Genetic relatedness analysis in sapota using SSR markers

Genetic relatedness analysis is the first step toward efficient conservation, maintenance, and improvement of the existing genetic diversity. Recently, DNA-based markers have been widely used due to their reliability and technical advantages. In the present study, twenty Simple Sequence Repeats (SSR) primers were used to evaluate genetic relatedness among ten sapota genotypes. The SSR analysis produced a total of 59 alleles with a range of 88 to 239bp. The maximum numbers of alleles (4) were recorded in SapSSR-15, SapSSR-5, SapSSR-21, SapSSR-39, and SapSSR-59. The Highest Nei genetic diversity was recorded in SapSSR-37 (0.500), whereas the lowest was in SapSSR-23 (0.320). The highest Shannon's information index (I) was observed for SapSSR-37 (0.693), while SapSSR-23 showed the lowest I value (0.499). The PIC value was in the range of 0.71–0.89 among the different primers, where the highest was observed for SapSSR-54. Based on marker analysis, SapSSR-4, SapSSR-21, SapSSR-36, and SapSSR-54 were found to be most effective for the genetic diversity analysis of sapota. The wide range of Jaccard's similarity coefficients (0.29–0.86) reported a moderate to high level of diversity among the studied sapota genotypes. Further, the dendrogram analysis showed clustering of genotypes based on geographical origin. The PCA analysis reported the evenly distribution of all genotypes across the four coordinates. The variety-specific alleles reported in this work can be exploitable for molecular fingerprinting purposes. The genetic relatedness revealed in this study can be useful for both varietal identification and sapota improvement programs.