利用甘蔗叶绿体荧光参数及活性氧代谢等指标评价甘蔗品种的耐旱性

利用ＯＳ５－ＦＬ叶绿素荧光仪研究干旱胁迫下蔗叶叶绿体荧光参数的变化及其与甘蔗耐旱性关系。应用干旱胁迫下蔗叶活性氧代谢变化等耐旱鉴定指标鉴定参试品种的相对耐旱性。结果表明,干旱胁迫下甘蔗生长受抑制,蔗叶叶绿素含量、相对含水量、叶绿体ＤＣＩＰ光还原活性下降,ＭＤＡ含量和质膜相对透性提高;叶绿体荧光参数Ｆｖ／Ｆｍ、Ｆｖ／Ｆｏ、Ｔ１／２均明显降低,表明干旱胁迫使蔗叶光系统Ⅱ（ＰＳⅡ）原初光能转换效率、ＰＳⅡ潜在活性受到抑制;研究还表明干旱胁迫下蔗叶叶绿体光合量子产额（Ｙｉｅｌｄ）及其潜在活性（Ｆｄｓ／Ｆｓ）降低,说明干旱胁迫直接影响了光合作用的电子传递和二氧化碳同化过程。上述荧光参数的受抑程度因品种抗逆性能而异,不抗旱品种降幅明显高于抗旱品种。最后讨论了叶绿素荧光动力学在甘蔗抗旱育种及抗旱鉴定上应用的可能性。     

The Physiology and Biochemical Tolerance of Cabbage to Se (VI) Addition to the Soil and by Foliar Spraying

The effects of selenium (Se) (VI) soil fertilization with 2 μg Se L^?1 or foliar spraying twice with 20 mg Se L^?1 in the form of sodium (Na) selenate on the physiological and biochemical characteristics of cabbage plants were studied. The ability of the plants to take up Se and translocate it to different parts of the plants was also studied. Despite the high concentration of Se in the foliar solution, there was no effect on photosynthesis, transpiration rate, photochemical efficiency of PSII, or electron transport system activity. The amount of chlorophyll and anthocyanins were unchanged. At harvest, the concentration of Se in control plants was lower than 100 ng Se g^?1 dry weight (DW), while plants treated with 20 mg Se L^?1 contained 5500 ng Se g^?1. Selenium enriched cabbage could be used in human nutrition. The tolerance of cabbage to Se could be explained by the formation of insoluble compounds that are not available for the plant.     

Herbicidal action of 2-hydroxy-3-alkyl-1,4-naphthoquinones

The main mode of herbicidal activity of 2-hydroxy-3-alkyl-1,4-naphthoquinones is shown to be inhibition of photosystem II (PSII). The herbicidal and in vitro activities have been measured and correlated with their (Log)octanol/water partition coefficients (Log Ko/w). The length of the 3-n-alkyl substituent for optimal activity differed between herbicidal and in vitro activity. The maximum in vitro activity was given by the nonyl to dodecyl homologues (Log Ko/w between 6.54 and 8.12), whereas herbicidal activity peaked with the n-hexyl compound (Log Ko/w = 4.95). The effect of chain branching was also investigated using isomeric pentyl analogues substituted at position 3. All exhibited similar levels of in vitro activities but herbicidal activities differed, albeit moderately, with the exception of one analogue that was much less phytotoxic. Other modes of action were also investigated using two representative compounds. They did not show any activity on photosystem I or mitochondrial complex I, or generate toxic oxygen radicals by redox cycling reactions. Only moderate activity was found against mitochondrial complex III from plants, in contrast to much higher corresponding activity using an insect enzyme.     

Metabolomics - A robust bioanalytical approach for the discovery of the modes-of-action of pesticides: A review

The agrochemical industry is facing great undertaking that includes increasing demand for the development of new crop protection agents that are safe for the environment and the consumers, and at the same time combat the issue of the emergence of resistance pest strains. The mode-of-action (MoA) is among the features of a bioactive compound that largely determine whether the abovementioned issues are addressed or not, and subsequently whether its commercial development will be addressed. The early discovery of the MoA of bioactive compounds could accelerate pesticide research and development by reducing the required time and costs. Based on advances in synthetic and natural product chemistry, scientists have access to a vast number of compounds that could potentially be developed as crop protection agents. The screening of such compounds with respect to their MoA requires accurate and robust bioanalytical tools. Metabolomics is a powerful bioanalytical tool that will likely play a significant role in the acceleration of the discovery of MoA of bioactive compounds. In the present review, the capabilities and principles and applications of metabolomics for the study of the MoA of herbicides, insecticides, acaricides, fungicides, and antibiotics are discussed.     

Spatial and temporal changes in chlorophyll fluorescence images of Nicotiana benthamiana leaves following inoculation with Pseudomonas syringae pv. tabaci

Inoculation of Nicotiana benthamiana leaves with virulent and avirulent strains of Pseudomonas syringae pv. tabaci resulted in increasing changes in F_v/F_m, and NPQ over time. Images of these chlorophyll a fluorescence measurements revealed different changes in different zones of the leaf. For the virulent strain, the infiltrated zone and zone directly surrounding it showed decreased F_v/F_m, and NPQ before the appearance of visible symptoms, and these decreases corresponded with increasing bacterial populations and putative tabtoxin activity. Another distinct zone of reduced F_v/F_m and NPQ extended several centimetres from the lesion to the nearest leaf margin, but only very low bacterial populations and no putative tabtoxin activity were detected in this zone. For the avirulent strain, a hypersensitive response occurred, bacterial populations remained low, and there was little detectable putative tabtoxin activity. Decreased F_v/F_m and NPQ, but not , were observed in the infiltrated zone prior to the hypersensitive response, followed by decreased values in a zone directly surrounding it. Following that, no further changes were observed. These results demonstrate that in addition to detecting pre‐symptomatic impacts of bacteria, chlorophyll a fluorescence imaging can also show that there are highly distinct regions of affected tissue that can extend considerably beyond the area of bacterial colonization. This should be considered in selecting leaf tissues for examining the effects of pathogens on plants, such as altered host gene expression or protein levels.     

盐胁迫对葡萄砧木‘3309C’叶片光抑制的影响

探讨氯化钠盐胁迫对葡萄砧木‘3309C’叶片光系统Ⅰ(PSI)和光系统Ⅱ(PSII)活性的影响,为滨海盐碱地葡萄栽培提供理论参考。以1年生葡萄砧木‘3309C’为试材,通过同时测定葡萄叶片叶绿素荧光快速诱导动力学曲线和P700+再还原动力学曲线,结合叶绿素荧光淬灭分析,探讨了持续盐胁迫(100 mmol/L)对葡萄砧木叶片PSI和PSII活性的影响。随着盐处理时间的延长,PSII最大光化学效率逐渐降低,PSII放氧复合体受破坏的程度和反应中心电子传递受阻程度均明显增大,最大荧光显著降低,盐胁迫导致葡萄叶片PSII与PSI间激发能分配严重偏离平衡,最大光氧化P700显著降低,且发生降低时间明显早于PSII最大光化学效率。P700+再还原动力学曲线分析表明持续盐胁迫下葡萄叶片P700⁺再还原半衰期逐渐增大,环式电子传递受阻。持续盐胁迫导致葡萄砧木叶片2个光系统激发能分配严重偏离平衡状态,抑制了光系统活性,更多的能量被用来进行热耗散,而围绕PSI的环式电子传递活性的降低则进一步加剧了葡萄叶片光系统的光抑制程度。     

牡丹早衰与晚衰品种在衰老过程中光系统活性的变化

为了探讨牡丹在衰老过程中叶片光合机构活性的变化与光合能力的维持关系,本试验以早衰品种‘肉芙蓉,和晚衰品种‘卷叶红’为材料,通过快速叶绿素荧光诱导动力学测定技术(JIP test)和820 nm光吸收技术,研究牡丹在衰老过程中的净光合速率(Pn)、叶绿素含量及光合机构活性的变化.结果表明:在衰老进程中,牡丹Pn和叶绿素含量以相同的趋势下降,肉芙蓉’快于‘卷叶红’的下降.通过对荧光参数的分析,发现牡丹叶在衰老时,PSⅡ电子受体侧受到的伤害大于电子供体测,而单位面积有活性的反应中心数量(RC/CSo)显著下降,同时PS Ⅰ的活性也大幅下降.无论PSⅡ还是PS Ⅰ的活性,肉芙蓉’的下降幅度都大于‘卷叶红’.由此得出:PS Ⅰ和PSⅡ光系统活性的快速下降和光合电子传递能力的衰退是牡丹叶片光合能力迅速下降的重要原因之一.     

两个玉米品种维管束鞘叶绿体的非光化学淬灭对干旱胁迫的响应

【目的】光系统Ⅱ的非光化学叶绿素荧光淬灭是高等植物响应环境变化最快速的光保护机制,玉米具备叶肉和维管束鞘2种叶绿体结构,本研究通过比较2个玉米品种的光合耐旱能力,探究维管束鞘叶绿体的非光化学淬灭对玉米耐旱性的意义。【方法】以成单30和仲玉3号2个玉米品种为研究材料,设置土壤相对含水量为70%—80%田间持水量(FWC)(充足浇水,对照)、50%—60%FWC(中度干旱胁迫)和35%—45%FWC(重度干旱胁迫)3个土壤水分梯度处理。测定玉米叶片的水分状况、叶绿素含量、活性氧积累、质膜透性和气体交换等参数;应用叶绿素荧光动力学显微成像观测,比较玉米叶肉和维管束鞘叶绿体的叶绿素荧光参数Fv/Fm和NPQ;通过免疫印迹法,分析玉米叶肉和维管束鞘细胞光系统Ⅱ亚基S(PsbS)稳态水平的变化差异;采用蓝-绿胶温和电泳分离,检测玉米光系统Ⅱ蛋白复合体的水平。【结果】干旱胁迫导致叶片气孔导度和蒸腾速率下降,2个玉米品种间没有明显差异。但成单30在重度干旱下表现出更好的水分状况、更低的活性氧损伤以及更高的光合速率。玉米叶肉和维管束鞘叶绿体的NPQ水平及PsbS蛋白含量受干旱诱导明显上升,维管束鞘中的上...