植物铝抗性基因及抗铝毒基因工程研究进展

酸性土壤占世界可耕作土壤的30％,而铝毒是酸性土壤中植物生长和作物生产的主要限制因素.近年来,在植物中鉴定了一系列抗铝基因,如有机酸通道蛋白基因(ALMT1和MATE),ABC通道蛋白基因(STAR1和STAR2)和转录因子基因(STOP1和ART1).通过基因工程手段在植物中过表达有机酸通道蛋白基因、有机酸代谢酶基因和其他铝胁迫响应基因均获得了很大的进展.本文综述了植物抗铝基因的克隆与鉴定,以及通过遗传操作提高植物的抗铝能力.     

植物对铝毒害的抗逆性研究进展

铝毒是酸性土壤中限制作物产量的一个重要障碍因子。从铝的存在形态、铝毒机制、植物耐铝毒机理及影响铝毒效应的因素等方面综述了近几年国内外对铝毒的研究进展,提出了该领域研究中存在的问题,为进一步开展植物对铝毒的抗逆性研究提供参考。     

植物耐铝机理研究进展

铝毒是酸性土壤上作物生产的主要限制因子,植物耐铝机理以及与耐铝有关基因的研究是近十多年来研究的热点。本文对植物耐铝的生理、遗传及分子机理的研究进展作了综述。明确了目前取得的突破性进展已使通过植物遗传育种及生物技术手段提高粮食作物耐铝性成为可能;同时,本文对今后的研究方向作了简要的讨论。     

植物耐铝毒作用机制研究进展

铝毒害是酸性土壤中作物生产的主要限制因子。针对土壤中Al元素的构成、Al毒害表现、植物相关耐铝机制及耐铝基因的克隆等问题,综述了国内外研究现状和进展。其中以主要农作物水稻与小麦为例,对这两种重要农作物耐铝毒研究进行了归纳和总结,在比较二者研究内容的完善程度的同时,为今后参照水稻耐铝毒研究,通过多种实验手段开展小麦系统化耐铝毒研究提供参考和依据,并提出今后的研究动向。     

植物耐铝性机制的研究进展

铝毒害是酸性土壤上作物生长的主要限制因素和森林大面积退化的重要原因。本文综述了近年来对植物耐铝性机制研究的进展，指出在植物体内存在多条耐铝性途径。     

生物措施缓解酸性土壤铝毒害研究进展

酸性土壤在世界上广泛存在,Al毒是酸性土壤限制作物生长和产量的主要限制因子之一.本文概述了酸性土壤Al毒害问题以及作物的耐Al机制,总结了遗传改良植物的耐Al性、向土壤或植物根际接种外生菌根真菌和其他耐Al微生物以缓解酸性土壤Al毒害的研究进展.以上措施在酸性土壤中的生态系统恢复具有应用前景.     

铝毒胁迫下植物的响应机制

铝(Al)毒胁迫会引起植物一系列的生理生化响应。本文针对Al毒胁迫下植物的不同响应机制展开了综述,分别介绍了根系有机酸的分泌、根表黏胶物质、细胞壁成分的变化及pH和酚类物质的变化与抗Al性的关系,尤其以细胞壁胼胝质的形成为重点给予了详细的论述。最后结合Al毒的研究现状,为未来相关领域的研究提出了自己的一些看法。     

低分子量有机酸对可变电荷土壤中铝吸附的影响

铝毒是酸性土壤上植物生长不良的主要限制因素,铝的生物毒性与铝离子的化学形态有密切的关系[1, 2],而铝的化学形态又受包括低分子量有机酸在内的多种因素的影响[3, 4].低分子量有机酸是土壤中广泛存在的一类非常活泼的物质,植物在生长过程中其根系会不断分泌出各种有机酸,植物残体分解过程中和土壤微生物代谢过程中均会产生有机酸[5, 6].一些有机酸阴离子可以被可变电荷土壤吸附,并影响土壤的某些表面化学性质;另一方面某些有机酸阴离子能够与铝形成稳定的络合物从而改变铝离子在溶液中的存在形态,这两方面的原因都有可能对可变电荷土壤中铝的吸附产生影响.     

造纸污泥堆肥对酸性土壤铝污染的影响

通过盆栽试验,研究在砖红壤中施加富含铝盐的造纸污泥堆肥后,土壤－作物体系中的铝毒效应。试验结果表明：盆栽初期,添加造纸污泥堆肥各处理土壤中的总酸溶性铝和总单核铝浓度较CK呈显著上升趋势,并随堆肥用量的增加而增加;随着种植时间推移,各处理（除了CK）总酸溶性铝和总单核铝浓度显著降低,且在盆栽结束时各处理总酸溶性铝浓度均低于原砖红壤中总酸溶性铝浓度;在整个盆栽期间,总单核铝是土壤中活性铝的主要存在形态;添加堆肥的各处理玉米植株的根部和地上部分铝含量均显著小于CK,玉米的生长状况均优于CK,说明在酸性土壤中添加造纸污泥堆肥,能起到很好的肥效作用,且不会对玉米生长形成铝毒效应,其中10%为本试验的最佳配比;另外,土壤理化性质测定结果显示：添加造纸污泥堆肥能有效减缓土壤酸化、增加土壤有机质和有效磷含量,提高土壤质量。     

不同抗铝处理对土壤-银杏系统的影响研究

红壤种植银杏进行不同抗铝处理,结果表明：氮、磷、钾肥配合施用石灰和有机肥能显著地降低土壤酸度和凝胶－交换性铝的含量,改善土壤的农化性状、消除铝毒危害,促进幼树生长。     

Amelioration of Aluminum Toxicity by Pretreatment with Phosphate in Aluminum‐Tolerant Rice Cultivar

Abstract

The phytotoxicity of aluminum (Al) in relation to preculture with phosphates was examined in the rice cultivar Arkansas fortuna. In plants precultured with phosphates, Al did not inhibit shoot growth, while Al retarded shoot growth in plants precultured without phosphates. In contrast, Al inhibited root elongation, irrespective of the presence of phosphates in the preculture solution. A large proportion of the Al in roots was in unknown, insoluble forms. In phosphate‐precultured plants, Al deposition was slightly increased, presumably due to the formation of aluminum phosphates in the roots, and phosphorus levels in shoots were markedly increased. Binding with phosphates may ameliorate the toxicity of Al when it enters the shoots and account for the uninhibited shoot growth in the presence of Al in plants precultured with phosphates.     

Aluminum toxicity in corn at near neutral soil pH levels

Aluminum toxicity to plants is often responsible for yield reductions under acid soil conditions. Despite the fact that Al becomes insoluble in the slightly acid to neutral pH range, there are indications that it can still be taken up and become toxic to plants. Corn plants were grown in the greenhouse on three highly weathered soils (Oxisol and Ultisols) containing substantial quantities of exchangeable Al. The soils were limed at various rates up to pH values near or above neutrality. On all soils a positive yield response to lime occurred at low pH values while on two of the soils, yields decreased significantly as the pH approached neutrality. Yield and Al content of the tissue were exponentially related irrespective of the level of phosphate applied (r² = 0.34 and 0.71). The mechanism by which Al becomes increasingly available to the plant as the pH approaches neutrality is not clear and needs further investigation. Strong Al‐Mg and Al‐P antagonisms occur at the high and low pH values. The existance of Al toxicity at near‐neutral pH values can be invoked to explain many of the anomolous results reported in the literature concerning yield depressions previously ascribed a posteriori to such factors as micro‐element or P deficiencies.     

铝对荞麦铝和其它营养元素运输的影响

铝胁迫下铝和其它元素的吸收、运输和分布是铝毒害的基础。采用土培法。研究荞麦（Fagopyrum esculentum Moench）在不同的铝浓度水平下对铝的吸收和运输，以及铝胁迫对氮、磷、钾、钙、镁、钠、锌、铜、铁、锰等元素的吸收和运输的影响。结果表明：在铝胁迫下，养麦植株铝含量迅速上升，而其他元素的吸收均受到一定的阻碍影响，在植株各部的含量均有所下降；花期荞麦与真叶期相比，地上部分的铝含量及根部含量均大幅下降，植株的其他元素含量同阳增加，表明铝胁迫得到缓解，可见养麦作为一种铝积累植物对铝毒有较强的适应能力。     

Effect of Nitrogen Sources on Aluminum Toxicity in Wheat Varieties Differing in Tolerance to Aluminum

Extract

As previously reported (Taylor and Foy 1985; Keltjens and Ulden 1987; Grauer and Horst 1990; Galvez and Clark 1991), plant species and varieties widely differ in Al tolerance. Although many hypotheses about the physiological mechanism(s) involved in Al tolerance have been formulated, the mechanism(s) has not been elucidated. However, it is obvious that when exposed to Al at high concentrations, Al-tolerant plants seem to be able to avoid the toxicity by refraining from excess uptake of Al or by chelating of Al in the rhizosphere or in the roots. In such ways, Al can not affect the growth of tolerant plants (Foy et al. 1978).     

Effects of Boron on Aluminum Toxicity on Seedlings of Two Soybean Cultivars

Boron (B) is an essential micronutrient for higher plants. It has been suggested that addition of B at an optimal concentration might alleviate Al toxicity. Little information is available about B effects on soybean seedling growth under Al stress and differential alleviation of B on Al toxicity. In the present study, the seedlings of two soybean cultivars (Williams and Nanrong 73-935) were grown in a solution with factorial combinations of Al (0, 2, and 5 mM) and B (0, 5, and 50 μM) in a randomized complete block design experiment for 18 days. The results showed that high B was found to ameliorate Al toxicity by significantly increasing the growth characters including root length under 2 mM Al stress, and epicotyl length and fresh weight under 5 mM Al stress of the two cultivars. However, high B concentration did not significantly increase chlorophyll content under Al stress. Williams was more sensitive than Nanrong 73-935 on the growth characters and chlorophyll content under double stresses (B deficiency combined with Al toxicity), although they had similar sensitivity to B deficiency stress alone for growth characters. In addition, high B concentration was found to cause toxicity symptoms on root length and older leaves of both cultivars under no Al stress.     

Responese of Two Cultivars of Winter Wheat Differing In Sensitivity to Aluminum Toxicity

A experiment was carried to evaluate the effects of Al on growth,accumulations of free proline and amino acid in 2 wheat cultivars(Triticum aestivum L.),Yangmai No.5 and Jian 864,differing in Al Sensitivity.Plants grew initially in a nutrient solution without Al for 13 days before the addition of Al and finally in a nutrient solution containing 0.5mmol Al(L^-1)for 19 days,the results showed that there were marked deceases in dry weight,relative growth rate(RGR) and net assimilation rate (NAR)of Al-treated seedlings compared with control plants.The Al effects were more evident in Yangmai No.5 than Jian 864.Leaf area ratio(LAR) was little affected by Al.RGR was highly correlated with NAR rather than LAR.Aluminum increased the concentrations of free proline and total free amino acid in shoots of both the cultivars.The increases were greater in Yangmai No.5 than in Jian 864.The percentage of free proline in total amino acid in shoots was not affected by Al treatment.It was possible that accumulation of proline was merely a symptom of Al injury.The concentrations of total nitrogen in Al-treated plants did not significantly differ from those of control plants.Nitrate reductase activity(NRA),in leaves was severely decreased by Al,and a greater decrease was noted in Yangmai No.5 than in Jian 864,but NRA in roots of both the cultivars was not affected.The decreases in NRA might be and indirect(accumulation of amino acid) rather than a direct result of Al toxicity.     

Silicon Effect on Nutrient Acquisition of Peanut (Arachis hypogaea L.) Under Aluminum Stress

Aluminum (Al) toxicity represents one of the main yield-limiting factors for crops in acid soils. Silicon (Si) is known to increase tolerance in higher plants. This study was conducted to determine whether treatment with Si could improve nutrient uptake by peanut under Al stress. Peanut (Arachis hypogaea L. cv Zhonghua 4) was raised with or without Si (1.5 mM) in the growth chamber under 0 and toxic Al (0.3 mM) levels. Aluminum stress significantly decreased the root- and total-dry weight by 52.4% and 32.0%, respectively. The content of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) was significantly decreased, but that of Al increased markedly in shoots and roots after Al exposure at seedling, flower-needle, and pod-setting stage. Silicon alleviates Al toxicity in peanut plants in relation to Al distribution and allocation of tissue P, K, Ca, and Mg by favoring the partitioning of dry mass to roots.     

荞麦和金荞麦根际土壤铝形态变化及对其生长的影响

不同形态的铝对不同植物的毒害不同。以荞麦和金荞麦为实验材料,设置4个不同的土壤铝处理浓度（0,0.1,0.2,0.4 g Al^3＋/kg）,研究荞麦和金荞麦根际土壤中铝形态变化及对其生长的影响。结果表明,当土壤铝处理浓度〈0.2 g/kg时,尽管根际土壤液中铝溶出量较对照组有明显上升,毒性大的交换态铝和单聚体羟基铝（称为活性铝）占可提取铝总量的比例增加,但荞麦和金荞麦茎伸长和水分利用增强,地上部分生物积累量增多,表明荞麦和金荞麦对低铝胁迫有一定的适应;当土壤铝处理浓度达到0.4 g/kg时,荞麦和金荞麦根际土壤pH降至最低,根际土壤液中铝的溶出量增至最高,严重抑制了荞麦和金荞麦叶片光合作用的正常进行,各项指标和对照差异达到显著水平,荞麦和金荞麦的生长表现出明显的铝毒害症状。因此,我们推断在根际土壤活性铝溶出量为0.106-0.143 m g/g和0.046-0.057 m g/g间可能分别存在着荞麦和金荞麦耐受铝毒害的某个阈值。     

Phosphorus Alleviates Aluminum Toxicity in Al-Sensitive Wheat Seedlings

The role of phosphorus (P) in the amelioration of aluminum (Al) toxicity to plants is still unclear. The aim of this study was to examine the amelioration of Al toxicity by P supply. The study involved growing Al-sensitive wheat seedlings for 13 days in an acidic soil [pH 4.5 in calcium chloride (CaCl₂)] with increasing added rates of P (0, 20, 40, and 80 mg P kg^?1 soil) and Al [0, 50, and 150 mg aluminum chloride (AlCl₃) kg^?1 soil]. The results indicated that the effects of Al toxicity in this soil could be fully alleviated by the application of P at 50 mg AlCl₃ kg^?1. The 150 mg kg^?1 AlCl₃ treatment significantly reduced root growth, but this was partially overcome by the 80 mg kg^?1 P treatment. High P significantly reduced the concentration of Al in the apoplast, root, and shoot. It is possible that an insoluble Al-P complex forms in the soil and this decreases Al bound in apoplast as well as uptake into the roots. High P decreased the translocation of Al from root to shoot. This study also concluded that detoxification of Al³⁺ by P mainly occurs in soil but not within the plant tissue.     

铝诱导蚕豆气孔保卫细胞凋亡研究

植物叶表面的气孔保卫细胞是研究信号转导的模式实验系统,对环境变化反应灵敏而准确,采用蚕豆叶面气孔保卫细胞,研究了铝（AlCl3）对细胞的毒性效应。结果表明,在1～10 mmol.L^-1范围内,AlCl3可使气孔保卫细胞活性降低,部分细胞死亡,且随着浓度的增高细胞死亡率增高;死细胞呈现核固缩、核降解、凋亡小体等典型凋亡特征。凋亡抑制剂Z-Asp-CH2-DCB或TLCK与AlCl3共同作用时,保卫细胞死亡率显著降低;一定浓度的抗坏血酸（AsA）或过氧化氢酶（CAT）以及Ca2＋螯合剂乙二醇四乙酸酯（EGTA）或Ca2＋通道抑制剂LaCl3与AlCl3共同作用时,细胞死亡率降低。研究结果表明,铝诱导的蚕豆保卫细胞死亡可能是一种细胞凋亡过程,由胁迫诱发的活性氧介导,通过激活质膜钙通道,引起胞内Ca2＋水平改变,进而介导细胞凋亡。