Pheno-Genotypic Screening of Medium Slender Rice Genotypes for Bacterial Leaf Blight (BLB) Disease Resistance

Abstract

The bacterial leaf blight of rice caused by Xanthomonas oryzae pv. oryzae (Xoo) is an economically important and one of the most destructive disease of rice in both irrigated and rainfed environments in Asia. In particular, in recent years, the occurrence of abnormal climate and warming phenomena has produced a good environment for bacterial leaf blight. The rice yield continues to decrease, causing 30 to 50% yield loss. Since bacterial pathogen is difficult to manage by other means effectively, developing host plant resistance is the most effective way to control this disease. So, the study was carried out during rain-fed season (July–November 2019) at Agricultural Research Station (ARS) Gangavati, Karnataka, India to identify the bacterial leaf blight resistance reaction among 22 medium slender genotypes of rice by both phenotyping and genotyping by using molecular markers linked with resistance governing bacterial leaf blight genes. Alongside TN-1 was used as susceptible check and screening was done by artificial clip inoculation method. The disease reactions were recorded one week after inoculation, with Standard Evaluation Scale (SES) for BLB ranging from 0–9, when the susceptible check (TN-1) was completely killed. None of the genotypes showed a resistant reaction, but three genotypes viz. IET-27904, IET-25520 and Rp Bio-226 showed resistant reaction against BLB. The six major BLB resistant genes genetic frequencies varied from 42.85% to 14.28% in the molecular evaluation of promising genotypes for major BLB resistant genes using three Simple Sequence Repeats (SSR) and Sequence Tagged Sites (STS) markers respectively.