钙离子对PSII颗粒放氧活性的影响

外加5 mmol/L Ca~(2 )可以使菠菜PSⅡ颗粒的放氧活性增高。PSⅡ颗粒经EGTA透析、低pH值、光照、2 mol/L NaCl等处理后,放氧活性下降,同时,这些颗粒的钙含量也相应降低。但当外加 5 mmol/L Ca~(2 )时,可使这些颗粒全部或部分地恢复放氧活性。PSⅡ颗粒中存在的钙对放氧起着重要作用;钙在PSⅡ颗粒中的结合位点不止一个,其结合状态有紧密和松散之别。     

低温胁迫对麻竹叶片和根系抗性生理指标的影响

采用室内人工低温处理,研究了麻竹(Dendrocalamus latiflorus)叶片及根部质膜透性、丙二醛、可溶性蛋白、可溶性糖含量,超氧化物歧化酶(SOD)、过氧化物酶(POD)活性和膜脂脂肪酸组成的变化,寻找与竹类植物耐寒性关系最密切的抗性生理指标。结果表明:低温预处理(8℃)15d后,麻竹叶片中可溶性糖、可溶性蛋白含量、POD活性显著提高,根部可溶性糖含量、POD活性显著升高;低温胁迫处理(-2℃)72h后,经低温预处理的麻竹叶片可溶性糖、可溶性蛋白质含量、SOD、POD活性显著高于未经低温预处理,而质膜透性显著低于未经低温预处理,但膜脂过氧化程度显著高于-2℃处理前;经低温预处理的麻竹根部SOD、POD活性及膜脂不饱和脂肪酸相对含量显著高于未经低温预处理,而质膜透性、膜脂过氧化程度较-2℃处理前无显著差异。说明剧烈降温对麻竹生理特征造成严重影响,叶片通过提高可溶性蛋白、可溶性糖含量,维持较高的POD活性以减轻低温伤害;根系则通过维持较高的SOD、POD活性以减轻低温下膜脂过氧化水平,并通过提高膜脂不饱和脂肪酸比例降低质膜透性来抵御低温对膜的伤害。     

高温胁迫下不同光强对‘赤霞珠’葡萄PSII活性及恢复的影响

本文研究了高温与不同光强结合处理对‘赤霞珠’葡萄叶片PSII活性及恢复的影响。结果表明,高温黑暗处理（40℃,0μmaol·m-2．s-1）导致叶片PSII最大光化学效率（Fv/Fm）、反应中心吸收的光能用于电子传递的量子产额（ψEo）与单位反应中心光能的传递（ETo/RC）降低明显,且无恢复趋势,K点相对荧光（Vk）、单位反应中心光能的吸收（ABS／RC）与捕获（TRo／RC）显著升高。高温弱光处理（40℃,200μmol·m-2．s-1）后的叶片PSII活性明显恢复,ETo／RC降低明显,TRo/RC无显著变化。高温强光（40℃,1600μmol·m-2．S-1）处理导致单位面积有活性反应中心数量（RC/CSm）抑制程度最大,恢复程度较低。实验结果说明,高温处理下黑暗对葡萄PSII功能活性及恢复均会造成抑制,而弱光可以显著缓解高温对葡萄叶片的胁迫作用,并促进PSII的恢复,强光导致胁迫下的PSII功能抑制最明显。     

根区缓冲降温处理对葡萄叶片冻害的影响

为探索根区降温条件对葡萄(Vitis vinifera)叶片冻害的影响,以1年生美乐葡萄(V.vinifera cv.‘Merlot’)幼苗为试材,设置根区正常降温和缓冲降温2种降温条件,人工模拟霜冻,分析了叶片冻害指数和叶片的荧光参数。结果表明,根区正常降温会导致根系受冻,同时叶片发生严重的冻害,冻害指数达74.36%;根区缓冲降温使根区温度保持在0°C以上,叶片冻害指数降低53.29%,仅有21.07%的叶片遭受了冻害。根区缓冲降温处理能有效提高叶片霜冻恢复过程中光化学淬灭系数(qP)和天线色素转化效率(F_v~'/F_m~'),加快PSII光合电子传递量子效率(Φ_(PSII))的恢复,提高热耗散能力(NPQ),减轻霜冻后的光抑制(F_v/F_m),有利于叶片霜冻后的恢复。     

低温处理对北美冬青叶片抗氧化能力的影响

为了解低温对北美冬青(Ilex verticillata)生长的影响,对2年生扦插苗经低温处理(-6℃)后的生长和抗氧化能力进行了研究。结果表明,随着低温处理时间的延长,北美冬青叶片的叶绿素/类胡萝卜素比值和叶绿素b含量增加,而其他色素含量都呈下降趋势;相对电导率(REC)和H_2O_2含量(72 h除外)显著增加。低温处理对超氧化物歧化酶(SOD)活性影响不大,却显著降低CAT的活性。低温处理过氧化物酶(POD)活性显著提高,48 h活性达到最高;而抗坏血酸过氧化物酶(APX)活性在处理12 h达最高,然后下降。还原型抗坏血酸(As A)、还原型谷胱甘肽(GSH)含量均呈先升高再下降的趋势。因此,北美冬青在短时间内(≤24 h)能够忍受低温(-6℃),抗氧化防御系统在低温初期起关键的作用,但随时间延长(72 h)其抗氧化能力减弱。     

根系环境温度变化对根系吸水和叶片蒸腾的影响

以木本植物银合欢（Ｌｅｕｃａｅｎａｌｅｕｃｏｃｅｐｈａｌａ（Ｌａｍ．）ｄｅＷｉｔ．）和禾本科植物玉米（ＺｅａｍａｙｓＬ．）为材料,研究了根系温度变化对根系吸水和叶片蒸腾的影响。当根系周围温度从２５℃降至１５℃,短时间内（１４ｍｉｎ）可显著促进根系的吸水和提高植株的蒸腾速度,这种促进作用随着低温处理时间的延长而消失。如将根系周围的温度又从１５℃提高到２５℃对根系的吸水和植株的蒸腾速度无明显的影响。低温处理短时间内（２０ｍｉｎ）可提高根系的水导和植株的蒸腾速度,但随着低温处理时间的延长,根系水导和植株的蒸腾速度迅速下降。低温处理３０ｍｉｎ后显著促进根系ＡＢＡ的合成,提高木质部ＡＢＡ的浓度。外源ＡＢＡ处理根系显著降低叶片的蒸腾速度,但对根系的水导有促进作用。结果表明,处理初期低温对根系吸水和植株蒸腾速度的促进与根源ＡＢＡ无关     

氯化镉对葡萄根系线粒体特性与根系活力的影响

以巨峰、玫瑰香、龙眼和泽香4个葡萄品种一年生扦插苗为试材,研究了氯化镉（CdCl₂）处理后葡萄根系线粒体过氧化氢（H₂O₂）、膜通透性转换孔（MPTP）、膜电位（Δψ）、细胞色素C（Cyt c）及根系活力的变化.结果表明：4个葡萄品种经0.5 mmol·L^-1的CdCl₂处理后,根系线粒体H₂O₂含量上升,MPTP开放程度增大,Δψ降低,Cyt c含量下降,根系活力明显降低;其中,H₂O₂含量和Cyt c 含量由高到低的顺序为：巨峰＞泽香＞玫瑰香＞龙眼,而根系活力、MPTP和Δψ由高到低的顺序为：龙眼＞玫瑰香＞泽香＞巨峰.表明巨峰葡萄根系活力比其他品种更易受到CdCl₂的影响,而龙眼葡萄根系活力在4个品种中受CdCl₂影响最小.     

低温处理对植物幼苗生长及根系ATPase同工酶的影响

过去所得的实验表明,植物中ＡＴＰａｓｅ活性变化与耐冷性有关。春小麦和番茄对低温是非常敏感的,当将这两种植物的幼苗在低温下培养时,质膜ＡＴＰａｓｅ活性下降甚至消失。相反,在冬小麦中,当幼苗在低温下处理时,质膜ＡＴＰａｓｅ活性增加．为了研究ＡＴＰａｓｅ同工酶变化与植物耐冷性之间的关系,以小麦等四种植物为材料,在０－１℃低温下处理２天、２周和４周,然后检测幼苗根系内的ＡＴＰａｓｅ同工酶,结果发现,在０－１℃培养时,幼苗根系内ＡＴＰａｓｅ同工酶谱带减少,ＡＴＰａｓｅ同工酶谱带变化与植物幼苗耐冷性呈一定相关性。ＡＴＰａｓｅ同工酶谱带变化可能是受冷害所致。     

Effect of Root Temperature on Cytokinin Activity in Root Exudate of Vitis vinifera L

Root exudates of plants of Vitis vinifera L. cv. Thompson Seedless, grown in nutrient cultures with root temperatures maintained at either 20° or 30° and with shoots at a common air temperature, were assayed for cytokinin activity. After chromatography of freeze-dried sap on paper with n-butanol/acetic acid/water (4:1:1). activity was detected with a soybean callus assay. For both root temperatures, major activity appeared between R_F 0.6 and R_F 0.8, at about the same concentration in each case. The major difference between the 2 samples was the presence of activity at R_F 0.1 to 0.2 in the 20° sample and its absence in the 30° sample.

The higher root temperature resulted in increased shoot and root elongation, increased dry matter accumulation by both shoots and roots, and also altered the morphological appearance of the roots.

     

Effect of Low Temperature on the Protein Metabolism of Wheat Leaves

The effect of low temperature on the protein metabolism of wheat primary leaves was examined. In seedlings transferred from 25 to 5 °C, total soluble protein accumulation, in vivo protein synthesis and breakdown, in vitro protein breakdown, and SDS-PAGE profiles of proteinases in gelatine-containing gels were analysed. Leaf protein content increased within a 7-d period (70 % over the initial value) in plants exposed to 5 °C. The fast protein accumulation observed on days 0 – 2 was mainly attributed to a decreased breakdown. In further days, parallelly to a slowdown in the rate of protein accumulation, the leaf proteolytic activity increased. The incubation temperature also had an influence on the proteolytic activity: Q ₁₀ values for the 15 – 5 °C range were 80 – 200 % higher than those observed for the 25 – 15 °C range. On the other hand, the in vivo protein synthesis capacity, at either 25 or 55 °C, was not significantly modified in cold-treated plants. In addition to the enhanced activities of two serine-proteinases (previously found in control plants by SDS-PAGE analysis), cold-treated plants displayed a new proteinase, which had not been detected so far.     

低温对玉米叶片PEP羧化酶及其调节特性的影响

低温贮存期间,玉米叶片PEP羧化酶活性随贮存时间的延长而明显降低,对效应剂Gly的敏感性也减弱。多羟基醇(甘油和山梨醇)以及PEP羧化酶的正效应剂G-6-P在与Gly和甘油同时作用时,对PEP羧化酶在低温贮存期间的活性和对Gly的敏感性均有保护效应,且对两者的保护程度相一致,表明低温贮存期间PEP羧化酶对效应剂敏感性减弱与其低温失活有直接关系。     

生长温度对烟草叶片环式电子传递活性的影响

高等植物的光合机构在环境胁迫条件下非常容易产生光抑制,环式电子传递在光合机构的光保护中发挥着重要的作用.但是,生长温度对环式电子传递的影响并不清楚.本研究测定了在24/18℃和32/26℃条件下生长40天的烟草(K326)叶片的气体交换、叶绿素荧光和P700氧化还原态的光响应曲线.结果表明,烟草叶片在两种生长温度下的的光合能力、光化学淬灭、非光化学淬灭和通过光系统Ⅱ的电子传递速率(ETR Ⅱ)均没有差异.但是,在强光条件下,生长在24/18℃的叶片比生长在32/26℃的具有更高的通过光系统Ⅰ的电子传递速率(ETRⅠ)和ETRⅠ/ETR Ⅱ比值.短时间的强光处理后,生长在24/18℃的叶片具有较高的光系统Ⅱ最大量子产额(Fv/Fm),表明环式电子传递活性的上调有助于缓解生长在24/18℃的叶片光系统Ⅱ受到的光损伤.综上所述,环式电子传递活性的增强是植物适应较低生长温度的重要策略.     

The Effect of Low Temperature upon Starch, Sucrose and Fructan Synthesis in Leaves

Measurements on plants in a temperature gradient tunnel showthat diurnal accumulation of starch in illuminated leaves wasgreatly reduced at temperatures below 8 °C, whereas sucrosesynthesis was less affected under similar conditions. High chillingsensitivity for leaf starch accumulation was observed in a numberof chilling resistant temperate species. Enzymes of sucroseand fructan metabolism from mature leaves of Lolium temulentumwere less strongly inhibited at low temperatures than enzymesinvolved in starch synthesis. These results are discussed inrelation to carbon partitioning in species which grow and aremetabolically active at chilling temperatures. Lolium temulentum, starch, sucrose, fructan, temperature, enzyme activity, carbon partitioning     

Effects of Low Temperature on Winter Wheat and Cabbage Leaves

Contents of soluble proteins, proline and chlorophyll in winter wheat (Triticum aestivum cv. Doğu-88) and cabbage leaves (Brassica oleracea convar. acephala) during acclimation to low temperature were investigated. When both of the plants species were cold acclimated, soluble proteins, proline and chlorophyll contents were higher than in the controls (non-acclimated). Also protein patterns differed between the plants at control and cold conditions. This revised version was published online in July 2006 with corrections to the Cover Date.     

低温胁迫对螺旋藻脱氢酶活性的影响

低温胁迫试验结果表明,处理的温度越低、天数越长,鄂尔多斯高原碱湖的钝顶螺旋藻S1、引进的钝顶螺旋藻S2和极大螺旋藻S3细胞内脱氢酶活性越低。在每一种处理下,脱氧酶活性高低的排列顺序均为S1〉S2〉S3。脱氢酶活性的Q10值变化范围排列为S1〈S2〈S3。S1的生理活动临界低温为5℃,S2和S3的为15℃。S1对低温有较强的适应性,为耐寒植物;S2和S3为冷敏感植物。     

The Effect of Root Formation on Photosynthesis of Detached Leaves

The CO₂ exchange of fully expanded detached primary leaves ofdwarf bean (Phaseolus vulgaris) with roots on the petioles hasbeen measured. Rates of apparent photosynthesis and respirationincreased as roots grew, decreased when roots were removed,and increased again as root regenerated. Rates of photosynthesisof different leaves were highly correlated with the dry weightof root on their petioles. Photosynthesis and respiration weredecreased when root growth was restricted by kinetin, and wereincreased when root growth was stimulated by IAA. Photosynthesisof an attached leaf declined with time while that of a comparabledetached leaf increased. The results suggest that photosynthesisis correlated with the size of the roots that are a sink forphotosynthates.