Loca Lization And Functional Analysis Of PEX2 In Arabidopsis

Plant sexual reproduction depends on highly specific interactions between pollen and pistil, the male and female reproductive organ. The stigma has a pollen-receptive surface and several underlying secretory cell layers. The style connects the stigma to the basally located ovary containing the ovules. Within each ovule, an egg cell develops inside the embryo sac. In compatible pollination, the pollen grain germinates and extrudes a pollen tube upon landing on the stigmatic surface. Each pollen tube penetrates the stigmatic cell layers and elongates within a specialized tissue in the style called the transmitting tissue, eventually reaching the ovary, where it enters an ovule and penetrates the embryo sac. The pollen tube tip bursts in the embryo sac to release the male germ cells for fertilization. Incompatible pollen may be arrested at the stigma or anywhere along the pathway of pollen tube elongation. . Recently, TOML-4 and PEX1 has been obtained from tomato and Maize. The Pexl (pollen extensin-like) gene is expressed exclusively in pollen, not in vegetative or female tissues, and is not induced in leaves upon wounding. It has been proposed that the encoded protein may have a role in reproduction, either as a structural element deposited in the pollen tube wall during its rapid growth or as a sexual recognition molecule that interacts with molecules in the pistil.It is significant to know how pollen and pistil extracellular components interact and how these interactions transduced and translated into the activities needed for pollen tube growth. It has been studied extensively in pollen - pistil recognized signal ,but a little is known about polarized growth and the transduced signal in this process.From Arabidopsis genome we have clone a gene PEX2 ,which do not have any intron and was composed of 2544bp. the encoded protein has a globular domain rich in leucine repeats and a consevesd domain of Melanoma Antigen family(MAGE). The MAGE family are expressed in a wide variety of tumours but not in normal cells with the exception of the male germ cells, placenta, and possibly ,cells of the developing embryo.PEX2 has high degree of identity with ZmPEX that expressed exclusively in Maize flower and AtLRX1 that expressed exclusively in arabidopsis root hair. To study this gene expression ,we do northern blotting using PEX2 gene as probe , the results showed that there is strongly expression signal in flowers,but almost no signals in root,stem,leaves and fruits ;To further verify its expression and biological fuction, we construct"promoter -GUS"expression vector and transform it into the Arabidopsis, the results reavls that GUS express in pollen and nodes. In addtion, we buy T-DNA inserted mutants(SALK line) and obtain homozygotes.but its phenotype do not inherted stablly .so we consruct over expressed vector of PEX2 in T-DNA inserted mutants(SALK line). And the result will be got soon.