Guo Huishan’s wish eight years ago was finally realized. On September 26th, Nature-Plant published a new achievement from the team of Guo Huishan, which revealed that they used the genetic "small scissors" - RNAi to create a new line of cotton against Verticillium wilt that effectively attacked cotton "cancer" The secret of yellow wilt.
In August 2008, Guo Huishan, a researcher at the Institute of Microbiology, Chinese Academy of Sciences, saw the long stretch of cotton fields in Xinjiang for the first time. However, what she saw was not a gratifying harvest, but a yellow, deciduous leaf, and the desperate face of the cotton farmers. This scene is like a nail stuck in her heart, let her crazy to understand what it is like.
Recently, Guo Huishan's team has published three articles. They have for the first time globally revealed how the Verticillium wilt fungus “knocks†into the “gate†of cotton. For the first time, the new gene silencing technology, the RNAi gene “small scissorsâ€, is used to block entry. The bacteria in the cotton body spreads arbitrarily, and a new cotton line with higher resistance to Verticillium wilt is cultivated in the upland cotton.
"These studies have clarified the pathogenesis of Verticillium wilt and created new disease-resistance techniques to provide technical support for reducing disease, increasing cotton yield, improving cotton fiber quality, and achieving sustainable development of poverty alleviation and social stability. Theoretical research goes to application and breaks through the typical example of technical bottlenecks in the industry,†said Dong Xiuzhu, deputy director of the Institute of Microbiology.
Reveal how fungi enter the cotton body
"Study on cotton verticillium will cause the leaves and buds of cotton plants to fall off and the yield is seriously lost." On September 26, Guo Huishan said in an interview with the reporter of the Chinese Journal of Science.
China's annual cotton output is 6 million to 8 million tons, accounting for 30% of the world's total output. It ranks first in the world and is most seriously affected by yellow wilt disease. As the largest high-quality cotton production base in China, the cotton planting area in Xinjiang reached more than 34 million mu in 2015, but the area of ​​verticillium disease exceeded 50%.
However, since the pathogen causing the disease lives in the soil layer of 40 cm in the soil and the variation is frequent, the conventional fungicides and chemical agents are difficult to control. Moreover, its host has more than 120 plants, and the short-term effect of the traditional rotation disease resistance model is not satisfactory.
To prevent disease, we must first find the pathogenic mechanism. The research team finally unveiled the "figure cloth" of Verticillium dahliae through trial and error, and first revealed the "culprit" of Verticillium wilt in the world - the infection structure of Verticillium dahliae .
"Verticillium dahliae is a semi-living parasitic fungus that usually lurks in the soil in the form of micro-sclerotia. Once exposed to plant tissue, they will produce a 'nail'-like infestation structure like Transformers. Break through the cell wall of the plant, drill into the root vascular tissue, and then gradually occupy the entire vascular tissue, causing the plant to wilted and sick," Guo Huishan explained.
"Then, it began to use the dead plant saprophytic, returned to the ground after the plant nutrients were exhausted, waiting for the opportunity to start a new round of harm." Guo Huishan said.
"Small scissors" silences disease-causing genes
The most effective way to control cotton verticillium is to use disease-resistant varieties. However, more than 90% of the cultivars in most cotton areas in China belong to upland cotton. Due to the lack of disease-resistant germplasm resources, the innovation of resistance to Verticillium wilt is difficult.
Guo Huishan's team took a different approach and used RNAi to attack this sly plant “killer†and managed to develop a new upland cotton disease resistance line.
RNAi is a small piece of RNA produced by double-stranded RNA, which can cleave or inhibit translation of homologous target RNA. Guo Huishan compares it to the "small scissors" of the gene. Dong Xiuzhu said: "This new gene silencing technology is like a target. When it hits, it will stop the target gene."
Using this "small scissors", the researchers used RNAi technology to develop a new line against Verticillium wilt in early-maturing upland cotton. After identification, its resistance to Verticillium wilt was increased by 22.25% compared with the control variety. Related results were published in Molecular Plants in June this year.
“By RNA interference technology, cotton can allow Verticillium dahliae to enter its body, but it will not let it expand normally through the cotton vascular system, and will not let it go to every cell of cotton.†Guo Huishan's postdoctoral peak Added.
At the B-class jury of the Chinese Academy of Sciences, Dr. Chen Yiyu and Academician Yan Tingyun believed that this study was of great significance and had great value.
The new line comes with "cross-border" disease resistance
So, how does the new cotton disease resistance line fight against verticillium? Further research by the research team found that plants with better disease resistance induced the accumulation of a class of plant endogenous small ribonucleic acids (miRNAs), which can transcend the boundaries between plants and pathogens, transport them to pathogen cells, and degrade pathogenic bacteria. Genes to achieve disease resistance. The study, published in Nature-Plant, demonstrates for the first time the existence of a new disease-resistant pathway for plant-fungal transboundary small RNAs to induce pathogen target gene silencing. It provides important theoretical support for the effective application of HIGS technology in cotton against Verticillium wilt, and opens up a new field for future host-pathogen interaction research.
“Mr. Guo’s research on plant pathology is a major underlying strategic issue.†Qian Wei, deputy director of the State Key Laboratory of Plant Genetics at the Institute of Microbiology, said that China uses 7% of the world’s land to feed 30% of the world’s population. The price is that China's pesticide application also accounts for 30% of the world. He believes that the use of pesticides to kill germs and insects has reached a dead end.
“Plant pathologists have a dream to develop green agriculture.†Qian Wei believes that the significance of this research by Guo Huishan’s research team is that it was first discovered that “the host has driven its own small RNA into the fungus to control the physiological activities of the fungus. "Methods. It is equivalent to using the existing immune system of plants and adding RNAi "small scissors" to improve the disease resistance of cotton.
“This is an example of a breakthrough in major fundamental research that has really led to major technological obstacles.†Qian Wei said, “Is China discussing basic research or not? Do you spend so much money? In fact, this is not the case. Good basic research is The best technology."
However, in Guo Huishan's view, this is only the first step of the Long March. “It’s just using a 'small pair of scissors' to increase the cotton's resistance to Verticillium blight by 22.5%, which is '0 to 1' work.†She said that in the future there will still be work from 1 to 100, she will Verticillium wilt "dead to the end". Next, the team will establish a variety of high-efficiency RNAi “small scissors†target libraries to screen out more and more effective cotton varieties resistant to Verticillium wilt, so that more Xinjiang farmers can get rid of the disease caused by Verticillium wilt. pain.
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