外源海藻糖对PEG渗透胁迫下小麦Rubisco及其活化酶的影响

以抗旱品种‘晋麦47’和干旱敏感品种‘郑引1号’为材料,通过室内水培试验研究了外源海藻糖对PEG渗透胁迫下小麦叶片净光合速率、1,5-二磷酸核酮糖羧化酶/加氧酶(Rubisco)和1,5-二磷酸核酮糖羧化酶/加氧酶活化酶(RCA)含量和相关基因表达特性的影响。结果表明:(1)外源海藻糖和渗透胁迫均能显著增加2个小麦品种叶片海藻糖含量。(2)渗透胁迫显著降低了2个品种小麦叶片的净光合速率,而外源海藻糖能显著缓解受胁迫小麦叶片净光合速率的降低幅度。(3)渗透胁迫仅使‘郑引1号’Rubisco大亚基基因(rbcL)相对表达量及相应蛋白含量显著降低;渗透胁迫显著降低了小麦RCAα和β亚基基因相对表达量,并显著降低RCA蛋白含量,而外源海藻糖不能缓解RCA蛋白含量的降低;渗透胁迫显著降低了Rubisco总活性、初始活性、活化状态及RCA活性,而外源海藻糖则能显著缓解上述酶活性的下降。(4)小麦叶片净光合速率与其rbcL、RCAα和β亚基基因相对表达量及Rubisco总活性、初始活性、活化状态及RCA活性均呈极显著正相关关系。研究发现,在渗透胁迫条件下,外源海藻糖主要从翻译后层面对小麦叶片Rubisco和RCA的活性发挥显著保护作用,从而缓解了小麦净光合速率的降低。     

低温锻炼对水稻幼苗叶片中Rubisco的影响

低温锻炼能提高水稻幼苗的抗冷力,低温锻炼虽不能明显提高Ｒｕｂｉｓｃｏ活性,却提高了冷却条件下Ｒｕｂｉｓｃｏ的稳定性和增强了胁迫后正常生长条件下其活性的恢复能力。分别用火箭免疫电泳分析Ｒｕｂｉｓｃｏ蛋白和ＳＤ－ＳＰＡＧＥ分析大,小亚基量表明：低温锻炼未提高Ｒｕｂｎｉｓｃｏ蛋白的合成能力,但增加了大,小亚基的合成量。     

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。     

蔗糖对水稻幼苗叶片谷氨酰胺合成酶和1,5-二磷酸核酮糖羧化酶/加氧酶的影响

报道了在光照和暗处培养下,不同的浓度的蔗水稻幼苗叶片GS及其同工酶、1,5－二磷酸核酮糖羧化酶／加氧酶（Rubisco）的影响。无论是在光照或在暗处,蔗糖对GS活性均有抑制作用,尤其是在较高蔗糖下作用更为明显;虽然Rubisco及可溶性蛋白的水平在光照和暗处有显著的差别,但蔗糖对其未见明显影响。NativePAGE与活性染色表明,在光照下或在暗处,蔗糖对GS2的抑制蔗糖浓度升同而加强,但对GS1未有明显影响。这些结果提示,在水稻幼苗生长中,蔗糖不能象不光一样诱导叶水GS活性及其同工酶表达。     

不同光质对烟草叶片组织结构及Rubisco羧化酶活性和rbc、rca基因表达的影响

通过对烟草植株覆盖白、红、黄、蓝、紫色滤膜获得不同光质,研究了烟草叶片在7～70d的生长发育期内,不同光质处理对烟叶组织结构特征、核酮糖1,5-二磷酸羧化酶/加氧酶（Rubisco）羧化酶活性、Rubisco基因（rbc）表达及其活化酶（Rca）基因（rca）表达的影响。结果表明,与黄膜处理下生长的烟叶相比,红、蓝、紫膜处理下生长的烟叶有较高的叶片厚度、栅栏组织厚度、海绵组织厚度、栅栏细胞密度和较小的组织空隙率。此外,红、蓝、紫膜处理的叶片有较高的Rubis-co羧化酶活性和净光合速率及较强的rbc和rca基因表达。实验结果表明不同光质对烟草叶片的组织结构特征有显著影响,光质可能通过影响Rubisco羧化酶活性进而影响叶片光合效率,而光质、叶片组织结构和光合效率之间存在某种程度的相互联系。     

光照强度对雨生红球藻合成虾青素的影响

雨生红球藻（Haematococcus pluvialis）是一种单细胞绿藻,在强光照射条件下能够合成并大量积累具有强抗氧化性的次生类胡萝卜素-虾青素。然而,其合成机理目前还不明确,导致虾青素诱导合成过程中操作的盲目性,限制了虾青素产量的提高。     

遮荫对凤眼莲生长及其生理适应机制

2011年于南京对凤眼莲进行不同光处理(全天遮荫、7:00～11:00遮荫、11:00～15:00遮荫和15:00～19:00遮荫),遮荫下光强为自然光强的70%,以全自然光为对照(CK),处理25d,每5d分别测定生长指标、单株鲜重、单株干重、光合净光合速率(Pn)、抗氧化酶、非酶系统的总抗氧化能力(AOC)以及1,5-二磷酸核酮糖羧化加氧酶(Rubisco)活性等生理指标,以阐明光强对其生长以及适应机制,为提高凤眼莲生物量提供依据。结果显示:与CK相比,全天遮荫明显降低了叶片数量、叶面积、根长、分株和单株鲜重等生长指标,而11:00～15:00遮荫虽抑制叶片数量和子代分株的产生,但促进根的伸长和叶面积的增加,其单株鲜重比对照增加;同时,还可诱导最大净光合速率(Pnmax),超氧化物歧化酶(SOD)、过氧化物酶(POD)、抗坏血酸过氧化物酶(APX)、谷胱甘肽还原酶(GR)和AOC活性的增加,减少了体内丙二醛(MDA)和超氧阴离子自由基(O2.-)的累积,稳定Rubisco活性,减轻光氧化胁迫。研究表明,全天遮荫不利于凤眼莲的生长,但中午遮荫有利于缓解光氧化伤害,促进其物质累积。     

低温锻炼对水稻幼苗叶片中Rubisco的影响

低温锻炼能提高水稻幼苗的抗冷力,低温锻炼虽不能明显提高Rubisoc活性,却提高了冷胁条件下Rubisoc的稳定性和增强了胁迫后正常生长条件下其活性的恢复能力。分别用火箭免疫电泳分析Rubisoc蛋白和SDS-PAGE分析大、小亚基量表明：低温锻炼未提高Rubisoc蛋白的合成能力,但增加了大、小亚基的合成量。经锻炼、冷胁迫以及恢复后Lsu／Ssu比值的变化主要是由于小亚基对温度变化更敏感所致。Rubisco酶特性分析表明,低温锻炼有减少水稻幼苗Rubisoc表面的SH数,并提高Rubisco蛋白在高、低温下的稳定性。     

宁波港压载水浮游植物多样性的研究

为了避免压载水作为媒介转移外来物种并造成污染危害,利用分子生物学技术研究宁波港来自印度洋、新加坡和美洲的压载水浮游植物。结果显示,新加坡和美洲的压载水没有检测到浮游植物。而印度洋的压载水里面含有硅藻门的直链藻属(Aulacoseirasp.)、海链藻属(Thalassiosirasp.)、骨条藻属(Skeletonemasp.)、冠盘藻属(Stephanodiscussp.)和星盘藻属(Discostellasp.);隐藻门的全沟藻属(Teleaulaxsp.)和斜片藻(Plagioselmissp.);绿藻门的括小球藻属(Chlorellasp.)、卵囊藻属(Oocystissp.)和Pseudococcomyxasp.;链形植物门包括新月藻属(Closteriumsp.)。同宁波港的港池浮游植物相比,生长速度快、抗逆性强的硅藻数量明鲜增多,有些种类是外来的。     

佛手低温胁迫相关基因的差异表达

佛手(Citrus medica L.var.sarcodactylis Swingle)是药用及观赏价值都很高的经济植物,但它对低温反应敏感,容易发生冻害现象.因此,了解其冷敏感机制对提高抗寒性起着重要的作用.以佛手为试材,-4℃低温处理24 h后,采用mRNA差异显示技术(DDRT-PCR)和半定量RT-PCR技术,分析和鉴定与冷敏感相关的差异表达基因.DDRT结果获得差异片段121个,经生物信息学分析,差异表达序列中有33条为功能已知序列,88条为未知序列(其中5条具有开放性阅读框);半定量结果获得34个阳性基因片段,其中上调基因片段29个,下调基因片段5个.除了3个基因功能未知外,其余基因主要涉及植物防御/应激反应,细胞壁的修饰,信号转导,代谢,氨基酸转运,氧化损伤,转录和蛋白质的合成,其中与植物防御/应激反应和光合作用有关的基因可能是造成佛手寒敏感的主要原因.     

Inhibition of photosynthesis by osmotic stress in pea (Pisum sativum) mesophyll protoplasts is intensified by chilling or photoinhibitory light; intriguing responses of respiration

The effects of reduced osmotic potential on photosynthesis and respiration were studied in mesophyll protoplasts of pea (Pisum sativum). Osmotic stress was induced by increasing the sorbitol concentration in the medium from 0·4 kmol m⁻³ (-1·3 MPa) to 1·0 kmol m⁻³ (-3·1 MPa). Protoplasts lost up to 35% of the maximum capacity of photo-synthetic carbon assimilation (but not PS II mediated activity) soon after exposure to 1·0 kmol m⁻³ sorbitol. The response of protoplast respiration to osmotic stress was intriguing. Respiration was stimulated if stress was induced at 25°C, but was inhibited when protoplasts were subjected to osmotic stress at 0°C. Photosynthesis was also much more sensitive to osmotic stress at 0°C than at 25°C. The inhibitory effects of osmotic stress on photosynthesis as well as respiration were amplified by not only chilling but also photoinhibitory light. The photosynthetic or respiratory activities of protoplasts recovered remarkably when they were transferred from hyperosmotic (1·0 kmol m⁻³ sorbitol) back to iso-osmotic medium (0·4 kmol m⁻³ sorbitol), demonstrating the reversibility of osmotic-stress-induced changes in protoplasts. Respiration was more resistant to osmotic stress and was quicker to recover than photosynthesis. We suggest that the experimental system of protoplasts can be useful in studying the effects of osmotic stress on plant tissues.     

Light-dependent damage to photosynthesis in olive leaves during chilling and high temperature stress

Abstract The leaves of olive are long lived and likely to experience both chilling and high temperature stress during their life. Changes in photosynthetic CO₂ assimilation resulting from chilling and high temperature stress, in both dim and high light, are investigated. The quantum yield (φ) of photosynthesis at limiting light levels was reduced following chilling (at 5°C for 12 h), in dim light by approximately 10%, and in high light by 75%; the difference being attributed to photoinhibition. Similar reductions were observed in the light-saturated rate of CO₂ uptake (A_max). Decrease in A_max correlated with a halving of the leaf internal CO₂ concentration (c_i), suggesting an increased limitation by stomata following photoinhibition. Leaves were apparently more susceptible to photoinhibitory damage if the whole plant, rather than the leaf alone, was chilled. On return to 26 °C, I he photosynthetic capacity recovered to pre-stress levels within a few hours if leaves had been chilled in high light for 8 h or less, but did not fully recover from longer periods of chilling when loss of chlorophyll occurred. Leaves which were recovering from chilling in high light showed far more damage on being chilled a second time in high light. Three hours in high light at 38 °C reduced φ by 80%, but φ recovered within 4h of return to 26 °C. Although leaves of Olive are apparently less susceptible to photoinhibitory damage during chilling stress than the short-lived leaves of chilling-sensitive annual? crops, the results nevertheless show that photoinhibition during temperature stress is potentially a major factor influencing the photosynthetic productivity of Olive in the field.     

植物光合系统对高温胁迫的响应机制

温度变化是影响植物生长和发育的一个非常重要的因素,而光合作用是植物对温度变化最为敏感的生理过程.高温胁迫给植物光合器官造成了严重的危害,但在高温胁迫下,植物并不是消极被动的,并且能够在生理生化及分子水平上发生各种变化来渡过逆境.本文结合当今国内外研究进展,从光合系统热量耗散与光合修复的相关因素,如类囊体膜上相关蛋白,热激蛋白,水杨酸,抗过氧化物酶及抗坏血酸等几个方面展开分析,阐述了植物光合系统对高温胁迫的防御机制,并对今后的研究方向进行了探讨和展望.     

紫球藻多糖浓度增加对其他逆境适应性的改变

紫球藻 (Porphyridiumsp .)是一种海水单细胞红藻 ,是多种天然产物的来源。在其培养繁殖过程中 ,能够合成藻胆蛋白、高不饱和脂肪酸、硫酸酯多糖等生物活性物质 ,具有广阔的应用前景。盐胁迫会导致紫球藻的结合态多糖浓度的增加 ,由此可能产生相应的耐盐性的提高 ,并有利于对其他逆境的适应。该项研究采用外加紫球藻多糖或采用盐逆境诱导紫球藻多糖的积累 ,然后解除盐逆境的胁迫的方法获得多糖含量有显著提高的紫球藻试材 ,再给与其他的逆境 :如光抑制 ,低温处理 ,并测定主要的生理生化参数。试验结果表明 ,外加 0 .0 5 %紫球藻多糖的藻细胞光合效率 ,在光抑制条件下 ,低于不加多糖的对照 ,但在低温 ( 4℃ )时 ,高于对照。外加多糖对PSⅡ没有显著影响。紫球藻在去盐后的 48h恢复培养时间内 ,多糖的含量以及光抑制和低温条件下的光合效率都逐渐恢复到对照的水平。但是 ,去盐恢复培养的紫球藻PSⅡ效率在光抑制条件下却高于加盐及未加盐的两种对照 ,显示盐诱导的紫球藻多糖可能增加了PSⅡ对光抑制的忍耐程度。