Abstract
Plastidic phosphate translocators are classified into four subfamilies; triose phosphate/phosphate translocator (TPT), phosphoenolpyruvate/phosphate translocator (PPT), glucose-6-phosphate/phosphate translocator (GPT) and pentose phosphate/phosphate translocator. Four kinds of cDNAs (McTPT1, McPPT1, McGPT1 and McGPT2) belonging to three of these subfamilies were isolated from a facultative Crassulacean acid metabolism (CAM) plant, Mesembryanthemum crystallinum. The transcript levels of these genes are differentially regulated during C3-CAM transition of M. crystallinum by salt stress.
To compare the structures of these translocator genes, we are trying to isolate their genomic clones. So far, we have sequenced transcribed regions of McGPT1 and McGPT2, and found that they are separated by four introns at the same positions as GPT genes in Arabidopsis and rice. Moreover, we have isolated the 0.9 kb and 2.6 kb upstream regions of McTPT1 and McGPT2, respectively. The putative promoter structures of these genes will be compared with other CAM-specific and nonspecific genes from M. crystallinum.
