The Resistance Analysis Of Transgenic Populus Ussuriensis Kom. Over Expressing LbDREB Gene To Drought And Salt Stress

Since aridity and salinization of land increased year by year, conventional breeding is a long time and can not meet the needs of forestry production.In this study, transgenic technology was used to cultivate three stress-resistant varieties of Populus ussuriensisKom.,which. was one of the most significant means of molecular breeding.This study was based on three expressed LbDREB lines and one wild type (WT).The treatment of PEG6000 indicated the drought stress and the treatment of sodium chloride indicated the salt stress. We investigated the growth of different lines, researched the relative expression levels of LbDREB and biochemical indicators.The main results of these studies are as follow:1. LbDREB transcription factor is directly responsive to the stress without transmembrane transport. LbDREB transcription factoris not gender gene, it is unstable, the performance of a hydrophilic, comprising a coiled-coil structure. The biological function of the recognition molecules in plants, regulation of metabolic processes, membrane channel transport processes may have important significance.2. Under salt stress and drought stress, the root phytomass of expressed LbDREB line was more than wild type.The leaves shape of transgenic Populus ussuriensisKom.performed better than that of the WT.3. Transgenic lines LbDREB gene expression more strongly than the wild type, wild type changes stability during stress. Under salt stress, transgenic lines Dr22 andDr2 relative gene expression are showing a downward trend after the first rise, Dr8 showing a rising trend. Under drought stress, relative gene expression have shown a rapid decline after the first rising and then rising.4. Meanwhile, the variation trends of SOD and POD were similar to the LbDREB expression level, which presented the upward trend followed by the downward trend and eventually rised.Additionally, transgenic lines contained more strongerprotective enzymes activity.5. Transgenic lines contained more proline content than wild type.Proline content under salt stress is unstable, but proline content lines Dr22 is still significantly higher than other strains, salt resistance is more significant. Drought stress proline content of transgenic lines showed an upward trend, proline content lines Dr2, Dr8, Dr22 reaches the maximum value in 96h, and high than WT (lines Dr8, Dr22, Dr2 proline content is6.9 times,11.4times, 6.6times of WT).6. Under salt or drought stress, MDA content were increased at first and then decline and then an upward trend, transgenic lines contained more MDA content than wild type.Under salt stress, WT lines MDA content was significantly higher than the transgenic plants, salt resistance ability WT<Dr8<Dr2<Dr22. Under drought stress, transgenic lines Dr2, Dr8, Dr22 increased by 1.24,1.17,1.39 times; and WT increased by 1.54 times, drought resistance ability WT<Dr22<Dr2<Dr8.7. Relative conductivity of transgenic lines were less than that of wild type. Under salt stress, WT maximum increase (48.21%), Dr22 minimum (29.15%). Each lines salt resistance Dr22> Dr2> Dr8> WT. Under drought stress, WT maximum increase (57.56%), Dr2 minimum (22.36%). Each lines drought resistance Dr2> Dr22> Dr8> WT.8. Under Stress, WT lines sustained loss water, relative water content continued to decline, transgenic lines maintain a higher water content than WT, comparison found that Dr8= Dr22> Dr2> WT9. Chlorophyll and maximalquantum yield of PS Ⅱ of WT decreases faster than that of the transgenic lines.Under salt stress, SPAD chlorophyll content float small change, and continued to decline, transgenic lines Dr2, D22 has always maintained a high chlorophyll content, which salt resistance of Dr22 performance stronger. Each lines of PS Ⅱ photochemical energy conversion rates continue to decline, but WT has more obvious decline, after stress was found Dr22> Dr8> Dr2> WT. Under drought stress, transgenic lines Dr2, Dr8 always maintained a high chlorophyll content showed a high drought tolerance. WT conversion rate is 64.16% of the original, but each of the transgenic lines Dr8, Dr22, Dr2 reached 77.75%,79.95%,79.35% of the original; WT lines of PS Ⅱ photochemical energy conversion decreases faster than the transgenic lines, to a greater extent.What’s more, the tolerance ability of transgenic lines to drought was more superior to that of wild type.Overall, the up-regulated expression of LbDREB may play an important role inresistant to drought and salt in plant.