根分泌作用与植物对金属毒害的抗性

在金属污染进入体内之前将其有效性和毒性降低是植物的主要抗金属机制之一,根系是金属等土壤污染物进入植物的门户,它能分泌有机酸、氨基酸,糖、生长物质等根分泌物与根际环境,根分泌物在植物吸收金属的过程中影响很大,它们可以通过改变根球环境的ＰＨ、Ｅｈ等物理、化学性质而影响根系对金属的吸收;通过螯合、络合,沉淀等作用将金属污染物滞留于根外;通过改变根际微生的组织,活性和分泌作用而改变根际环境中金属的数量和活     

甜菜夜蛾的抗性及抗性机理研究进展

甜菜夜蛾Spodoptera exigua(Hübner)是世界性农业害虫,近年来在我国由次要害虫上升为主要害虫。甜菜夜蛾对很多种化学杀虫剂和生物杀虫剂产生了抗性。本文分别阐述了甜菜夜蛾对常用杀虫剂如有机磷类、拟除虫菊酯类、氨基甲酸酯类、生长调节类杀虫剂、Bt杀虫剂等的抗性发展现状,并且对抗药性机理进行了总结,提出了抗性治理措施。     

蒙古柳金属硫蛋白的拟南芥遗传转化及抗性分析

本文研究在NaC l胁迫下筛选抗性pY ES2-蒙古柳c DNA-酵母菌,通过克隆得到蒙古柳c DNA序列,生物信息学分析该序列编码区为240 bp,编码79个氨基酸,在NCBI数据库中BLASTp分析表明和旱柳和毛果杨金属硫蛋白MT2序列有较高相似性。把克隆得到的cD NA与pB I121质粒通过Bam HI和XhoI进行酶切连接,通过农杆菌的介导法转入拟南芥。用Kana筛选的抗性苗提取基因组DNA,PCR鉴定得到6株转基因株系。将转基因拟南芥和野生型拟南芥在不同逆境下进行抗性分析,结果表明转基因拟南芥在NaC l、NaH CO3、H2O2、CuC l2、ZnC l2、CdC l2和Sorbitol胁迫培养基中表现出比对照强的抗性,其中在CdC l2培养基中比野生型植株表现出强的抗性。     

植物四倍体抗性及其机理研究进展

植物四倍体是重要的育种资源,其创制和抗性研究受到越来越多的关注。针对植物四倍体的抗性研究,国内外学者开展了大量的工作。本文对近年来四倍体与二倍体植物的抗性（抗寒、抗旱、抗热、抗盐、抗病等）差异进行了总结,并从植物组织细胞结构、生理、分子应答和表观遗传组修饰等方面对其抗性机理进行了探讨。     

PR—蛋白与高等植物的诱导抗性

一某些过敏性寄主植物在感染病毒或其它病原物后,以牺牲局部叶片(在接种叶片上形成局部枯斑或坏死)而使全侏免遭罹难,当相关性或非相关性病原物再次侵染时,植株即表面出抗性。这种抗性不同于植物本身所固有的先天抗性,由于它是在受病原物侵染(或化学药物处理)后诱导产生的,故称之为诱导抗性(或获得抗性)。诱导抗性的共同特征是作用的非持异性,即由病毒诱导的抗性不仅可以抵抗非相关病毒的侵染,还可以抵抗     

铝胁迫下植物根系的有机酸分泌及其解毒机理

酸性土壤中的铝毒害问题,已成为限制植物生长发育的主要因素之一.耐铝植物通过根系分泌有机酸来解除或减轻铝的毒害是外部解铝毒的重要机制.文章对铝胁迫下植物根系分泌有机酸的种类,有机酸解铝毒机理、解铝毒能力,有机酸分泌方式及调控其分泌的主要因素等相关研究进行综述.     

微生物消毒剂抗性机理

在物体表面和传播介质中,消毒剂能有效抑制或杀死微生物,广泛用于食品、卫生、健康、防疫等领域.在新型冠状病毒肺炎(COVID-19)疫情期间,全球消毒剂的使用量激增,对有效防控病毒传播和防止疫情扩散起到重要作用.但消毒剂的不正确使用会降低其有效性,甚至会诱导微生物产生抗性,从而增加传染性疾病的传播风险.微生物的消毒剂抗性...     

有机酸在疫霉营养中作用的进一步研究

利用放射性同位素标记的~(14)C-琥珀酸跟踪,进一步证明有机酸在晚疫病菌的营养中作为碳架与铵盐结合而合成菌体的氨基酸,同时也进入三羧酸循环参加呼吸。所以其作用不仅仅是缓冲作用。所试6个生理小种19株国内外晚疫病菌都对有机酸有迫切需要而旺盛生长,只有两株国外菌种长势太弱。其他测试过的疫霉P.boehmeriae,P.capsici,P.cinnamomi,P.citrophthora,P.colocasiae,P.erythroseptica,P.fragariae,P.megasperma f.sp.glycinea,P.palmivora,P.parasitica,P.sinensis和P.syringae 12种包括A_1与A_2交配型共18株菌都对有机酸有需要,只在迫切程度上不同。但有机酸在疫霉属营养上有普遍意义则是显而易见的。     

Mechanisms of metal resistance in plants: aluminum and heavy metals

Plants have evolved sophisticated mechanisms to deal with toxic levels of metals in the soil. In this paper, an overview of recent progress with regards to understanding fundamental molecular and physiological mechanisms underlying plant resistance to both aluminum (Al) and heavy metals is presented. The discussion of plant Al resistance will focus on recent advances in our understanding of a mechanism based on Al exclusion from the root apex, which is facilitated by Al-activated exudation of organic acid anions. The consideration of heavy metal resistance will focus on research into a metal hyperaccumulating plant species, the Zn/Cd hyperaccumulator, Thlaspi caerulescens, as an example for plant heavy metal research. Based on the specific cases considered in this paper, it appears that quite different strategies are used for Al and heavy metal resistance. For Al, our current understanding of a resistance mechanism based on excluding soil-borne Al from the root apex is presented. For heavy metals, a totally different strategy based on extreme tolerance and metal hyperaccumulation is described for a hyperaccumulator plant species that has evolved on naturally metalliferous soils. The reason these two strategies are the focus of this paper is that, currently, they are the best understood mechanisms of metal resistance in terrestrial plants. However, it is likely that other mechanisms of Al and/or heavy metal resistance are also operating in certain plant species, and there may be common features shared for dealing with Al and heavy resistance. Future research may uncover a number of novel metal resistance mechanisms in plants. Certainly the complex genetics of Al resistance in some crop plant species, such as rice and maize, suggests that a number of presently unidentified mechanisms are part of an overall strategy of metal resistance in crop plants.     

有机酸在植物对重金属耐性和解毒机制中的作用

植物对重金属的耐受和解毒机制可分为外部排斥和内部耐受两大类。该文综述了有机酸作为一类金属配位体, 在植物对重金属的这两大类机制中的重要作用。在重金属的外部排斥过程中, 植物根系分泌有机酸, 与金属离子形成稳定的金属配位体复合物, 改变重金属的移动性和生物可利用性, 阻止金属离子进入植物体内或避免其在根部敏感位点累积。此外, 有机酸还可与进入植物体内的金属离子螯合, 使其转化为无毒或毒性较小的结合形态, 缓解重金属的毒害效应, 实现植物对重金属的内部耐受。     

有机酸去除污泥重金属前后硝态氮和铵态氮浓度变化

研究了柠檬酸、草酸和乙酸溶液对污泥中重金属(Cd、Pb、Cu和Zn)的去除效果,以及处理前后析出液和污泥中硝态氮和铵态氮的浓度变化.结果表明,0.8mol.L-1柠檬酸溶液可去除污泥中76.0%的Pb和92.5%的Zn,是较好的重金属去除剂.污泥经有机酸处理后,有大量的硝态氮和铵态氮溶解于析出液中,与加入蒸馏水的对照处理相比,有机酸可大幅度增加析出液中铵态氮的含量,减少硝态氮含量.由于污泥处理过程中有其他形态的氮的转化,处理后污泥中仍含有较高浓度的硝态氮和铵态氮.0.5mol.L-1草酸处理的析出液中硝态氮和铵态氮浓度分别为2.8和888.1mg.L-1,且重金属含量不高,可作为较好的液体肥料进行回收利用.     

Role of organic acids in detoxification of aluminum in higher plants

Phytotoxicity of aluminum ion (Al3+) is a serious problem limiting crop production on acid soils. Organic acids with Al-chelating ability play an important role in the detoxification of Al both externally and internally. Al is detoxified externally by the secretion of organic acids such as citric, oxalic, and/or malic acids from the roots. The secretion of organic acids is highly specific to Al and the site of secretion is localized to the root apex. The kind of organic acids secreted as well as secretion pattern differ among plant species. There are two patterns of Al-induced secretion of organic acids: In pattern I, there is no discernible delay between the addition of Al and the onset of the release of organic acids. Activation of the anion channel seems to be involved in this pattern; In pattern II, there is a marked lag phase between the addition of Al and the onset of organic acid release. The action of genes related to the metabolism and secretion of organic acids seems to be involved in this pattern. Internal detoxification of Al in Al-accumulating plants is achieved by the formation of Al-organic acid complex. For instance, the complex of Al-citrate (1:1) in hydrangea and Al-oxalate (1:3) in buckwheat has been identified.     

有机酸对Pd 、Cd的土壤化学行为和植株效应的影响

有机酸对Pd,Cd的络合作用将其对土壤吸附Pd,Cd的影响和植株效应差异的研究表明,柠檬酸,草酸与Pd,Cd络合能力的大小与重金属本身的性质有关,络合作用影响土壤对Pd,Cd的吸附量,柠檬酸降低土壤对Pd,Cd的吸附,草酸则增加土壤对Pd,Cd的吸附,水培试验表明,柠檬酸可减轻Pb对小麦,水稻幼苗的毒害,柠檬酸对Cd的植株外观毒性效应影响不显著,但能促使植株茎叶,根中Cd含量下降,Pd和Cd复合处理条件下,Cd存在促使水稻植株对Pd吸收量增加,Pd存在抑制水稻植株对Cd的吸收。     

有机物和重金属复合污染水体的修复植物筛选及修复性能

通过植物的采集、培育和选种,获得了海芋、合果芋、蜘蛛兰和密穗砖子苗等4种同时具备去碳、脱氮、除磷和积累重金属的高效修复植物,并对这些植物修复污染水体的性能进行了研究.结果表明,这4种植物均能有效地处理有机物和重金属复合污染水体.鲜重55-60g的植物,处理10LBOD₅、COD_Cr、TP、TN、Cu²⁺和Cr⁶⁺浓度分别为140、280、6,8、40、10和10mg·L^-1的模拟水样14d后,上述指标的去除率分别高达80%、72%、64%、53%、75%和68%以上,植物的促进作用分别为32%、27%、27%、28%、37%和19%以上.处理后水样的pH和DO分别为6.63～7.63和3.02～3.84mg·L^-1.     

Extracellular and cellular mechanisms sustaining metal tolerance in ectomycorrhizal fungi

This review focuses on recent evidence that identifies potential extracellular and cellular mechanisms that may be involved in the tolerance of ectomycorrhizal fungi to excess metals in their environment. It appears likely that mechanisms described in the nonmycorrhizal fungal species are used in the ectomycorrhizal fungi as well. These include mechanisms that reduce uptake of metals into the cytosol by extracellular chelation through extruded ligands and binding onto cell-wall components. Intracellular chelation of metals in the cytosol by a range of ligands (glutathione, metallothioneins), or increased efflux from the cytosol out of the cell or into sequestering compartments are also key mechanisms conferring tolerance. Free-radical scavenging capacities through the activity of superoxide dismutase or production of glutathione add another line of defence against the toxic effect of metals.     

外生菌根缓解植物酸雨胁迫的机理研究进展

森林作为陆地生态系统的主体,是酸雨污染的主要受体,酸雨对生态系统产生着巨大的影响。菌根是菌根真菌与植物营养根的共生体。外生菌根真菌与宿主植物间互惠互利,在森林生态系统中,外生菌根在维持生态系统的养分平衡和改善树木营养等方面有重要的作用。本文综述了国内外关于菌根和酸雨关系的研究,酸雨能抑制外生菌根的形成,降低其活力;但另一方面,外生菌根能够缓解酸雨造成的植物危害,提高植株对酸雨的耐受力。外生菌根主要通过以下几方面缓解酸雨胁迫:(1)菌根形态结构的物理屏蔽作用;(2)增加养分吸收,增加御酸能力;(3)增强酶活性,提高植物生存能力;(4)产生有机酸或其他物质。