Genotype-specific expression of selected candidate genes conferring resistance to leaf rust of rye (Secale cereale L.)

Abstract

Abstract Leaf rust (LR) caused by Puccinia recondita f. sp. secalis (Prs) is a highly destructive disease in rye. However, the genetic mechanisms underlying the rye immune response to this disease, especially the expression of genes conferring Prs resistance, remain relatively uncharacterised. In this study, we analysed the expression of the following four genes in 15 unrelated rye inbred lines inoculated with a Prs isolate (No. 1.1.6) at 20 and 36 h post-treatment (hpt): DXS (1-deoxy-D-xylulose 5-phosphate synthase), Glu (beta-1,3-glucanase), GT (UDP-glycosyltransferase), and PR-1 (pathogenesis-related protein 1). The RT-qPCR analysis revealed the up-regulated expression of the four genes in response to Prs in all inbred lines and at both time-points. The gene expression data were supported by the microscopic examination, which revealed that seven lines were highly susceptible to LR, three lines exhibited an intermediate response, and five lines were highly resistant to LR. A clear relationship between the infection profiles and the expression of the analysed genes was observed: in the resistant lines, the expression level fold-changes were usually higher at 20 hpt than at 36 hpt, while the opposite trend was observed in the susceptible lines. The study results indicate that DXS, Glu, GT, and PR-1may encode proteins crucial for the rye defence response to the LR pathogen.