An international team of scientists, which includes researchers from Virginia Tech, has cracked the genetic code of a plant pathogen that causes downy mildew disease. Downy mildews are a widespread class of destructive diseases that cause major losses to crops as diverse as maize, grapes, and lettuce. The paper describing the genome sequence of the downy mildew pathogen Hyaloperonospora arabidopsidis, which attacks the widely studied model plant Arabidopsis thaliana, is the cover story of this week's edition of the journal Science.
In the paper, the sequence of H. arabidopsidis is compared with other fully sequenced genomes of destructive plant pathogens to shed light on the differences in the ways microbes interact with their host and how those differences evolve. The payoff could be new ways to investigate how these pathogens wreak havoc and, in the long-term, finding how to prevent billions of dollars of losses for farmers growing crops across the globe.
Downy mildew pathogens are so highly specialized for parasitizing plants that they can no longer survive away from their hosts. However, they are close cousins of pathogens such as the Sudden Oak Death pathogen Phytophthora ramorum, which can attack hundreds of forest species but can also survive away from its hosts by feeding on dead plant matter. Comparisons of the genetic sequence of H. arabidopsidis with other related plant pathogens such as P. ramorum have revealed a massive loss of genes related to the microbe's plant-dependent lifestyle.
"Some plant pathogens like H. arabidopsidis must keep their host alive throughout the infection cycle in order to survive," said Brett Tyler, professor at the Virginia Bioinformatics Institute (www.vbi.vt.edu) at Virginia Tech and one of the lead authors of the study. "Others, including Phytophthora species that destroy soybean and potato crops as well as oak tree forests, keep plants alive for part of
|Contact: Barry Whyte|