Characterization of disease resistance in nine traditional rice (Oryza sativa L.) cultivars and expression of chennellu PR1 gene in response to Xanthomonas oryzae pv. oryzae

Bacterial blight (BB) is one of the most destructive diseases of rice, resulting in substantial economic losses. There is difficulty in controlling BB, so the molecular characterization of rice pathogenesis related (PR) genes may help in the selection of higher resistance rice plants against Xanthomonas oryzae pv. oryzae (Xoo), BB pathogen. The objective was to analyze the best resistant cultivar with the susceptible rice variety to BB as control and estimate the expression level of PR1 gene in resistant cultivar compared to susceptible variety. PR1 gene studies have been subject to extensive research in view of their possible role in resistance against pathogens. To assess the traditional resistant rice cultivars in response to BB, physiological and biochemical profiling (total chlorophyll, Proline, and total protein) was done in a set of nine traditional rice cultivars from Wayanad, northern Kerala using IR24 (an improved Indian rice variety susceptible to rice blight) as a control. Less lesion length and increased biochemical parameters suggested that Chennellu is the most resistant against Xoo among the others. Expression study of PR1 gene was conducted using qRT-PCR in Chennellu as well as IR24 as control. The results showed that PR1 gene was expressed at the highest level (7859.06 ± 116.5-fold up-regulated) during 48 hpi in Chennellu compared to IR24. Hence the analysis provides fundamental knowledge about the expression of PR1 genes in the interaction between rice and Xoo and can improve the agricultural economy by providing transgenic varieties using traditional cultivar Chennellu. © 2020, Indian Phytopathological Society.