Expression Patterns of PR3, PR1-1a and LOX 1 genes in Leaves
The PR3 was upregulated in P. melonis -infected leaves of all genotypes in the first 48 hpi followed by a decrease at 72 hpi, while the overall expression remained lower in the high susceptible genotypes (Mini 6-23 and Extrem) when compared to resistant Ramezz and moderately resistant (Ramezz and Baby). The expression level ofPR3 in the leaves of Ramezz increased as much as 8.01 fold at 48 hpi compared with the control, while in Baby increased 9.72 fold which decreased in both Ramezz and Baby at 72 hpi (Fig2.e). The transcript levels of PR1-1a were increased in leaves of cucumber plants at 24 hpi and thereafter (Fig2. d). The expression levels of PR1-1ain leaves of Ramezz at 24, 48 and 72 hpi up-regulated 2.37, 2.18 and 3.32 fold, respectively, in Baby by 3.34, 2.73 and 5.39 fold, respectively, compared to the control. Interestingly, the PR1-1agene expression was significantly higher in Baby than Ramezz at all the time points. The transcript levels of LOX1 gene increased (24,48 and 72 hpi) in leaves of the resistant and moderately resistance genotypes, higher in Ramezz than Baby (Fig2.c). Although the relative expression of LOX1 in Mini 6-23 and Extrem was significant at 48 and 72 hpi, but the expression level was lower than Ramezz and Baby. TheLOX1 expression in Ramezz and Baby was up-regulated about 11.81 and 8.36 fold in the leaves, respectively, compared to the control (Fig2.c). The higher level of transcript for LOX , PR1-1aand PR3 in Ramezz and Baby suggests that they are likely responsible for a large part of resistance in cucumber.