Molecular analysis on the shoot apical meristem of truncated leaf syndrome plantlets of oil palm (E. guineensis Jacq.)

Abstract

Truncated leaf syndrome (TLS) is a vegetative somaclonal variant of oil palm that is regenerated from cultured somatic cells. Until now, there are no molecular clues associated to this abnormality. Forward and reverse suppressive subtractive hybridization (SSH) libraries were constructed to isolate the differentially expressed genes from the shoot apical meristem (SAM) of severe TLS plantlets. From the suppressive SSH libraries, 278 and 132 transcripts were up-regulated and down-regulated respectively in severe TLS SAM. The annotated 54 and 24 % unique gene sequences from the forward and reverse libraries had significant matches with known proteins and were further classified based on their putative functions. Real time RT-PCR indicated that six transcripts, namely a putative finger transcription factor, a Ring H2 Finger Protein, a putative far-red impaired response protein, a Pescadillo N-terminus family protein, a TLD family protein and a maternal effect embryo arrest 14 protein from the forward library were expressed at higher levels in the severe and moderate TLS SAM and at a lower level in the mild TLS SAM compared to the calibrator (normal SAM). Four transcripts that are hypothetical protein-1, hypothetical protein-2, catalase and cation transporter from the reverse library exhibited lower expression levels in the severe and moderate TLS shoot apical meristem compared to the calibrator (normal SAM). The present findings provide a basic molecular knowledge on some of the genes associated to the TLS syndrome in oil palm. However, it is unclear whether upregulation or downregulation of these genes are a consequence of TLS or the cause of TLS.