Population structure, gene flow and genetic diversity analyses based on agro-morphological traits and microsatellite markers within cultivated and wild germplasms of okra [Abelmoschus esculentus (L.) Moench.]

Okra [Abelmoschus esculentus (L.) Monech.] is an annual herb of the family Malvaceae and has tremendous nutritional and industrial potential. However, the unknown genome size, variation in ploidy level makes it more challenging for okra breeders to enhance their genetic potential. In this context, the genetic analysis of allelic polymorphism and population structure analysis of okra germplasm is pivotal for its genetic improvement. In the present investigation, a total of 96 okra genotypes were undertaken for morpho-genetic diversity analyses using 13 morphological parameters and 65 SSR markers. Out of 65 SSRs, 50 primers were polymorphic and the mean polymorphic information content (PIC) value was 0.38. The polymorphic loci AVRDC OKRA 64 revealed a maximum PIC value of 0.71 and the number of alleles per locus varied from 2 to 7, with an average of 3.34 alleles per locus. The neighbour-joining (N-J) tree grouped the genotypes into three distinct clusters (I-III), of which Cluster I comprised of cultivated species, A. esculentus and A. caillei, while, Cluster II and III consisted of other related wild species. Furthermore, the population structure analysis distinguished the okra genotypes into two distinct genetic groups comprising cultivated (A. esculentus) and wild-type okra. The variability analysis based on 13 agro-morphological traits revealed that the genotype DOV-92 exhibited the highest per se performance for total fruit yield, followed by Pusa Bhindi-5. The PCA (Principal Component Analysis) analysis revealed that the first three components account for more than 50% of the total genetic variation. The present investigation deciphered a high morphological and genetic diversity in cultivated and wild okra germplasm. Thus, it could serve as important genetic resources for okra improvement programmes.