Characterizing physiological functions of metabolite transporters located in plastidic envelope membranes

1.拟南芥基因敲除和过表达植株的分析我们测量了敲除植株叶绿体的运输活性，发现苹果酸盐和谷氨酸盐的运输主要由AtpDCT1促进。此外，草酰乙酸的转运仅由AtpDCT1和AtpOMT1介导。我们还制作了OMT或DCT基因的过表达系，并比较了它们在胁迫条件下的光化学电子传递活性和叶绿体微观结构，以研究OMT和DCT与碳/氮同化和苹果酸值的关系。从nadp -苹果酸酶型c4植物玉米中分离到4个cdna ZmpOMT1和ZmpDCT1 ~ 3。我们得出结论，这些OMT和DCTs在C_4光合途径中起作用：ZmpOMT1参与将草酰醋酸盐输入叶肉叶绿体以换取基质苹果酸，ZmpDCT2/3可以将从叶肉细胞转运的苹果酸盐输入束鞘细胞。水稻OMT和dcts基因分析我们从水稻中鉴定出1个OMT基因OspOMT1和2个DCT基因OspDCT1、OspDCT2。基因表达分析表明，与玉米相比，C_3植物水稻的OMT和DCT基因不具有丰富的细胞特异性表达机制。

1.Analysis of Arabidopsis knockout and overexpressed plantsWe measured transport activities of chloroplasts isolated from knockout plants and found that the transport of malate and glutamate is facilitated mainly by AtpDCT1. Moreover, it was revealed that oxaloacetate transport is mediated only by AtpDCT1 and AtpOMT1. We also produced overexpression lines for OMT or DCT genes, and are comparing their photochemical electron transport activities and chloroplast microstructure under stress conditions to investigate the relationship of OMT and DCT to carbon/nitrogen assimilation and malate valve.2.Analysis of maize OMT and DCTsWe isolated four cDNAs, ZmpOMT1 and ZmpDCT1 to 3,from maize, a NADP-malic enzyme-type C_4 plant. We concluded that these OMT and DCTs function in the C_4 photoshynthetic pathway : ZmpOMT1 participates in the import of oxaloacetate into mesophyll chloroplasts in exchange for stromal malate and ZmpDCT2/3 could import malate that is transported from mesophyll cells into bundle sheath cells.3.Analysis of rice OMT and DCTsWe identified one OMT gene (OspOMT1) and two DCT genes (OspDCT1,OspDCT2) from rice. Gene expression analyses suggested that a C_3 plant rice does not possess an abundant and cell-specific expression mechanism on its OMT and DCT genes in contrast to maize.