Targeted spatio-temporal expression based characterization of state of infection and time-point of maximum defense in wheat NILs during leaf rust infection.

Leaf rust, caused by the fungus Puccinia triticina, is the most devastating disease of wheat worldwide, which sometimes becomes epidemic. The pathogen evolves into new strains, making its control difficult. Though more than 60 leaf rust resistant genes are now known, only limited insight is available into the molecular mechanism involved in this host pathogen interaction. In the present study, quantitative real-time PCR based differential gene expression profiling was examined for five target genes encoding for chitinase3, β-1,3/1,4 glucanase, thaumatin-like protein, peroxidase2 and mitogen activated protein kinase1 to unravel their coordinated action during compatible and incompatible interaction, to inhibit the pathogen progression and to identify the time-period of maximum defense activity. Spatio-temporal expression profiling suggested that the maximum defense activity occurred at 12-24 hours post inoculation, whereas the state of infection and degree of resistance was predicted using coordinated unique expression signatures of target genes. The significant differences of targeted gene expression between resistant mock inoculated, resistant infected and susceptible infected plants were evaluated using t test at significance level of p < 0.01. The differences occurred can be attributed to the presence of seedling leaf rust resistance Lr28 gene, which facilitated prevention of leaf rust infection in resistant wheat plants.