Whole Genome Sequencing of the Moruga Hill Rice (Oryza glaberrima) Reveals Its African Ancestry and the Presence of Candidate Stress-Tolerance Genes

Abstract

Moruga Hill Rice (MHR) is an African rice (Oryza glaberrima Steud.) brought to Trinidad by formerly enslaved African Americans and has been grown for many generations in Trinidad at subsistence and commercial scale. Despite its historical and agricultural significance, genomic resources specific to MHR remain unexplored, and its genetic composition, evolutionary history, and potential agronomic traits have not been characterized. This current study presents the first draft genome assembly of the MHR genome using a hybrid sequencing approach. The MHR genome size was found to be ~372.9 Mb with 56,073 predicted genes. Variant analysis revealed a total of 3,318,242 variants, of which 2,440,476 were SNPs, and 877,766 were InDels. Several candidate genes encoding proteins with orthology to previously characterized biotic resistance and abiotic stress-responsive genes in rice were identified. Potential gene families identified prompt further investigation of their roles in MHR drought and salt stress responses. Phylogenomic analysis of O. glaberrima landraces suggests that MHR shares close genetic affinity with the IRGC−104595 Malian landrace, consistent with historical records. This assembly thus expands the African rice genomic repository, providing a foundation to understand the genetic architecture underlying key phenotypic traits and identifying potential novel gene sources in MHR for rice improvement in the Caribbean region.