Assessment of the genetic diversity and population structure of apricot (Prunus armeniaca L.) germplasm of the Northwestern Himalaya using SSR markers

Apricot is considered an ecologically and economically important tree species of the stone-fruit crops that is widely grown in temperate regions of the world. Very few studies on apricot genetic diversity assessment have been carried out from the regions of Kashmir and Ladakh. In this backdrop, the present study was carried out to analyse the genetic diversity and population structure of 120 apricot genotypes collected from both the regions using 21 SSR markers. A total of 52 alleles were amplified with average values of marker index (MI) = 0.7084, resolving power (RP) = 2.8690, polymorphism information content (PIC) = 0.3132, Na = 2.317, Ne = 1.720, I = 0.572, Ho = 0.284, He = 0.360 and an average polymorphism of 91.2% per assay indicating high level of genetic diversity. The neighbour-joining (NJ) dendrogram generated three main clusters among selected apricot genotypes independent of their geographical locations. Interestingly, the result of the dendrogram coincides with the results of structure analysis which showed that the 120 apricot genotypes could be assigned to three (K = 3) sub-populations and the grouping of genotypes did not follow their geographical location suggesting that they share the same genetic pool. Moreover, analysis of molecular variance showed that 73% of the variation was attributed to differences within the individuals, 25% among individuals while only 2% of the variation was observed among the populations. The present study represents the most comprehensive analysis of the genetic diversity and population structure of apricot genotypes in Kashmir and Ladakh regions of India.