Journal of Oil Palm Research (Special Issue - July 2008), p. 21-29
LIGHT-HARVESTING CHLOROPHYLL A/B BINDING PROTEIN (LHCB) PROMOTER FOR TARGETING SPECIFIC EXPRESSION IN OIL PALM LEAVES
Oil palm leaves have the potential to be manipulated as a green factory to produce novel metabolites. In order to direct the specific expression of transgenes into the leaf tissue, a leaf-specific promoter is required. In these studies, efforts were carried out to isolate a leaf-specific gene and its regulatory sequence from the oil palm. Rapid amplification of 5’-cDNA Ends (5’-RACE) resulted in isolation of a 962 bp full length sequence of the light-harvesting chlorophyll a/b binding protein (LHCB). The amino acid sequence of this gene exhibited more than 88% homology with the LHCB1 gene isolated from monocots and dicots. Characterization of this transcript using Northern blot analysis revealed LHCB to be abundantly expressed in oil palm green leaf tissues, but not in the non-photosynthetic tissues such as kernel, mesocarp, germinated seedlings and inflorescences. Results from Southern blot analysis confirmed that at least four copies of the LHCB gene are present in the oil palm genome. The promoter region of LHCB was then obtained through genome walking approach. Based on the sequence analysis, it was found that the LHCB promoter lacks a TATA-box. Initiation of transcription can therefore be replaced by an initiator element (Inr) located at positions -1 to -7. Furthermore, a few putative cis-acting elements responsive to light, wounding, abscisic acid and heat-shock were also found in the distal and proximal regions of the LHCB promoter.KEYWORDS:
* Malaysian Palm Oil Board,
P. O. Box 10620,
50720 Kuala Lumpur, Malaysia.
** Department of Agricultural Technology,
Faculty of Agriculture,
Universiti Putra Malaysia,
43400 UPM Serdang, Selangor, Malaysia.
+ Faculty of Science and Technology,
School of Biosciences and Biotechnology,
Universiti Kebangsaan Malaysia,
43600 UKM Bangi, Selangor, Malaysia.
Journal of Oil Palm Research Special Issue on Malaysia-MIT Biotechnology Partnership Programme: Volume 2 - Oil Palm Metabolic Engineering