Expression of bacterial blight under different levels of drought stress condition in rice

Abstract

Xanthomonas oryzae pv. oryzae (Xoo), the causal agent of rice bacterial blight is a common reason for severe economic yield losses in rice. Plant response to one type of stress can be affected by simultaneous exposure to a second stress, for example when abiotic and biotic stresses occur together. In this study, two genotypically contrasting genotypes were challenged inoculated under different drought levels (based on field capacity). In compatible interaction, the susceptible genotype TN-1 showed great response to infection and expressed highly under all drought conditions. Symptoms appeared firstly at 6 DPI (day post inoculation) and gradually increased up to 14 DPI. Maximum lesion length was observed at drought level of 60% field capacity (12.02 cm) and minimum (5 cm) was recorded at no drought condition (100% field capacity) on 14 DPI. Same in case of bacterial multiplication rate, maximum CFUs (colony forming units) were recorded at drought level of 60% field capacity and minimum were recorded at no drought condition. In incompatible reaction, BPT5204 genotype showed no symptoms, on the contrary bacteria multipled in the host and observed maximum numbers of colonies at drought level of 60% field capacity. This study has shown the direct responses of the two contrasting genotypes under different drought stress.