Genetic Analysis of Blast Resistance in Rice with Simple Sequence Repeats (SSR)

Abstract

Gene-linked markers are powerful tools to detect the presence of gene(s) for rice (Oryza sativa) blast resistance; they are useful in conducting marker-assisted selection. Eight genotypes of rice were used for genetic analysis with 85 gene-linked SSR markers for rice blast resistance and defensive response genes to study the parental polymorphism between resistant and susceptible genotypes. PCR-amplification results revealed that 39 primers out of 85 exhibited distinct polymorphism among the eight genotypes. The number of alleles varied from 2 to 4, with a mean of 2.26. The genetic associations among eight genotypes were examined via unweighted pair group method with arithmetic mean (UPGMA) analysis. Cluster analysis revealed that two blast-resistant genotypes (WGL167 and NBR 16) and susceptible genotype (BPT 5204) were grouped into cluster I, showing polymorphic loci for RM 138 (pib) and RM 3330 (pi40) gene-linked markers. Three other blast-resistant genotypes (NBR 11, MTU 1003, and NLR 34449) and a susceptible genotype (MTU 2077) were grouped into cluster II, exhibiting polymorphic loci for RM 144 (piK-S) gene-linked marker. Cluster III had only one susceptible genotype, MTU 3626. The susceptible and resistant genotypes exhibited polymorphic alleles for RM 6468 and RM 260 (oxalate oxidase), RM 542 (thaumatin), and RM 5426 (DHAP) candidate gene co-localized markers. Efficiency of detecting blast-resistance gene depended on genotypes and gene-linked markers. These results indicated scope for utilization of blast-resistant genotypes with detected gene-linked markers in marker-assisted selection.