CHANGES IN SALICYLIC ACID AND GENE EXPRESSION LEVELS DURING BARLEYBLUMERIA GRAMINIS INTERACTION
M. Jawhar, E. Al-Shehadah, A. Shoaib, M. Orfi, A. Al-Daoude
Powdery mildew, caused by Blumeria graminis f. sp. hordei (Bgh) is a common foliar disease of barley worldwide. To better understand barley mechanisms to resist this disease, compatible/incompatible barley-Bgh interactions and some marker genes involved in salicylic acid (SA) pathway were evaluated using qRT-PCR across four-time points after pathogen challenge. Data showed that SA level contents of tolerant and susceptible genotypes increased one day post inoculation (dpi) in comparison with non-inoculated plants, and that the tolerant genotype contained three-fold of total SA than the susceptible one. This might be evidence that SA plays a positive role in signaling events during fungal infection by Bgh. In general, our study shows a remarkable discrepancy in the expression pattern of those marker genes between compatible and incompatible barley-Bgh interactions. The results of qPCR revealed that the defense-related genes PR2, PAL and LSD1 were expressed in the tolerant genotype over the inoculation time points with 3.8, 4.11 and 3.16-fold increases after 6 dpi . Moreover, the increase in gene expression of the genes was closely related to the activation of SA levels. Taken together, our results provide an insight into the signaling pathway that accounts for classical gene expression changes elicited during barley-Bgh interactions.