低温胁迫对水稻幼苗不同叶龄叶片叶绿素荧光特性的影响

以‘蜀恢162’(‘Shuhui 162’)、‘糯89-1’(‘Nuo 89-1’)、‘蜀恢162/糯89-1’(‘Shuhui 162/Nuo 89-1’)、‘奇妙香’(‘Qimiaoxiang’)和早黄矮(‘Zaohuang’ai’)5个水稻(Oryza sativa L.)品种(系)为研究对象,采用叶绿素荧光成像系统研究了低温(4℃)胁迫对水稻3叶期幼苗不同叶龄叶片叶绿素荧光特性的影响。结果表明:经低温胁迫处理后,5个水稻品种(系)幼苗3个叶龄叶片的各叶绿素荧光参数变化有明显差异,其中第一叶的各项参数均降至0。经低温处理后5个水稻品种(系)幼苗3片叶片的PSⅡ最大光化学量子产量(Fv/Fm)均明显小于对照(25℃),其中第一叶的降低幅度最大、第三叶最小。经低温胁迫处理后,5个水稻品种(系)幼苗第三叶的非光化学淬灭系数(qN)均显著大于对照,耐冷性品种‘糯89-1’幼苗第二叶的qN较对照显著增大,而其他水稻品种(系)幼苗第二叶的qN均显著小于对照;‘糯89-1’幼苗第二叶的光化学淬灭系数(qP)较对照略有增大,第三叶的qP显著大于对照;‘早黄矮’幼苗第三叶的qP也大于对照但差异不显著,而其余水稻品种(系)幼苗第二叶和第三叶的qP均显著小于对照。经低温胁迫后5个水稻品种(系)幼苗3片叶片的PSⅡ最大相对电子传递速率(rETRmax)和半饱和光强(Ik)均显著小于对照;除‘糯89-1’幼苗第三叶外,5个水稻品种(系)幼苗3片叶片的快速光响应曲线初始斜率(α)也均显著小于对照,总体上第一叶的rETRmax、Ik和α下降幅度最大、第三叶最小。研究结果揭示:受低温胁迫后,叶片自身生理差异是导致水稻幼苗不同叶龄叶片受伤害程度不同的主要因素。     

低温处理葡萄根系对叶片PSII活性的影响

以美乐葡萄(Vitis vinifera cv. ‘Merlot’)幼苗为试材, 对叶片进行霜冻胁迫的同时控制土壤降温过程, 造成根系冷胁迫(2°C)和冻胁迫(0°C)。测定霜冻胁迫后和恢复期间叶片的快速叶绿素荧光参数, 并分析低温胁迫不同根系对叶片霜冻害程度的影响。结果表明, 根系在不同低温胁迫下会影响叶片对霜冻的反应, 根系冻胁迫造成叶片严重的霜冻伤害, 光系统II (PSII)反应中心活性难以得到恢复; 根系冷胁迫能避免叶片严重的低温伤害, 低温胁迫后PSII的活性也能很快恢复。     

冷锻炼对甜椒叶片光合作用及其低温光抑制的影响

以冷敏感植物甜椒 (CapsicumannuumL .)抗冷性不同的两个品种为试材 ,利用CIRAS 1光合测定系统和FMS2调制式荧光仪 ,在控温控光条件下分析比较了冷锻炼苗与未经锻炼苗的叶片光合特性、叶绿素荧光参数对温度的响应。结果表明 ,随着温度的降低 ,无论是否经过锻炼 ,低温主要通过抑制碳同化能力来影响光合作用 ,并使光能过剩 ,导致低温光抑制。提高环境CO2 浓度以增强暗反应对光能的利用 ,低温光抑制减轻。 5d的亚适温锻炼过程中甜椒叶片已发生一定程度的光抑制 ,但锻炼苗叶片能在低温下维持较高的光系统II光化学效率(ФPSII)、光化学猝灭系数 (qP)和光适应下光系统II最大光化学效率 (Fv′/Fm)值 ;冷锻炼提高了两品种低温下对光抑制的抗性 ,而且对抗冷品种的作用效果更明显     

转Bt基因水稻对白符跳虫适应低温环境与排泄的影响

【目的】为探讨转基因Bt水稻种植对土壤重要分解者跳虫的潜在生态风险性。【方法】将同一非转基因亲本插入3种不同的Bt基因(cry1C、cry2A、cry1Ab/Ac)的转Bt基因水稻叶片残体饲养白符跳虫Folsomia candida,通过放入不同低温环境下观察其存活率和粪便排泄速率以分析白符跳虫取食Bt水稻叶片后的适应低温行为。【结果】结果表明,3种转Bt基因水稻相对于非转基因亲本水稻品种而言,不会影响白符跳虫的适应低温环境;而不同Bt基因插入后导致的水稻成分的变化可能影响了白符跳虫对水稻残体的偏好性,进而影响其在低温环境下的适应行为。【结论】结果可为评估转Bt水稻对土壤生态系统影响提供参考价值,为转Bt水稻安全性评价提供科学的依据。     

紫茎泽兰茎和叶片色素及叶绿素荧光相关参数对不同温度处理的响应差异

通过人工模拟低温(12 ℃)、常温(25 ℃)、高温(35 ℃)生境,对紫茎泽兰茎和叶片色素(叶绿素a,b,类胡萝卜素,花青素)含量和组成、叶绿素荧光参数包括最大荧光效率Fv/Fm、光系统II效率ФpsⅡ、光化学淬灭系数qP、非光化学淬灭系数NPQ、热耗散速率HDR进行了动态测定.结果表明:在低温和高温胁迫处理过程中,茎和叶片的色素含量和组成随时间变化趋势基本一致,但茎的变化幅度明显低于叶片.与此类似,茎和叶片叶绿素荧光参数在不同温度处理过程中的变化趋势一致,但是茎各指标的变化幅度普遍小于相应叶片的变化幅度:低温下,茎的ФpsⅡ和ETR较对照最大降低44%,而叶片降低超过60%;高温下,茎的ФpsⅡ和ETR较对照下降16%～57%;而叶片则下降50%～80%.其产生原因在于:在温度胁迫条件下,叶片获取光能用于光化学过程的份额(qP)大幅下降,用于热耗散的份额(NPQ)大幅上升,茎的情况相反,所获取光能用于光化学电子传递的份额较常温下更多、用于热耗散的减少,这使得茎的耗散速率(HDR)升高的幅度显著低于叶片的升高幅度(p<0 05).综合3个温度的测定结果,茎的叶绿素含量相当于叶片的1/3～1/6,茎的叶绿素a/b较叶片低20%左右,但是光合电子传导速率ETR与叶片相当,这使得茎的光合色素利用效率ETR/Chl远高于叶片.叶片和茎叶绿素荧光参数在不同温度处理下变化趋势一致、但叶片的变化幅度远大于茎的这一响应差异,使得在适宜温度下紫茎泽兰叶片光合对整体光合贡献增大,而在温度胁迫条件下茎的光合贡献增大,这种策略使得这一植物在适宜生境下通过叶片光合、快速生长迅速占据生境,而在逆境条件下茎等非同化器官光合贡献增加,有利于其在逆境中的保存.     

杂交水稻灌浆期光合生理特性的研究

本文对3个杂交水稻及其亲本灌浆期叶绿体诱导荧光动力学光谱、活体叶片光合放氧速率、叶绿体低温(77k)荧光发射光谱与二磷酸核酮糖羧化酶的活性研究结果表明:强优势的杂种均表现出高活性和高效率,而弱优势的杂种则相反。并对光合优势的生理机制进行了分析。     

低温胁迫对水稻幼苗PEP羧化酶的影响

水稻幼苗经低温(0℃)处理后,叶片中PEP羧化酶活性明显地降低.Km值增大。经1—2天低温处理者,增加反应底物的浓度,有减少PEP羧化酶活性降低的幅度;当低温伤害严重时(0℃4天),这种效应则消失。这些结果表明:水稻叶片中PEP羧化酶对低温反应是敏感的,其活性的下降是由于该酶对底物的亲和力的降低。     

转gfp基因大麦中gfp基因表达的半定量RT-PCR方法分析

本研究以5种转绿色荧光蛋白基因(gfp)大麦的不同株系(A,B,C,D,F)及野生型Igri为材料,对供试材料的叶片中gfp基因的荧光表达量利用荧光显微镜测定,并对各株系进行半定量RT-PCR分析。研究结果表明:5种转基因大麦叶片的gfp基因荧光表达量不同,检测结果为FA≈B≈CD;同一转基因材料(C、F)的gfp基因表达存在组织差异,其花粉、叶片及根尖等不同器官中的gfp表达强度不同;转gfp基因D系的gfp基因沉默是gfp基因在转录水平失活。     

转玉米PEPC基因水稻中有限的C4光合微循环及其生理作用

用转PEPC基因水稻(OryzasativaL.subsp.japonicaKitaake)和原种水稻Kitaake为材料,研究了不同基因型水稻叶片中的C4光合微循环及其功能。通过测定与光合C4途径有关的关键酶,如磷酸烯醇式丙酮酸羧化酶(PEPC)、NADP -苹果酸酶(NADP -ME)、NADP -苹果酸脱氢酶(NADP -MDH)和丙酮酸磷酸双激酶(PPDK),说明原种水稻叶片中具有完整的C4光合酶体系;用外源OAA或MA饲喂叶切片或叶绿体后明显增加光合速率,证明原种水稻中具有一个有限的光合C4微循环。将玉米的PEPC基因导入原种水稻后,可大幅度提高光合C4微循环的速率。测定不同基因型的CO2交换速率,看出水稻中C4光合微循环的增强有提高净光合速率(Pn)和降低光呼吸速率/净光合速率(Pr/Pn)比值的作用。叶绿素荧光特性分析表明,C4光合微循环的增强伴随着PSⅡ电子传递效率(Fv/Fm)和光化学猝灭(qP)的增加以及非光化学猝灭(qN)的降低;这些结果为通过基因工程手段提高作物光合效率的遗传育种提供了科学根据。     

温州蜜柑叶片气体交换和叶绿素荧光对低温的响应

研究了低温对温州蜜柑叶片气体交换和叶绿素荧光的影响 ,结果表明 :(1) 8℃低温处理 18h对气体交换和叶绿素荧光影响不大。 (2 ) 2℃低温处理 15h后 ,净光合速率 (Pn)、气孔导度 (Gs)、羧化效率 (CE)下降 ,胞间CO2 浓度 (Ci)升高 ,表观量子效率 (AQY)和叶绿素荧光参数F0 及Fv/Fm没有显著变化。 (3)室外自然低温处理 2和 7d ,Pn、Gs、CE、饱和CO2 光合速率、AQY及Fv/Fm显著下降 ,Ci及F0 显著升高 ;在 2 0℃室内 ,Fv/Fm、F0 和AQY比CE和Pn恢复快。 (4 )低温胁迫使Jf(依据叶绿素荧光参数计算所得的电子传递速率 )和Jc(依据CO2 同化测定所得的电子传递速率 )下降 ,Jf/Jc 值升高。 (5 )低温处理降低了Pn和光呼吸速率 (Pr) ,但Pr下降的速率小于Pn下降的速率     

光和暗条件下低温对黄瓜和水稻叶绿素蛋白质复合体的影响

本试验以黄瓜和水稻幼苗为材料,研究了光照和黑暗条件下低温对植物叶绿素蛋白质复合体的影响。SDS—PAGE电泳结果表明:5℃及12h 280μmol m~(-2)S~(-1)处理2d,Chl-蛋白质复合体的降解明显大于5℃暗低温处理;低温与光照对P700-CPa_1的影响大于LHCP。叶绿素荧光测定表明;5℃及12h 280μmol m~(-2)s~(-1)的处理对PSⅡ的影响亦大于暗低温处理。由此认为:低温与光对植物叶绿体的PSⅠ和PSⅡ都有明显的影响,其机理可能与常温下高光强引起的光抑制相类似;不同的是低温下中等光强就能引起光抑制。因此,在光照低温下往往加剧植物冷害的发生。     

低温胁迫对水稻幼苗抗坏血酸含量的影响

随着低温时间的延长,水稻幼苗抗坏血酸和GSH的含量均平行地下降,抗坏血酸含量与电解质渗出率之间呈负相关。增强低温胁迫程度,随着抗坏血酸含量逐渐减少,MDA含量则逐渐增加。经低温处理后在不同光强下恢复时,抗坏血酸和MDA含量的变化不同。抗氧化剂(GSH、半胱氨酸和巯基乙醇)的预处理可抑制低温引起的抗坏血酸含量的下降。     

冷锻炼和ABA诱导水稻幼苗提高抗冷性期间膜保护系统的变化

冷锻炼和ＡＢＡ处理提高了水稻幼苗叶绿体ＳＯＤ和ＧＲ活性及叶片抗氧化剂ＡｓＡ和ＧＳＨ的含量,降低了膜电解质泄漏,增强了幼苗的抗冷性．等电聚焦电泳分析表明,冷锻炼和ＡＢＡ处理苗叶绿体ＳＯＤ三条同工酶带和ＧＲ１、２、３和６同工酶带都有不同程度的增强．低温胁迫后,处理和未处理首的ＳＯＤ、ＧＲ活性和ＡＳＡ、ＧＳＨ含量均有所下降．但处理苗的水平仍维持在未处理苗之上．亚胺环已酮可抑制因冷锻炼和ＡＢＡ诱导增加的ＳＯＤ和ＧＲ活性,并使叶片电解质泄漏增大．本试验结果表明冷锻炼或ＡＢＡ诱导水稻幼苗抗冷性提高时,对防御活性氧的保护系统有类似的影响。     

Relative contributions of photochemical and non-photochemical routes to excitation energy dissipation in rice and barley illuminated at a chilling temperature

The mechanistic basis for differential sensitivities to chilling-induced photoinhibition among two rice ( Oryza sativa L.) cultivars (an Indica and a Japonica type) and one barley cultivar ( Hordeum vulgare L. cv. Albori) was examined. When leaf segments were exposed to moderate illumination at 4°C, a sustained decrease in the photochemical efficiency of photosystem (PS) II measured as the ratio of variable to maximal fluorescence (F_v/F_m) was observed for several hours. An analysis of fluorescence quenching revealed a sudden drop in PSII-driven electron transport rate (ETR) and a rapid rise in the reduction state of the primary electron acceptor Q_A upon exposure to chilling in moderate light. There was no appreciable difference in the level of non-photochemical quenching (NPQ) nor in the xanthophyll cycle activity between Japonica rice and barley. However, barley was capable of sustaining a higher ETR, thereby keeping a lower reduction state of Q_A throughout the chilling for 6 h. The Indica rice was characterized by the lowest ability to develop the xanthophyll cycle-associated NPQ, particularly the fast relaxing NPQ component (qf), accompanied by the highest reduction state of Q_A and photoinhibitory quenching (qI). It is concluded that the lower susceptibility of barley to chilling-induced photoinhibition than Japonica rice is attributable to its higher potential to dissipate excess light energy via a photochemical mechanism, whereas Indica rice is more sensitive to photoinhibition at a chilling temperature than Japonica rice, due primarily to its lower capacity to develop an efficient NPQ pathway.     

Chilling Sensitivity in Oryza sativa: The Role of Protein Phosphorylation in Protection against Photoinhibition

The effects of exposure to low temperature on photosynthesis and protein phosphorylation in chilling-sensitive and cold-tolerant plant species were compared. Chilling temperatures resulted in light-dependent loss of photosynthetic electron transport in chilling-sensitive rice (Oryza sativa L.) but not in cold-tolerant barley (Hordeum vulgare L.). Brief exposure to chilling temperatures (0-15°C, 10 min) did not cause a significant difference in photosynthetic O₂ evolution capacity in vivo between rice and barley. Analysis of in vivo chlorophyll fluorescence in chilling-sensitive rice suggests that low temperatures cause an increased reduction of the plastoquinone pool that could result in photoinhibitory damage to the photosystem II reaction centers. Analysis of ³²P incorporation into thylakoid proteins both in vivo and in vitro demonstrated that chilling temperature inhibited protein phosphorylation in rice, but not in barley. Low temperature (77 K) fluorescence analysis of isolated thylakoid membranes indicated that state I to state II transitions occurred in barley, but not in rice subjected to chilling temperatures. These observations suggest that protein phosphorylation may play an important role in protection against photoinhibition caused by exposure to chilling temperatures.     

外源ABA对黄瓜幼苗抗低温胁迫的作用

在光照下对黄瓜(Cucuntis sativus L.)离体子叶圆片和幼苗分别使用10~(-6)mol/l 与10~(-4)mol/l ABA 处理,有防御低温伤害的作用,表现为降低子叶圆片的电解质渗漏,阻抑幼苗子叶的谷胱甘肽含量的下降和膜脂过氧化产物丙二醛(MDA)的累积,减缓叶片的光合作用的下降和叶绿素荧光的猝灭,提高幼苗的存活率。但这种作用可被黑暗和光合抑制剂(DCMU)所限制。     

氧化胁迫对水稻幼苗抗冷力的影响

利用Ｈ２Ｏ２和甲基紫精（ＭＶ）对水稻幼苗作三种不同程度的氧化胁迫预处理。结果表明：轻度氧化胁迫预处理（１０ｕｍｏｌ／ＬＨ２Ｏ２或１０ｕｍｏｌ／ＬＭＶ处理４ｈ）提高了水稻幼苗的抗冷力,严重氧化胁迫预处理（１０ｕｍｏｌ／ＬＨ２Ｏ２或１０ｕｍｏｌ／ＬＭＶ分别处理１６ｈ和４０ｈ）则削弱水稻幼苗的抗冷力。氧化胁迫预处理刺激了水稻幼苗叶片抗氧化酶（ＳＯＤ,ＣＡＴ,ＰＯＸ和ＡＰＸ）的活性。经冷胁迫后,不同预处理苗的叶片抗氧化酶活性、膜脂过氧化和膜结构的变化趋势不同：轻度氧化胁迫预处理使幼苗仍保持较高的抗氧化酶活性,减轻了由冷胁迫引起的膜脂过氧化和细胞膜的渗漏程度,而严重氧化胁迫预处理则相反。因此,水稻幼苗对氧化胁迫感知并作出反应的机制（氧化应激机制）在水稻幼苗对低温反应和适应过程中起着很重要的调节作用。     

Photochemical Efficiency of PSⅡand Membrane Lipid Peroxidation in Leaves of indica and japonica Rice (Oryza sativa) Under Chilling Temperature and Strong Light Stress Conditions

Relationships between fluorescence parameters and membrane lipid peroxidation in leaves of indica and japonica rice (Oryza sativa L.) during later growth stage were studied under chilling temperature and strong light stress conditions. Results showed that D1 protein contents of PSⅡ in photosynthetic app aratus dropped, the generation of antheraxanthin (A) and zeaxanthin (Z)of xanthophyll cycle were inhibited partly, PSⅡ photochemical efficiency （Fv/Fm）and non photochemical quenching (qN) were also decreased obviously. In addition, endogenous active oxygen scavenger—superoxide dismutase (SOD) reduced, superoxide anion radical (O[SX(B-*3)-[]·[SX]]2) and malondialdehyde (MDA) accumulated, as a result, photooxidation of leaves occurred under chilling temperature and strong light stress conditions. Obvious differences in the changes of the above mentioned physiological parameters between indica and japonica rice were observed. Experiments in leaves treated with inhibitors under chilling temperature and strong light conditions showed that indica rice was more sensitive to chilling temperature with strong light and subjected to photooxidation more than japonica rice. Notable positive correlation between D1 protein contents and Fv/Fm or (A+Z)/(A+Z+V), and a marked negative correlation between Fv/Fm and MDA contents were obtained by regression analysis in indica and japonica rice during chilling temperature and strong light conditions. According to the facts mentioned above, it was inferred that PSⅡ photochemical efficiency（Fv/Fm） was the key index to forecast for the prediction of photooxidation under stress circumstances and the physiological basis were the synthetic capacity of D1 protein and the protection of xanthophyll cycle.     

Characteristics of chlorophyll fluorescence and antioxidative system in super-hybrid rice and its parental cultivars under chilling stress

Characteristics of chlorophyll fluorescence and antioxidative system were investigated in rice (Oryza sativa L.) super-hybrid Liangyoupeijiu (LYPJ), maternal cultivar Peiai64s, and paternal cultivar indica rice 9311 under chilling stress. During 6-d chilling treatment, chlorophyll content of all three genotypes was gradually declined. However, the decrease in photosystem 2 (PS 2) maximum photochemical efficiency (F_v/F_m) and quantum yield of PS 2 (Φ_PS2) was less expressive in LYPJ than in parental cultivars The electrolyte leakage and malondialdehyde content in all cultivars increased after chilling treatment, but LYPJ exhibited the least increasing tendency. Activities of superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione reductase (GR) were higher in LYPJ than in parental cultivars. The results demonstrated that tolerance to chilling stress in LYPJ might be adopted mostly from its maternal cultivar.