Zea mays cultivar:Nathan Transcriptome or Gene expression
In order to characterize defense responses not only cytologically, but also on the transcript level, genome-wide sequencing of mRNA isolated from non-infected control leaves and from leaves inoculated either with the WT or with GLS1 overexpressing strains was performed, using Illumina Next Generation Sequencing Technology. In order to identify transcripts specifically induced in leaves infected by ß-1,3-glucan-exposing strains, transcript patterns of leaves inoculated with GLS1 overexpressing PtrpC:GLS1 strains were compared with those of the WT. In PtrpC:GLS1-inoculated leaves, a total of 2179 genes were more than 2.5-fold increased, with many genes known as genes typically up-regulated in PAMP-triggered defense responses. These genes include genes encoding PR proteins enzymes involved in cell wall re-inforcemen, and terpene synthases possibly involved in phytoalexin synthesis. Furthermore, increased transcript abundance of genes encoding serine-threonine receptor-like kinases calmodulin, as well as zinc-finger and WRKY transcription factors have been identified. Other up-regulated genes encode proteins involved in protein degradation, i.e. proteases, ubiquitin ligases, as well as enzymes involved in synthesis of auxin or cytokinin phytohormones. In comparison, 2164 genes were more than 2.5-fold down-regulated in maize leaves infected by PtrpC:GLS1 strains, as compared to WT-infected leaves. Several of the encoded proteins are known susceptibility factors. Forty-six down-regulated genes code for proteins containing iron or manganese, or are involved in uptake of these ions, suggesting major re-arrangement of the redox-status in maize leaves after ß-glucan perception. Overall design: Examination of plant defense responses in maize plants inoculated with 2 different Colletotrichum graminicola strains.