大豆磷、硫转运蛋白研究进展

磷、硫转运蛋白是大豆（Glycine max（L.）Merr.）体内磷、硫转运的重要载体,参与调节磷和硫酸盐的吸收与转运,对提高大豆的磷、硫利用效率至关重要。大豆磷转运蛋白可划分为Pht1、Pht2、Pht3、Pho1和Pho2 5大家族,目前对Pht1的研究最为深入。大豆14个Pht1家族可分为3个亚家族,他们对磷吸收和转运具有重要作用。大豆硫转运蛋白基因GmSULTR1;2b可在大豆根中特异性表达并被低硫胁迫诱导。本文基于大豆磷、硫的营养吸收、转运与利用过程中的相关性,对Pht1家族以及GmSULTR1;2b基因在大豆中的研究进展进行了综述,并对近年来大豆磷、硫转运蛋白的研究进展及未来的研究方向进行了展望。     

ZIP蛋白在植物中的功能分析

锌和铁是植物生长发育所必需的微量营养元素,在植物的光合作用、呼吸作用以及许多生化反应中起着非常重要的作用。植物体内锌铁处于平衡状态才能保证其正常的生长发育,而锌铁调控转运体ZIP对于锌铁吸收、转运及体内平衡的调节有重要作用。目前,对于植物中ZIP家族基因的研究有一定进展。对植物ZIP基因的表达、蛋白定位、酵母互补实验、过表达及基因敲除等研究结果进行综述,揭示了ZIP蛋白在植物发育过程中的作用。了解ZIP对于锌铁吸收、转运及体内平衡中的作用有助于通过转基因改良及常规育种将ZIP蛋白应用于农业生产上。     

高等植物硝酸盐转运蛋白的功能及其调控机制

硝酸盐是植物从土壤中吸收的重要无机氮素形态。植物为适应含有不同浓度NO3-的土壤环境,进化出了高亲和硝酸盐转运系统(HATS)和低亲和硝酸盐转运系统(LATS),两个基因家族NRT1和NRT2家族分别参与了LATS和HATS的NO3-的吸收和转运。近年来,随着分子生物学技术和植物基因组学的快速发展,研究人员克隆出了大量参与硝酸盐吸收和转运的基因,并对这些基因的功能进行了深入研究,逐渐形成了复杂的硝酸盐调控网络。综述了植物中硝酸盐转运蛋白基因的克隆、表达及调控,并对进一步的研究作了展望,这些结果对于理解植物硝酸盐吸收的调控机制具有重要作用。     

拟南芥COPT家族蛋白研究进展

铜(Cu)是植物必需的微量元素, 作为多种酶的辅因子参与许多植物生理生化反应。Cu缺乏和过量均影响植物正常生长发育, 因此植物进化出精妙复杂的调控网络来严格控制植物体内的Cu含量。植物Cu转运蛋白COPT家族成员与Cu有很高的亲和力, 能够调节植物对Cu的吸收和转运, 在维持植物体内Cu稳态平衡过程中发挥重要作用。COPT蛋白涉及不同的Cu转运功能, 如从外界环境中摄取Cu、从细胞器中输出Cu、长距离运输Cu以及在不同器官间动用和再分配Cu。此外, COPT蛋白在其它离子的稳态平衡维持、昼夜节律性生物钟调控、植物激素合成和植物对激素信号的感受过程中也发挥重要作用。该文综述了模式植物拟南芥(Arabidopsis thaliana) COPT家族各成员的表达和定位、调控机制以及生物学功能等方面的最新进展。     

植物的硫同化及其相关酶活性在镉胁迫下的调节

植物对土壤中硫的利用包括根系对硫酸盐的吸收、转运、同化、分配等过程,也是由一系列酶和蛋白质参与和调节的代谢过程。近年来的研究表明,在植物体内,硫同化与植物对镉等重金属元素的胁迫反应机制有着密切关系。镉胁迫能调节植物对硫酸盐的吸收、转运、同化,以及半胱氨酸、谷胱甘肽（glutathione,GSH）和植物螯合肽（Dhytochelatins,pc）的合成。植物在镉胁迫下通过多种调节机制,增强对硫酸盐的吸收和还原,迅速合成半胱氨酸和谷胱甘肽等代谢物,从而合成足够的PC,以满足植物生理的需要。     

拟南芥COPT家族蛋白研究进展

铜(Cu)是植物必需的微量元素, 作为多种酶的辅因子参与许多植物生理生化反应。Cu缺乏和过量均影响植物正常生长发育, 因此植物进化出精妙复杂的调控网络来严格控制植物体内的Cu含量。植物Cu转运蛋白COPT家族成员与Cu有很高的亲和力, 能够调节植物对Cu的吸收和转运, 在维持植物体内Cu稳态平衡过程中发挥重要作用。COPT蛋白涉及不同的Cu转运功能, 如从外界环境中摄取Cu、从细胞器中输出Cu、长距离运输Cu以及在不同器官间动用和再分配Cu。此外, COPT蛋白在其它离子的稳态平衡维持、昼夜节律性生物钟调控、植物激素合成和植物对激素信号的感受过程中也发挥重要作用。该文综述了模式植物拟南芥(Arabidopsis thaliana) COPT家族各成员的表达和定位、调控机制以及生物学功能等方面的最新进展。     

植物中铵转运蛋白的研究进展

铵转运蛋白在众多生物中被克隆与鉴定,它是一种广泛存在于微生物、植物细胞及动物的细胞膜上主动转运铵离子的载体,分子量约为48kD,含有10～11个跨膜域.本文阐述了植物铵转运蛋白分离鉴定的过程,对于铵转运蛋白的结构、功能、基因表达调控等方面作了较详细叙述.不同氮素条件下,铵转运蛋白基因通过转录调控表现了对铵离子吸收转运的不同特点,使植物根系在较宽的浓度范围中吸收铵离子,为细胞内铵离子库的内稳态提供了理论依据.铵转运蛋白有助于作物更有效的吸收氮素,为农业生产粮食增收提供了有利保障.     

玉米ST和ATPS部分cDNA序列克隆及分析

硫酸盐转运蛋白(ST)和ATP硫酸化酶(ATPS)是根系吸收硫酸盐和植物体内硫酸盐同化过程的关键蛋白和酶,在硫酸盐的生物转运过程中具有重要作用.以水培玉米农大108根系为材料,并根据已报道的玉米的硫酸盐转运蛋白和ATP硫酸化酶基因保守序列分别设计PCR引物对,采用RT-PCR方法克隆到783 bp和820 bp的部分硫酸盐转运蛋白和ATP硫酸化酶cDNA片段,分别命名为ST_ND108和ATPS_ND108.序列分析和比对结果显示,ST_ND108与已报道的玉米和水稻的高亲和型硫酸盐转运蛋白基因同源性分别为99%和85%;而ATPS_ND108与已报道的玉米ATP硫酸化酶基因同源性达到97%,进化树聚类分析和预测氨基酸的BLAST结果证实ST_ND108为高亲和性硫酸盐转运蛋白基因片段,ATPS_ND108为质体ATP硫酸化酶基因片段.     

拟南芥无机氮素转运蛋白及其磷酸化调控研究进展

氮元素是植物必需的营养元素之一, 氮素供需失衡会严重影响植物的生长发育。无机氮(硝酸根NO₃^-和铵根NH₄⁺)是植物体内氮素的主要来源, 对其有效吸收和利用依赖于多种类型转运蛋白的协同作用。其中, 部分无机氮素转运蛋白的活性受到可逆磷酸化作用的精准调控。该文将对模式植物拟南芥(Arabidopsis thaliana)中硝酸根和铵根转运蛋白的分类、结构、定位和功能特点等进行总结, 并重点对可逆磷酸化调控转运蛋白的分子机制加以阐述。     

脯氨酸转运相关基因的研究进展

作为植物中普遍存在的一种逆境适应机制, 脯氨酸积累一直被认为是其合成和降解调控的结果。然而越来越多的研究表明, 脯氨酸转运也可能在其积累过程中起重要作用。在植物中, 有多个氨基酸转运蛋白家族, 如氨基酸通透酶家族(AAPs)、赖氨酸组氨酸转运蛋白家族(LHTs)和脯氨酸转运蛋白家族(ProTs)参与脯氨酸在各个器官间的运输。该文对参与脯氨酸运输的基因家族成员的表达模式、生理功能及表达调控进行了综述, 以期为脯氨酸运输与积累在植物抗逆方面的研究提供参考。     

Transporter gene families in plants: the sulphate transporter gene family — redundancy or specialization?

Analysis of the Arabidopsis genome has indicated that the gene families encoding for specific solute transporters are surprisingly large. An example is the sulphate transporter family, which in Arabidopsis , consists of 14 isoforms showing homology to one another. H⁺-sulphate co-transport has been demonstrated for some, but not all, of these Arabidopsis isoforms. Occurrence of the sulphate transporter is ubiquitous and many examples have been cloned from a variety of plant species, animals and yeast. This is a unique transporter family with no apparent homology to any other transporter type. Phylogenetic analysis of the plant gene or amino acid sequences indicates that there are 5 or more distinguishable clusters within the family of sulphate transporters. Analysis of functional characteristics and patterns of regulation together with localization data, suggests that these groups have specific roles, such as high affinity uptake in the root, translocation in vascular tissues and cell to cell transfer in leaves and seeds. Additionally, some members of this sulphate transporter family may have discrete subcellular locations in plastid or tonoplast membranes. Within individual groups, there are often multiple isoforms from the same species, indicating an even greater degree of specialization or alternatively, redundancy. This mini-review will summarize the available data to distinguish between specialization and redundancy.     

Plant sulphate transporters: co-ordination of uptake, intracellular and long-distance transport

Proton/sulphate co-transport in the plasma membrane of root cells is the first step for the uptake of sulphate from the environment by plants. Further intracellular, cell-to-cell and long-distance transport must fulfil the requirements for sulphate assimilation and source/sink demands within the plant. A gene family of sulphate transporters, which may be subdivided into five groups, has been identified with examples from many different plant species. For at least two groups, proton/sulphate co-transport activity has been confirmed. It appears that each group represents sulphate transporters with distinct kinetic properties, patterns of expression, and cell/tissue specificity related to specific roles in the uptake and allocation of sulphate. High-affinity sulphate uptake and low-affinity vascular transport, as well as vacuolar efflux, are controlled by the nutritional status of the plant. Most notably there is an apparent increase in capacity for cellular sulphate uptake and vacuolar efflux when sulphur supply is limiting. Within the groups, the individual sulphate transporters may be further subdivided by differences in temporal, cellular and tissue expression. Many of the transporters are regulated by the nutritional status of the individual tissues, to optimize sulphate movement within and between sink and source organs.     

Xenopus oocytes as an expression system for plant transporters

The Xenopus oocyte provides a powerful system for the expression and characterisation of plant membrane proteins. Many different types of plant membrane proteins have been expressed and characterised using this system. As there are already several general reviews on the methodology for oocyte expression of channel proteins, we have summarised the particular advantages and disadvantages of using the system for the characterisation of plant cotransporter proteins. As an example of how the system can be used to identify transporters, we describe evidence for a low affinity nitrate transporter in oocytes injected with poly(A) RNA extracted from nitrate-induced barley roots. Furthermore, we describe evidence that the expression of some transporters in oocytes can modify the properties of endogenous membrane proteins. We conclude that although care must be taken in the interpretation of results and in choosing appropriate controls for experiments, oocyte expression is an excellent tool which will have an important role in characterising plant membrane proteins.     

Characterization by RFLP analysis and genomic in situ hybridization of a recombinant and a monosomic substitution plant derived from Hordeum vulgare L. x Hordeum bulbosum L. crosses.

Interspecific crosses in Hordeum have been made with the aim of transferring desirable traits, such as disease resistance, from a wild species, Hordeum bulbosum, into cultivated barley (Hordeum vulgare). Interspecific recombinants have previously been identified using several methods, but there are limitations with all the techniques. We improved our ability to characterize progeny from H. vulgare x H. bulbosum crosses by using genomic in situ hybridization (GISH). The plant material comprised a recombinant and a monosomic alien substitution plant derived from H. vulgare x H. bulbosum crosses. The recombinant possesses a pubescent leaf sheath conferred by a gene transferred from H. bulbosum into barley cultivar Golden Promise. The use of GISH on a plant homozygous for the pubescence gene confirmed the presence of H. bulbosum DNA located distally on two barley chromosomes and we mapped the introgression to barley chromosome 4HL using RFLP analysis. Furthermore, by means of an allelism test we found that the transferred gene for pubescence is allelic or closely linked to a gene for pubescence (Hs) located on barley chromosome 4HL. The presence of a single H. bulbosum chromosome in the monosomic substitution plant was confirmed by GISH. A distal introgression of H. bulbosum DNA was also observed on one barley chromosome, which was located on chromosome 3HL by RFLP analysis.