A research team at the São Paulo State University's Bioscience Institute (IB-UNESP) in Rio Claro, Brazil, has identified 29 fungi with proven action against Xanthomonas citri, a bacterium responsible for citrus canker, an endemic disease in all citrus-producing countries. The origin of the fungi is surprising. They were isolated from samples of soil and marine sediment collected in Antarctica.
"These fungi live in isolated conditions and proliferate under inhospitable conditions including low temperatures and high levels of ultraviolet radiation," says Daiane Cristina Sass, a professor at UNESP who heads a project researching microorganisms that produce compounds with antibacterial action for use in agriculture.
More efficiency on fighting citrus canker
Although the Xanthomonas citri bacterium can be combated in several ways, none is sufficient to eradicate the disease. Therefore, new chemical or biological methods of protecting citrus groves have to be pursued.
Professor Sette, curator of a collection of fungi, gathered from Antarctic summer expeditions to the South Shetland Islands in 2013 and 2015, isolated 33 filamentous fungi from samples collected in soil under rotten wood. The FAPESP-funded research found that 29 of the 86 Antarctic fungi they isolated (19 of marine origin and 10 terrestrial) contained compounds with proven action against X. citri.
According to eurekalert.org, the researchers plan to patent the compounds they identify. They also hope to persuade pesticide manufacturers to develop commercial products for combating citrus canker based on these compounds.