氯化镧对铝胁迫下大豆幼苗抗氧化能力及光合性能的影响

目的:探究镧对大豆铝胁迫的缓解效应;方法:以铝敏感大豆BD2为材料,进行50μmol/L铝胁迫处理,然后添加不同浓度氯化镧(10、100和1000 mg L/L)测定大豆幼苗抗氧化及光合指标;结果:与对照组相比较,铝胁迫导致大豆幼苗根系伸长率、根冠比、鲜重及干重显著降低,叶片SOD、POD活性显著降低,且MDA含量显著升高,叶绿素与类胡萝卜素含量、光合速率、蒸腾速率、气孔导度及胞间CO_2浓度也均显著下降;而与铝胁迫处理相比,不同浓度镧处理对大豆幼苗根长、鲜重与干重、SOD与POD活性有不同程度地促进作用,并显著降低MDA含量,同时提高叶绿素与类胡萝卜素含量,增强光合速率、蒸腾速率、气孔导度和胞间CO_2浓度,其中以10 mg/L镧处理效果最好;结论:适宜浓度的镧处理能够通过增强大豆幼苗的抗氧化能力,提高其光合性能,提高大豆幼苗对铝胁迫的适应能力,有效缓解铝对大豆幼苗生长的毒害。     

西南喀斯特地区黄荆叶片光合作用日变化的研究

选取桂林丫吉岩溶试验场优势植物黄荆（Vitex negundoL．）作为研究对象,对相同条件下黄荆叶片净光合速率（Pn）、气孔导度（Gs）、胞间二氧化碳浓度（Ci）和蒸腾速率（Tr）等光合作用特性的日变化进行了比较研究。结果表明：净光合速率（Pn）的日变化呈不对称的“双峰型”曲线,具有明显的光合“午休”现象;气孔导度曲线总体呈下降趋势;胞间CO2浓度日变化表现出单峰曲线;蒸腾速率（Tr）日变化呈不对称的双峰曲线,与净光合速率日变化基本一致,但主峰较净光合速率Pn主峰滞后1h,也出现了“午休”现象。     

植物系统演化研究中的旁证——光合作用色素-蛋白质复合体

就光合作用色素-蛋白质复合体是否可以作为系统演化的证据谈了作者的看法。在低等植物类群藻类中,光合作用色素-蛋白质复合体特别是捕光色素-蛋白质复合体Ⅱ可以作为推测其彼此间亲缘关系的旁证;在高等植物中,其捕光色素-蛋白质复合体Ⅱ组成成分相同,说明它们在演化中的渊源性,从而为高等植物起源于同一生物类群提供旁证。     

马铃薯Y病毒脉坏株系（PVY^N）的侵染对烟草光合作用和呼吸作用的影响

感染马铃薯Y病毒脉坏死株系后,烟草叶片的叶绿素含量和Hill反应活性均明显降低,光合速率在接种后2天出现增高现象,随后逐渐降低,呼吸速在接种的后2～6天明显降低,显症初期呼吸速率增高,随后大幅度降低．     

Cyclic electron flow around photosystem I is required for adaptation to high temperature in a subtropical forest tree, Ficus concinna

Dissipation mechanisms of excess photon energy under high-temperature stress were studied in a subtropical forest tree seedling, Ficus concinna. Net CO2 assimilation rate decreased to 16% of the control after 20 of high-temperature stress, and thus the absorption of photon energy exceeded the energy required for CO2 assimilation. The efficiency of excitation energy capture by open photosystem Ⅱ (PSII) reaction centres (Fv'/Fm') at moderate irradiauce, photochemical quenching (qp), and the quantum yield of PSII electron transport (φPSII) were significantly lower after high-temperature stress. Nevertheless, non-photochemical quenching (qHP) and energy-dependent quenching (qE) were significantly higher under such conditions. The post-irradiation transient of chlorophyll (Chl) fluorescence significantly increased after the turnoff of the actinic light (AL), and this increase was considerably higher in the 39 ℃-grown seedlings than in the 30 ℃-grown ones. The increased post-irradiation fluorescence points to enhanced cyclic electron transport around PSI under high growth temperature conditions, thus helping to dissipate excess photon energy non-radiatively.     

Characteristics of photosynthesis in rice plants transformed with an antisense Rubisco activase gene

INTRODUCTION Ribulose-1,5-bisphosphate carboxylase/oxy-genase (Rubisco) is a key enzyme that initiates bothphotosynthetic and photorespiratory carbon me-tabolism. However, Rubisco has to be activated andcarbamylated to become catalytically competent.Rubisco activase (RCA) can alter the activity ofRubisco by facilitating the dissociation of tightlybound sugar phosphates from Rubisco in a processthat requires ATP hydrolysis. RCA, a chloroplastprotein encoded by a nuclea…     

植物生命科学发展趋势

植物具有光合放氧功能的生命活动是生物圈进化及运转的关键环节,并和经济及社会的可持续发展密切相关。目前,与植物生命科学研究交叉的学科越来越多,它正在将微观和宏观的探讨整合起来为21世纪人类的生存和进步做出更大贡献。     

Effect of cadmium on growth and photosynthesis of tomato seedlings

A hydroponic experiment carried out to study the effect of five Cd levels on growth and photosynthesis of two tomato cultivars showed that the addition of 0.1 μmol/L Cd induced a slight increase in plant height of Hezuo 903 and the SPAD (the Soil-Plant Analyses Development) value of the 2 cultivars. However, at higher Cd levels, i.e., 1 and 10 μmol/L, root length and volume, plant height, and SPAD value were all significantly reduced. On an average of the 2 cultivars, exposure to 1 and 10μmol/L Cd for 33 d reduced plant height by 18.9% and 46.4% and SPAD value by 11.2% and 31.6%, compared with control,respectively. Similarly, root length was reduced by 41.1% and 25.8% and root volume by 45.2% and 63.7%, respectively. The addition of Cd in the growth medium also had significant deleterious effect on net photosynthetic rate (Pn) and intracellular CO2concentration (Ci), with Pn being reduced by 27.2% and 62.1% at 1 μmol/L and 10 μmol/L Cd treatments compared to the control,respectively, while Ci increased correspondingly by 28.4% and 39.3%.