Molecular characterization of parental lines of post-rainy sorghum using simple sequence repeat markers

Heterosis is related to genetic diversity among the parental lines, which is considered to be important for the development of superior hybrids. The objective of this study was to characterize 145 genotypes of post-rainy sorghum comprising of 40 maintainer and 105 restorer lines using 46 simple sequence repeat (SSR) markers, and assess the extent of genetic diversity among them. Among the 244 polymorphic alleles, 164 (67.21%) were common to both maintainer and restorer lines while 24 (9.84%) and 56 (22.95%) were unique to maintainer and restorer lines, respectively. Average relative gene diversity was 0.35 within maintainer lines, 0.32 within restorer lines, and 0.33 between these two groups. The cluster analysis following the UPGMA algorithm grouped the genotypes into four major clusters with an average similarity of 53%. Intermingling of maintainer and restorer groups was observed and more than 50% of the maintainer lines were grouped closer to restorer lines. The lines AKRB302, AKRB306, AKRB307, AKRB311, AKRB318, AKRB324, AKRB354, AKRB388, AKRB413 and SLR43 were distinct among the restorers with minimum similarity. These restorer lines along with the set of male sterile lines corresponding to the maintainer lines identified in this study could be employed in hybrid development. Even though diverse restorers were identified for exploitation in hybrid development, the study clearly exposes the narrow genetic base of the parental lines of post-rainy sorghum, underlining the need to use parental lines from a broader gene pool for the development of heterotic hybrids suited for the post - rainy situation

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Not AvailableKnowledge on genetic diversity is necessary to determine the relationships among the genotypes, which allow the selection of individual accessions for crop breeding programmes. The present study aimed at assessing the extent and pattern of genetic diversity within a set of 251 sorghum genotypes using SSR markers. A total of 393 alleles were detected from the 251 genotypes, with the number of alleles ranging from 2 (Xcup11) to 24 (Sb5-206) and an average of 10.07 alleles per primer pair. Pairwise Wright’s FST statistic and Nei’s genetic distance estimates revealed that the race and geographical origin were responsible for the pattern of diversity and structure in the genetic materials. In addition, the analysis also revealed high genetic differentiation between the rainy and post-rainy sorghum groups. Narrow diversity was observed among the different working groups in the rainy (restorers and varieties) and post-rainy (varieties and advanced breeding lines) sorghum groups. Neighbour-joining and STRUCTURE analysis also classified 44 elite lines broadly into two distinct groups (rainy and post-rainy). However, limited diversity within the rainy and post-rainy sorghum groups warranted an urgent need for the utilization of diverse germplasm accessions for broadening the genetic base of the Indian breeding programme. The diverse germplasm accessions identified from the mini-core accessions for utilization in breeding programmes are discussed.Partial financial assistance by NAIP project on ‘Bioprospecting of genes and allele mining for abiotic stress toleranc