Evaluation of resistance of rice genotypes (derived from the cross between HKR-127 and IRBB-60) against bacterial blight caused by Xanthomonas oryzae pv. oryzae

Abstract

Rice crop is susceptible to various bacterial diseases and one such commonly known disease is Bacterial Blight (BB) caused by the pathogenic bacteria Xanthomonas oryzae pv. oryzae (Xoo). Rice variety HKR-127 is widely accepted by rice farmers, users and buyers in Haryana (India) owing to its high agricultural produce, medium lanky grains, and outstanding cooking characteristics, however, HKR-127 exhibits less endurance to BB. The aim of the study conducted at CCS Haryana Agricultural University was to investigate the genetic potential of BC3F2 and BC3F3 pyramided rice genotypes (cross HKR-127 x IRBB -60) having resistance genes (Xa21, xa13, and xa5). These genotypes were tested for virulence against BB under artificial conditions using Clip method of artificial inoculation. On average, five leaves per plant were inoculated and visually scored after 14 days. Disease reaction rating was done on a 0-9 scale of the standard evaluation system (SES) for rice. Rice genotypes with all the three genes exhibited relatively low mean lesion length compared to single or double combinations thus establishing higher resistance of threegene genotypes to BB. The lines obtained in our study can be used as genetic resources for BB resistance in breeding programs that will be paving the way for an environmentally-friendly means to achieve a better disease management. Moreover, the success will facilitate future efforts to transfer combinations of BB resistance genes into other preferred rice cultivars.