SSR Marker Based Genetic Diversity Analysis and SNP Haplotyping of Genes Associating Abiotic and Biotic Stress Tolerance, Rice Growth and Development and Yield Across 93 Rice Landraces

Abstract I. Background: As rice is the staple food for more than half of the world population, enhancing grain yield irrespective of the variable climatic conditions is indispensable. Many of the traditionally cultivated rice landraces are well adapted to severe environmental conditions and have high genetic diversity that could play an important role in crop improvement.II. Methods and Results: The present study disclosed high level of genetic diversity among the unexploited rice landraces cultivated by farmers of Kerala. Twelve polymorphic markers detected a total of seventy- seven alleles with an average of 6.416 alleles per locus. PIC value ranged from 0.459 to 0.809 and to differentiate the rice genotypes, RM 242 was found to be the most appropriate marker with the highest value of 0.809. The current study indicated that the rice landraces were highly diverse with higher values of the effective number of alleles, PIC, and Shannon information index and utilizing these informative SSR markers for future molecular characterization and population genetic studies in rice landraces are advisable. Haplotypes are sets of genomic regions within a chromosome that are inherited together and haplotype-based breeding is a promising strategy for designing next-generation rice varieties. Here, haplotype analysis explored 270 haplotype blocks and 775 haplotypes from all the chromosomes of landraces under study. The number of SNPs in each haplotype block ranged from two to 28. Haplotypes of genes related to biotic and abiotic stress tolerance, yield-enhancing, and growth and development in rice landraces were also elucidated in the current study.III. Conclusions: The present investigation revealed genetic diversity of rice landraces and the haplotype analysis will open the way for genome wide association studies, QTL identification, and marker assisted selection in the unexplored rice landraces collected from Kerala.