DNA markers linked to BB resistance genes were based on published
results (Table 3). The RFLP markers were kindly provided
by Steve Tanksley, Cornell University, and the Rice Genome
Project, NIAR/STAFF, Tsukuba, Japan. Primer sequences for
a PCR marker linked to Xa-21 were from Chunwongse et al. (1993).
Additional PCR primers are based on DNA sequences derived by
manual sequencing from both ends of RFLP clones RG556 and
RG136 (Table 4). In the early stage of this study, Southern analysis
with RFLP markers was used for MAS because polymorphic PCR
markers were not yet available. The standard procedure of Southern
analysis was followed (Sambrook et al. 1989).