Effects of NaCl stress on seed germination, leaf gas exchange and seedling growth of Pteroceltis tatarinowii

Effects of NaCl on seed germination, leaf gas exchange and seedling growth were investigated. The germination of P. tatarinowii seeds was delayed in the presence of NaCl, and was significantly inhibited when NaCl concentration exceeded 17 mM (1.0 g·L⁻¹). NaCl treatments induced reductions of transpiration rate, stomatal conductance and net photosynthetic rate and their reductions were significant with the increasing of NaCl concentration. However, intercellular CO₂ concentration in seedling leaves under salt stress was significantly higher than that of controls. There was a significant reduction in survival, basal diameter increment and height increment with increasing NaCl concentration 50 days after NaCl treatment, and a significant reduction in the dry weight increment of roots, stems, and leaves was also observed in the NaCl treatments. The deleterious effect on the biomass increment was more evident in the case of stems and leaves. Results from this study suggest that P. tatarinowii is sensitive to salinity stress and the salinity threshold for seedling growth might be less 34 mM (2.0 g·L⁻¹). Biography: FANG Sheng-zuo (1963–), male, Professor, College of Forest Resources and Environment, Nanjing Forestry University, Nanjing 210037, P. R. China.     

植物抗寒性的生理生态学机制研究进展

综述植物在冷驯化过程中发生的一系列生理生化变化.环境对植物抗寒性的影响主要与光诱导、温湿度以及气候的变化有关.植物表面形成冰层会引起植物的无氧呼吸,导致植物受害;光抑制诱导活性氧的产生,从而导致植物光合系统的退化,抗寒能力下降,而短日照诱导植物休眠,有利于植物抗寒.光敏色素则被认为是启动冷驯化的光受体;植物通过冷驯化增加碳水化合物的积累及病原体相关蛋白的合成,以增强对低温病原体的抵抗能力;气候的变化使植物遭受了更大的冷伤害风险.微管最初遇冷时部分的解体可以有效诱导植物抗寒性;抗氧化酶活性增强,植物体内糖、脯氨酸、多胺等内含物含量上升.植物休眠状态中的生理变化(种子的休眠、芽的休眠)与ABA敏感性的差异有关.对植物抗寒性分子机制的研究表明:COR基因的表达对于植物抗寒性和冷驯化是十分关键的;与气候梯度有关的基因梯度的分布说明寒冷地区的树种更为抗寒;多表型性状的数量性状分析,为重要的农艺性状标记辅助选择(MAS)提供基础.对植物抗寒过程中的信号转导进行研究发现,Ca2 是低温下参与调节冷驯化应答机制中信号转导途径的重要的第二信使.未来植物抗寒领域的研究热点为信号转导和基因调节,低温抗性的遗传学和遗传应用及代谢组学,气候变化对于植物抗寒的影响等方面.     

毛白杨抗冻性低温诱导过程中糖的效应(英文)

在低温锻炼和结合蔗糖处理的低温锻炼下 ,对毛白杨 (Populustomentosa)幼苗枝条和叶片的可溶性糖含量 ,以及幼苗存活率和抗冻性分别进行了测定 .结果表明 ,低温锻炼明显提高了幼苗枝条和叶片的可溶性糖含量 ,同时也提高了幼苗的存活率和抗冻性 .2 0 %蔗糖处理对上述低温锻炼的作用有加强的效果 .进一步分析发现 ,无论是单纯的低温锻炼还是结合蔗糖预处理的低温锻炼 ,幼苗枝条中可溶性糖含量的提高程度均较叶片明显 ,而且它们的含量增加与幼苗抗冻性的提高密切相关 .这表明低温锻炼所引起的可溶性糖积累可能参与了幼苗抗冻性的诱导     

Ultrastructural and Extracellular Protein Changes in Cell Suspension Cultures of Populus euphratica Associated with Low Temperature-induced Cold Acclimation

Populus euphratica Olive is the only tree species that can grow in the saline land and also survive cold winters in northwest China, and it plays a very important role in stabilizing the vulnerable ecosystem there. A cell suspension culture was initiated from callus derived from plantlets of Populus euphratica. Cold acclimation was induced (LT50 of-17.5 ℃) in cell suspension at 4-5 ℃ in the dark for 30 days and the freezing tolerance increased from LT50 of-12.5 ℃ in nonacclimated cells to LT50 of-17.5 ℃ in cold-acclimated cells. Microvacuolation, cytoplasmic augmentation and accumulation of starch granules were observed in cells that were cold-acclimated by exposure to low temperatures. Several qualitative and quantitative changes in proteins were noted during cold acclimation. Antibodies to carrot extracellular (apoplastic) 36 kD antifreeze protein did not cross react on immunoelectroblots with extracellular proteins in cell suspension culture medium of Populus euphratica, indicating no common epitopes in the carrot 36 kD antifreeze protein and P euphratica extracellular proteins. The relationship of these changes to cold acclimation in Populus euphratica cell cultures was discussed.     

Determination of drought tolerance using root activities in Robinia pseudoacacia ''Idaho'' transformed with mtl-D gene

Idaho locust (Robinia pseudoacacia 'Idaho') is an exotic multi-purpose tree used in landscaping, soil and water conservation, fodder sources and others. To improve its drought tolerance for reclaiming arid land, five lines of transformed mtl-D gene, as osmotic regulator in plant cells, have been selected and managed to determine their drought tolerance under experimental conditions.Qualitative and quantitative variables of transformed plants were studied. The critical value of drought tolerance was determined by detecting the 2,3,5-triphenyl tetrazolium chloride (TTC) reductants in roots and soil water content (SWC). The critical value for drought tolerance was SWC 6% while for the control plants the critical SWC was 8%; a moderate level of SWC is 13% and the highest SWC for plant endurance was 18%. The method proved to be reliable and sensitive in the evaluation of drought tolerance for forest trees.     

刚毛柽柳 TheIF1A 基因的互作蛋白及其表达模式分析

翻译起始因子是一类翻译起始所必需的特异蛋白因子,前期研究表明柽柳翻译起始因子 (TheIF1A) 基因能对外界盐和干旱等非生物胁迫做出响应,且过表达 TheIF1A基因能提高酵母和烟草的抗旱耐盐能力。为进一步研究TheIF1A基因的抗逆机制,本研究通过酵母双杂交对柽柳翻译起始因子(TheIF1A) 基因的互作蛋白进行了筛选,共获得5个互作蛋白,分别为RNA聚合酶β II亚基 (RNA polymerase beta II subunit)、ATP合成酶CF1α亚基蛋白 (ATP synthase CF1 alpha subunit protein)、细胞色素b6/f 复合物亚基IV(cytochrome b6/f complex subunit IV)、核酮糖1,5-二磷酸羧化酶/加氧酶小亚基蛋白(ribulose 1,5-bisphosphate carboxylase/oxygenase small subunit)和组蛋白乙酰转移酶(histone acetyltransferase)。利用实时荧光定量PCR对这5个蛋白基因及 TheIF1A 基因在盐和干旱胁迫处理下的表达模式进行分析,结果表明:这些蛋白基因在盐和干旱胁迫下的表达模式与 TheIF1A基因基本一致,表明TheIF1A可能通过与这些蛋白相互作用来参与逆境胁迫应答。为进一步研究TheIF1A 基因的抗逆机理奠定了基础,有利于完善林木抗逆机制的研究,并为通过基因工程手段提高林木抗逆性提供了候选基因。     

8个中山杉新无性系耐盐力的水培试验研究

用水培法对8个中山杉新无性系进行不同质量分数氯化钠液处理,以相对生长量(RG)、盐害指数(SI)和相对电导率(RL)为指标,进行耐盐力评估。经聚类分析和相关性分析,结果表明:在水培条件下,不同无性系的耐盐力达0.30%~0.45%。中山杉118号具有较好的耐盐性,耐盐力为0.4%~0.45%;中山杉136号、1号、146号和149号耐盐力中等,为0.35%~0.40%;而中山杉102号,27号和24号的耐盐性较差,为0.3%~0.35%。RG与RL以及RG与SI两两均呈极显著负相关,RL和SI之间呈极显著正相关。相对生长量、盐害指数和相对电导率均可作为中山杉耐盐能力综合评价指标。     

Evaluation of Dutch elm disease susceptibility and pathogenicity of Ophiostoma ulmi using micropropagated elm shoots

Elm (Ulmus sp.) shoots from in vitro micropropagated plants were tested with Ophiostoma ulmi culture filtrates, at different dilutions to determine the susceptibility of different host clones to Dutch elm disease (DED). ‘Commelin’, a susceptible Dutch hybrid, showed a high wilting index but that of American elm was higher. Although U. pumila × japonica (Sapporo gold 2) was the most tolerant to spore inoculation, its wilting index was as high as that of ‘Commelin’. The absorption capacity and wilting index of the elm shoots showed consistent correlation to isolate effectiveness (as determined by inoculation experiments), to production of toxin (cerato-ulmin) and to filtrate dilution. This method could be used to assess the effectiveness of the different O. ulmi isolates and for the detection of elm genotypes that are highly susceptible to Dutch elm disease.     

外源水杨酸对盐胁迫下苦菜抗氧化系统的影响

以苦菜为试验材料,研究了5 mmol/L水杨酸（SA）预处理后,苦菜幼苗分别在0.6%、0.8%、1.0%NaCl溶液胁迫下5、10、15、20、25 d时抗氧化系统的变化。研究结果表明,5 mmol/L SA处理提高了盐胁迫下苦菜幼苗细胞SOD、POD的活性,抑制了CAT的活性;在盐胁迫处理后10、15 d,苦菜细胞内脯氨酸和H2O2含量分别达到峰值,并显著高于清水对照,说明SA通过诱导H2O2含量增加,提高抗氧化酶活力,缓解盐胁迫伤害,提高苦菜耐盐性。     

Cold tolerance of Acacia karroo and A. nilotica, two tree species from South Africa, in Beijing

Fynbos plant communities developed under geographic and climatic conditions unique to South Africa. Acacia karroo is the most widespread tree species, well known for its drought tolerance. A. nilotica exudes a good quality gum which is edible and suitable for confectionery. The two species have been introduced to China but little is known about their adaptability under the new environmental conditions. For our present study, the growth potential and physiological and biochemical parameters of the two species in response to cold stress were investigated. The results, measured as seed qualities (purity, thousand seed weights, germination, etc.) show differences between A. karroo and A. nilotica. The seed germination rate was between 10% and 60%. Seedlings were established in fields, pots and plugs. Those in the field grew well during the growing season but completely died in the winter. Those in pots or plugs were moved to and managed in the greenhouse. The plants were green in winter. The electrical conductivity of cells, the contents of water soluble sugars, proteins, malondialdehyde (MDA) increased during eight hours of low temperature treatment at 4℃. The activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) decreased markedly during the eight hours of 4℃treatment. We conclude that A. karroo and A. nilotica have little adaptability to the cold winter weather and cannot survive in the outdoors in the Beijing area, but could grow well indoors as ornamentals.