高温和加富CO2温室中黄瓜Rubisco活化酶与光合作用的关系

 以温室嫁接黄瓜为试材,研究高温和加富CO₂条件下叶片净光合速率、Rubisco活性、Rubisco活化酶活性、蒸腾速率、胞间CO₂浓度的日变化规律及其相互关系。旨为高温季节温室黄瓜高产优质栽培提供理论依据和实践支持。研究结果表明：①高温 + CO₂条件下,净光合速率、Rubisco活性和Rubisco活化酶活性存在明显的光合日变化,均呈双峰曲线,存在“午休”现象,但与对照相比全天的数值明显增加,其中净光合速率在10：00、11：00、12：00、13：00、14：00和15：00时分别比对照高22%、47%、37%、27%、39%和28%;Rubisco活性在9：00、10：00、11：00、12：00、13：00、14：00和15：00时分别比对照高51%、69%、70%、42%、77%、61%和59%;RCA活性在8：00、9：00、10：00、11：00、12：00、13：00、14：00、15：00和16：00时比对照分别升高了40%、39%、23%、41%、43%、31%、60%、60%和54%;② Rubisco活化酶对光合速率的直接影响较小,其本质是调节Rubisco活性,从而影响光合作用;③高温 + CO₂可以有效提高Rubisco活化酶活力以及胞间CO₂浓度,从而提高光合速率。     

甜瓜幼叶对UV-B辐射的响应

研究了甜瓜幼苗(正甜-2和兴农-8)在UVB辐射下叶片Rubisco、GR及蛋白水解酶活性和H2O2、ASA、GSH含量的变化.结果表明:UV-B辐射显著提高了2个甜瓜品种幼苗H2O2含量和蛋白水解酶活性,降低了Rubisco、ASA、GSH、含量,兴农-8尤为明显.ASA处理能明显促进UV-B辐射下2个品种叶片GSH的合成和H2O2的清除,同时显著抑制蛋白水解酶活性的上升及Rubisco含量的下降.结果说明:UV-B辐射诱导Rubisco含量的降低可通过高水平H2O2产生从而加强蛋白水解酶系统的活化而加速了Rubisco的降解.     

黄瓜Rubisco 活化酶基因CsRCA 表达载体构建与遗传转化

 核酮糖–1,5–二磷酸羧化/加氧酶（Rubisco）是光合碳循环中的关键酶,为了探明其在植物体内的活化机制,用农杆菌介导法将Rubisco活化酶（RCA）基因CsRCA导入黄瓜,分别用PCR、real-time PCR和Western杂交法进行分子检测,分析转基因植株的表达量。酶切鉴定结果显示,CsRCA正向插入植物表达载体pCAMBIA1301的CaMV 35S启动子和NOS终止子之间,成功构建CsRCA的正义表达载体。将pCAMBIA1301-CsRCA导入黄瓜自交系‘08-1’,获得7株转基因植株,拷贝数均为2（非转基因植株的拷贝数为1）,转化率约为3.5%。表达分析结果表明,7株T0代转基因植株叶片的CsRCA mRNA表达量为野生型（WT）的1 ~ 1.98倍,在蛋白水平的表达信号显著强于WT。T1代转基因植株的叶片叶绿素和类胡萝卜素含量、光合速率（P_n）及可溶性糖和淀粉含量均显著高于WT。研究结果表明,利用农杆菌介导法获得了稳定遗传的黄瓜CsRCA转基因植株,CsRCA过量表达能显著提高黄瓜叶片的P_n,增加干物质积累。     

芍药不同品种1,5-二磷酸核酮糖羧化酶活性差异研究

为了揭示芍药不同品种Rubisco活性差异及其与光合速率和羧化效率之间的关系,进而为从芍药露地品种中筛选设施适用品种提供参考,本文以设施栽培中开花良好的‘大富贵’、‘桃花飞雪’和开花较差的‘多叶紫’为对象,对比研究了不同品种在露地栽培条件下Rubisco活性、最大净光合速率和羧化效率的动态变化.结果表明:芍药不同品种Rubisco活性存在差异,在现蕾期和开花期差异显著,而花后期差异不明显.不同品种Rubisco活性动态变化与最大净光合速率和羧化效率动态变化关系不一致.‘大富贵’和‘桃花飞雪’从现蕾期到花后期,Rubisco活性变化呈单峰型,在开花期最高,且在现蕾期和开花期与最大净光合速率和羧化效率动态变化趋势相同,但在花后期变化趋势不同,急剧下降;而‘多叶紫’Rubisco活性变化一直较小,呈平稳态势,这种变化趋势与最大净光合速率和羧化效率动态变化完全相同,表现出高度相关性.因此,露地栽培芍药品种在现蕾期、开花期Rubisco活性高低及其在理蕾期、开花期和花后期与最大光和速率和羧化效率的动态变化关系,可能有助于了解不同品种在设施环境中的生长潜力.     

Combining Phytate/Ca2+ Fractionation with Trichloroacetic Acid/Acetone Precipitation Improved Separation of Low-Abundant Proteins of Wheat (Triticum aestivum L.) Leaf for Proteomic Analysis

Proteomic assessment of low-abundance leaf proteins is hindered by the large quantity of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) present within plant leaf tissues. In the present study, total proteins were extracted from wheat (Triticum aestivum L.) leaves by a conventional trichloroacetic acid (TCA)/acetone method and a protocol first developed in this work. Phytate/Ca²⁺ fractionation and TCA/acetone precipitation were combined to design an improved TCA/acetone method. The extracted proteins were analysed by two-dimensional gel electrophoresis (2-DE). The resulting 2-DE images were compared to reveal major differences. The results showed that large quantities of Rubisco were deleted from wheat leaf proteins prepared by the improved method. As many as (758±4) protein spots were detected from 2-DE images of protein extracts obtained by the improved method, 130 more than those detected by the TCA/acetone method. Further analysis indicated that more protein spots could be detected at regions of pI 4.00–4.99 and 6.50–7.00 in the improved method-based 2-DE images. Our findings indicated that the improved method is an efficient protein preparation protocol for separating low-abundance proteins in wheat leaf tissues by 2-DE analysis. The proposed protocol is simple, fast, inexpensive and also applicable to protein preparations of other plants.     

Rubisco小亚基基因片段的亚克隆及其瞬时表达载体的构建

1,5一二磷酸核酮糖羧化酶／加氧酶位于植物叶绿体中,是绿色植物中含量最丰富的蛋白,它催化CO2固定和光呼吸作用的第一步。从含Rubisco小亚基基因片段的pGR107-rbcS质粒中亚克隆出Rubisco小亚基基因片段,将PCR产物与pGEM-T：Easy载体连接,用EcoRI酶切鉴定酶切重组载体,利用低溶点胶回收大约300bp大小的Rubisco小亚基基因片段,将其回收片段与pSLJ75515瞬时表达载体连接,用EcoRI酶切鉴定,筛选出阳性重组体,即为pSLJ75515-rbcS瞬时表达载体。本实验为进一步研究Rubisco小亚基基因功能和基因沉默机制奠定了基础。     

Effects of co-overproduction of sedoheptulose-1,7-bisphosphatase and Rubisco on photosynthesis in rice

Overproduction of Rubisco did not proportionately increase the rate of CO₂ assimilation (A) in rice probably because the capacity of regeneration of the substrate of Rubisco, ribulose-1,5-bisphosphate (RuBP), could not afford the increased Rubisco capacity. Since sedoheptulose-1,7-bisphosphatase (SBPase) is thought to be one of the limiting factors of RuBP regeneration capacity, SBPase and Rubisco were co-overproduced in rice in order to improve photosynthesis. Although SBPase and Rubisco contents increased by 82–102% and 20–30%, respectively, A did not increase under the conditions of high irradiance and different [CO₂] partial pressures. Thus, co-overproduction of SBPase and Rubisco did not improve photosynthesis in rice. Overproduction and antisense suppression of SBPase did not greatly affect A at high [CO₂], although it is thought to be determined by RuBP regeneration capacity. These results strongly suggest that SBPase does not determine RuBP regeneration capacity in rice. This is likely to be the reason for the unimproved photosynthesis by co-overproduction of SBPase and Rubisco.     

Irrigation Decreases Loss of Leaf Nitrogen and Rubisco During Pod Development in Chickpea

Chickpea ( Cicer arietinum L., var. Pusa 256) plants raised under unirrigated and irrigated field conditions showed a decrease in leaf nitrogen and soluble protein content after flowering during pod development. This was found to be associated with a decrease in Rubisco content after flowering. Leaf nitrogen, soluble protein and Rubisco content, however, were higher in irrigated than in unirrigated plants. The Rubisco content at the flowering and post-flowering stages was 29.43 and 16.59 %, respectively, of leaf soluble protein in unirrigated plants. Under irrigated conditions, the Rubisco content was 49.91 and 37.99 %, respectively, at the flowering and post-flowering stages. These results therefore indicated a decrease in the mobilization of leaf nitrogen by irrigation in chickpea. The findings are discussed in relation to the decrease in seed yield and harvest index by irrigation commonly observed in this crop under north Indian conditions.     

不同品种辣椒幼苗光合与呼吸对弱光的响应

分别在300μmol／m2·s和100μmol／m2·s的人工光源下。研究了“中椒5号”、“中椒6号”、“中椒10号”和“红英达”4个辣椒品种光合和呼吸特性对弱光的响应。结果表明,弱光下幼苗净光合速率(Pn)、暗呼吸速率(Rd)、夜闻呼吸速率(Rn)、饱和光强(SL)、光补偿点(LCP)、光饱和光合速率(Pmax)下降,表观量子效率(AQY)上升。弱光下辣椒Pn的下降是非气孔限制的结果,较低的Rubisco羧化活性是辣椒Pmax下降的一个重要原因。弱光下辣椒叶片叶绿素(Chl．)含量上升,Chl．a／b值和比叶重(SLM)下降。供试品种中“中椒10号”在弱光下具有较低的LCP、Rd、Rn以及较高的AQY,表现出较强的弱光耐受性。     

Effect of short term cold stress on rice seedlings

A method was developed for exposing riceseedlings to low temperatures for shortperiods. These seedlings were from 70F₉ inbred lines derived originallyfrom a hybrid of a salt tolerant cultivar,which provided a source of resistance toabiotic stress, and a non salt tolerantcultivar as the other parent. Seedlingswere grown hydroponically in a warm growthroom then placed in the air above afreezing bath for 6 hours at –0.2 ^°C,–1.0 ^°C or –2.0 ^°C beforereturning them to the growth room for a7–10 day period. Seedling survival in theinbred lines of rice was compared afterexposure to these temperature treatments toidentify the presence of low temperaturetolerance. An average survival of 93%occurred 7days after exposures to –0.2, and–1.0 ^°C and a survival of 35% afteran exposure of –2.0 ^°C. The non-salttolerant parent cultivar was killed byexposure to –2.0 ^°C but the salttolerant parent survived. The effect of lowtemperature exposure was examined in moredetail in lines selected for lowtemperature tolerance and susceptibility.Alterations to the total leaf proteinprofile, including fragmentation ofRubisco, were observed in these lines butno obvious difference was detected betweensusceptible and tolerant individuals.