Evaluation of the Expression Patterns of Mesocarp-specific Promoter MSP-C6 in Transiently Transformed Oil Palm Tissues

Genetic manipulation of oil synthesis in the mesocarp tissue of oil palm may ensure sustainability of palm oil production and fulfil the high demand for palm oil. The suitability of newly isolated promoters in driving a gene must be tested before they can be used for gene manipulation, hence an easy, rapid and manageable method for large sample size is needed. This study aimed to examine the mesocarp-specific expression of the MSP-C6 promoter in oil palm. The MSP-C6 promoter fragments of varying lengths were tested in regulating the red fluorescent protein (DsRED) gene in oil palm tissues through biolistic- and polyethylene glycol (PEG)-mediated transient transformation. Our results showed that the MSP-C6 promoter fragments were not able to express the DsRED gene in the bombarded mesocarp tissue. However, the DsRED signals were observed in the bombarded polyembryoid tissue driven by the MSP-C6-F1 (2014 bp) promoter. Meanwhile, the DsRED expression was also not observed in all the protoplasts isolated from mesocarp tissue transformed by PEG-mediated method. Based on these results, the transient assays of MSP-C6 promoter fragments in oil palm tissues may need further optimisation. This is important to confirm the mesocarp-specific expression of the MSP-C6 promoter as in previous stable transformation of tomato plants. Confirmation of the tissue specificity of the MSP-C6 promoter is crucial before this promoter can be used for the modification of lipid composition in mesocarp tissue oil palm fruit.