植物镁素营养的研究进展

总结近些年来有关镁素营养研究应用。详细综述植物对镁的吸收、镁在植物体内的分配与运输、镁的生理作用、植物体内镁与一些元素间的相互作用。     

植物镁离子转运及镁胁迫响应机制研究进展

镁离子是植物生长发育所必需的矿质元素,参与植物光合作用、碳水化合物代谢等一系列生理生化反应.缺镁严重影响植物生长发育及作物产量和品质.植物细胞中镁含量过高也会抑制植物生长,导致植株产生镁中毒症状.因此,植物细胞中镁离子动态平衡对于维持植物正常生长发育极其重要.植物细胞中镁离子动态平衡由定位于细胞膜及不同细胞器膜的镁离子...     

植物Mg2+转运蛋白与相关基因及其功能的研究进展

镁离子是植物细胞中最丰富的二价阳离子.在植物的生长发育中起着重要的作用.对Mg2+独特的几何和化学性质,Mg2对植物细胞体内中动态平衡的影响,植物中Mg2+转运相关蛋白与相关基因及其功能的研究进展进行了综述.     

植物Mg转运蛋白与相关基因及其功能的研究进展

镁离子是植物细胞中最丰富的二价阳离子,在植物的生长发育中起着重要的作用．对Mg^2＋独特的几何和化学性质,Mg^2＋对植物细胞体内中动态平衡的影响,植物中Mg^2＋转运相关蛋白与相关基因及其功能的研究进展进行了综述．     

东北羊草草地钙、镁含量特征的研究

本文探讨了东北羊草草地割草场的钙、镁含量特征。研究结果表明：羊草群落中,植物根的钙、镁含量最高,季节变化规律是在生长旺季较高。羊草地上部分钙、镁积累量的季节变化曲线基本为S型,寸草苔和针蔺为双峰型。群落地下部分钙、镁积累量分别占群落总积累量的97.13%和92.08%。群落中钙、镁积累量仅占根层土壤钙、镁贮量的0.05%和0.03%,占根层土壤交换性和水溶性钙、镁贮量之和的52.2%和14.62%。植物各器宫中钙含量和积累量均大于镁。     

镁肥对马尾松幼苗生长与叶片元素积累的影响

为了探讨上杭种源马尾松Pinus massoniana叶营养与生长对不同镁肥水平的响应,以其优良种源1年生苗为材料,设置4个镁肥梯度(42 g·m-2、85 g·m-2、170 g·m-2、339 g·m-2),测定移栽1年后苗木生长指标及叶内营养含量。结果表明,施镁能够促进元素P、K、Ca、Fe、Cu、Zn积累,抑制N、Mg、Mn积累;镁施肥量为85 g·m-2时,对N、Mg、Mn积累的抑制作用不显著,对P、K、Ca、Fe、Cu、Zn积累的促进作用最大,苗木生长最好,为最佳施肥量。施镁并不能促进苗木对镁的吸收,而是改变了营养供应的土壤环境,从而改变植物对其他营养的吸收比例,进而影响植物的生长。苗木的生长与Fe、P、K的关系最为密切,其次是Mg、Mn、Ca、N、Cu、Zn。     

土壤施镁矫治琯溪蜜柚缺镁的研究

本文探讨钙镁磷和硫酸镁的三种土壤施用量对矫治盛果期琯溪蜜柚缺镁的效应。试验结果表明,两种镁肥的土壤施用,对提高土壤有效镁和植株镁含量以及改善土壤和植株钾、钙与镁之间的平衡有一定的作用,从而不同程度地矫治了缺镁,并促进植林的生长与结果。试验结果还表明,施用钙镁磷的效果优于硫酸镁。作者推荐,盛果期每年株施钙镁磷1.5～2.0kg较为适宜。     

水稻镁离子螯合酶调控蛋白Gun4羧基末端的功能分析

植物叶绿素生物合成途径（镁分支）中的第一个酶是镁离子螯合酶,它由I（ChlI）、D（ChlD）和H（ChlH）三个亚基组成．各亚基不仅参与叶绿素的生物合成,而且还与叶绿体到细胞核的反向信号传导有关．Gun4是一个卟啉结合蛋白,它能提高植物镁离子螯合酶的活性,在缺乏Gun4的条件下,镁离子螯合酶整个复合物非常不稳定,不足以开始催化反应．我们以前的研究发现,Gun4 的C末端几个氨基酸具有重要作用．在本文中,通过缺失突变,获得了C端缺失了8个氨基酸残基突变的Gun4（Gun4L）.酵母双杂交与GST-pull down实验发现,Gun4L仍能与H亚基相互作用,原核表达和纯化Gun4L和镁离子螯合酶各亚基后,重组镁离子螯合酶的酶活分析证实,Gun4L对镁离子螯合酶的活性失去了激活作用．     

紫细菌光合反应中心中细菌脱镁叶绿素被置换后的光 …

采用新型表面活性剂ＬＤＡＯ,结合ＤＥＡＥ－纤维素层析法,我们提纯了紫细菌６０１的光合反应中心,在一定温度和丙酮的协同作用下,外加的植物脱镁叶绿素ａ可取代反应中心细菌脱镁叶绿素,形成含有脱镁叶绿素ａ的紫细菌光合反应中心。     

镁肥对水稻镁吸收与分配及稻米食味品质的影响

以‘宁粳2号’为材料,采用田间小区试验方法研究了单季粳稻施用镁肥后对镁吸收分配的影响。结果表明,从拔节到始穗期,水稻体内镁的阶段吸收量和吸收速度最高,分别为7.22 kg.hm-2和0.40 kg.hm-2.d-1;从拔节期到齐穗期,镁肥的施用促进了水稻对镁的吸收,其它生育期对外界镁浓度变化不敏感;镁肥的施用降低了镁在茎鞘和叶片中的分配比例,提高了镁在穗部的分配比例;齐穗后15~30 d为穗部积累镁的高峰期;在本实验范围内,随施肥水平的提高,稻米中的镁含量升高,RVA(Rapid of viscosity analysis)谱中最终黏度、回复值及消减值显著下降,最高黏度、热浆黏度和崩解值显著上升,糊化温度没有明显差异。施用镁肥提高了稻米食味品质,这其中以120 kg.hm-2用量效果最好。     

Nutritional Aspects of Magnesium Metabolism

The absolute necessity for magnesium in plant and animal nutrition is easily appreciated when one realizes that magnesium is found in high concentration in cells. It is necessary for photosynthesis in plants and for all reactions involving adenosine triphosphate in plant and animal cells. Although it is abundant in nature in general, deficiencies occur in both plants and animals. Human beings need about 5 mg of magnesium per kg of body weight per day. Infants and young children need twice as much. Children and women during pregnancy or lactation require significantly greater amounts than normal adults. Various diseases result in a deficiency of magnesium because of interruption of food intake or intestinal or renal wasting of the mineral.     

Overexpression of an Arabidopsis magnesium transport gene, AtMGT1, in Nicotiana benthamiana confers Al tolerance

Aluminium (Al) toxicity is the most important limiting factor for crop production in acid soil environments worldwide. In some plant species, application of magnesium (Mg(2+)) can alleviate Al toxicity. However, it remains unknown whether overexpression of magnesium transport proteins can improve Al tolerance. Here, the role of AtMGT1, a member of the Arabidopsis magnesium transport family involved in Mg(2+) transport, played in Al tolerance in higher plants was investigated. Expression of 35S::AtMGT1 led to various phenotypic alterations in Nicotiana benthamiana plants. Transgenic plants harbouring 35S::AtMGT1 exhibited tolerance to Mg(2+) deficiency. Element assay showed that the contents of Mg, Mn, and Fe in 35S::AtMGT1 plants increased compared with wild-type plants. Root growth experiment revealed that 100 microM AlCl(3) caused a reduction in root elongation by 47% in transgenic lines, whereas root growth in wild-type plants was inhibited completely. Upon Al treatment, representative transgenic lines also showed a much lower callose deposition, an indicator of increased Al tolerance, than wild-type plants. Taken together, the results have demonstrated that overexpression of ATMGT1 encoding a magnesium transport protein can improve tolerance to Al in higher plants.     

Influence of magnesium deficiency on rates of leaf expansion, starch and sucrose accumulation, and net assimilation in Phaseolus vulgaris

Twenty one-day-old Phaseolus vulgaris 'Saxa'plants were cultured in a growth chamber and the plants supplied with either a complete or a Mg-free nutrient solution. From 6 days after transfer to the Mg-free solution, the rate of increase of the area of the second trifoliate leaf was considerably reduced; by day 11 the sucrose concentration in the first trifoliate leaf had increased 6. 2-fold at the end of the dark period and 4. 6-fold after the light period as compared with the control plants. Corresponding starch concentrations increased 6. 6-fold and 2. 9-fold respectively. After days 5 to 6 the assimilation rates declined in the first trifoliate leaf of the plants showing deficiency, in comparison with the plants fully supplied with nutrients; respiration increased during darkness. The reduction in net assimilation rate was to a great extent reversible after resupply of magnesium.
The reduction of magnesium concentration in the deficient plants was much more marked in the expanding leaves than in the mature primary leaves and roots. Sucrose and starch accumulation did not occur when the first trifoliate leaf was partially shaded, although magnesium concentration, as in the unshaded leaves, was reduced to 13% of that of the control plants. The consequences of magnesium deficiency in the expanding first trifoliate leaf are discussed in terms of the possibility of sink limitation.     

Effects of silicon on the chemical composition of rice plants

Summary Rice plants were grown in nutrient culture solutions. Silicon was supplied to these plants at different rates. The plant samples of early vegetative, vegetative and flowering stages were analysed for nitrogen, phosphorus, potassium, calcium, magnesium, iron, manganese, silicon, protein and carbohydrate contents. The application of silicon generally decreased the nitrogen, protein and potassium content of rice plants. Its application also decreased the iron and manganese contents. The use of silicon resulted in an increase in phosphorus, calcium, magnesium, silicon and carbohydrate contents of rice plants.Reader and Head of the Department of Soil Science, University of Dacca, Dacca, East Pakistan.     

Calcium and Magnesium Levels in Agricultural Soil and Sewage Sludge in an Industrial Area from Southeastern Spain: Relationship with Plant (Saccharum officinarum) Disposition

This investigation was initiated to assess the following objectives: (1) to measure the total calcium and magnesium content in agricultural soil and sewage sludge from the Mediterranean coastal area of Motril (southeastern Spain); (2) to determine the pH values of indicated samples in order to evaluate first their influence on calcium and magnesium content, and second on levels of these minerals in the main crop (sugar cane: Saccharum officinarum) grown in the area; (3) to study the influence of industrial activities, first on calcium and magnesium cantents and pH values in agricultural soil, and second on calcium and magnesium concentrations present in sugar cane samples; (4) to check if the calcium and magnesium levels existing in agricultural soil exert any influence on corresponding element uptake by sugar cane plants. Calcium levels found in agricultural soil were significantly higher (p < 0.05) than those found in sewage sludge. Significant linear relationships between calcium and magnesium concentrations in agricultural soil and sewage sludge (p < 0.005) were found. Calcium concentrations found in soil from the industrialized area (39.2 ± 7.2 mg g^?1) were significantly higher than those corresponding to the non-industrialized area (31.0 ± 6.6 mg g^?1). The pH values determined in agricultural soil were significantly influenced by industrial activity (p < 0.05). The industrial activity and pH values measured in agricultural soil did not statistically influence either calcium or magnesium levels in the sugar cane plants. Calcium and magnesium concentrations existing in agricultural soil did not significantly influence the element uptake by sugar cane plants.     

Evidence of formation of glushinskite as a biomineral in a Cactaceae species

The X-ray diffractometric and infrared spectroscopic investigation of crystalline material isolated from the Cactaceae species Opuntia ellisiana shows the presence of a very complex mineral composition, including whewellite (monohydrated calcium oxalate), opal (SiO2), calcite (CaCO3) and glushinskite (dihydrated magnesium oxalate). This is the first report of the presence of magnesium oxalate in plants.     

Steady state kinetic mechanism of the Escherichia coli coenzyme A transferase.

Developing chloroplasts isolated from greening cotyledons and isolated etioplasts were capable of synthesizing and accumulating Mg-protoporphyrin IX monoester and longer wavelength metalloporphyrins when incubated in the dark in the presence of protoporphyrin and cofactors. These results constituted the first unambiguous demonstration of the insertion of magnesium into exogenous protoporphyrin in a cell-free system from higher plants. The metalloporphyrin synthetic activity did not occur in the absence of the plastids or when the plastids were heated in a 100 °C water bath for 2 min. It is thus suggested that, in higher plants, the in vitro insertion of magnesium into protoporphyrin is an enzymatic reaction.     

Investigation of the reaction of magnesium with p-nitro-o-carboxylazochromotropic acid and the determination of magnesium in plants and in water

The formation of a novel complex between magnesium and p-nitro-o-carboxylazochromotropic acid (NCBAC) has been observed which is sensitive and selective at pH 10.4 in the presence of ethylenediamine and fluoride. The constants of formation of this complex have been determined by a spectral correction technique, and the complexation reaction has been applied to the spectrophotometric determination of trace magnesium in plants and in water with satisfactory results.