【作者】 高静；

【导师】 王根轩；

【作者基本信息】 浙江大学 ， 生态学， 2014， 博士

【摘要】 植物气孔能够对叶际微生物免疫响应使其关闭以抵御病原菌的入侵,在气孔免疫抗病性方面已有较深入的研究。而气孔也是植物进行气体交换的重要通道,气孔免疫性关闭对植物吸收CO2和水分散失的影响尚不清楚,微生物诱导气孔免疫性关闭后能否提高水分利用效率(WUE)呢?基于光合作用和蒸腾作用对气孔开度响应动态的差异特征,我们提出气孔免疫响应可能在一定强度(浓度)范围和一定发育时期内提高水分利用效率的假说,由于作物气孔结构和代谢差异,同一微生物对不同植物的适宜浓度和植物生长期影响可能不同。本论文通过显微镜观察、叶绿素荧光成像和气体交换测定等技术来探讨作物气孔对酵母的免疫响应提高水分利用效率的适宜范围及其响应机制。主要结果如下：(1)作物气孔对酵母的免疫响应可以提高其内在水分利用效率(WUEi)且不同作物气孔免疫提高WUEi的适宜酵母浓度不同。将酵母喷施到蚕豆、番茄和水稻上后,提高了它们的WUEi。105、107和109cfu/ml酵母使蚕豆的WUEi提高的程度相似。番茄和水稻的最佳效果的酵母浓度分别是105和109cfu/ml。(2)作物气孔对酵母的免疫响应对WUE的效应在作物不同发育期间具有差异性。在充分浇水的情况下,酵母提高了水稻的WUEi和灌溉水分利用效率(IWUE)。在干旱处理的中期,酵母显著地影响了水稻的WUEi。在干旱条件下,外源喷施酵母增加了水稻的结实率、千粒重、谷物产量,经济系数、谷草比和IWUE。(3) H2O2、NO和Ca2+都参与了酵母诱导的气孔免疫响应。通过使用抑制剂,我们发现酵母诱导的气孔关闭主要是由细胞壁过氧化酶介导的,NO也参与了酵母诱导的气孔关闭,而且NO的来源是NO合成酶和硝酸盐还原酶。(4)海藻糖是酵母体内的应激保护剂,也能通过H2O2依赖的途径诱导气孔免疫响应,进而导致光合速率、气孔导度和蒸腾速率的下降。在喷施海藻糖8h和24h后,气孔因素限制了光合作用。在第48h和72h时,光合速率的下降则是由非气孔限制因素导致的。有关结果证明了受试作物气孔对酵母的免疫响应,在本实验条件下,适宜浓度范围和一定发育时期内可提高WUE；其适宜浓度和时期因作物而异。酵母体内的海藻糖作为重要效应物质通过作物保卫细胞内的H2O2、NO和Ca2+等细胞信号通路和调节水通道引发免疫响应。这对于深入理解气孔对酵母的免疫响应与作物水分生理过程和水分利用效率间的定量关系及其科学机制,研究微生物-植物之间的相互作用具有重要科学意义；对开发环境友好的新型气孔免疫蒸腾抑制剂,减少农业面源污染具有重要的应用前景。更多还原

【Abstract】 It has been proved that phyllosphere microorganisms can induce stomatal immunity against pathogen invasion. Previous studies mainly focused on the roles of stomatal closure in disease resistance. Stomata can also control gas exchange, but the effects of stomatal immunity on CO2uptake or water loss from the leaf is scant. Can yeast-induced stomatal closure increase water use efficiency (WUE)? Based on the principles of stomatal biology and photosynthetic physiology, we hypothesized that yeast-induced stomatal immunity can increase water use efficiency, but the plants differ in their manners in which concentration of yeast are applied. More specifically, microbes can induce stomatal closure as well as decrease transpiration and photosynthesis, resulting in increasing WUE. The appropriate concentration of microorganisms is changed with plant species and the growing stages due to variations in stomatal structures and metabolic differences. The main objectives of this work were to find out the mechanism of yeast-induced stomatal closure and to find out whether yeast can improve plant water use efficiency by using direct microscopic observation, gas exchange measurement and chlorophyll fluorescence imaging. We can summarize the results as follows:(1) Phyllosphere yeast increased intrinsic water use efficiency (WUEi) and the appropriate concentration of yeast is different for different plants. Yeast iecreased WUEi of broad beans, tomato and rice. WUEi of broad beans was increased to similar extents under treatment with105,107and109cfu/ml of yeast. The appropriate concentration of yeast is different for tomato and rice is10and10cfu/ml, respectively.(2) The effects of yeast for rice were different at different growing stages. Under well-watered conditions, application of yeast increased WUEi and irrigation water use efficiency (IWUE). Under drought conditions, applying yeast increased WUEi during middle stages compared with the drought without yeast. Under drought conditions, yeast application increased seed set rate,1000-grain weight, grain yield, harvest index(HI), grain:straw and IWUE compared with drought without yeast.(3) H2O2, NO and Ca2+are involved in yeast-induced stomatal closure. S. cerevisiae induced stomatal closure in a dose-dependent manner on Vicia faba L.(cv. Daqingpi). Using pharmacological inhibitors in this study, we found that H2O2was mostly produced by cell wall peroxidases and NO in guard cells of V.faba is derived from both NOS-like enzyme and nitrate reductase.(4) Trehalose can reduce stomatal aperture by a hydrogen-peroxide-dependent pathway on Vicia faba L., resulting in significantly lower values of net PN, gS and E. At8h and24h, the drastic reduction in photosynthesis was caused by stomatal inhibition. At48h and72h, the drastic reduction in photosynthesis was caused by non-stomatal inhibition.In summary, we revealed that in a certain developmental stage, the phyllosphere microbes-induced stomatal immunity can improve plant WUE at appropriate concentration of applied yeast. The appropriate concentration of microorganisms is changed with plant species and the growing stages. Stomatal immunity response is triggered by trehalose of yeast cell through adjusted cell signaling pathways such as H2O2, NO as well as Ca2+and water channels. Our results may have an important role for understanding the interactions between microbe and plants and finding out the mechanism and quantitative relationship between yeast-induced stomatal immunity response and crop water physiological processes as well as WUE. Furthermore, our findings can be used to develop a new environmental harmless anti-transpiration agent, which has a important application in reduction of agricultural pollution.更多还原