| The experiment choosed the seedling of Phyllostachys edulis as materials, using potting and waterplanting did experiment. PEG6000was been used to simulated the drought stress, with addingextracellular cell Ca2+chelating agent EGTA, calcium channel blockers LaCl3, calmodulin antagonistCPZ and calcium additives CaCl2to analyze the formation mechanism of calcium signal to the droughtresistance of Phyllostachys edulis’s seedling, and the influence and physiology mechanism ofexogenous Ca2+to the seedlings of Phyllostachys edulis. The main conclusions were drawn as follows:(1) Under drought stress, the distribution of Ca2+in the root tip of seedlings represented differentchanges and formed flow of Calcium ion. Ca2+in the normal root tip cell of Phyllostachys edulis mainlydistributed in the cell wall and cell nucleus; cytoplasm was full of Ca2+in the root tip cell in droughtcondition, Ca2+had been increased in cytoplasm with the addition of calcium ions, Ca2+had beendecreased in cytoplasm with the treatment of EGTA, little Ca2+existence in cytoplasm with the additionof LaCl3. It turned out that the root tip cells of Phyllostachys edulis’s seedling from extracellular andcell wall, cell nucleus and other calcium store moved to cytoplasm through the calcium ion channels,and then the distribution of Ca2+represented different changes, formed PD to produce calcium signal.Adding CPZ restrained the calcium ion combining with calmodulin on root tip cell of Phyllostachysedulis, and made the calcium signal transmission cannot proceed any further. The Ca2+in the root tipcell were mainly distributed in the cell nucleus, decreased in the cell wall and little in the cytoplasmwith the treatment of CPZ.(2) The fluorescence intensity of Ca2+in the root tip was highest when treated in normal, droughtstress and added exogenous calcium ions about15minutes, and the intensity of added three differentcalcium inhibitors was lowest about15minutes. The fluorescence intensity of Ca2+in root tip undernormal irrigation was relatively flat. But the fluorescence intensity in the group of added calcium ionswas always higher than other treatment. The second group was drought stress, however, the group ofadding different inhibitors was lower than other treatments all the time.(3) Calcium signals transduced by calmodulin (CaM) and calcium dependent protein kinase(CDPKs) and other intermediates under drought stress. The time of drought stress was longer within54 hours and the content of CaM and CDPKs was higher. And were positively related with calcium ionconcentration. Adding exogenous calcium made the content of CaM and CDPKs increasing.Therefore,adding different inhibitors made the content of CaM and CDPKs declining, and made calciumsignal’s transduction getting suppression, then influenced its regulated and controled relatedtranscription factors, and further affected the physiological response of Phyllostachys edulis’s seedling.(4) Calcium signals could adjust photosynthesis system of Phyllostachys edulis’s seedling underdrought stress. When the content of CaM and CDPKs increased,the Pn, Gs, Tr, Ci, Fv/Fm, ΦPSⅡ,ETR, qP was also improved, WUE, qN was declined. By increased the stomatal conductance andphotochemical efficiency to enhance the capacity of photosynthesis of Phyllostachys edulis’s seedlingunder drought stress.(5) Under drought stress, the activity of SOD, CAT, APX and POD were improved, the content ofsoluble protein and proline were increased; The relative water content was decreased. The rate of superoxygen free radical generation and cell membrane lipid peroxidation to speed up made the leaf relativeconductivity and MDA content increased. After adding1,5m mol/L exogenous Ca2+, the RWC, solubleprotein content and leaf SOD, POD, CAT enzyme activity increased significantly; but the content ofPro, APX enzyme activity dropped significantly, and made the electrical conductivity and MDA contentdecreased. So that the chlorophyll content, photosynthetic capacity, specific leaf area and tiller numberwere increased. The result of research indicated that1m mol/L of exogenous calcium ions could boostPhyllostachys edulis’s the ability of drought resistence better. |
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