| Tissue culture and regeneration system of Poplar (P. deltoides×P.nigra, 'shandis 1')was established in our experiment. Plant growth regulator alpha-naphthylacetic acid (NAA)and cell division element.6-animal pen a minopurine (6-BA) were used, in our experiment, toinduce buds and clump shoots. Indole butyric acid (IBA) was used for root generation andgrowth. The following was the media and hormone used in the poplar tissue culture: 1/2 MHculture medium (6-BA 0.5mg·L-1 and NAA 0.05mg·L-1) was used to induce and obtain theregenerated buds; MH culture medium (6-BA 0.5 mg·L-1 and NAA 0.05mg·L-1) was used togenerate clump buds; MH culture medium (6-BA 0.1 mg·L-1 and NAA 0.05mg·L-1) was usedto obtain strong shoots; 1/2 MH culture medium (IBA 0.3 mg·L-1) was used to induce andgenerate roots.The recombinant plasmid pYES2-Trx was obtained by connecting Trx gene and yeastexpression vector pYES2, pYES2-Trxis Transformed into yeast fungus INVScl,and Chose 11INVScI (pYES2-Trx)signal colonies randomly to prove Trx gene has been constructed inpYES2 vector through PCR. In an attempt to investigate the expression of exogenous geneTrxin yeast by inducing INVScl (pYES2-Trx) strain and 1NVScl (pYES2) strain. TheNorthern blotting shows that INVScI(pYES2-Trxecombinant yeast can express exogenousgene by inducing. The recombinant yeast INVScI (pYES2-Trx) was treated with NaCL,Na2CO3, NaHCO3,drought, rays.The result of this experiment reveals the stress-resistance ofNVScl (pYES2-cap) yeast was better than that of the control INVScl (pYES2) strain. Thatshows the Trx,expressed by Trx gene, protects the yeast cell when the yeast was treated withadversity stress. The result also proves the Trx gene,which came from Tamarix. spp, has thefunction to improve the stress-resistance ability of eukaryote.The Trx gene was obtained from the Tamarix androssowii cDNA library. The plantgenomic expression vector, pROKⅡ—Trx with the Trx gene, was constructed and transferredinto P.deltoides×P.nigra using Agrobacterium-mediated method. Moreover, the function ofthe Trx gene was exa mined under drought stress.In our study, 33 resistant lines were obtained through kanamycin selection, and 10 wellgrown lines which subjected to PCR assay all showed positive, primarily implying that Trxgene had intergrated into P.deltoides×P.nigra genome. The 10 PCR positive lines were usedfor Northern analysis. Northern hybridization showed that Trx gene had been normallytranscribed in 7 of resistant lines.In drought test, contents of malondialdehyde (MDA), activity of superoxide dismutase(SOD), rate of conductivity, growth rate and content of chlorophyll of the 7 lines were deter mined and analysed, When the transgenic lines were treated under drought condition for 8 days,the average relative conductivity are respectively 9.17% lower than the control line. the MDAcontent of transgenic and control lines is about 26μmol.g-1 and 30.015μmol·g-1 respectively.The average chlorophyll and SOD content of Trx transgenic lines is 23.233% and 90.0%higher than the control. These results demonstrated that the introduced exogenous Trx geneenhanced the drought stress tolerance of P.deltoides×P.nigra.All the experiments results indicated that the expression of Trx gene from T. androssowiican improve the stability of cell membrane, increase the SOD activity and chlorophyll content,and enhance the relative growth rate under adverse environment. That was Trx gene couldenhance the drought tolerance of plant.
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