Expression of the rice vdac isoform2: histochemical localization and expression level.

The voltage-dependent anion-selective channel (VDAC) is a mitochondrial outer membrane ion channel. The putative promoter of the rice vdac isoform2 (osvdac2) was isolated by screening a rice genomic library. Computer-based analyses predicted a TATA box, a putative transcription start and several transcription factor-binding sites including pollen specific elements. The promoter region was fused to the gus reporter gene and introduced into rice by Agrobacterium-mediated transformation. Histochemical and cell-type localizations indicated an overall expression of this promoter with a strong expression in actively growing lateral roots and in the pollen grains. Quantitative experiments showed that the osvdac2 promoter has a strong specific activity in both root and shoot. Thus, the osvdac2 promoter could be a good alternative to viral promoters (e.g. CaMV 35S) to overexpress genes in transgenic Poaceae.