Identification of the Vb Gene Which Confers Sensitivity to the Host-Selective Toxin, Victorin

点击翻译按钮获取中文摘要

9631442 Wolpert Victoria blight of oats is caused by the fungus Cochliobolus victoriae. This fungus is pathogenic because it produces the host-specific toxin, victorin. In the host, sensitivity to victorin, and thus, susceptibility to the pathogen, is conditioned by the dominant allele at the Vb locus. It has been hypothesized that the Vb gene conditions susceptibility by coding for a toxin "receptor" (site of action) which is functional in toxin-sensitive lines (susceptible lines) and either absent or altered in toxin-insensitive lines. Biologically-active, labeled derivatives of the toxin have been used to identify and 100 kDa protein that binds victorin only in toxin-sensitive (susceptible) genotypes of oats and a 15 kDa protein that binds victorin in both susceptible and resistant genotypes. The 100 kDa victorin-binding protein (VBP) has been identified as the P-protein component of the nuclear-encoded, mitochondrial multienzyme complex, glycine decarboxylase. Results have also indicated that the 15 kDa H-protein component of the glycine decarboxylase complex (GDC) is a VBP. This research will test a biochemical model that toxin specificity is regulated by the interaction of the two victorin binding proteins, the P- and the H-protein components of the GDC. The results will provide new information about the nature of Host-specific toxin dependent plant disease, which may lead to a new crop protection strategy.