Epigenetic analysis on somaclonal variants of oil palm (Elaeis guineensis Jacq.): evaluation on protein profiles and histone deacetylation activity
J.S. Yaacob
Malaysia
Abstract:
Mantled fruits in oil palm as a result of somaclonal variation are often observed from the oil palm plantlets regenerated via tissue culture. The mantling of fruits with finger-like and thick outer coating phenotypes reduces the seed size and oil production significantly. This poses a threat to oil palm planters and can further jeopardize the economic growth of countries that depend particularly on oil palm plantation. The molecular aspects of the occurrence of somaclonal variation are yet to be known, but one of the most likely factors is gene repression. There are several factors that can result in gene repression such as DNA methylation, histone methylation and histone deacetylation. Histone deacetylases (HDACs) involve in eukaryotic gene regulation by catalyzing the acetyl groups removal from the lysine residues on histone, hence HDACs transcriptionally repress gene expression. This present study seeks to investigate the effects of histone deacetylation and nuclear protein profiles of the somaclonal variants of oil palm. Because of the different phenotypes, the protein profiles of the mantled samples (leaves, fruits and florets) and the phenotypically normal samples were expected to be different. Also, the histone deacetylation suppresses gene expression, hence it was hypothesized that there should be higher HDAC activity in the mantled leaf samples as compared to that of the phenotypically normal leaf samples. In order to prove their clonal origin, the genomic DNA was extracted from the leaves of the phenotypically different oil palm trees and subjected to SSR analysis. Total protein and nuclear protein extractions were carried out using the 100% mantled, 50% mantled and normal samples (leaves, fruits and florets), and then subjected to SDS-PAGE analysis to separate the protein fragments and hence enabling the visualization of the differences between the mantled and phenotypically normal samples. This was followed by HDAC activity measurement by the means of ELISA method.
