Genetic diversity in Cucurbita pepo landraces revealed by RAPD and SSR markers

Cucurbita pepo landraces are important traditional leafy vegetable crops that are widely eaten in KwaZulu-Natal, South Africa, and elsewhere. The use of molecular markers is beneficial in the genetic study of landraces with different agro-ecological origins. In this study, genetic variation in seven selfed and unselfed C. pepo landraces from three districts in the KwaZulu-Natal Province was investigated using the random amplified polymorphic DNA (RAPD) and simple sequence repeat (SSR) markers. Of the 36 and 55 primers tested, 9 RAPD and 10 SSR primers were selected for their reproducibility and high polymorphism. A total of 100 fragments were detected by RAPD, out of which 94 (94%) fragments were considered polymorphic. SSR markers revealed a total of 56 alleles, where 38 (68%) alleles were polymorphic. The sizes of fragments ranged from 75 to 1800 bp and from 124 to 251 bp in RAPD and SSR markers, respectively. The number of fragments per primer ranged between 9 and 14 and between 1 and 12, in RAPD and SSR, respectively. The genetic differentiation coefficient between populations (GST) ranged between 0.0022 and 0.0100 with RAPD marker and between zero and 0.0076 with SSR marker. Both markers revealed overwhelming averages of gene flow: 97.78 and 132.09 in RAPD and SSR markers, respectively. Both techniques discriminated the landraces very effectively, but only the RAPD marker was able to discriminate landraces according to fruit colour change at maturity as well as their agro-ecological origins. Dendrograms of both markers depicted the close relationship between landraces originating from the Umkhanyakude district (MNS and MS landraces). All genetic parameters indicated that there was plentiful genetic diversity in C. pepo landraces of northern KwaZulu-Natal, South Africa.