Monitoring Drought Tolerance in Oil Palm: Choline Monooxygenase as a Novel Molecular Marker

Water scarcity negatively impacts oil palm production, necessitating the development of drought-tolerant varieties. This study aimed to develop molecular markers for oil palm breeding programs focused on drought tolerance. Genes associated with drought tolerance were selected, and single nucleotide polymorphism (SNP)-based markers were developed. Genomic DNA was successfully extracted from 17 oil palm varieties, and 20 primers out of 44 were effectively amplified. Screening with single-strand conformation polymorphism (SSCP) revealed an informative SNP marker from the choline monooxygenase (CMO) gene, exhibiting CC, CT, and TT genotypes. Notably, the oil palm variety La Mé showed the CT genotype, while Surat Thani 2 (Deli × La Mé) exhibited the CT and CC genotypes in a 1:1 ratio. Gene expression analysis confirmed the association of the CMO gene with drought tolerance in commercial oil palm varieties. The full-length CMO gene was 1308 bp long and shared sequence similarities with other plant species. However, amino acid sequence variations were observed compared with existing databases. These findings highlight the potential utility of the CMO marker for drought tolerance selection, specifically within the La Mé parent of oil palm Surat Thani 2 varieties, and strongly confirm the La Mé S5 population and Surat Thani 2 as drought-tolerant varieties.