水稻剑叶衰老期Rubisco活化酶对Rubisco活力和光合速率的调节

为明确Rubisco活化酶在叶片衰老期间是否对Rubisco羧化活性和光合速率起调节作用,本文研究了水稻剑叶衰老过程中叶片光合速率、可溶性蛋白含量、Rubisco初始羧化活力及含量,Rubisco活化酶活力及含量。结果表明:净光合速率与Rubisco初始羧化活力和Rubisco活化酶的活力间分别为r2=0.966 3和r2=0.702,Rubisco初始羧化活力与Rubisco活化酶的活力和含量间分别为r2=0.810 3和r2=0.814 3, Rubisco活化酶含量与Rubisco和可溶性蛋白间分别为r2=0.925 7和0.867 5, Rubisco活化酶的活力与含量间r2=0.758 7。Rubisco活化酶的含量占Rubisco含量的0.5%～1.0%,占叶片可溶性总蛋白质的0.5%～0.6%,随着剑叶衰老Rubisco活化酶所占的比值加速下降。这表明水稻剑叶衰老期间,Rubisco活化酶对维持Rubisco初始羧化活力和净光合速率有重要调节作用。     

去除紫花苜蓿叶片高丰度蛋白的方法及其应用

紫花苜蓿叶片中大量的高丰度蛋白(核酮糖-l,5-二磷酸羧化/加氧酶,Rubisco)干扰了蛋白质的动态分辨率,严重影响蛋白质组学研究中功能蛋白的检测与鉴定。为了探究去除高丰度蛋白的适宜方法,本研究利用Mg/NP-40与聚乙二醇(PEG)预分离紫花苜蓿叶片蛋白,通过双向凝胶电泳法比较了不同浓度PEG对叶片高丰度蛋白的分离情况。电泳图谱显示0,15%,17.5%,20%PEG处理的蛋白质中分别可以检测到(335±17),(417±3),(445±7),(459±11)个蛋白质点,0,15%,17.5%处理组间差异显著(P<0.05),17.5%和20%PEG 处理组间没有差异(P<0.05)。然而,17.5%PEG能够检测到更多的差异蛋白质点,证明其更能有效沉淀高丰度蛋白,便于检测被Rubisco遮盖的蛋白质点。将该方法应用于紫花苜蓿叶片响应低温胁迫的蛋白质组学研究中检验其应用效果,与三氯乙酸/丙酮法提取的全蛋白相比,去除高丰度蛋白后鉴定出8个新的蛋白质差异点,证明该方法适用于实际的蛋白质组学研究。可见,Mg/NP-40与17.5%PEG法是最适宜去除紫花苜蓿叶片高丰度蛋白的方法。     

龙须菜中rbcL和hsp70对高温和植物激素的响应

龙须菜已在我国沿海从南到北广泛栽培,但其栽培周期受夏季高温的限制。本研究采用qRT-PCR和Western blot技术研究了龙须菜核酮糖-1, 5-二磷酸羧化酶/加氧酶大亚基(rbcL)和热休克蛋白70(HSP70)对高温胁迫及3种抗逆植物激素的响应。结果显示：①高温(33 ℃)显著抑制了龙须菜rbcL转录和蛋白的表达水平,而100 μmol/L水杨酸(SA100)和50 μmol/L茉莉酸甲酯(MJ50)的添加可减轻高温的不利影响。在SA100和MJ50组中,rbcL转录表达量分别为高温组的1.31倍和1.32倍(3 h),rbcL蛋白表达量分别为高温组的1.36倍和2.10倍(24 h);并且这2种激素也能一定程度上缓解高温对藻体Rubisco活性的抑制作用,恢复Rubisco活化状态。但是50 μmol/L脱落酸(ABA50)的添加则基本上抑制了rbcL表达及Rubisco活性。②3种激素进一步促进了高温诱导的龙须菜HSP70的表达,在激素添加后,其转录水平升高0.53~1.00倍(3 h),蛋白水平升高0.93~2.45倍(24 h)。可见,植物激素SA、MJ和ABA在调控由高温引起的光合作用酶的抑制和热休克蛋白的诱导表达方面发挥了一定的作用。     

两株蛋白核小球藻 rbcS cDNA 全序列的克隆和分析

以2株蛋白核小球藻(Chlorella pyrenoidosa)F-9和820为实验材料,根据已知绿藻rbcS基因设计简并引物,分别克隆到2条245bp的cDNA片段,以此片段为基础使用cDNA末端快速扩增(RACE)技术,获得了2条长度分别为861bp和907bp的rbcS基因。序列分析表明,蛋白核小球藻F-9和820的rbcS分别编码181和184个氨基酸,编码区具有与高等植物rbcS保守序列YYDGRYWTMWKLPMFG相类似的结构,起始密码子附近有Kozak保守序列(A/GXXATGG),3′非翻译区有加尾信号TGTAA。同源性分析结果表明,F-9与蛋白核小球藻(GenBank登录号BAE48226)的相似性最高(91%),而F-9与820、F-9和普通小球藻(C.vulgaris)的相似性分别为64%和50%。这2条rbcS基因与其他绿藻和高等植物也表现了广泛的同源性,但相似性不高。该研究旨在为rbcS基因的功能和表达研究奠定基础。     

巴夫杜氏藻1,5-二磷酸核酮糖羧化酶/加氧酶小亚基基因的克隆和分析

1,5-二磷酸核酮糖羧化酶/加氧酶(Rubisco)是光合作用中的一个关键酶,其小亚基rbcS具有调控羧化反应催化效率和影响该酶对二氧化碳/氧气底物特异性的功能。从巴夫杜氏藻中克隆rbcS基因及其5′-上游序列,并对基因及5′-上游序列进行了分析。根据已知rbcS基因保守核苷酸序列设计引物,分别克隆到1 841 bp的DNA和380 bp的cDNA序列。以此为基础,使用染色体步移(Genome walking)和cDNA 末端快速扩增(RACE)技术,获得了799 bp的5′端DNA序列和500 bp的3′端cDNA序列。序列分析发现,巴夫杜氏藻rbcS DNA全长为2 031 bp(不包括476 bp 5′-上游序列),cDNA全长包括570 bp开放读码框(GenBank登录号:HQ315783)和294 bp 3′端非翻译区。5′-上游序列区域存在一系列预测的顺式作用元件。该研究旨在为后继的rbcS 基因的功能和表达研究、Rubisco的遗传改造奠定基础。同时,rbcS启动子因其可驱动基因高效表达而引起广泛关注,因此获得的rbcS 5′-上游序列经验证和优化后,可用于在嗜盐微藻中驱动转基因的高效表达以及完善微藻转化系统。     

Correlation of Chlorophyll Meter Readings with Gas exchange and Chlorophyll Fluorescence in Flag Leaves of Rice (Oryza sativa L.) Plants

Abstract

The objective of this study was to establish the correlation of the chlorophyll meter (SPAD) readings with the contents of chlorophyll (Chl) and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), the gross photosynthetic rate (P_g), and the maximum quantum yield of photosystem II (PSII) (F_v/F_m) in flag leaves of rice (Oryza sativa L.) in ripening stage. The SPAD readings significantly correlated with the Chl content, the Rubisco content, P_g and F_v/F_m (R² = 0.848, 0.648, 0.671 and 0.712, respectively), which suggests that the SPAD meter has the potential to estimate the photosynthetic capacity of the flag leaves. However, both P_g and F_v/F_m had a stronger relationship with the Rubisco content than the SPAD readings, indicating that the PSII photochemical and CO₂ assimilation capacities are strongly influenced by the Rubisco content. Therefore, accurate calibration would be indispensable to obtain the physiological information from the SPAD readings of flag leaves.     

Drought priming during the vegetative stage can enhance post-anthesis drought tolerance by improving photosynthetic capacity in winter wheat

Drought stress during the reproductive period of cereal crops leads to significant yield reductions, therefore, exploring effective methods to improve tolerance to post-anthesis drought is necessary. Pot experiment was carried out to investigate the effects of pre-drought priming on physiological characteristics and grain yield with drought stress at post-anthesis. Moderate water deficits (60–65% of the field capacity) were imposed to prime wheat plants during either the tillering or jointing stages, while severe drought stress (40–45% of the field capacity) was applied during the grain filling stage. The priming treatments significantly improved grain yield resulting in higher biomass. Compared to the control, the grain yield and biomass of the non-priming, tillering priming, and jointing priming treatments were reduced by 15.7, 9.1, and 9.3% and by 11.1, 6.1, and 10.5%, respectively. The primed plants exhibited higher adaptability to subsequent severe drought stress during grain filling, showing higher photosynthetic capacities and light use efficiencies with higher leaf water potentials, soluble protein contents, and Rubisco contents and enhanced enzymatic antioxidant systems. The tillering stage is more responsive to drought priming based on the observed grain yield. These results indicate that moderate drought during the vegetative period is conducive to the development of water-saving agriculture to cope drought stress during grain-filling in wheat.     

水稻Rubisco及其活化酶的免疫金标定位

采用免疫胶体金标记电镜技术对水稻叶片中的Rubisco及其活化酶进行细胞器定位,结果表明Rubisco主要分布于叶绿体,Rubisco活化酶特异性分布于叶绿体和线粒体中,预示Rubisco活化酶可能具有除活化钝化态Rubisco以外的其他功能.     

高产大豆1012与多根瘤品系0498苗期生育特性的比较

[目的]为进一步开发、利用大豆优良育种材料1012、0498提供参考。[方法]以多根瘤大豆品系0498和高产大豆品系1012为材料,比较研究了它们苗期的生育特性。[结果]在苗期,1012的株高增长比0498快,叶色值始终比0498高,单株地上部干重比0498高,单株地上部干重的增加量也比0498大,播种后30 d Rubisco含量比0498多27.5%;0498的根瘤数远比1012多,且增幅大;2个供试材料的气孔导度相差不明显。10:00～12:00时2个大豆品系的Fv/m都较大,1012的Fv/m始终比0498大。[结论]1012有较强的光合作用能力,0498具有较强的固氮潜力。