Evaluation of rice germplasm for multiple disease resistance under artificial inoculation conditions

Abstract

One thousand and eighteen rice germplasm lines were evaluated against the prevalent pathotypes viz., PbXo-7 and PbXo-10 of Xanthomonas oryzae pv. oryzae causing bacterial blight, brown spot and sheath blight diseases under artificial inoculation conditions. Virulence/ avirulence of the two pathotypes to Xa/xa genes indicated that all the pathotypes were virulent on the most of bacterial blight resistant single Xa/xa gene (s). Pathotype PbXo-7 was virulent to known Xa genes namely Xa 1, Xa 3, Xa 4, xa 5, Xa 7, xa 8, Xa 10 and Xa 11 and cultivars PR 114, PR 116 and PR 118 growing in Northern regions of India. PbXo-10 was virulent on all these genes including newly identified gene Xa38. None of the single gene is effective against the pathotypes prevalent in Punjab. Two years data revealed that 46 lines (5.4%) showed resistant reaction to pathotype PbXo-7 and 30 lines (2.9%) showed resistance to newly emerged pathotype PbXo-10. Twenty two lines showed resistant reaction to both the pathotypes. Most of the entries which were resistant to PbXo-10 also showed resistant to the PbXo-7. Germplasm line IC No.346207 showed resistant reaction and IC Nos. 114315 and 320826 showed moderately resistant reaction to brown spot. None of the germplasm line showed resistance to sheath blight. These resistant entries can either be released as new varieties or further utilized as donors in multiple disease resistance breeding programmes.