| Soil salinization has become a global environmental problem. Soil alkalization and salinization frequently co-occur in nature. Saline-alkaline stress more complex and serious destructive effect on ecological environment than both of them. It also limited crop growth and reduced agricultural productivity. Jerusalem artichoke(Helianthus tuberosus L.) has been considered as a kind of promising biological energy materials in saline and alkaline soils, with large biomass and numerous industrial uses.In order to study the adaptive mechanisms of Jerusalem artichoke seedlings responded to saline-alkaline stress(molar ratio of Na Cl :Na2SO4:Na HCO3:Na2CO3=5:23:9:51), based on the screening results of different varieties resisting the stress, ZH-5(the sensitive) and ZH-2(the resistant) were selected for the actual study. Under saline-alkaline stress, a series of issues were analyzed, including osmoregulation, antioxdative enzyme activities, sodium potassium absorption and distribution, changes of pigment contents and chl a fluorescence analysis. Comparison of the changes and difference of above matters between two varieties, the adaptive mechanisms of Jerusalem artichoke seedling responded to saline-alkaline stress were generally stated. Meanwhile using the two-dimensional electophoresis technology to detect the changes of proteins in leaf, to understand the physiological differences leading to salt resistance and to elucidate the molecular mechanisms that underlyed this physiological response at molecular level. It hoped to provide a scientific basis for future genetic improvements and breeding in salt-alkaline tolerance within that genus. The major results were as follows:(1) The aboveground fresh weight, underground fresh weight and plant fresh weight were generally decreased by Y150.Under the treatment, the differnce between control of all the parameters in 4 materials was great. The treatment of Y150 was appropriate concentration for screening salt-tolerance among Jerusalem artichoke(2) There was significant difference in different Jerusalem artichoke varieties based on the membership function, four groups on saline-alkaline tolerance were sorted from the 16 Jerusalem artichoke varieties according to the clustering analysis(CA). The analysis showed that both ZH-2 and ZH-3 were strongly tolerant of saline-alkaline conditions, ZH-4, Taiyangdao, Qingyu001 had medium tolerance, and that ten of 16 cultivars were less tolerance, e. g. ZH-5 and ZH-6, ZH-10 and that ZH-9 was the most sensitive one.(3) Saline-alkaline stress inhibited the pigments contents in Jerusalem artichoke, along with the time, ZH-2 increased pigment contents,which were still decresed in ZH-5 significantly. Salinty stress significantly decreased Fv/Fm, F′v /F′m,and Fv/Fo in ZH-5 and no significant difference was noticed in ZH-2.Compared with ZH-5 in which ΦPSII was notably lowed, ZH-2 kept ΦPSII unchanged in 14 d and 21 d treatment. In the 7d treatment, NPQ was dramatically increased in ZH-2,but decreased in ZH-5.(4) Plant accumulated inorganic anions and orgnic compounds to dissipate the osmotic stress. Saline-alkaline stress increased the Na+ contents,compared to ZH-5, ZH-2 sequestered more Na+ in stems and roots, and sustained a better cellular environment. In the 7d treatment, ZH-2 limited large K+ in roots and no significant change was found in leaves.Whereas ZH-5 accumulated amount of K+ and proline in leaves to osmotic adjustment.Salinity significantly increased K+ contents in leaves of ZH-2 but lowed the proline contents after 14 d treatment. In the 21 d treatment, compared with ZH-5, ZH-2 has no significant difference compared to control about K+ in leaves, and accumulated lots of proline in leaves.(5) Plant improved antioxidant enzymes to minimize the oxidative stress caused by salinity stress. In the 7d treatment, ZH-2 increased the SOD, CAT and POD activities in leaves compared to control, whereas EH-5 only had SOD activity improved.Salinity stress significantly reduced the SOD, CAT and POD activity in leaves of ZH-5, but ZH-2 kept high activities of SOD, CAT in leaves after 14 d treatment. In the 21 d treatment, a dramatical increase was noticed in SOD, CAT and POD activity in leaves of ZH-5 and only CAT SOD activity in ZH-2 was unchanged, the result showed the kay that resistance to saline-alkaline was to launch the antioxidative system frequently.(6) A total of 22 different protein spots were changed obviously in the two-dimensional electrophoresis between ZH-2 and ZH-5 after treated with 150 m M mix salt-alkaline for 7d. Mass spectrometry analysis helped to identify as 22 different proteins, which were classified into 5 functional categories that included photosynthesis, metabolism, signal transduction, defending proteins, and unknown proteins. Of the 22 differential expressed proteins, 3 were up-regulated,19 were down-regulated,in particular,some important proteins for salt tolerance were noticed to be up-regulated in EH-2 under salt stress such as signal transduction proteinsOver all, Y150(150mmol·L-1) was appropriate concentration for screening salt-tolerance among Jerusalem artichoke, above fresh weight, plant dry weight and SOD parameters could be the parameters to screen the salt-tolerance of artichoke seedlings. Along with the time,ZH-2 improved the pigment in leaves, and had Fv/Fm, Fv′/Fm′,Fv/Fo and ΦPSII no significantly change. ZH-2 Kept more Na+ in roots and stems, and induced more NPQ to decrease the damage by excess light. In the same time, the SOD, POD, CAT activities were higher than control in the 7d treatment and 22 protein pots identified. |
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