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

9631442燕麦的Wolpert维多利亚枯萎病是由真菌Cochliobolus victoriae引起的。 这种真菌是致病性的，因为它产生宿主特异性毒素，维克多林。 在宿主中，对维克托灵的敏感性以及因此对病原体的易感性由Vb基因座处的显性等位基因调节。 已经假设Vb基因通过编码毒素“受体”（作用位点）来调节易感性，所述毒素“受体”在毒素敏感品系（易感品系）中起作用，并且在毒素不敏感品系中缺失或改变。 生物活性，标记的衍生物的毒素已被用来确定和100 kDa的蛋白质，结合Victorin只在毒素敏感（敏感）基因型的燕麦和15 kDa的蛋白质，结合Victorin在敏感和耐药基因型。 100 kDa victorin结合蛋白（VBP）已被确定为核编码的线粒体多酶复合物甘氨酸脱羧酶的P蛋白组分。 结果还表明，甘氨酸脱羧酶复合物（GDC）的15 kDa H-蛋白组分是VBP。 本研究将测试一个生化模型，即毒素特异性是由两个维克多林结合蛋白（GDC的P-和H-蛋白组分）的相互作用调节的。 这些结果将为寄主特异性毒素依赖性植物病害的本质提供新的信息，这可能导致新的作物保护策略。

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.