4were used,and a non-transgenic(NT)wheat cv.Yangmai12 (Y12)was used as control.For drought tolerance assay,four-week-old wheat plants grown in pots(12cm×14cm)were subjected to drought stress for14 days,followed by re-watering.The pots were kept in a growth chamber under conditions of16/8h day/night at18–20◦C.For each genotype,21plants were assayed and three replicates were used. Leaves were sampled at0,3,6,9and14days after the onset of drought treatment to measure relative leaf water content(RLWC %)as described[31].Chlorophyll contents(SPAD unit)were also estimated at the same days using a SPAD-502Minolta chlorophyll meter(Japan).SPAD values indicated the relative amounts of total chlorophyll in plant leaves[32].Twenty-one days after re-watering, survival rates were determined.The plants were photographed at the indicated times.For salt tolerance analyses,14seedlings per transgenic line along with the non-transgenic control Y12were germinated on Petri dishes(90mm)in three replicates.The germinated seeds were transferred to Hoagland’s liquid medium[33],grown for8days, subjected to2%NaCl treatment for7days,and then transferred back to normal Hoagland’s liquid medium as described previously[34]. After15days of recovery,survival rates were determined.Fresh shoot and root weight(g)and dry root weight(mg)of each plant were measured.Photographs were taken at the indicated times, and the experiment was carried out in three replicates.2.7.Abscisic acid(ABA)sensitivity assayWheat seeds of two transgenic lines A2and A4along with non-transgenic control Y12were tested for abscisic acid(ABA)sen-sitivity.Seeds were germinated and incubated in0,5and10M ABA for7days at20◦C[35].Fourteen seedlings per transgenic line or non-transgenic Yangmai12were assayed.Root length and shoot 2.8.Statistical analysisFisher’s LSD test was used to reveal significant differences of plant tolerance to drought and salinity between the transgeniclinesFig.2.PCR,RT-PCR and Southern blot analyses of T3transgenic wheat.(A)PCR products amplified with DNA isolated from the leaves of transgenic lines A2and A4,as well as the non-transgenic Yangmai12(Y12)using primers S-SNA and NOSR.(B)RT-PCR products amplified from cDNA derived from leaves using primers S-SNA and NOSR.(C)RT-PCR products of actin gene amplified using primers PwactF1and PwactR1.(D)Genomic DNA from leaves of transgenic lines and non-transgenic Y1236 A.S.I.Saad et al./Plant Science203–204 (2013) 33–40and the non-transgenic control Y12using IBM SPSS Statistics17.0 (IBM Corporation,New York,USA).3.Results3.1.Transformation and molecular characterization of the transgenic plantsImmature embryos from an elite wheat cv.Yangmai12were cul-tured to induce calli,which were then bombarded with pUbiSNAC1 (Fig.1).Transgenic calli were selected on medium containing phos-phinothricin(PPT)[29].A total of18PPT-resistant T0transgenic plantlets were gen-erated and analyzed by PCR,and used for the production of T1 progenies.For T1to T3generations,PPT was used for the selection of transgenic plants.Two transgenic lines showed good perfor-mance under salt treatment in the T1generation(data not shown). They were designated as A2and A4and used for subsequent analy-ses.A392-bp SNAC1fragment was amplified from A2and A4using primers S-SNA and NOSR(Fig.2A).RT-PCR analyses confirmed the presence of SNAC1transcripts in the two transgenic lines with the same primers(Fig.2B),while internal control actin transcripts were present in all transgenic plants and the non-transgenic Y12 plants(Fig.2C).Southern blot analyses revealed that the SNAC1 gene was indeed integrated into the wheat genome with different numbers of hybridization bands in the two lines,suggesting that A2has at least one copy and A4has at least2copies(Fig.2D).All the transgenic plants had comparable morphologies with the non-transgenic plants(Fig.3A,0day).And no significant differences were observed in grain yield under normal irrigation between the transgenic wheat plants A2and A4and the non-transgenic Y12 plants(data not shown).3.2.Drought tolerance of the transgenic plantsTo investigate whether the SNAC1gene improved drought tol-erance of transgenic wheat plants,the two transgenic lines A2and A4expressing SNAC1and the non-transgenic(NT)control Y12were tested for drought tolerance under controlled drought condition in a growth chamber.Irrigation was suspended for14days,after which plants were re-watered.All transgenic and NT plants showed no discernible developmental differences during thefirst4weeks from germination(Fig.3A,0day).Moreover,no difference was seen in chlorophyll contents and relative leaf water content(RLWC) among all the plants during that period(Fig.3B and C,0day).In thefirst three days after the drought treatment,no significant difference of RLWC was observed between the transgenic plants and NT Y12control plants,although the NT plants started to show visual symptoms of drought-induced damage such as drying with a concomitant loss of chlorophyll content(Fig.3C).However,sig-nificant differences were observed6days after drought treatment. On the14th day after the treatment,the RLWC of the NT plants was only21%,whereas the transgenic plants contained signifi-cantly higher RLWCs ranging from28%to30%(Fig.3B).Inaddition,Fig.3.Drought tolerance and relative leaf water content and chlorophyll content of the non-transgenic Yangmai12and the transgenic wheat plants expressing SNAC1gene.(A)Phenotypes of transgenic wheat plants and non-transgenic control Yangmai12(Y12)under drought stress.Representative transgenic wheat plants from T2transgenic lines A2and A4,as well as the control Y12were shown at the indicated time points.Four-week-old plants were treated under drought stress condition for14days.Plus sign (+)denotes the days after re-watering of plants treated under drought stress condition.(B)The relative leaf water content(RLWC)(%)of transgenic lines and the control Y12 at different time points upon drought stress.(C)Chlorophyll content(SPAD unit)of transgenic lines and the control Y12at different time points upon drought stress.DataA.S.I.Saad et al./Plant Science203–204 (2013) 33–4037 Table2Survival rates(%)of T2and T3transgenic wheat plants and non-transgenic Yangmai12under drought and salinity stresses,and grain yield(g)of T3transgenic wheat in comparison with non-transgenic Yangmai12.Genotype Drought(%)a Salinity(%)b Grain yield(g)c T2T3T2T3T3A252.22±22.84a,b74.60±8.47a56.41±9.04a88.1±4.1a 1.55±0.43aA469.93±17.05a77.78±8.47a51.59±8.47a81.0±8.3a 1.69±0.45aCK(Y12)d30.16±2.75b55.56±2.11b20.47±6.51b43.7±6.0b0.79±0.16bDifferent letters indicate significance at P<0.05with Fisher’s LSD test.±,standard deviation.a Drought tolerance data were from three independent experiments and21plants per experiment were assayed.b Salinity tolerance analyses were from three independent experiments and14plants per experiment were assayed.c Grain yields were from8plants per independent transgenic line or genotype under drought stress.d Non-transgenic control Yangmai12with stresses.significant differences in chlorophyll contents were also observed between the transgenic lines and the NT Y12on6th day after the onset of drought stress(Fig.3C).These results suggested that the expression of SNAC1improved the water and chlorophyll contents in the transgenic plants,and delayed the drying of wheat plants under drought stress.Further analyses showed that the survival rates of plants after re-watering were significantly different between the transgenic plants and the NT Y12control.On the21st day after re-watering (+21days),30%of the NT control plants survived,whereas52–70% of the A2and A4transgenic plants survived,with73–133%more plants survived during the T2generation(Table2).Thus,the trans-genic wheat plants showed strong drought tolerance.In addition, after re-watering,the transgenic wheat plants recovered faster than the NT Y12control plants(Fig.3A).The drought tolerance of T3transgenic wheat plants was com-parable with that of T2transgenic wheat lines.Three weeks after re-watering,the survival rate of the NT Y12control plants was55%, whereas75–78%transformed plants survived(Table2).Moreover, the transgenic wheat plants had significantly higher grain yield than the NT control Y12under drought stress(Table2),although no significant difference was observed between the transgeniclinesFig.4.Salinity tolerance,fresh weight and root dry weight of transgenic wheat plants expressing SNAC1gene and non-transgenic Yangmai12.(A)Phenotypes of T3transgenic lines A2and A4,as well as the non-transgenic Y12under salinity treatment.The8-day-old seedlings(0day)were grown in the presence of2%NaCl for7days(7day)and then transferred to normal growth medium.Plus sign(+)denotes days after transferring the transgenic plants into normal growth medium.Representative plants were presented at the indicated time points.(B)Plant fresh weight(biomass).(C)Root dry weight.Data presented in(B)and(C)were from plants transferred into normal growth medium38 A.S.I.Saad et al./Plant Science 203–204 (2013) 33–40Fig.5.ABA sensitivity,root length and shoot height of transgenic wheat plants expressing SNAC1gene and non-transgenic Yangmai12.(A)–(C)Phenotypes of seedlings from T3transgenic lines A2and A4,as well as non-transgenic Y12.Plants were grown in the absence (A,0M)or presence (B,5M;C,10M)of ABA for 7days.(D),(E)and (F)Root length and shoot height derived from (A),(B)and (C),respectively.Vertical bars bearing different letters in one treatment indicate significant differences at P <0.05and error bars represent standard errors.For each genotype 42plants were assayed.and the control Y12under normal conditions (data not shown).These results clearly indicated that the expression of SNAC1sig-nificantly enhanced drought tolerance of transgenic wheat plants during vegetative growth.3.3.Salt tolerance of the transgenic plantsThe salt tolerance of transgenic lines was evaluated for both T2and T3generations at seedling stage.Before salt treatment,no discernible differences in growth and morphology were observed between the transgenic wheat plants and the NT Y12control plants (Fig.4A,0day).After salt treatment in Hoagland’s liquid medium supplemented with 2%NaCl,however,the survival rate of the NT plants was only 20%after recovery for two weeks in normal medium.In contrast,the T2transgenic plants showed survival rates of 52–56%(Table 2).Salt tolerance assays of T3transgenic wheat plants revealed a similar pattern as observed for the T2transgenic turned yellow,and the survival rate was 43.7%.Whereas the sur-vival rates of the transgenic plants were 81.0–88.1%,an increase from 85%to 101%(Table 2;Fig.4).Furthermore,the transgenic plants produced significantly higher biomasses than the NT Y12control plants (Fig.4B and C).Thus the SNAC1gene from rice clearly enhanced salt tolerance of transgenic wheat plants.3.4.ABA sensitivity of the transgenic plantsThe ABA sensitivity of the transgenic wheat plants express-ing SNAC1was assayed.After germination,wheat seeds were transferred to Hoagland’s liquid medium containing different con-centrations of ABA (0,5M and 10M ABA).In the absence of ABA,no differences in root length and shoot height were found between the transgenic wheat seedlings and NT Y12control (Fig.5A and D).However,in the presence of 5M ABA,the growth of roots and shoots were significantly inhibited in the transgenic plants,but notA.S.I.Saad et al./Plant Science203–204 (2013) 33–4039Fig.6.qRT-PCR analyses of four genes in the T3generation of transgenic lines A2 and A4in comparison with non-transgenic Yangmai12.RNA was isolated from four-week-old leaves.Fold changes of transcripts in the transgenic lines A2and A4relative to the non-transgenic Yangmai12are presented.Error bars represent standard errors.F).These results suggested that the expression of a rice SNAC1gene led to increased sensitivity to ABA,which resulted in a retarded growth of the transgenic plants.3.5.The expression of genes regulated by SNAC1in the transgenic plantsTo investigate whether the expression of the rice SNAC1gene affected the expression of other genes involved in the signal transduction pathways of drought stress in the transgenic wheat plants,the expression levels of21previously reported stress-responsive genes[36]were evaluated in the T3transgenic plants A2and A4and in the non-transgenic Y12using qRT-PCR.Four stress-responsive genes SPS(sucrose phosphate synthase),PI3K (1-phosphatidylinositol-3-phosphate5-kinase),PP2C3(type2C protein phosphatases)and RCAR(regulatory components of ABA receptor)were found to be regulated by rice SNAC1(Fig.6).PI3K is required for ABA-induced stomatal closure.SPS participates in the osmoregulation in plants.RCAR is an important player in ABA signal transduction.These three genes had1.3–3.4-fold higher expression in the transgenic wheat plants than in the NT Y12control(Fig.6).On the other hand,the expression of PP2C3gene in the two transgenic wheat lines was clearly repressed to only34%and33%for A2and A4,respectively,of the amount of PP2C3transcripts in the NT Y12 control(Fig.6).These results indicated that the exogenous SNAC1 gene effectively regulated the expression of different endogenous wheat genes involved in abiotic stress tolerance.4.DiscussionImprovement of drought tolerance in elite wheat cultivars has been a challenge,because drought tolerance is governed by a multi-gene family and affected by many factors.NAC transcription factors have been shown to regulate abiotic stress response and a wide array of stress related genes[20,24].In this study,we introduced an exogenous OsSNAC1gene into a commercial wheat cultivar toExpression of a stress-responsive NAC gene from rice regu-lated by a maize ubiquitin promoter has been shown to display a constitutive expression pattern in cereal crops[27].Our results showed that transgenic wheat plants showed normal morphology and growth,implying that SNAC1appeared to be mainly responsive to stress signals without impairing the normal growth and devel-opment of wheat.In addition,the transgenic wheat plants showed significantly enhanced tolerance to drought and salinity,and pro-duced significantly more grains than the non-transgenic control Y12.These results suggest that the rice SNAC1gene is an apposite candidate of genetic engineering for improving drought tolerance of wheat.Compared with the non-transgenic control Y12,the transgenic wheat plants expressing the rice SNAC1gene showed higher ABA-sensitivity(Fig.5)and higher water and chlorophyll contents (Fig.3B)under drought stress.ABA is an important hormone reg-ulating stomatal closure[36,37].It plays an important role in vegetative tissues under water stress by promoting stomatal clo-sure,and by regulating the expression of many genes controlling dehydration[38].A higher ABA sensitivity in transgenic wheat may stimulate sto-matal closure to retain water and increase survival rates.In our study,the SNAC1-regulated ABA sensitivity apparently failed to impair the growth of transgenic wheat plants without the applica-tion of exogenous ABA,under which retarded growth of roots and shoots was observed.A similar phenomenon has been reported in rice overexpressing the same SNAC1gene[24,25].Therefore,the exogenous SNAC1gene likely regulates the ABA pathway in wheat in a manner similar to that in rice.Different endogenous genes associated with drought stress response were activated in the transgenic wheat plants expressing the NAC gene(Fig.6).PI3K is required for ABA-induced stomatal closure.It is essential for normal plant growth and diverse physio-logical functions including auxin-induced production of reactive oxygen species,root gravitropism,increased plasma membrane endocytosis,salt tolerance,cold response,and movements of sto-matal closure[36,39,40].SPS was also strongly activated in the transgenic wheat plants expressing the rice SNAC1gene(Fig.6).The SPS gene is up-regulated in the drought resistant wild emmer wheat [36].An increased enzymatic activity of SPS and increment in leaf sucrose and/or hexose content have been observed in durum wheat under drought treatment,and changes in leaf sucrose and/or hex-ose content are known to contribute to osmoregulation under stress conditions[41].Promoter sequences of PI3K and SPS genes(Zhao et al.,unpublished results)from D genome donor(Aegilops tauschii) of common wheat indeed carry conserved cis-elements for recogni-tion(CATGTG)and binding(CACG)by NAC as previously identified [15,24],suggesting that PI3K and SPS genes in wheat may be direct targets of rice NAC.Overexpression of RCAR1affects all facets of ABA signaling including adjustment of stomatal and regulation of gene expression[42].Some RCAR genes are expressed in different Ara-bidopsis tissues including roots,stomata,and parenchymal cells of the vasculature[42].RCAR is highly up-regulated in drought resis-tant wild emmer wheat in response to drought[36].Our data also showed the repression of a type2C protein phosphatases(PP2C) gene expression in the transgenic wheat lines A2and A4express-ing the rice SNAC1gene(Fig.6).PP2C is negatively regulated by ABA signaling[38,42].Taken together,the profound changes in the expression of these stress-responsive genes in the transgenic wheat plants indicated an efficient regulatory role of rice SNAC1gene in the ABA pathway,which helped to close the stomata and reduce water release under drought stress.Our study demonstrated the generation of genetically stable transgenic wheat plants that con-tained a rice stress-responsive NAC gene and displayed an enhanced。
