Interaction-Dependent Gene Expression inMla-Specified Response to Barley Powdery Mildew[W]

Abstract

Plant recognition of pathogen-derived molecules influences attack and counterattack strategies that affect the outcome of host-microbe interactions. To ascertain the global framework of host gene expression during biotrophic pathogen invasion, we analyzed in parallel the mRNA abundance of 22,792 host genes throughout 36 (genotype 3 pathogen 3 time) interactions between barley (Hordeum vulgare) and Blumeria graminis f. sp hordei (Bgh), the causal agent of powdery mildew disease. A split-split-plot design was used to investigate near-isogenic barley lines with introgressed Mla6, Mla13, and Mla1 coiledcoil, nucleotide binding site, Leu-rich repeat resistance alleles challenged with Bgh isolates 5874 (AvrMla6 and AvrMla1) and K1 (AvrMla13 and AvrMla1). A linear mixed model analysis was employed to identify genes with significant differential expression (P value < 0.0001) in incompatible and compatible barley-Bgh interactions across six time points after pathogen challenge. Twenty-two host genes, of which five were of unknown function, exhibited highly similar patterns of upregulation among all incompatible and compatible interactions up to 16 h after inoculation (hai), coinciding with germination of Bgh conidiospores and formation of appressoria. By contrast, significant divergent expression was observed from 16 to 32 hai, during membrane-to-membrane contact between fungal haustoria and host epidermal cells, with notable suppression of most transcripts identified as differentially expressed in compatible interactions. These findings provide a link between the recognition of general and specific pathogen-associated molecules in gene-for-gene specified resistance and support the hypothesis that host-specific resistance evolved from the recognition and prevention of the pathogen's suppression of plant basal defense.

Defense gene expression in Sorghum bicolor against Macrophomina phaseolina in leaves and roots of susceptible and resistant cultivars

“…The transcripts of chitinase and stilbene synthase exhibited a rapid upregulation as early as 24 HPI and reached maximum, then down-regulations were noted at later stages. Similar defense response patterns were observed by Caldo et al (2004) for compatible and incompatible interactions involving Mla1-like genes in barley in response to powdery mildew; transcripts build-up of defense-related genes were same in both resistant and susceptible varieties except that during later stages of infection expression levels get decreased. In our experiment, we used actin gene as an internal control; this gene has been used in Brassica rapa infected with club root disease and its expression has not been affected by fungal expression (Schuller & Muller 2006).…”

Differentially expressed genes during malting and correlation with malting quality phenotypes in barley (Hordeum vulgare L.)

“…Analysis of gene expression proWles using cDNA-based microarrays has proven useful for deciphering biochemical pathways involved in plant responses to stress and pathogens (Caillaud et al 2007;Caldo et al 2004;Venu et al 2007). DiVerentially expressed genes during germination in barley were also studied using cDNA arrays (Potokina et al 2002;Watson and Henry 2005).…”

Blufensin1Negatively Impacts Basal Defense in Response to Barley Powdery Mildew

“…Bln1 (represented by Barley1 GeneChip probe set Contig12219_ at) was one of 22 genes found to be differentially expressed at a threshold P value of ,0.0001 and a false discovery rate of ,7% (Fig. 1, experiment BB4; Caldo et al, 2004). To further characterize Bln1 response in the scope of the barley transcriptome, we extended the analysis of Caldo et al (2004) to another large expression-profiling experiment involving nearly isogenic lines C.I.…”

“…1, experiment BB4; Caldo et al, 2004). To further characterize Bln1 response in the scope of the barley transcriptome, we extended the analysis of Caldo et al (2004) to another large expression-profiling experiment involving nearly isogenic lines C.I. 16151 (Mla6) and C.I.…”