Tanzania Journal of Agricultural Sciences 2000, Vol. 3(1) : 39-46
Ten rice cultivars from the International Rice Germplasm Centre originating from Bangladesh were
analysedfor the~r genetics of resistance to bacterial blight. The test cultivars were selected on the basis
of their high level ofresistance to races IV & VI ofXanthomonas oryzae pv. oryzae. The mode ofinheritance
was studied by crossing the test cultivars with Taichung Native 1 (TNI) which is highly susceptible
to the races 1,2,3;4 & 6 of X. Oryzae pv. oryzae. The genetic analysis revealed that the test cultivars
have two recessive genes conferring resistance to races 1 (PX 061) and 6 (PX 079) of X. oryzae pv
oryzae, respectively. The allelic relationship of genes conferring resistance with xa-S and xa-13 was
studied in progenies derived from crosses between the cultivars and IRBBS and IRBB13 which are near
isogenic lines carrying genes xa-S and xa-13 respectively. The Chi-square analysis of F2 populations revealed
that resistance ilJ these cultivars to race 1 was conferred by xa-S. Resistance to race 6 was found
to be conferred by another gene which was non-allelic to xa-13.