Rice cultivars CO39 and Tadukan were susceptible (score 5)
and resistant (score 0/1), respectively, to the blast isolate B157.
Chi-square analysis of the blast phenotypic segregation data of
100 F2 plants (72 resistant and 28 susceptible individuals)
showed that a major dominant gene was conferring resistance
to blast and was segregating in a Mendelian fashion (3 : 1)
against the isolate (Table 1). The cultivar RIL29 was also
resistant (score 1) to this isolate. The 75 F2 plants derived from
the Tadukan · RIL29 cross showed digenic segregation,
with 71 resistant to four susceptible (Table 1).
Ch