PHENOTYPIC AND MOLECULAR ASSESSMENT OF BLB RESISTANT ADVANCED RICE LINES AND THEIR YIELD PERFORMANCE

Abstract

Four of Xanthomonas oryzae pv. oryzae isolates viz. Iso1 to Iso4 were isolated from different diseased samples collected from BRRI during T. Aman 2019 season. Isolates phenotypic characters e.g, colony color, shape, growth patterns were examined and found similar. Typical slimy and cream colored bacterial growth was observed in peptone sucrose agar medium for all four isolates. Molecular markers were used to confirm the Xanthomonas oryzae pv. oryzae isolates and two isolates namely Iso1 and Iso4 were confirmed as Xoo. Five BLB resistant advanced breeding lines, P-3-58, P-5-1, P-7-70, P-7-82 and P-8-78 were tested against Xoo with susceptible check variety Purbachi and all five advanced lines showed resistance reaction. These five advanced lines were molecularly screened for four BLB resistance genes Xa4, xa5, xa13 and Xa21using four molecular markers MP, xa5 Multiplex, xa13-prom and pTA248. Among the advanced lines, P-5-1, P-7-70, P-7-82 and P-8-78 possessed Xa4 gene and P-358, P-5-1,

P-7-70 and P-8-78 possessed xa5 gene. A field experiment was set with five advanced lines along with one susceptible check (Purbachi) and two standard checks (BRRI dhan39 and BRRI dhan49) to find out the BLB resistant advanced line. All the selected lines showed good performance in terms of BLB resistance and yield. The highest yield (3.32 t ha ix

-1 ) was recorded in P-7-70. Considering all other agronomic traits and resistance reaction, P-7-70 line can be used in further BLB resistance variety development programs.