| Saline soil accounts for about 10% of the cultivable land area in the world, and there are approximately 0.2 hundred million hectare saline soil in our country. Due to the industry pollution's pricking up, the irrigated farming's development and the unsuitable using of fertilizer etc, the area of saline soil is continuing to expand, brought a large losing for agriculture production. Boyer(1982)'s statistic result revealed that , between 1939 to 1978 , in the diversified environment factor that impacting on crop yield, the reduction of output owing to drought and saline exceeded 40% .Recently, the research on salt-resistant for plant has taken out obvious evolvement, example for the cultivation of salt-resistant cell series, the transfer of infiltration adjusting gene and the using of salt-inducing gene etc. At the same time, the research on salt-resistant mechanism also has acquired evident progress.In the environment, high concentration of Na~+ and Cl~- in soil lead salt intimidation (like seawater irrigation), limited the plant's growth, therefore the plant have produced diversified changes on physiology and biochemistry, including the limit of photosynthesis, the cumber of ingesting for nutrition substance, the disorganization of plasma membrane, the increase of active oxygenic and the accumulation of metabolized poison etc, badly, the plant will lead to death. When some plant meet salt intimidation, their growth will be limited , even cause death, whereas, the other plant have finer adaptability to salt. Biologist have taken a lot of research on the plant's salt-resistant mechanism, they find that it is quite complex. The mechanism is relative to some protein's synthesis and expression of correlative genes, including mini-molecule infiltration matter, mass protein occurred in terminal embryo, infiltration adjusting protein (OSM), AQP, K~+ channel protein and ATPase etc.Water is a main part of alive cell. The water proportion is 70% of a cell weight. Lots of cell biochemistry reaction process in water condition. It is a very important and basic problem in life science that how dose the water transport the membrane.Although the water can use free pervasion, but it is very slowly. Science research proved that water tansport the membrane fastly is depend on a kind of protein which named AQP. One AQP1 can transport 3000 million water molecules per sec. AQP are integral membrane proteins occurring in mammals, plants and microorganisms. In plants, AQP participate in roots imbibe and keep the water balance directly. As a result of AQP, fast regulate for volume and osmotic stress can be happened. Therefore, AQP is crucial for the life.Bruguiera gymnorrhiza belongs to Rhizophoraceae, Bruguiera; Avicennia marina belongs to Verbenaceae, Avicennia. They are used to growing in salty soil, which is periodically drowned by a tide in tropic and semitropical. They are make a good effort for keeping zoology balance, decreasing the disaster and protecting the riverbank. In the last decade, the research for mangrove plants mostly concentrate on physiology and bionomy, as a plant which growing high salty soil and press almost none of people pay attention to salt-stress tolerance genes molecular biology research. There is no report about the expression of BgPIP2.A cDNA, named BgPIP2, was cloned from Bruguiera gymnorrhiza by RT-PCR and RACE. Degenerated primers were designed based on the conserved sequences in PIP cDNAs. The amino acid sequence compared by Blast revealed that it is belongs to PIP subfamilyⅡ. GenBank Accession Number EF126757. The BgPIP2 cDNA was 1068 bp and contained a 843 bp whole open reading frame, encoding a polypeptide of 281 amino acids with a molecular mass of 29.84 kD and dimorphic structure. The protein sequence predicts 7 transmenbrane helices. Comparison of this protein sequence with those of Mimosa pudica , Vitis vinifera and Arobidopsis thaliana showed that the amino acid homology was 90% ,91% and 88%, respectively. Northern blotting analysis indicated that the expression level of the excluders mangrove BgPIP2 in taproot, sideroot was higher than in stem and leaf.Secreters mangrove Avicennia marina is adapt to abroad salinity,which currently cultured in 5‰-20‰seawater respectively.In laboratory, Avicennia marina is well growing in 0‰-30‰salinity condition. It is a good material for salt-stress tolerance research and AQP gene isolation. We used DNA segment of BgPIP2. A isotope[α-P32]dCTP sign probe is made . Northern blotting analysis the taproot,sideroot and stem,leaf which cultured in diffirent salinity conditions , the results indicated that the expression level of the roots were positive regulated when the concentration of salinity increased and the other organs were unconspicuous.
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