Trans-Conduct Melon K~+ Channel Gene Into Arabidopsis Thaliana And Research On The Salt Tolerance Of Transgenic Plants

Soil salinization is a global problem; one method of utilizing saline-alkali soil is to cultivate salt tolerant plants. Melon (Cucumis melo L.), an important cultivation in china, has a strong salt tolerance. This character makes it to become a salt tolerant or desalination plant resource.Infiltration wither section is an important mechanism of salt tolerant through absorbing and accumulating of inorganic salts or synthesizing of solute-sike in plant cells. Uptaking sodium potassium to reduce the concentration of salt on the ground part of plants is an important mechanism of salt tolerant in plants. As the main way of absorport and transformation of potassium, K + channel may be related to salt tolerance of plants.In our previous work a K+ channel gene MIRK (melon inward rectifying K+ channel, Genbank accession number: DQ116940) was cloned from Chunli (Cucumis melo L.). The full length cDNA of MIRK is 2506 bp, encoding a peptide of 701 amino acids. Transferred MIRK into Xenopus oocytes, electrophysiological analysis showed that Na+ inhibited on the transport of MIRK (unpublished), this phenomenon demonstrate that MIRK probably play an important role under the conditions of salt stress in the melon plants.We constructed a plant transformation vector of melon K+ channel Gene MIRK, and transferred it into Arabidopsis thaliana by Floral Dip method. Resistance testing, PCR results and Southern hybridization confirmed that MIRK has been integrated into the genome of Arabidopsis thaliana. Conversion efficiency of Floral Dip method was 4.3%. Transgenic plants provide a experimental system for further study.In order to study the relationship between MIRK and salt tolerant in plants, watered transgenic plants(T3-generation) with different concentrations of NaCl solution (0,50,100,150,200 mmol/L) every day, and determined relative water content (Rwc), photochemical efficiency of PSâ…¡(Fv/Fm), relative electronic conductivity (Rec)and chlorophyll content (Chla+b,Chla/b) after 0,4,8,12,16 days'salt stress. The phenotype of transgenic plants and negative control plants show that they were getting worse and worse while NaCl concentration and stress time increased gradually, but transgenic plants grown better than control plants; after 16 days'stress of 200 mmol/L NaCl, relative electronic conductivity of transgenic plants is 57.5 percent of the control plants, relative water content and the Fv/Fm value of transgenic plants were higher than those in control plants, chlorophyll content (Chla+b, Chla/b) of transgenic plants were 1.2 times of the control,,the ratio of potassium to sodium of transgenic plants were 2.3 times of the control; the differences between them reached a significant level. Those results indicated that melon K+ Channel Gene MIRK transformation could further improve salt tolerance of plant.