【作者】 孙宪芝；

【导师】 王秀峰； 郑成淑；

【作者基本信息】 山东农业大学 ， 园艺环境工程， 2008， 博士

【摘要】 本研究以生产上的主导白色切花菊品种‘神马’(Dendranthema grandiflora‘Jinba’)为试材,在33/28℃与40/35℃两种高温条件下分别进行不同时间的胁迫处理,从菊花对高温胁迫的光合响应、叶绿素荧光动力学参数变化及菊花叶片过氧化防御系统对高温胁迫的响应等方面,研究了菊花光合作用对高温胁迫响应的生理机制;通过不同高温胁迫强度处理后的恢复生长,进一步研究了高温胁迫对菊花光合作用及光合系统活性的影响。在此基础上,研究了外源Ca2+对高温胁迫下菊花各相关生理指标的动态变化,探讨了Ca2+对菊花抗氧化酶活性的影响及其与抗高温胁迫的关系,旨在为Ca2+在实际生产中的应用提供理论基础。主要研究结果如下:1.光合机构运转遭受的破坏与高温胁迫强度呈明显正相关。在40/35℃高温胁迫下,净光合速率(Pn)与气孔导度(Gs)大幅度持续降低。胁迫前期,胞间二氧化碳浓度(Ci)上升,表明高温下菊花叶片Pn的降低主要是由非气孔因素导致的;9 d后Ci与Pn同时降低,气孔限制成为光合作用降低的主要因素。33/28℃胁迫初期Pn逐渐降低,Gs无明显变化,但胁迫后期也表现出明显的气孔性限制,表明短期的亚高温不会致使气孔的关闭,但长期处于亚高温下,光合作用同样会遭受严重影响。2.随胁迫时间的延长,光饱和点(LSP)、光合能力(Pm)和表观量子效率(AQY)、羧化效率(CE)均明显降低,而光补偿点(LCP)、CO2补偿点(CCP)均明显升高,表明菊花叶片利用强光与弱光的能力降低,1,5-二磷酸核酮糖羧化/加氧酶(Rubisco)活性以及利用低浓度CO2的能力降低。叶绿素、胡萝卜素含量均在高温下逐渐降低,是光合速率降低的主要原因之一。低强度高温胁迫下菊花植株形态上表现出叶缘反卷、下位叶下垂等现象;高强度胁迫下,出现下位叶片枯萎、生长点坏死等症状。3.高温使菊花叶片的PSⅡ潜在活性(Fv/Fo)、最大光化效率(Fv/Fm)、实际光化效率(ΦPSⅡ)与天线转换效率(Fv’/Fm’)降低,天线热耗散(D)增加,表明高温下菊花通过降低光能的捕获与通过PSⅡ的电子传递效率来保护反应中心免受伤害。33/28℃条件下光化学猝灭系数(qP)呈先下降后上升的趋势,推测此温度下受体端电子传递首先受到抑制;40/35℃下qP持续增加,表明放氧复合体(OEC)可能是菊花光合系统中极端高温伤害的原初位点。4.短期33/28℃高温胁迫下抗氧化酶均表现出先上升后下降的趋势,但40/35℃下只有超氧化物歧化酶(SOD)与抗坏血酸过氧化物酶(APX)有小幅度的上升然后快速下降,过氧化氢酶(CAT)与过氧化物酶(POD)表现持续降低;菊花叶片中抗氧化物AsA与GSH对高温敏感,在两种高温强度下均出现持续降低的趋势。随胁迫时间的延长,膜脂过氧化逐渐加剧,MDA大量积累,细胞渗漏逐渐增加。5. 33/28℃亚高温下胁迫时间短于7 d的处理在转入23/18℃后Pn、Fv/Fm、ΦPSⅡ等指标均可在5 d内得到恢复,7 d以上的处理各参数也可在5d后恢复到处理前的70%以上;40/35℃高温下,5 d以上的处理都不能完全恢复,超过9d的处理Pn在恢复条件下继续降低,光合系统出现不可逆失活。6.高温胁迫下外源Ca2+降低了菊花叶片叶绿素a、b和类胡萝卜素的降低幅度, Pn、Fv/Fm、ΦPSⅡ均比对照有不同程度的增加,而Fo降低,表明Ca2+可以有效缓解短期高温对菊花光合系统的伤害,可能是由于降低了高温对PSⅡ反应中心的破坏或失活。另外,外源Ca2+明显激活了高温胁迫下叶片SOD、POD、CAT的活性,降低了高温胁迫对细胞膜结构的损伤与MDA的积累。更多还原

【Abstract】 In the present studies, Seedlings of a white cut chrysanthemum cultivar‘Jinba’(Dendranthema grandiflora‘Jinba’) were treated by extreme high temperature (40/35℃) or sub-high temperature (33/28℃) for different time respectively to study effects of high temperature stress on both operation of photosynthesis organization and physiological response in chrysanthemum plants. Net photosynthesis rate, gas exchange, chlorophyll fluorescence and the response of active oxygen scavenging enzyme system to high temperature were detect as the main indexes. Through the study on recovery of chrysanthemum seedlings after different menace dosage, the possible response mechanism of high temperature on photosynthesis and activities of light system were discussed. In addition, the effects of exogenous Ca2+ on photosynthetic organization and active oxygen scavenging enzyme system as well as relation with high temperature in chrysanthemum plants were explored in the aim of providing alternative method for chrysanthemum growers. The main results of this study are as follows:1. The net photosynthesis rate (Pn) of chrysanthemum decreased gradually treated by 33/28℃, stomatal conductance (Gs) decreased evidently at 5th day; Pn and Gs decreased dramatically in plants treated by 40/35℃. Rise of intercellular CO2 concentration (Ci) at early stage under the given high temperatures showed that the inhibition of photosynthesis by high temperature stress was resulted from nonstomatal limitations, 9 days later, stomatal limitation mainly induced the decrease of Pn.2. With the prolonging of the high temperature stress, light saturation point (LSP ) , max Pn (Pm), apparent quantum yield (AQY) and corboxylation efficiency (CE) evidently all decreased; meanwhile, both CO2 compensation point (CCP) and light compensation point (LCP) increased. The result showed that the capabilities of chrysanthemum seedling to use weak light and high intensive light were lower than the control. The activity of Rubisco and the capability of using lower concentration of CO2 were lower too. Decreased of contents of chlorophyll and carotenoid under high temperature stress maybe is one mainly cause resulting in the reducing of Pn. Middle leaf is revolute and lowest leaves drooped under lower high temperature dosage; middle leaves drooped with yellow spot and lowest leaves perished under high stress dosage.3. The intrinsic photochemical efficiency (Fv/Fm), quantum yield of PSⅡ(ΦPSⅡ),the efficiency of excitation energy capture by open PSⅡreaction center(Fv’/Fm’)of plants that were treated by 33/28℃and 40/35℃all decreased with antenna heat dissipation increasing,showed that react center were protected by decreased light capture and efficiency of electron transfer through PSⅡ. Photochemical quenching (qP) of plants under 33/28℃descended first and then turned to rise, suggested that the electron transfer was firstly restrained by the stress; contrastively, qP rise continuously under 40/35℃, indicating oxygen-evolving complex (OEC) was the most sensitive location to extreme high temperature in chrysanthemum photosynthesis apparatus.4. All the antioxidation enzymes of SOD, POD, CAT, APX was activised by Short-term 33/28℃, SOD and APX raised slightly under 40/35℃, with the durative reduce of CAT and POD;antioxidation matter AsA and GSH are both sensitive to high temperature stress,appeared durative reduce under given two high temperature intensity. With the prolonging of stress, membrane lipid peroxidization prick up, following MDA accumulation and cell leakage increasing.5. Pn、Fv/Fm、ΦPSⅡof chrysanthemum leaves treated by 33/28℃within 7 d could recovered after transfer to 23/18℃; the above parameters could recovered to 70% of control treated beyond 7 d; contrastly, the photosynthesis of chrysanthemum leaves treated by 40/35℃beyond 5 d can not recovery , that treated beyond 9 d even keep on reducing transfer to control condition, light react center is permanent injured.6. Additions of exogenous Ca2+ significantly enhanced the contents of chlorophyll a, chlorophyll b and carotenoid of chrysanthemum leaves under high temperature stress. All of net photosynthetic rate (Pn), photochemical efficiency of PSⅡ(Fv/Fm) and quantum yield of PSⅡelectron transport (ΦPSⅡ) increased, whereas initial fluorescence (Fo) decreased. Ca2+ treatment significantly enhanced the activities of SOD, POD and CAT. In conclusion, addition of Ca2+ efficiently protected chrysanthemum leaves against photosynthetic organization damage under high temperature stress conditions, and the active oxygen was scavenged by the enhanced antioxidant enzymes, which hence significantly alleviated the membrane lipid peroxidization and MDA accumulation.更多还原