*4.6. Detection of Haplotypes of Pi21*

Genomic DNAs of the rice accessions (Supplementary Table S2) were subjected to genotyping for haplotypes of *Pi21*. PCR products were amplified with primers P21-F (5- -CAAGGCTAATCAG CAGTGT-3- ) and P21-R (5- -TTGGCGTTGTCCTCGGTGT-3- ). DNA sequences of PCR products were aligned using Clustal W [46].
