A Purdue University plant molecular biologist and his collaborators in Austria and North Carolina identified the gene that helps plants recognize pathogens and also triggers a defense against disease. The gene and its defense mechanisms are similar to an immunity pathway found in people and in the laboratory research insect, the fruit fly.
As Botrytis cinerea, a pathogen that makes strawberries gray and fuzzy, tries to invade a plant, the gene BIK1 recognizes the pathogen and sets off a defensive reaction. Botrytis is a type of pathogen that can infect and obtain nutrients from dead cells on a plant and actually secretes toxic substances into plant tissue in order to gain entry. Another type of pathogen, called a biotroph, must feed on live plant cells. As a strategy to contain a pathogen, plants actually kill their own cells at the site where a biotrophic pathogen is attempting to invade.
"This gene, BIK1, makes plants resistant to pathogens such as Botrytis, but it allows biotrophic pathogens to invade," said Tesfaye Mengiste, a Purdue plant molecular biologist and assistant professor of botany and plant pathology. "The mutant plant that doesn't have BIK1 actually shows decreased immunity to two pathogens, including Botrytis. But unexpectedly, it is completely resistant to virulent strains of the biotrophic bacteria."
The study of BIK1's role in plant resistance to these two types of pathogens appeared in the January issue of the journal Plant Cell. The study also shows that the gene impacts plant growth and development as evidenced by abnormally short roots, overabundance of root hairs and wrinkly leaves on plants lacking the gene, according to the scientists.