MOLECULAR INVESTIGATION OF BACTERIAL BLIGHT OF RICE IN THE FOOTHILLS OF THE WESTERN HIMALAYAS, PAKISTAN

Bacterial blight (BB) is caused by Xanthomonas oryzae pv. oryzae ( Xoo ) is one of the most devastating diseases in rice crops, which adversely affect the annual rice production (quantity and quality) in tropical and sub -tropical regions of the world. The present study was conducted to identify and characterize Xoo strains obtained from infected rice leaves samples collected from foothills of the Himalayas at Mansehra District, Pakistan. A total of 20 samples were collected. The infected leaf samples were plated on nutrient agar and gave light yellow, circular, smooth, convex and viscous bacterial colonies. The collected samples were later on amplified, and their various morphological and genetic traits were accordingly checke d on the Super Basmati and Basmati 385 seedlings. A total of 6 pure isolates were obtained, preserved, and were confirmed as Xoo using Xoo specific primers in PCR which showed 230 bp bands. Pathogenicity of Xoo isolates was confirm by Koch's postulates on rice varieties super basmati and basmati 385. The amplification of 16S rRNA gene of these isolates was carried out using a pair of universal primers. Besides, the disease incidence (%) was also taken under consideration, in which super Basmati variety was found significant, Xoo -1 (65%), followed by Xoo -6 (48.10%) and Xoo -2 (53.30%) as compared to Basmati-385. The present study provides a base for rice breeders to initiate regional resistance breeding programs.