Genome-Wide Association Studies for Sex Determination and Cross-Compatibility in Water Yam (Dioscorea alata L.)

Yam (Dioscorea spp.) species are predominantly dioecious, with male and female flowers borne on separate individuals. Cross-pollination is, therefore, essential for gene flow among and within yam species to achieve breeding objectives. Understanding genetic mechanisms underlying sex determination and cross-compatibility is crucial for planning a successful hybridization program. This study used the genome-wide association study (GWAS) approach for identifying genomic regions linked to sex and cross-compatibility in water yam (Dioscorea alata L.). We identified 54 markers linked to flower sex determination, among which 53 markers were on chromosome 6 and one on chromosome 11. Our result ascertained that D. alata is characterized by the male heterogametic sex determination system (XX/XY). The cross-compatibility indices, average crossability rate (ACR) and percentage high crossability (PHC), were controlled by loci on chromosomes 1, 6 and 17. Of the significant loci, SNPs located on chromosomes 1 and 17 were the most promising for ACR and PHC, respectively, and should be validated for use in D. alata hybridization activities to predict cross-compatibility success. A total of 61 putative gene/protein families with direct or indirect influence on plant reproduction were annotated in chromosomic regions controlling the target traits. This study provides valuable insights into the genetic control of D. alata sexual reproduction. It opens an avenue for developing genomic tools for predicting hybridization success in water yam breeding programs.