VECTOR CONSTRUCTION AND TRANSIENT EVALUATION IN OIL PALM CALLI VIA Agrobacterium-MEDIATED TRANSFORMATION

Current oil palm transformation efficiency was relatively low compared to other monocots such as rice and sorghum. Thus, the construction of efficient transformation vectors is crucial for Agrobacterium-mediated oil palm genetic engineering to elevate the transformation efficiency. In this study, six transformation vectors, which contain phosphinothricin acetyltransferase (bar), modified green fluorescent protein (mgfp) and synthetic green fluorescent protein (sgfp(S65T)) genes driven by either maize ubiquitin (Ubi-1) or cauliflower mosaic virus (CaMV35S) promoters, were assembled in pBINPLUS/ARS or pCAMBIA0380 backbones. The efficiency of these vectors was evaluated in oil palm calli. Based on transient GFP signals, the pBINPLUS/ARS-based vectors produced a higher number of GFP signals than the pCAMBIA0380-based vectors. The CaMV35S promoter was more excellent than the Ubi-1 promoter in driving the expression of gfp genes. Furthermore, the sgfp(S65T) variant was more suitable for oil palm transformation than the mgfp variant because it produced more GFP signals in the oil palm calli than the mgfp variant. These results suggested that the pBAR65 vector, which carries the bar and sgfp(S65T) genes driven by the CaMV35S promoter in the pBINPLUS/ARS backbone, is the most suitable vector and could be used to develop an efficient Agrobacterium-mediated transformation system for oil palm.