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Bottle gourd [Lagenaria siceraria (Molina) Standl.] landraces are widely grown in South Africa, and genetic diversity analysis is necessary to identify promising genotypes for breeding or systematic conservation. Sixty-seven diverse bottle gourd landraces were genotyped using 14 selected simple sequence repeat (SSR) markers. The number of alleles detected per marker ranged from 4 to 11, with a total of 86 putative alleles being amplified. Allele sizes ranged from 145 to 330 base pair (bp). Number of effective alleles (N e ) ranged from 1.58 to 6.14 with a mean of 3.10. Allelic richness varied from 3.00 to 8.90 with a mean of 5.23. Expected heterozygosity (H e ) values ranged from 0.37 to 0.84 with a mean of 0.65. The mean polymorphic information content (PIC) was 0.57. Jaccard’s coefficient of similarity values ranged from 0.00 to 1.00, with a mean of 0.63. Analysis of molecular variance (AMOVA) revealed that 79%, 17%, and 4% of the variation in bottle gourd landraces was attributable to among landraces, within landraces, and between populations, respectively. The study established the existence of considerable genetic diversity among South African bottle gourd landraces. Unique landraces such as BG-4, BG-6, BG-8, BG-9, and BG-15 from cluster I; BG-55, BG-42, BG-57, and BG-58 from cluster II; BG-28, BG-23, BG-29, and BG-34 from cluster III were selected based on their highest dissimilarity index. These could be useful for bottle gourd breeding and systematic conservation.
Genetic diversity analysis is fundamental for effective breeding and genetic conservation. The objective of this study was to determine the genetic diversity present among dessert watermelon (Citrullus lanatus var. lanatus) and citron watermelon (C. lanatus var. citroides) landraces widely grown in South Africa and to select genetically diverse and complimentary genotypes for strategic breeding or conservation. Thirty-one dessert watermelon and 34 citron watermelon landraces were genotyped using 10 polymorphic simple sequence repeat markers. The number of alleles detected per marker ranged from 2 to 23 alleles, with a mean of 13.5 alleles. A total of 135 putative alleles were amplified from sampled watermelon populations. Number of effective alleles ranged from 1.99 to 10.88 alleles with a mean of 5.83 alleles. The mean observed and expected heterozygosity were 0.50 and 0.79, respectively. The mean polymorphic information content was 0.79. Cluster and principal coordinate analyses grouped the two watermelon populations into two separate clusters. The two populations were genetically differentiated with low gene flow, suggesting the presence of high genetic differences between the two populations. Overall, the study established the existence of considerable genetic diversity among South African grown dessert and citron watermelon landraces. Unique dessert watermelon landraces such as SWM-39, SWM-24, SWM-01, SWM-40, SWM-18, SWM-36, and SWM-26; and citron watermelon genotypes including WWM-24, WWM-37, WWM-28, WWM-34, WWM-02, WWM-22, WWM-50, and WWM-36 were selected based on their high dissimilarity index. These could be useful for breeding and systematic conservation.