内源水杨酸参与黄瓜叶片光合系统对低温胁迫的响应

 为了探讨内源水杨酸（salicylic acid,SA）在黄瓜幼苗光合系统响应低温胁迫中的作用机制, 采用高效液相色谱法测定低温下黄瓜叶片中内源SA 含量的变化;通过SA 合成抑制剂Paclobutrazol（Pac, 100 μmol · L^-1）喷施和外源SA（50 μmol · L^-1）饲喂的方法调节内源SA 含量,并测定不同处理幼苗的叶 绿素荧光参数和光合碳同化关键酶基因的转录水平。结果显示：低温引起黄瓜幼苗内源SA 含量升高,Pac 预处理抑制SA 的积累。低温导致PSⅡ的最大光化学效率（F v/F m）、实际光化学效率（Φ PSII）、潜在光化 学活性（F v/F o）和光合电子传递效率（ETR）等降低,叶片光化学猝灭参数[（Y（NO）]升高;内源SA 含量降低使PSⅡ活性下降幅度增大,加重了叶片的光损伤程度。低温下PSⅡ吸收的光能分配于光反应的 部分减少,而以非光化学反应的过剩能量耗散Ex 为主要的光能分配途径,内源SA 含量降低会加剧光能 向Ex 的分配。低温时喷施Pac 的幼苗中Rubisco 小亚基基因（RbcS）和碳酸酐酶基因（CA）的表达水平 显著低于对照植株。对喷施Pac 的幼苗外源饲喂SA 后,内源SA 含量升高,低温下叶片光合活性得到有 效恢复,光损伤降低,光能分配趋于合理,RbcS 和CA 的表达水平升高。上述结果表明,低温下内源SA 的积累有助于维持黄瓜叶片中较高的光系统活性和碳同化能力,从而保护光合系统,降低低温胁迫对植 物的损伤。     

29种中药提取物抗结核药物敏感性研究

本研究选取29种对结核分支杆菌和其他呼吸疾病有治疗作用生长在中国的药用植物,通过MABA (Microdilution alamar blue assay) 药敏实验方法检测了这些药物的乙醇和水提取物对结核分支杆菌M. tuberculosis H37Rv的敏感性。筛选到金银花、大蓟、小蓟和水车前等有显著的抗结核活性,为进一步考查其单体化合物的作用机制和有新型作用机制的抗结核药物开发打下基础。     

Chilling Stress Accelerates Degradation of Seed Storage Protein and Photosynthetic Protein during Cotton Seed Germination

Low temperature is one of the major abiotic stresses limiting the productivity and geographical distribution of many important crops. To gain a better understanding of chilling stress responses in cotton ( Gossypium hirsutum L . ), we carried out a comparative proteomic analysis. Cotyledon proteins of 1-week-old cotton seedlings treated with or without chilling treatment at 4 °C were extracted, separated by a two-dimensional gel electrophoresis and compared. Among 1500 protein spots reproducibly detected on each gel, 25 protein spots were down-regulated and 29 were up-regulated. Seven cotton proteins were identified by mass spectrometry analysis as beta-globulin A precursor fragments. One was identified as a Rubisco large subunit fragment, providing evidence of both seed storage protein and photosynthetic protein destruction by chilling stress. The related physiological and biochemical analysis showed that there was a significant increase in endopeptidase activity and activated oxygen generation rate, and an obvious decrease in carboxylation efficiency and maximum net photosynthetic rate of cotton seedlings under chilling stress. Based on the above results, the degradation mechanisms of beta-globulin and Rubisco under chilling stress were discussed. In conclusion, our study provides new insights into chilling-stress responses in cotton and demonstrates the advantages of proteomic analysis.     

超高产水稻生育后期剑叶光合生理特性变化的研究

笔者研究了黑龙江省第一积温带5个产量不同的主栽品种生育后期剑叶叶绿素含量、净光合速率和RuBP羧化酶活性变化规律.结果表明:超高产品种生育后期的剑叶叶绿素含量、光合速率和RuBP羧化酶活性均高于常规品种,品种间差异显著.因此,将剑叶生育后期叶绿素含量、净光合速率和RuBP羧化酶活性的变化研究,作为寒地粳稻高光效育种和超高产育种中的一项措施是可行的.     

Mechanism of High Photosynthetic Capacity in BC2F4 LinesDerived from a Cross between Oryza sativa and Wild Relatives O. rufipogon

Abstract

We found that several BC₂F₄ lines had high leaf photosynthetic rates under light-saturated and ambient CO₂ conditions. These lines are progenies of BC₂F₁ plants with high photosynthetic capacities which were generated by backcrossing between Oryza rufipogon (W630) and O. sativa cv. Nipponbare, as a recurrent parent. Some photosynthetic characteristics of the BC₂F₄ lines were investigated to identify the factors increasing photosynthetic rates. Photosynthetic rates of these lines under light-saturated conditions at 50 to 700 ppm CO₂ concentrations were higher than those in Nipponbare. The estimated-maximum photosynthetic rates under light-saturated and CO₂-saturated conditions in BC₂F₄ lines were also higher than that in Nipponbare. The photosynthetic rate under light-saturated and ambient CO₂ conditions was positively correlated with the carboxylation efficiency as an indicator of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activity in vivo rather than stomatal conductance. Initial and total Rubisco activities in vitro tended to be higher in the BC₂F₄ lines than in Nipponbare. The content of active Rubisco calculated from the activation state of Rubisco was also higher in the BC₂F₄ lines than in Nipponbare. These results suggest that high photosynthetic capacities of BC₂F₁ plants can be maintained high in their progenies and high photosynthetic rates under light-saturated and ambient CO₂ conditions in the BC₂F₄ lines are achieved mainly by the high activity of Rubisco due to the high active Rubisco content.     

超高产水稻生育后期剑叶光合生理特性变化的研究

笔者研究了黑龙江省第一积温带5个产量不同的主栽品种生育后期剑叶叶绿素含量、净光合速率和RuBP羧化酶活性变化规律。结果表明：超高产品种生育后期的剑叶叶绿素含量、光合速率和RuBP羧化酶活性均高于常规品种,品种间差异显著。因此,将剑叶生育后期叶绿素含量、净光合速率和RuBP羧化酶活性的变化研究,作为寒地粳稻高光效育种和超高产育种中的一项措施是可行的。     

怀山药根际土壤微生物、酶活性和酚酸物质变化及其关系研究

对不同生育期怀山药根际土壤微生物数量、土壤酶活性及酚酸物质的变化及其交互作用进行研究。结果表明：怀山药在其生长发育过程中,根际土壤中酚酸物质的含量和土壤细菌、放线菌、真菌数量均呈显著升高趋势,且根茎膨大速度越快时上升趋势越明显;根际细菌绝对数量一直占根际土壤微生物的80%左右,并呈增长趋势;过氧化氢酶、多酚氧化酶、蛋白酶活性逐渐增强,蔗糖酶、磷酸酶、脲酶活性呈下降趋势;根际土壤中酚酸物质的含量与根际土壤中微生物的含量和多数土壤酶活性呈显著相关性。     

黄瓜幼苗Rubisco与Rubisco活化酶对光强的响应

以津优3号幼苗为试材,研究弱光(LL:100 μmol· m-2·s-1)、亚弱光(SL:300 μmol·m-2·s-1)下黄瓜幼苗光合速率(Pn)、核酮糖-1,5-二磷酸羧化/加氧酶(Rubisco)、Rubisco活化酶(RCA)活性及其基因表达量的变化.结果表明,11d弱光处理后,黄瓜幼苗叶片的Pn、Rubis...     

盐胁迫对黄瓜幼苗光合作用及其关键酶基因表达特性的影响

以对盐胁迫敏感性不同的两个黄瓜品种中农大22号和戴多星为材料,研究了盐胁迫下黄瓜幼苗叶片光合特性、叶绿体超微结构以及光合作用关键酶1,5-二磷酸核酮糖羧化酶/加氧酶(Rubisco)和磷酸烯醇式丙酮酸羧化酶(PEPC)活性及其编码基因表达的变化。结果表明:盐胁迫(150 mmol·L~(-1)NaCl处理)下,黄瓜幼苗光合色素(叶绿素和类胡萝卜素)含量、净光合速率、暗呼吸速率和蒸腾速率显著降低;叶绿体类囊体片层结构垛叠程度下降,淀粉粒变小且数量减少;Rubisco大亚基编码基因rbc L、PEPC编码基因Csppc2的表达水平先响应性上调,随后下降;Rubisco和PEPC活性呈降低趋势。相对中农大22号,戴多星具有较强的盐胁迫耐受性。     

Root restriction-induced limitation to photosynthesis in tomato (Lycopersicon esculentum Mill.) leaves

Root restriction often depresses photosynthetic capacity and the mechanism for this reduction, however, remains unclear. To identify the mechanism by which root restriction affects the photosynthetic characteristics, tomato (Lycopersicon esculentum Mill.) seedlings were subjected to root restriction stress with or without supplemental aeration to the nutrient solution. With the development of the root restriction stress, CO₂ assimilation rate was decreased only in confined plants without supplemental aeration. There were also significant decreases in leaf water potential, stomatal conductance (g_s), intercellular CO₂ concentration (C_i), and increases in the stomatal limitation (l) and the xylem sap ABA concentration. Meanwhile, the maximum carboxylation rate of Rubisco (V_cmax) and the capacity for ribulose-1,5-bisphosphate regeneration (J_max) also decreased, followed by substantial reductions in the quantum yield of PSII electron transport (Φ_PSII). Additionally, root restriction resulted in accumulation of carbohydrates in various plant tissues irrespective of aeration conditions. It is likely that root restriction-induced depression of photosynthesis was mimicked by water stress.