Differential Expression of Phenylalanine Ammonia-lyase Between Barley Spot Blotch (Cochliobolus sativus) and Net Spot Blotch (Pyrenohora teres f. sp. maculata)

Cochliobolus sativus and Pyrenophora teres f. sp. maculata, are economically important barley pathogens worldwide. Although they are very different in vegetative and reproductive forms, their spot blotch symptoms are quite similar, so the question is whether barley reacts to the disease similarly. Phenylpropane metabolic pathway plays a crucial role in plant responses to fungal diseases. In the present work, expression of phenylalanine ammonia-lyase (PAL) gene was monitored in susceptible barley genotype at early time points of infection using quantitative real-time PCR (qPCR). Data displayed significant variance in PAL expression between barley C. sativus and P. teres interactions as compared to the non-infected controls. It is remarkable that PAL expression and spot severity were higher and faster in plants infected with C. sativus as compared with those infected with P. teres during the infection process, with a maximum PAL expression (3.55 and 1.43-fold) respectively, at 96h post infection. This indicates that the severity of spot blotch symptoms seems to be associated with the degree of gene expression that will require further investigation. This work may provide useful information regarding barley reaction to two foliar pathogens causing similar disease symptoms.