高盐下条斑紫菜光合特性和S-腺苷甲硫氨酸合成酶基因表达的变化

为了研究条斑紫菜耐盐机理,对条斑紫菜叶状体进行了高盐胁迫处理,继而采用氧电极法测量了光合放氧速率和呼吸耗氧速率的变化,采用实时荧光定量PCR技术测量了S-腺苷甲硫氨酸合成酶(命名为PySAMS)基因的表达变化。结果显示藻体的光合与呼吸作用均受到高盐度海水的显著影响,随着盐度的增加,光合放氧率逐渐降低,呼吸耗氧率也逐渐降低。高盐度海水对PySAMS基因表达量也产生了显著影响,40和50盐度的海水诱导了PySAMS表达,但60至80盐度的海水却不同程度地抑制了PySAMS表达。据此推测,在面对较高盐度胁迫时条斑紫菜叶状体将逐步降低体内新陈代谢以度过不良环境。     

香港巨牡蛎与长牡蛎种间配子兼容性

为了评估香港巨牡蛎与长牡蛎的配子兼容性,于2010年7月,以性腺成熟的香港巨牡蛎和长牡蛎为材料,研究了环境因子温度(16、20、24、28、32℃)、盐度(10、15、20、25、30)及内在因子精子浓度(100、101、102、103、104个/μL)、个体差异(240次杂交实验)对其受精率的影响,并计算了以上条件下的F50临界值。结果表明:香港巨牡蛎卵子可以与长牡蛎精子受精,但相反方向不能受精,存在着单向受精现象。温度是影响长牡蛎配子兼容性主要因子,盐度是影响香港巨牡蛎的主要因子,而温度、盐度交互作用是影响种间配子兼容性的最主要因子。种间配子温度、盐度的F50临界值分别为20.90℃、14.7。精子浓度及单对杂交中的个体差异均显著影响配子兼容性,精子浓度的F50临界值为2.40个/μL;在240次杂交实验中,有91次受精率不足50%,说明个体差异比例的F50临界值37.92%。从其内在因子来看,长牡蛎平均受精率最高(96.83%),配子兼容性较好;对于香港巨牡蛎(70.98%)与种间配子(58.70%)而言,受精水平相对较低,且存在着较大的个体差异。     

黄河三角洲典型植被与地下水埋深和土壤盐分的关系

土壤盐分和地下水埋深是影响黄河三角洲植被发育和分布的重要因素.本文通过野外调查与统计分析,研究了黄河三角洲区域典型植被(翅碱蓬 柽柳、刺槐、芦苇和棉花)、地下水埋深、土壤盐分之间的关系.结果表明: 研究区地下水埋深显著影响土壤盐分,平均影响系数为0.327,地下水埋深在0.5～1.5 m的土壤盐渍化最严重;整个研究区内植被发育较差,其中,研究区78%面积的归一化植被指数(NDVI)<0.4,地下水埋深、土壤盐分对天然植被分布有显著影响;土壤盐分对研究区翅碱蓬-柽柳、刺槐、芦苇及棉花NDVI的影响显著,地下水埋深对翅碱蓬-柽柳NDVI的影响显著,对芦苇、棉花、刺槐NDVI的影响不显著.     

盐胁迫下施肥对棉花生长及氮素利用的影响

利用海水配制不同含盐量(0、0.15%、0.3%)的土壤盆栽棉花,在可移动遮雨棚内研究了不同施肥(N、NK、NP、NPK)处理对棉花生长、氮素吸收与利用的影响.结果表明: 盐胁迫和施肥均影响棉花生物产量、棉株氮素农学利用效率、氮素生物利用效率和氮素积累量,且两者存在显著的互作效应.施肥能提高盐胁迫下棉株氮素利用效率及氮素积累量,并显著增产,不同施肥处理中以N、P、K肥料配合施用的效果最好;施肥效果受盐胁迫程度的影响,低盐胁迫(0.15%)下的施肥效果好于中度盐胁迫(0.3%).     

Optimization of Exopolysaccharide Overproduction by Lactobacillus confusus in Solid State Fermentation under High Salinity Stress

It is believed that high concentrations of sodium chloride (NaCl) suppress the biosynthesis of exopolysaccharide (EPS) in lactic acid bacteria (LAB). Nevertheless, overproduction of EPSs due to high salinity stress in solid state fermentation performed on an agar surface was demonstrated in this study using a response surface methodology via a central composite design (CCD). Under optimized conditions with NaCl 4.97% and sucrose 136.5 g/L at 40.79 h of incubation, the EPS yield was 259% (86.36 g/L of EPS), higher than the maximum yield produced with the modified MRS medium containing only 120 g/L of sucrose without NaCl (33.4 g/L of EPS). Biosynthesis of EPS by Lactobacillus confusus TISTR 1498 was independent of biomass production. Our results indicated that high salinity stress can enhance EPS production in solid state fermentation.     

Exogenous application of mannitol and thiourea regulates plant growth and oxidative stress responses in salt-stressed maize (Zea mays L.)

Abstract

The mechanism of growth amelioration in salt-stressed maize (Zea mays L. cv., DK 647 F1) by exogenously applied mannitol (M) and thiourea (T) was investigated. Maize seedlings were planted in pots containing perlite and subjected to 0 or 100 mM NaCl in full strength Hoagland's nutrient solution. Two levels of M (15 and 30 mM) or T (3.5 and 7.0 mM) were sprayed to the leaves of maize seedlings 10 days after germination. Salinity stress caused considerable reduction in plant dry biomass, chlorophyll content, and relative water content in the maize plants. However, it increased the activities of catalase (CAT; EC 1.11.1.6), superoxide dismutase (SOD; EC 1.15.1.1), and polyphenol oxidase (PPO; EC 1.10.3.1), and levels of hydrogen peroxide (H₂O₂) and electrolyte leakage, but it did not change peroxidase (POD; EC 1.11.1.7) activity. Foliar application of M or T was found to be effective in checking salt-induced shoot growth inhibition. Exogenously applied M or T reduced the activities of CAT, SOD, POD, and PPO in the salt-treated maize plants compared to those in the plants not fed with these organic compounds. Salinity increased Na⁺ contents but decreased those of K⁺, Ca^{2 +}, and P in the leaves and roots of the maize plants. Foliar-applied M or T increased the contents of K⁺, Ca^{2 +}, and P, but decreased that of Na⁺ in the salt-stressed maize plants with respect to those of the salt-stressed plants not supplied with mannitol or thiourea. Mannitol was found to be more effective than thiourea in improving salinity tolerance of maize plants in terms of growth and physiological attributes measured in the present study.     

Exogenous application of penconazole regulates plant growth and antioxidative responses in salt-stressed Mentha pulegium L.

The mechanism of growth amelioration in salt-stressed pennyroyal (Mentha pulegium L.) was investigated by exogenous application of penconazole (PEN). Seven weeks after sowing, seedlings were treated with increasing NaCl concentrations (0, 25, 50, and 75 mM) with or without PEN (15 mg l^?1) and were harvested randomly at different times. Results showed that some growth parameters and the relative water content (RWC) decreased under salt stress, while lipid peroxidation, H₂O₂ content, activities of superoxide dismutase (SOD; EC 1.15.1.1), peroxidase (POX; EC 1.11.1.7), polyphenol oxidase (PPO; EC 1.10.3.1), catalase (CAT; EC 1.11.1.6), and ascorbate peroxidase (APX; EC 1.11.1.1) remarkably increased. Exogenous application of PEN increased some growth parameters, RWC, antioxidant enzyme activities, and H₂O₂ content, but the effects of PEN were more significant under salt stress conditions. PEN treatment also decreased lipid peroxidation. These results suggest that PEN-induced tolerance to salt stress in M. pulegium plants may be related to regulation of antioxidative responses and H₂O₂ level.     

Alleviating the inhibitory effect of salinity stress on nod gene expression in Rhizobium tibeticum – fenugreek (Trigonella foenum graecum) symbiosis by isoflavonoids treatment

Rhizobia-legume symbiosis depends on molecular dialog, which involves the production of specific plant flavonoid compounds as signal molecules. Rhizobium tibeticum was recovered from the root nodule of fenugreek and identified by sequencing the 16S rRNA gene. The effect of salinity stress on nod gene expression was measured in terms of β-galactosidase activity. R. tibeticum containing Escherichia coli lacZ gene fusions to specific nodulation (nod) genes were used to determine β-galactosidase activity. Combination of hesperetin (7.5 µM) and apigenin (7.5 µM) significantly increased β-galactosidase activity more than the single application of hesperetin or apigenin. Preincubation of R. tibeticum with hesperetin and apigenin combination significantly alleviates the adverse effect of salinity on nod gene expression and therefore, enhances nodulation and nitrogen fixation of fenugreek.     

35S::GmPM30在拟南芥的根系生长中表现为对ABA的敏感性降低(英文)

LEA protein,late-embryogenesis-abundant protein,is importantin response to thesalt and drought stresses in plants.Here,weidentified a cDNA full length of LEA from soybean and found that LEA enhance the ability of anti-salinity in transgenic Arabidopsis thaliana.The expression of GmPM30 increases highly under salinity,cold or ABA treatment,and enhances by certain degree under drought stress.The germination rates,primary root lengths and survival rate of GmPM30 over-expression lines are obviously higher than that of the wild-type after suffering the salinity stress.Our studies displays that GmPM30-ox apparently enhances the tolerance to salinity in Arabidopsis thaliana.     

Subtidal macrozoobenthic community resilience to change following natural mouth breaching of the temporarily open/closed East Kleinemonde Estuary,South Africa

The East Kleinemonde Estuary, on the south-east coast of South Africa, typically opens for only short periods, usually <10 days. During a nine-month study in 2006, marine influence persisted for a near-continuous period of three months. This provided an opportunity to explore potential changes in the structure and pattern of the subtidal estuarine macrozoobenthic community. Salinity changes were minimal after mouth opening, decreasing by c. 4 and 8 in the lower and upper estuary, respectively. Salinity decrease was due to river dominance over tidal influence. Two biotic assemblages, structured by sediment characteristics, typified the community throughout the study: a sand-associated group near the mouth and a mud-associated group upstream. Amphipods were proportionally the most abundant group within each assemblage and on each sampling occasion. At the species level, high variability typified the community, with no trends or patterns observed. However, species richness declined from 27–30 to 23 after mouth opening. The number of species returned to former levels at the time of the final survey and just before final mouth closure. An analysis of the subtidal macrozoobenthos in the East Kleinemonde and other temporarily open/closed estuaries (TOCEs) of similar size in the bioregion indicated that communities were typically composed of relatively few, broadly tolerant euryhaline species with no species unique to TOCEs.