Chinese medicine herbs could defeat devastating cotton virus, study suggests
- Scientists find some chemicals can kill the cotton leaf curl Multan virus and others can boost cotton plants’ immunity to it
- It is feared the virus could wreak havoc in China’s Xinjiang region, which produces most of the country’s cotton
Chinese scientists have found chemicals in medicinal herbs that could tame a destructive plant virus threatening the cotton industry in its western Xinjiang region.
Some small-molecule chemicals in herbs commonly used in Chinese medicine can effectively suppress cotton leaf curl Multan virus, according to ongoing research led by Professor Ye Jian at the Institute of Microbiology in Beijing.
By targeting WRKY20, a gene in the virus’ DNA, the chemicals could disrupt the viral infection and transmission, Ye’s team found.
Some early findings from their research were published last month in the journal Science Advances.
The leaf curl virus – a species of Begomovirus, the largest genus of plant viruses – poses a significant threat to the world’s cotton plantations, causing leaf curling, stunted growth and lower yields of cotton fibre. It costs the cotton industry in the Indian subcontinent about US$1 billion a year, according to a press release about the study from the Chinese Academy of Sciences.
Were there to be a pandemic in China, the drop in output and measures to contain it could cost the cotton farming industry 50 billion yuan (US$7 billion), according to some researchers’ estimates, the academy added.
The first known cases of the virus in China over the past decade were limited to coastal areas in the country’s east, but several cases have now been reported in Xinjiang Uygur autonomous region.
“We are running out of time,” Ye told the South China Morning Post.
Cotton is a pillar industry in Xinjiang, which provides more than 80 per cent of China’s total cotton production. The industry also contributes up to 50 per cent of the income of farmers involved in it, according to government statistics.
Exact figures for infections in the region are not available, but outbreaks so far remain isolated, according to Ye and other researchers with knowledge of the situation.
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However, Professor Gao Feng, cotton researcher at the Agricultural College of Shihezi University in Xinjiang, warned that leaf curl virus could reduce cotton production in an infected field to almost zero.
“A large-scale outbreak has not occurred yet, but the threat is very serious and people are very nervous,” Gao told the Post. “We are in desperate need of a solution.”
The challenges facing China’s pork industry highlight the danger viruses can pose to the domestic market. A swine fever outbreak that has wiped out 100 million pigs caused pork prices to rise, forcing China to look to new countries to import from, such as Portugal and Argentina.
Its biggest overseas supplier of cotton is the United States, with which it is locked in a protracted trade war. In July, the government allowed some Chinese companies to buy a total of 50,000 tonnes of cotton from the US without tariffs being charged.
The central and regional governments fear that falling incomes caused by the impact of an outbreak on the cotton industry would increase the risk of ethnic conflict, social instability and anti-government thoughts.
Ye’s team adopted two approaches to fighting the virus.
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Some chemicals they discovered could improve cotton plants’ immunity against the infection by stimulating them to generate an antibody that killed the virus. The other chemicals they found could target the virus, directly reducing its intensity.
“They can be used as sprays,” Ye said, adding that he planned to reveal the chemical composites and related herbs in a paper to be published in a peer-reviewed journal in the coming months.
The discovery could offer an environmental benefit, too. Cotton farmers in Xinjiang use pesticides to deter the whiteflies that transmit the virus, but their overuse has affected Xinjiang’s delicate ecology, which in its desert areas is particularly vulnerable to disturbance.
In the agricultural research community, there is growing concern that some whitefly species will become resistant to pesticides. “If that happens, we will have a major problem,” Ye said.
He said the chemicals identified in the ongoing study would not harm the environment. “These chemicals come from plants, so the negative impact to the environment would be minimal,” he said.
The study also found that it may be possible to use the cotton leaf curl Multan virus to benefit farmers. It stimulates cotton plants to generate a chemical that is harmful to other insects, such as the bollworm, that compete with whiteflies for food, meaning that it could be genetically modified into a pest control agent.
Most cotton species in commercial plantations are genetically modified to produce an insecticide to kill bollworm. Ye said a man-made virus could reduce the dependence on genetically modified plants.
