Elucidating genetic diversity and population structure in jamun [Syzygium cumini (L.) Skeels] using morpho-physiological traits and CAAT box-derived polymorphism

Abstract

• Assessment of morpho-physiological and molecular diversity in Syzygium cumini . • Population structure analysis using CBDP markers. • CBDP markers were highly informative in detecting the polymorphism. • Evidence for high levels of gene flow and less genetic differentiation. The use of molecular markers has received little attention in jamun [ Syzygium cumini (L.) Skeels], an underutilized fruit crop highly valued for its medicinal and nutraceutical properties. In this study, 50 jamun accessions from four different populations were analyzed using 21 morpho-physiological traits and 22 polymorphic gene-targeted CAAT box-derived polymorphism (CBDP) markers. The morpho-physiological variability was fairly high among the jamun accessions. The UPGMA analysis based on morpho-physiological traits produced three clusters with a cophenetic correlation of 0.75, reflecting a good fit between the original matrix and the clustering algorithm. The average polymorphism of 91.17% and the wide-ranging heterozygosity values (0.282-0.499) for the CBDP markers revealed considerable genetic variation among jamun genotypes. The average PIC of 0.352 evinced a high discriminatory power of the CBDP markers in distinguishing the accessions. CDBP data-based UPGMA clustering and population structure analysis identified four distinct populations; albeit with overlaps among them. This, together with the existence of admixed types in all four populations, indicated a fairly high degree of gene flow within jamun populations sampled in this study. It is therefore likely that despite widely differing geographic origins, some accessions in all the populations have a shared ancestral origin. Analysis of Molecular Variance also supports this assumption, as an exceedingly higher within-population variance (84%) than among-population variance (16%) reflected a high degree of gene flow and low genetic differentiation for the Jamun populations examined. Our findings improve the existing understanding vis-à-vis genetic diversity and population structure in jamun, and are expected to increase the use of CBDP and similar marker techniques in cultivar development programs.