Trait specific marker-based characterization and population structure analysis in rice (Oryza sativa L.) germplasm of...

Rice is a key food grain contributor to the global food grain basket and is considered the main food crop in India with a large number of varieties released every year. SSR markers have proven to be an excellent tool for studying genetic diversity. As a result, the present study was done to characterize and assess genetic diversity as well as population structural aspects.

Fifty genotypes of rice were characterized using 40 SSR markers to assess the genetic diversity and genetic relationship. A total of 114 alleles were amplified with an average of 2.85 alleles per locus. The Polymorphism Information Content (PIC) values varied from 0.30 (RM162) to 0.58 (RM413) with an average of 0.44. Gene diversity was in the range of 0.35 (RM162) to 0.66 (RM413), with an average value of 0.52, while heterozygosity ranged from 0.18 (RM27) to 0.74 (RM55), with an average of 0.39. The population structure revealed a narrow genetic base with only three major subpopulations. Analysis of molecular variance revealed that 74% of the variation was attributed within individuals, 23% was among individuals, and 3% was among populations. Pairwise Fst value of population A & B is 0.024, population B & C is 0.120 and population A & C is 0.115. Dendrogram grouped the genotypes into three clusters with wide variation among the accessions.

Genotyping combined with phylogeny and population structure analysis proved to be a powerful method for characterizing germplasm in this study. There is significant gene flow within populations, as well as the presence of different combinations of alleles, and that allelic exchange rates within the populations are higher than among the populations. Assessing the genetic diversity among individual genotypes within populations is quite useful in selecting candidate parents for future breeding programs to improve the target traits in rice for the Himalayan region.