Evaluation of expression pattern of several pathogenesis related genes and PAL in sour orange plant following treatment with SA and JA in response to citrus blast bacterium Pseudomonas viridiflava

Plant diseases are one of the major limitations in agricultural production. Citrus blast disease is one of the most common diseases in citrus producing regions of the world, with the exception of tropical regions. Plants respond to bacterial pathogens by activating genes encoding defense proteins. One of the defense mechanisms of plants against pathogens is the accumulation of Pathogenesis related proteins associated. The aim of this study was to evaluate the expression of several defense genes against Pseudomonas viridiflava after treatment of seedlings with Salicylic acid and Jasmonic acid.

The expression levels of PR1, PR2, PR3, PR4, PR5, POX, LOX pathogenesis related and PAL genes in the early stages of citrus blast disease in Citrus aurantium were assessed using RT-PCR. In this study, UBI gene was used as a housekeeping gene. The total RNA of the samples was extracted and after cDNA synthesis, the expression level changes of the declared genes were calculated and measured using the formula 2 - (ΔΔCT).

Increased expression of PR1, PR2, PR3, PR4, PR5, POX, LOX Pathogenesis related and PAL genes in the early stages of citrus blast disease in sour orange mostly occurred at 24 and 48 hours after challenging with the citrus blast causal agent P. viridiflava.

The results of this study was showed that salicylic acid treatment had a greater effect on the expression of PR1, PR2, PAL, POX and PR5 genes than jasmonic acid and jasmonic acid treatment was showed a greater effect on the induction of PR4, PR3 and LOX genes than salicylic acid. Furthermore, the expression of PR1, PR2, LOX, PR4, PAL and PR5 genes peaked in 24 hours after infection in sour orange plant by both treatments and it seems that these mentioned inducer of resistance genes involved in citrus blast disease resistance in host plant