Powdery mildew also lacks many of the genes necessary for attacking the plant cell. For example, it only produces a few transport proteins; other plant diseases produce an entire collection of these proteins. They use these to infiltrate toxins into the plant cell or to pump the plant's immune defence proteins out of the cell so that they no longer pose a threat. Powdery mildew also forms very few enzymes that can be used to perforate the wall of the plant cell wall and thereby gain entry to it. "The powdery mildew fungus obviously lacks the genetic equipment to launch a broad attack on the plant cell. Instead, its strategy is to slip into the plant unobtrusively. It tries not to give the plant immune system any opportunity for a defensive reaction. This also suits its parasitic way of life. Powdery mildew is not interested in the destruction of the host plant. What it wants is the subtle and enduring subjugation of its host", says Panstruga.
The mildew pathogen colonizing barley uses just four percent of its genetic armoury for this subjugation. The Cologne-based scientists only identified 248 genes that could possibly be used for such a task. The comparison with other mildew species for example pea or Arabidopsis mildew revealed that the three species share only seven of these genes. All of the others are found only in the barley mildew. This exclusivity shows that its genetic equipment developed with a view to establishing a parasitic existence in close association with the relevant host plant. The other mildew species have clearly found other genetic solutions.
|Contact: Ralph Panstruga|