Journal of Oil Palm Research (Special Issue), p. 1-17 SITI NOR AKMAR, A*; CHEAH, S C*; AMINAH, S*; LESLIE, C L O*; SAMBANTHAMURTHI, R*; MURPHY, D J**
Two different stearoyl-ACP desaturase genes are expressed in the mesocarp of oil palm (E. guineensis) fruits. Their nucleotide sequences share 93% and 76% homologies within the coding and 3’untranslated regions, respectively. Southern blot analysis showed that there are at least two copies of stearoyl-ACP desaturase genes in the oil palm genome. Northern blot analysis using gene specific probes showed that the two genes from the mesocarp are differentially regulated. One gene is constitutively expressed with a high level of expression in various oil palm tissues. The other gene was found to be developmentally regulated with its expression pattern correlating with the pattern of oil synthesis in both the mesocarp and kernel tissues. Polyclonal anti-bodies were raised against a peptide containing the N-terminal sequence of the mature oil palm stearoyl-ACP desaturase. The antibodies recognized the predicted size protein of 37kDa in total protein fractions of oil palm mesocarp after separation on denaturing polyacrylamide gels. Western blot analysis using the polyclonal antibodies showed the enzyme level is high in the mesocarp at late stage of ripening and remains high in ripe fruits. The leaf form of the enzyme appeared to be about 2kDa larger. High levels of enzyme and gene expression were detected in young mesocarp tissue consistent with the requirement for high levels of unsaturated fatty acids for membrane lipid biosynthesis.KEYWORDS:
* Palm Oil Research Institute of Malaysia,
P.O. Box 10620, 50720 Kuala Lumpur, Malaysia.
** Department of Brassica and Oilseeds Research,
John Innes Centre,
Norwich Research Par, Norwich NR4 7UH, UK.