Abstract
BackgroundThe genetic base of soybean cultivars in India has been reported to be extremely narrow, due to repeated use of few selected and elite genotypes as parents in the breeding programmes. This ultimately led to the reduction of genetic variability among existing soybean cultivars and stagnation in crop yield. Thus in order to enhance production and productivity of soybean, broadening of genetic base and exploring untapped valuable genetic diversity has become quite indispensable. This could be successfully accomplished through molecular characterization of soybean genotypes using various DNA based markers. Hence, an attempt was made to study the molecular divergence and relatedness among 29 genotypes of soybean using SSR markers.Methods and resultsA total of 35 SSR primers were deployed to study the genetic divergence among 29 genotypes of soybean. Among them, 14 primer pairs were found to be polymorphic producing a total of 34 polymorphic alleles; and the allele number for each locus ranged from two to four with an average of 2.43 alleles per primer pair. Polymorphic information content (PIC) values of SSRs ranged from 0.064 to 0.689 with an average of 0.331. The dendrogram constructed based on dissimilarity indices clustered the 29 genotypes into two major groups and four sub-groups. Similarly, principal coordinate analysis grouped the genotypes into four major groups that exactly corresponded to the clustering of genotypes among four sub-groups of dendrogram. Besides, the study has reported eight unique and two rare alleles that could be potentially utilized for genetic purity analysis and cultivar identification in soybean.ConclusionIn the present investigation, two major clusters were reported and grouping of large number of genotypes in each cluster indicated high degree of genetic resemblance and narrow genetic base among the genotypes used in the study. With respect to the primers used in the study, the values of PIC and other related parameters revealed that the selected SSR markers are moderately informative and could be potentially utilized for diversity analysis of soybean. The clustering pattern of dendrogram constructed based on SSR loci profile displayed good agreement with the cultivar’s pedigree information. High level of genetic similarity observed among the genotypes from the present study necessitates the inclusion of wild relatives, land races and traditional cultivars in future soybean breeding programmes to widen the crop gene pool. Thus, hybridization among diverse gene pool could result in more heterotic combinations ultimately enhancing genetic gain, crop yield and resistance to various stress factors.
Highlights
Soybean (Glycine max (L.) Merr.) is one of the world’s most important economic legume crops and second most important oilseed crop of India
In India, even though there is momentous increase in the area and production of soybean during last three decades through the adoption of new varieties, the crop yield potential remained static and becoming major concern among researchers [4, 5]. This could be attributed to the narrow genetic base of soybean cultivars that is either inherited from the crop genetic architecture or due to the extensive use of selected genotypes as parental lines in the breeding programmes [6]
A total of 48 alleles were detected from these 14 primer pairs of which, 34 alleles were polymorphic with an average of 2.43 alleles per primer pair
Summary
Soybean (Glycine max (L.) Merr.) is one of the world’s most important economic legume crops and second most important oilseed crop of India. In India, even though there is momentous increase in the area and production of soybean during last three decades through the adoption of new varieties, the crop yield potential remained static and becoming major concern among researchers [4, 5] This could be attributed to the narrow genetic base of soybean cultivars that is either inherited from the crop genetic architecture (self-pollination) or due to the extensive use of selected genotypes as parental lines in the breeding programmes [6]. The genetic base of soybean cultivars in India has been reported to be extremely narrow, due to repeated use of few selected and elite genotypes as parents in the breeding programmes This led to the reduction of genetic variability among existing soybean cultivars and stagnation in crop yield. Hybridization among diverse gene pool could result in more heterotic combinations enhancing genetic gain, crop yield and resistance to various stress factors
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