Screening of wild oil palm (Elaeis guineensis) germplasm for lipase activity

Abstract

Palm oil comprises mainly triacylglycerols (TAG) that account for about 0.95 of its composition. Lipolysis of TAG releases free fatty acids that are then oxidized, impairing oil quality. Lower endogenous lipase activity is therefore desirable for better quality oil. Identifying genotypes for this should allow production of oils with improved shelf-life. A novel non-radioactive cold-activation titration assay was used to assay for lipase activity in 49 randomly selected Elaeis guineensis palms using the novel method as well as the traditional radioactive method. The results confirmed significant correlation between the radioactive and novel non-radioactive methods. A total of 148 E. guineensis palms originating from Angola, Cameroon, Guinea Conarky, Nigeria, Senagal, Sierra Leone, Tanzania and Zaire were then screened for lipase activity using the novel non-radioactive method. The analysis revealed genotypes with significantly different lipase activities, indicating that the activity is genotype-dependent. Quantitative polymerase chain reaction indicated similarity in pattern between gene expression and lipase activity determined by the novel assay. Several low and high lipase genotypes were identified. The findings pave the way for selection and breeding for low lipase genotypes. They are also relevant to genetic marker development for oil quality. Evidence is presented for the presence of at least two different lipases that determine oil quality in the oil palm mesocarp.