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.     

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。     

芥菜Rubisco小亚基的基因克隆及其在芜菁花叶病毒侵染后的表达分析

以耐病性叶用芥菜为材料,克隆和分析了芥菜Rubicso小亚基的基因序列,研究了芜菁花叶病毒（Turnip mosaic virus,TuMV）侵染对Rubicso小亚基基因表达的影响。结果显示：Rubicso小亚基基因全长为842bp,其开放阅读框（ORF）可编码181个氨基酸,其中包括2个α螺旋及4个β折叠二级结构,...     

小麦Rubisco抗体的制备和旗叶中Rubisco含量的ELISA测定

Rubisco(核酮糖-1,5-二磷酸羧化酶/加氧酶)为光合生物中的关键性酶。以小麦(Triticum aestivum L. cv.)叶片为材料，在(NH4)2SO4盐析和DEAE-Sepharose F F层析纯化的基础上添加了Sephacryl S 300分子筛，进一步纯化了Rubisco。 将纯化的Rubisco免疫大白兔制备了Rubisco的多克隆抗体， 经Western blot检测，Rubisco抗体与Rubisco呈免疫反应特异性。并运用Rubisco抗体，采用ELISA方法直接测定小麦旗叶生长发育过程中Rubisco含量的变化，结果表明：不同生长阶段，旗叶的Rubisco含量与光合速率大小呈正相关。该方法比免疫沉淀法更为快捷、准确。     

水菖蒲不同提取物对德国小蠊的生物活性比较

分别比较了水菖蒲根茎5种不同溶剂和4种不同提取方法的提取物对德国小蠊3龄若虫和雄成虫的杀虫活性.先考察了水菖蒲根茎甲醇、乙醇、乙酸乙酯、氯仿、石油醚5种有机溶剂冷浸提取物的触杀活性,结果表明水菖蒲甲醇浸提物对德国小蠊具有更好的杀虫活性.在浓度22 mg/ml处理120 h后,德国小蠊3龄若虫、雄成虫死亡率分别达到96.67%和100%.后研究了冷浸法、索式提取法、超声波萃取、超临界CO2萃取4种方法得到的水菖蒲提取对德国小蠊的触杀活性.浓度10mg/ml超临界CO2萃取物处理24 h后,德国小蠊3龄若虫、雄成虫死亡率分别为96.25%和78.75%.结果表明超临界CO2萃取物对德国小蠊具有更优的杀虫活性.     

人工老化对两个玉米自交系生理特性的影响

探讨玉米种子老化过程中活力与生理特性变化的规律,以自交系NT6621和自交系T6种子为试材,通过人工加速老化的方法进行研究。结果表明：高温(45±1℃)、高湿（100%相对湿度）密闭条件下随老化时间的延长而两个玉米自交系的发芽率、发芽势、脱氢酶活力降低,MDA随老化程度的加剧而升高。酯酶同工酶试验,自交系NT6621有6条酶带（Rf值分别为0.60、0.45、0.40、0.30、0.14、0.04）,当老化24h时Rf值为0.30、0.14、0.04的酶带突然变浅,酶活性开始降低,随着老化时间的延长酶活性逐渐降低;自交系T6有6条酶带（Rf值分别为0.60、0.48、0.40、0.29、0.14、0.05）,当老化24h时Rf值为0.40、0.29、0.14、0.05的酶带开始变浅,酶活性开始降低,随着老化处理时间的延长酶活性逐渐降低.     

Varietal Differences in Photosynthetic Rates in Rice Plants,with Special Reference to the Nitrogen Content of Leaves

Abstract

The photosynthetic rate in the fl ag leaf of rice at the full heading stage was examined in three japonica varieties, Koshihikari, Aikoku and Asanohikari, and the indica high-yielding variety Takanari at the same level of leaf nitrogen. At an ambient CO₂ concentration of 350 µL L-₁, Takanari had a higher photosynthetic rate and stomatal conductance than the japonica varieties when plants were compared at a leaf nitrogen content of approximately 1.5 g m-₂. Stomatal conductance increased considerably with increases in leaf nitrogen content in the japonica varieties. As a result, at a leaf nitrogen content of approximately 2.0 g m-₂, differences in terms of the photosynthetic rate among varieties were small. By contrast, there were no clear varietal differences in Rubisco content at any identical nitrogen content of leaves. We conclude that stomatal conductance is responsible for the varietal differences in photosynthetic rate examined at the same leaf nitrogen content.     

人工老化对两个玉米自交系生理特性的影响

探讨玉米种子老化过程中活力与生理特性变化的规律,以自交系NT6621和自交系T6种子为试材,通过人工加速老化的方法进行研究.结果表明:高温(45±1℃)、高湿(100%相对湿度)密闭条件下随老化时间的延长而两个玉米自交系的发芽率、发芽势、脱氢酶活力降低,MDA随老化程度的加剧而升高.酯酶同工酶试验.自交系NT6621有6条酶带(Rf值分别为0.60、0.45、0.40、0.30、0.14、0.04),当老化24h时Rf值为0.30、0.14、0.04的酶带突然变浅,酶活性开始降低,随着老化时间的延长酶活性逐渐降低;自交系T6有6条酶带(Rf值分别为0.60、0.48、0.40、0.29、0.14、0.05),当老化24h时Rf值为0.40、0.29、0.14、0.05的酶带开始变浅,酶活性开始降低,随着老化处理时间的延长酶活性逐渐降低.     

钾营养对水稻剑叶光合作用关键酶活性的影响

低钾导致净光合速率下降,Rubisoo及Rubisco活化酶活性和含量均降低,其中尤以Rubisco初始活性的降低为最大;低钾处理水稻抽穗当天剑叶叶绿素含量还高于正常钾处理,但随着剑叶衰老,降低较快.外源钾对Rubisco及Rubisco活化酶活性影响的研究表明,钾离子对光合有关酶类没有直接的活化作用.