Evaluation of Pathogenic Potential of Xanthomonas Oryzae Isolated from Kamphaeng Phet Province

Abstract

Phitsanulok 2 (PSL2) is a popular rice cultivar for cultivation in the lower northern region of Thailand. This cultivar is high-yielding rice but still susceptible to bacterial blight (BB) disease caused by bacteria Xanthomonas oryzae pv. oryzae (Xoo), results in huge losses in grain yield. The aims of this study were to isolate the bacteria Xoo obtained from infected rice foliar samples and evaluate the pathogenic potential of isolated Xoo in resistant and susceptible to bacterial blight disease rice varieties in a greenhouse condition. In this study, two Xoo isolates (KP1 and KP2) were isolated from Kamphaeng Phet Province. The hybrid cultivar carrying Xa21 gene (PSL2-BC₅F₃ + Xa21) showed moderate resistance to the BB disease (5.54 cm) compared to PSL2 (30.54 cm) and IRBB21 (4.26 cm) which are susceptible and resistant rice varieties, respectively. Among these two Xoo isolates, KP2 showed more virulent in the severity reaction than KP1 Xoo isolate in resistant rice varieties. Theses implied that there was variation among the bacteria Xoo in Kamphaeng Phet Province.