热胁迫对豌豆生理的影响

[目的]揭示高温影响豌豆生长发育的生理学基础。[方法]通过测定热胁迫下豌豆幼苗的电导率、丙二醛(MDA)、抗坏血酸(AsA)变化及下胚轴长度,探讨热胁迫对豌豆一些生理指标的影响。[结果]温度越高,豌豆细胞膜的完整性损伤越大,外渗的胞内电解质越多。高温使更多的膜脂过氧化,导致MDA含量升高。高温胁迫明显造成叶片中抗氧化剂AsA的损失,降低了豌豆抵抗高温引发的氧化损伤的能力。在高温胁迫下,幼苗下胚轴的生长受抑制,热激温度越高下胚轴越短。[结论]热胁迫使豌豆细胞膜完整性受损,膜脂更多地被过氧化,AsA含量下降,下胚轴生长受到抑制。     

苏铁蕨中脂溶性成分的提取及GC-MS分析

采用微波-乙醇工艺提取苏铁蕨的木质根上茎直立部分,经GC-MS分析,分离出60个峰,并确认了其中55个成分,所鉴定的组分占总峰面积的97.88%.苏铁蕨中的脂溶性成分被划分为4类化合物:有机酸类、倍半萜类、烷烃类和环硅氧烷类.经结构分析,各类化合物内部的分子结构间存在高度的相关性,特别在烷烃类与环硅氧烷类中,相邻的化合物间具有相同的结构差.其中环硅氧烷的结构在蕨类植物研究中尚未见报道.     

棉蚜在塑料大棚和日光温室青椒上的分布规律

为了明确棉蚜在塑料大棚和日光温室青椒上的分布规律,运用聚集度指标和Taylor幂方法,对塑料大棚和日光温室2种设施青椒植株上的棉蚜分布情况进行了分析。结果表明:在塑料大棚和日光温室青椒上,棉蚜的空间分布型均为聚集分布,聚集程度随密度升高而增大。棉蚜种群在青椒上的垂直分布规律为上部叶片分布最多,占整个青椒植株虫量的比例达到50%以上;中部次之,下部叶片棉蚜数量最少,但二者差异不显著。     

国际粮食市场价格风险评估研究

为探讨国际粮食市场价格风险管理,本研究构建了国际粮食市场价格风险评估的基本模型,建立国际粮食市场价格波动序列,拟合国际粮食市场价格波动概率分布和计算国际粮食市场的风险价值（VaR）。通过对国际大米、玉米、小麦和大豆市场价格风险的实证分析,结果表明：正态分布并不是国际粮食市场价格波动的最优概率分布模型,国际粮食市场价格波动表现为服从Lognormal、Log-logistic和Burr分布;就整体而言,国际粮食市场价格风险较为严重,上涨的风险要大于下跌的风险;就具体品种而言,国际大米的市场价格风险最大,其上涨和下跌的VaR分别达到69.23%和34.31%,远高于玉米、小麦和大豆。     

低氧胁迫对河川沙塘鳢抗氧化酶及ATP酶活性的影响

研究了在急性低氧1.5 h、5 h和慢性低氧3 d下,河川沙塘鳢(Odontobutis potamophila)5种组织(心、脑、肝、鳃和肾)的超氧化物歧化酶(SOD)、过氧化氢酶(CAT)及谷胱甘肽过氧化物酶(GPX)3种抗氧化酶和ATP酶活性的变化规律。结果显示:在急性低氧暴露1.5 h时,河川沙塘鳢SOD和GPX的活力在各组织中与对照组相比均无显著差异,CAT活力在心、鳃和肝3种组织呈现显著升高(P0.05),ATP酶活力在心和肝组织极显著升高(P0.01);在急性低氧暴露5 h时,除肝组织SOD酶活性显著降低外(P0.05),其它4种组织的CAT、GPX和ATP酶均不同程度显著升高(P0.05);在慢性低氧处理3 d时,心、脑组织的抗氧化酶已基本恢复至与对照组无显著差异的水平,但鳃、肝和肾中酶活力仍较高(P0.05)。研究表明,河川沙塘鳢能通过自身调节抗氧化酶及ATP酶活性,改变代谢底物,提高机体适应低氧环境的能力。     

草甘膦与2,4-D混用对柑橘园杂草的防治效果

研究了10.8％草甘膦·2,4-D水剂(AS)对柑橘园杂草的田间防治效果.结果表明,10.8％草甘膦·2,4-D AS制剂用量15 750～31 500 mL/hm2几乎对所有禾本科、阔叶类和其他类杂草均有较好的防治效果,防效与41％草甘膦异丙胺盐AS制剂用量4 116 mL/hm2相当,显著优于72％ 2,4-D丁酯EC制剂用量8 100 mL/hm2的防效,作用较快,持效期较长.     

代谢组解析商品成熟与生理成熟芒果内在品质和类胡萝卜素合成差异

为更好地了解芒果果实"后熟"过程中果实色泽与内在品质相关次生代谢产物的变化,也为通过基因工程改善和促进果实的品质形成和着色机理提供理论依据,本研究利用广泛靶向代谢组学和类胡萝卜素代谢组学对商品成熟期和生理成熟期芒果果实进行了测定与分析.结果表明:商品成熟和生理成熟芒果果实中差异表达的次级代谢产物共有309种,包括有机酸...     

Hydro-physical responses of gypseous and non-gypseous soils to livestock grazing in a semi-arid region of NE Spain

Pasture productivity depends on soil hydro-physical properties, which in turn are deeply affected by livestock grazing. However, the comparative response of different soil types, and particularly gypseous soil types, to grazing has hardly been studied before. This paper compares the effect of grazing on the soil hydro-physical properties of silty gypseous (Gy) and non-gypseous (NGy) soils located in a semi-arid region (Middle Ebro Valley, NE, Spain). Two different soil managements were selected: ungrazed natural shrubland (N) and grazed shrubland (GR) soils. The gypsum, CaCO₃ and organic matter content (OM), soil texture, soil bulk density (ρ_b), penetration resistance (PR), saturated sorptivity (S), hydraulic conductivity (K), and the water retention curve (WRC) for undisturbed soil samples from 1 to 10 cm depth soil layer were measured. The ρ_b and PR in NGy soils were significantly higher than those observed in the Gy ones. Soil compaction due to grazing treatment tended to increase ρ_b and decrease the K and S values. While no differences in PR were observed in the Gy soils between grazing treatments, the PR measured in the NGy soils under GR was significantly higher than the corresponding values observed under N. Differences in K and S between GR and N treatments were only significant (p < 0.05) in NGy soils, where K and S values under the N treatment were almost four times greater than the corresponding values measured under GR. Overall, no differences in the WRCs were observed between soil types and grazing treatments. While the WRCs of NGy soils were not significantly affected by the grazing treatment, Gy soils under N treatment present a significantly higher level of soil macropores than under GR treatment. The hydro-physical features of Gy soils tended to be less affected by grazing than those of the NGy soils. These results suggest that livestock grazing, in both Gy and NGy soils, has a negative effect on the physical soil properties, which should be taken into account by land managers of these semi-arid regions where silty gypseous and non-gypseous areas coexist.     

玉米抗南方型锈病基因共分离分子标记的研究

本文以玉米(Zea mays L.)抗南方型锈病自交系P₂₅和感病自交系F₃₄₉的F₁与F₃₄₉回交,并连续回交所得BC₅代的F₃₄₉抗病近等基因系（nearly isogenic lines,NILs）为材料,以RGA（resistance gene analogs）的方法,在抗病自交系中克隆出一条321 bp的特异性DNA条带。根据序列比对的结果,设计出新的引物作为分子标记,在96株BC₇、BC₄F₅NILs及其亲本和杂种F₁群体上进行鉴定,其中94株的田间抗感结果与分子检测结果一致,选择的有效率达97.9%。此标记扩增效果清晰,可重复性强,在抗玉米南方型锈病的分子标记辅助育种研究中有应用价值。     

Engineering of a Single Chain Variable Fragment Antibody Specific for the Citrus tristeza virus and its Expression in Escherichia coli and Nicotiana tabacum

Citrus tristeza virus (CTV) is one of the most destructive citrus virus diseases in the world. The construction of an engineered antibody, EMBL accession number AJ278109, able to specifically recognize its antigen, i.e. the coat protein of CTV, directly on infected plant material without any purification or manipulation of the entire woody plant. The potential uses of this engineered antibody are discussed.