Identification and transcriptional analysis of powdery mildew-induced barley genes

Differential screening by subtractive hybridisation and a random primer approach revealed 19 barley cDNAs representing gene transcripts, which accumulate during attack of Blumeria graminis f.sp. hordei race A6 (BghA6) in barley lines carrying the race specific resistance gene Mlg. The encoded proteins were in part not reported from plant-pathogen interactions, so far, such as a putative blue copper binding protein and a putative tyrosine phosphatase. To elucidate a potential link between different types of powdery mildew resistance, we compared gene expression profiles in the interaction of barley with the appropriate BghA6, the inappropriate wheat powdery mildew fungus (Bgt), and upon chemical treatment with the resistance-inducing chemical benzothiadiazole (BTH). Except for a tyrosine phosphatase gene, all the genes were induced after inoculation with the nonhost pathogen Bgt, and 18 genes were induced by appropriate BghA6 in plants lacking the race-specific Mlg gene while only three genes were stronger expressed after treatment with BTH. The copper binding protein and CJP74, a gene without known homologs, showed a higher BghA6-induced expression in resistant Mlg-lines compared to susceptible near-isogenic (mlg) lines. Together, these findings suggest a significant overlap between basal, race-specific and nonhost resistance.