摘要 : Barley is an alternative host for the rice blast fungus <i>Magnaporthe oryzae</i> but is resistant to <i>Magnaporthe</i> species associated with the grass genera <i>Pennisetum</i> and <i>Digitaria</i>. The latter cases are example... 展开 Barley is an alternative host for the rice blast fungus <i>Magnaporthe oryzae</i> but is resistant to <i>Magnaporthe</i> species associated with the grass genera <i>Pennisetum</i> and <i>Digitaria</i>. The latter cases are examples for nonhost resistance which confers effective and durable protection to plants against a broad spectrum of pathogens. Comparative transcript profiling of host and nonhost interaction revealed an early and pronounced change in gene expression in epidermal tissue of barley infected with a <i>Magnaporthe</i> nonhost isolate. Interestingly, this set of genes did not overlap considerably with the transcriptional response of barley against nonhost rust or powdery mildew isolates. For a functional testing of candidate genes a combined approach of virus-induced gene silencing (VIGS) and subsequent pathogen challenge was established. As anticipated, VIGS-mediated down-regulation of <i>Mlo</i>-transcripts led to higher resistance against <i>Blumeria graminis</i> f.sp. <i>hordei</i> and enhanced susceptibility against <i>M. oryzae</i>. 收起