大豆耐铝毒候选基因GmSTOP1的克隆与表达分析

酸性土壤中的铝毒害是限制作物生长和产量的主要因素之一。拟南芥中的At STOP1(Arabidopsis thaliana sensitive to proton rhizotoxicity 1)是一个调控多种铝毒耐受机制相关基因表达的转录因子,在拟南芥耐铝毒中发挥重要作用。为研究大豆中STOP1-like基因的表达特性,本研究利用RT-PCR从耐铝毒大豆品种科丰1号中克隆了一个位于第16染色体的STOP1-like基因,命名为Gm STOP1。该基因的编码区(coding DNA sequence,CDS)序列长度为1566 bp,编码521个氨基酸。在Gm STOP1起始密码子上游1500 bp的核苷酸序列区间预测到多种顺式作用元件,包括与激素、热、逆境响应等相关的应答元件,如ABRE、HSE、TC-rich重复序列等。蛋白质结构预测表明Gm STOP1不具有跨膜结构和信号肽,含有4个保守的Cys-2-His-2锌指蛋白结构域。系统进化分析显示Gm STOP1与菜豆(Phaseolus vulgaris)中的STOP1-like蛋白亲缘关系较近。亚细胞定位结果显示Gm STOP1定位于细胞核,说明Gm STOP1蛋白可能在细胞核中发挥其功能。Gm STOP1基因在种子中的相对表达量最高,在根、茎尖分生组织、茎、叶、花、荚等多种组织中也均有表达。用25μmol L–1 Al Cl3溶液处理大豆幼苗,Gm STOP1基因在根中上调表达,24 h达到最高相对表达量,约为对照(0μmol L–1 Al Cl3)的9.2倍,表明该基因的表达受铝离子的诱导。此外,ABA、Na Cl和PEG等胁迫也能诱导大豆根和叶中Gm STOP1基因的上调表达。由此推测Gm STOP1基因可能参与大豆对铝毒、高盐和渗透等非生物胁迫的应答过程。     

铝对小麦根细胞质膜ATP酶活性和膜脂组成的影响

 铝胁迫下 ,耐铝性不同的两个小麦品种 ( Altas66,耐铝 ;Scout66,铝敏感 )根细胞质膜 H+ - ATP酶或 Ca2 + -ATP酶活性变化趋势相似。 2 0 μmol/ L 和 10 0 μmol/ L 铝处理 5 d,质膜 Ca2 + - ATP酶活性明显下降 ;H+ - ATP酶活性在 2 0 μmol/ L 铝处理时上升 ,10 0 μmol/ L 铝时下降。质膜磷脂含量下降 ,糖脂含量上升 ,但铝敏感的 Scout66磷脂 /糖脂比值下降较耐铝的 Altas66显著。 2 0和 10 0 μm ol/ L 铝处理后 ,Scout66的亚麻酸含量和脂肪酸不饱和指数明显下降 ,Altas66的脂肪酸不饱和指数则稍有上升     

大麦耐铝毒机理及遗传改良研究进展

综述了大麦酸铝毒害及其遗传改良研究进展。大麦铝毒害的首要症状是根系的生长发育受阻 ,根系微观结构改变 ,其机制可能包括 :铝引起细胞死亡、缺乏细胞壁合成底物、铝影响DNA合成以及矿质元素吸收等几个方面。大麦可以通过增加根际分泌物如有机酸、多肽等螯合根际铝 ,也可提高根际 pH使铝沉淀 ,减弱铝毒性 ,对进入细胞内的铝也可通过与铝形成无毒的复合物 ,或将铝主动运入液泡中 ,解除内部铝毒。对大麦的遗传研究表明 ,大麦耐铝性是由单基因控制 ,耐铝性不同的品种分别是由多基因座控制。利用苏木精染色等方法已鉴定出一些耐铝材料 ,通过突变体筛选已获得了一些抗铝的大麦品种。运用分子生物学技术 ,有望将小麦耐铝基因导入大麦 ,显著提高大麦耐铝毒的能力     

Effects of vegetation type on soil resistance to erosion: Relationship between aggregate stability and shear strength

Soil water erosion and shallow landslides depend on aggregate stability and soil shear strength. We investigated the effect of vegetation on both soil aggregate stability and shear strength (through direct shear tests) in former croplands converted to vegetated erosion protection areas within the context of China's sloping land conversion programme. Four treatments were analysed in plots comprised of (i) 4 year old crop trees, Vernicia fordii, where understory vegetation was removed; (ii) V. fordii and the dominant understory species Artemisia codonocephala; (iii) only A. codonocephala and (iv) no vegetation. Soil samples were taken at depths of 0–5 cm and 45–50 cm. Root length density (RLD) in five diameter classes was measured, soil organic carbon (SOC), hot water extractable carbon (HWEC), texture and Fe and Al oxides were also measured. We found that mean weight diameter after slow wetting (MWD_SW) in the A-horizon, was significantly greater (0.94–1.01 mm) when A. codonocephala was present compared to plots without A. codonocephala (0.57–0.59 mm). SOC and RLD in the smallest diameter class (< 0.5 mm), were the variables which best explained variability in MWD_SW. A significant positive linear relationship existed between MWD_SW and soil cohesion but not with internal angle of friction. As herbaceous vegetation was more efficient than trees in improving aggregate stability, this result suggests that the mechanisms involved include modifications of the cohesive forces between soil particles adjacent to plant roots and located in the enriched in SOC rhizosphere, thus also affecting shear strength of the corresponding soil volume. Thus, vegetation stabilised soil under different hierarchical levels of aggregate organisation, i.e. intra- and inter-aggregate. Our results have implications for the efficacy of techniques used in land conversion programs dedicated to control of soil erosion and shallow landslides. We suggest that mixtures of different plant functional types would improve soil conservation on slopes, by reducing both surface water erosion and shallow substrate mass movement. Planting trees for cropping or logging, and removing understory vegetation is most likely detrimental to soil conservation.     

铝胁迫对龙眼叶和根细胞超微结构的影响

用扫描电镜、透射电镜、荧光显微镜研究铝胁迫对龙眼叶、根超微结构的影响。结果表明 ,铝胁迫造成龙眼叶片超微结构的破坏。其中最明显的变化是叶绿体的破坏 ,表现为叶绿体膜系统受损加重 ,基粒片层扭曲紊乱 ;其次是细胞壁的降解 ,细胞之间间隙变小 ,部分液泡膜破裂 ,液泡消失 ;线粒体膜系统受到破坏 ,嵴数量明显减少甚至消失。铝胁迫下龙眼根端膨大 ,根尖变粗变短 ,从外表皮到中柱出现不同程度的龟裂 ,且随铝浓度的提高 ,这种伤害程度不断加重 ;根伸长区细胞细胞壁发生降解 ,细胞间距变小 ;膜系统遭到破坏 ,核膜、线粒体膜破裂 ;细胞中淀粉粒明显减少 ,甚至消失 ;根尖分生组织细胞核变形 ,细胞核数量大大减少。     

铁锅外表面局部热浸渗铝工艺研究

本文根据热浸渗铝法,可有效提高金属表面抗氧化能力,我们对“低碳钢板热冲压成型铁锅外表面进行局部热浸渗铝”的工艺,进行了探讨和研究,经产品试制和质量检验,取得了较好的结果。     

飞机草的急性LD50和亚急性毒性研究初报

 给昆明种雌性小白鼠经口灌服飞机草水提物，用改良寇氏法测定了飞机草全草的急性LD50；另取一批小白鼠，每隔3d分别用浓度为5g/ml、2.5g/ml、1.25g/ml和0.625g/ml的飞机草水提物经口灌服一次，共灌服5次，进行试验期为35d的飞机草亚急性毒性试验。结果发现，飞机草全草水提物对昆明种雌性小白鼠的急性LD50为227091.02mg/kg，95%可信限为227090.96~227091.07 mg/kg，即飞机草水提物对昆明种雌性小白鼠实际无毒。但飞机草具有亚急性毒性作用，供试小白鼠出现中毒体     

Effects of Aluminum on ATPase Activity and Lipid Composition of Plasma Membranes from Wheat Roots

The effects of aluminum on ATPase activity and lipid composition of the plasma membranes isolated from root tips of Al-tolerant (Altas 66) or Al-sensitive (Scout 66) cultivar of Triticum aestivum L.was assayed. The results showed that both cultivars had similar changes in H+ -ATPase and Ca2+ -ATPase activities after aluminum treatment. Exposure of both cultivars to 20 and 100 (mol/L aluminum for 5 d significantly decreased the activities of Ca2+ -ATPase of plasma membranes. The activities of H+-ATPasc in plasma membrane increased under 20 μmol/L aluminum and decreased at 100 μmol/L aluminum. With aluminum treatment, the PL content of plasma membrane decreased, but GL content increased. The ratio of PL to GL decreased more distinctly in Scout 66 than that in Altas 66. Treated with 20 and 100 μmol/L aluminum, linolenic acid content and the index of unsaturated fatty acids decreaced greatly in Scout 66, but the index of unsaturated fatty acids in Altas 66 increased slightly.     

Aluminum contents of the edible portions of the winged bean,Psophocarpus tetragonolobus (L.) DC. (Fabaceae): Field study and caveat

The winged bean,Psophocarpus tetragonolobus (L.) DC has been widely recognised as a potentially useful source of protein for tropical regions of the world. A neglected aspect of the plants nutritional quality has been the reporting of the accumulation of aluminum (Al) in the edible parts of the plant; the leaves, pods, seeds and tubers. The accumulation of Al in the plant on acidic tropical soils and the implication of Al to human health problems further justified the inclusion of Al in nutritional analysis. Field experiments on two varieties of the winged bean, the USDA-releaseHi-Flyer and an unnamed variety from the Phillipines, showed that all edible portions of the plant accumulate Al from high to very high levels when compared to an average of usually less than 300 ppm in other crop plants. Aluminum accumulation is generally highest in the youngest tissues particularly in the young roots with levels recorded as high as 25,000 ppm and these contents are as high as levels for recognised Al accumulators such as the leaves ofPinus and tea. Future improvement breeding programs for the winged bean will necessarily require identifying and taking advantage of possible variation in Al accumulation between varieties.