植物己糖激酶的信号转导作用

己糖激酶在植物细胞的信号转导中起着重要的作用。近年来,有关植物己糖激酶的研究工作已经较多,受到足够的重视。现对植物己糖激酶的特性、亚细胞定位、编码基因分子特征、感受己糖与信号转导功能、依赖己糖激酶的糖信号转导途径及其调控作用进行介绍。     

高等植物EIN3/EILs转录因子研究进展

Ethylene-insensitive3(EIN3)和EIN3-like(EIL)蛋白是乙烯信号转导途径中重要的核转录因子。目前已经从多种高等植物中分离得到EIN3/EILs,其属于一个小的转录因子家族。这类转录因子在氨基酸序列N端高度保守,包括酸性氨基酸区、脯氨酸富集区、碱性氨基酸簇等涉及DNA结合的重要结构域,它们通过直接结合到初级乙烯反应元件(PERE)上来调节相关基因的表达。EIN3/EILs转录因子家族不同成员在不同物种间时空表达特性、表达调控模式等均有所差异,各成员主要参与调节植物对乙烯的反应,包括影响幼苗的"三重反应"、植株的生长发育等,并作为乙烯与其他信号间交叉点发挥重要作用。就近几年关于高等植物EIN3/EILs转录因子的研究进展进行综述,以期为后续研究提供理论依据。     

大豆GeBP转录因子基因家族的生物信息学分析

GeBP转录因子调控植物表皮毛的生长发育,并且参与控制植物叶片的发育。该文利用生物信息学方法,在大豆全基因组范围内搜索GeBP基因家族,并从氨基酸理化性质、基因结构、染色体的物理分布、系统进化、序列比对、功能结构域、组织表达情况等基本特征方面对GmGeBP基因家族进行分析。结果表明:(1)共获得9个GmGeBP转录因子基因家族成员,其中仅2个基因含有内含子,且都只有1个内含子,表明该家族成员基因构造比较简单但稳定。(2)GmGeBP编码的蛋白分子量为39.65~49.24 kD,理论等电点为4.65~9.08;这些成员基本上都是酸性氨基酸,属于亲水性、不稳定蛋白。(3)这9个基因不均匀的分布于7条染色体上,10和20号染色体上分别分布2个GeBP基因,3、5、13、15、19号染色体上各分布1个基因。(4)系统进化分析表明,大豆与拟南芥对应的GeBP成员亲缘关系较近,分别聚类到4个分支,而与水稻的距离较远。(5)结构域分析表明,9个GmGeBP成员都包含DUF573结构域,推测该部分在GeBP转录因子中很可能是与靶标基因顺式作用元件互作的结构域。(6)通过分析大豆GmGeBP转录因子基因家族的组织表达,发现不同基因在大豆不同组织的表达量不同,具有一定的特异性。该文对大豆GeBP转录因子基因家族的分析和鉴定为进一步研究大豆表皮毛发育的分子作用提供了理论基础。     

西瓜接穗对嫁接苗根系糖代谢及生长发育的影响

该研究以西瓜品种‘早佳8424’、南瓜品种‘伟砧1号’为试验材料,设置2个嫁接组合西瓜/南瓜(W/P)和南瓜/南瓜(P/P),采用贴接法嫁接,并以不嫁接的南瓜自根苗(P)为对照,通过玻璃温室营养钵育苗试验测定了西瓜接穗对嫁接苗根系生长发育及糖代谢的影响。结果表明:(1)西瓜嫁接苗(W/P)根系生长指标(鲜质量、干质量、根体积等)和根系活力,以及地上生长指标(地上部鲜质量、干质量和叶面积)均显著低于南瓜嫁接苗(P/P)和南瓜自根苗(P)。(2)幼苗根系总糖、可溶性糖、还原糖、淀粉以及蔗糖、葡萄糖和果糖含量均表现为W/P P/P P,且在嫁接后18 d时各处理间均存在显著性差异。(3)在嫁接后18 d时,W/P嫁接苗根系中细胞壁转化酶(CWIN)和己糖激酶(HXK)的活性和相关基因(CWIN、HXK)表达水平较南瓜嫁接苗(P/P)和南瓜自根苗(P)均显著降低。研究发现,西瓜接穗可能通过抑制嫁接苗根系糖的积累,以及抑制CWIN和HXK的活性,从而抑制嫁接苗的根系生长和活力。     

葡萄TST基因家族鉴定及表达分析

【目的】液泡膜糖转运蛋白（tonoplast sugar transporter,TST或者TMT）是植物发育过程中发挥重要作用的一种糖转运蛋白。为探究该基因家族在葡萄生长发育中的作用,并进一步为阐明TST基因功能提供坚实的基础。【方法】通过同源分析法从葡萄基因组中鉴定出13个TST基因,对基因的结构和编码蛋白质进行生物信息学分析;利用qRT-PCR技术分析‘鄞红’葡萄发育过程中不同组织的TST表达水平,并与不同时期葡萄果肉中可溶性糖含量进行相关性分析。【结果】结果表明：该基因家族分布在6条染色体上,存在3对片段重复和3对串联重复基因;根据系统发育将其分为3个亚家族,各亚族家族成员结构相似;顺式作用元件表明TST基因含有大量与激素、光和胁迫响应相关的顺式作用元件;蛋白质结构均显示该家族由α-螺旋和无规则卷曲组成,各亚族蛋白模型相似;qRT-PCR结果显示,VvTST在不同组织中均有表达,并存在时空表达特异性;对葡萄果肉中基因表达量变化与可溶性糖含量变化进行相关性分析发现,4个VvTST（VIT_18s0001g12560、VIT_18s0122g00850、VIT_04s0023g01860和VIT_03s0038g03940）的表达水平与葡萄果肉中可溶性糖的积累呈现相似趋势。【结论】上述研究结果表明,VvTST可能对葡萄果肉中可溶性糖积累起到至关重要的作用。     

全基因组分析杨树WOX基因家族在茎部发育中的作用

WUSCHEL-related homeobox(WOX)家族是植物特有的转录因子家族,参与分生组织细胞分裂分化、初生和次生物质代谢及植物激素信号转导等多个发育过程,目前尚未有从全基因组分析该基因家族参与杨树茎部发育的相关研究。本项研究旨在对杨树WOX基因家族进行鉴定,在杨树基因中发现18个WOX候选基因,将这些候选基因分为三组,同一分组的大多数WOX家族成员具有相似的基因结构和保守的基序。根据不同发育阶段茎部转录组数据,系统分析了WOX家族成员在茎部不同发育阶段的特异表达情况,并采用qRT-PCR对上述结果进行了验证。结果表明,杨树WOX基因家族在茎部不同发育阶段表现出不同的表达模式,为毛果杨WOX家族的功能研究与利用奠定基础。     

雷蒙德氏棉HSP70基因家族的进化分析及其同源基因在陆地棉中的表达分析

热激蛋白70家族(HSP70)是一类在植物中高度保守的分子伴侣蛋白,在细胞中协助蛋白质正确折叠。文章利用隐马可链夫模型(HMM)在雷蒙德氏棉(Gossypium raimondii L.)全基因组范围内进行HSP70基因家族成员进化分析,共得到30个HSP70家族成员。利用生物信息学对雷蒙德氏棉HSP70基因的结构、染色体分布、基因倍增模式以及系统进化进行分析,结果表明,HSP70基因家族根据亚细胞定位结果可分为不同的基因亚家族,各亚家族中HSP70基因具有相对保守的基因结构;染色体片段重复和串联重复是雷蒙德氏棉HSP70基因家族扩增的主要方式。通过对不同物种的HSP70基因家族进行系统进化分析可知,HSP70亚组的分化发生在单细胞植物形成前,且细胞质型HSP70成员大量扩增。比较陆地棉棉纤维发育不同时期的深度测序表达谱,发现HSP70基因可能参与棉纤维的生长发育。本研究结果有助于了解棉属植物HSP70基因家族的功能,以期为深入研究棉纤维发育过程中的分子调控机理提供基础。     

植物的糖信号及其对碳氮代谢基因的调控

介绍了植物蔗糖和已糖转运蛋白（SUT,HXT）及各自糖转运功能与调控,总结了不同糖类的胞内信号转过程及其对碳,氮代谢基因表达调控的最新研究进展,同时分析了蛋白激酶如已糖激酶（HXK）,SNF1相关激酶（SnRK1)等在植物糖信号转导中的作用,以及糖信号与氮信号的互作及对同化物分配的调控。     

菜粉蝶osiris基因家族鉴定与发育动态

osiris基因家族是昆虫特异性基因,迄今尚未在昆虫纲以外的物种中发现同源基因。本研究利用菜粉蝶转录组数据,鉴定了菜粉蝶16个osiris基因家族成员,分属11个亚家族。通过与菜粉蝶基因组比对,发现菜粉蝶osiris基因均为断裂基因,外显子数量为3-15个;通过结构域分析,发现菜粉蝶Osiris完整编码蛋白含有信号肽和一个未知功能结构域DUF1676,且多数Osiris蛋白含跨膜结构域。系统发育分析表明,osiris基因家族成员与其他昆虫种类相应成员更似直系同源,而非种内基因扩张,再次验证了osiris基因是在昆虫物种分化之前就已形成的多基因家族。发育转录组基因表达分析表明,osiris家族不同成员表达量在不同发育阶段趋势几乎完全一致,多在菜粉蝶1龄幼虫和5龄幼虫高表达,卵期、蛹期与成虫期低表达,预示着osiris基因家族不同成员转录调控机制的相似性与发育的相关性。     

大豆Glyma03g24460基因功能预测及表达分析

大豆Glyma03g24460基因,与拟南芥ECERIFERUM1(CER1)基因具有高度的同源性,是一种植物角质层蜡质基因,参与植物角质层蜡质的合成。本研究对其进行基因功能预测和表达分析,利用Plant CARE分析启动子元件发现在基因启动子序列中含有黄酮合成、激素响应、生物和非生物胁迫相关的元件。氨基酸序列比对发现Glyma03g24460与其他物种的脂肪醛脱羧酶基因家族成员有很高的相似度。Glyma03g24460在大豆的q RT-PCR结果表明,它主要在植物的地上器官表达,并且可以受到ABA及干旱等非生物胁迫的诱导表达。     

Two newly identified membrane-associated and plastidic tomato HXKs: characteristics, predicted structure and intracellular localization

Two new tomato hexokinase genes, LeHXK3 and LeHXK4, were cloned and characterized, placing tomato as the first plant with four characterized HXK genes. Based on their sequence, LeHXK3 is the third membrane-associated (type-B) and LeHXK4 is the first plastidic (type-A) HXK identified in tomato. Expression of HXK-GFP fusion proteins in protoplasts indicated that the LeHxk3 enzyme is associated with the mitochondria while LeHxk4 is localized in plastids. Furthermore, LeHxk4::GFP fusion protein is found within stromules, suggesting transport of LeHxk4 between plastids. Structure prediction of the various plant HXK enzymes suggests that unlike the plastidic HXKs, the predicted membrane-associated HXKs are positively charged near their putative N-terminal membrane anchor domain, which might enhance their association with the negatively charged membranes. LeHxk3 and LeHxk4 were analyzed following expression in yeast. Both enzymes have higher affinity for glucose relative to fructose and are inhibited by ADP. Yet, unlike the other HXKs, the stromal HXK has higher Vmax with glucose than with fructose. Expression analysis of the four HXK genes in tomato tissues demonstrated that LeHXK1 and LeHXK4 are the dominant HXKs in all tissues examined. Notably, the plastidic LeHXK4 is expressed in all tissues including starchless, non-photosynthetic sink tissues, such as pink and red fruits, implying phosphorylation of imported hexoses in plastids. It has been suggested that trehalose 6-phosphate (T6P) might inhibit HXK activity. However, none of the yeast-expressed tomato HXK genes was sensitive either to T6P or to trehalose, suggesting that unlike fungi HXKs, plant HXKs are not regulated by T6P.The nucleotide sequence data of LeHXK3 and LeHXK4 appear in the GenBank Nucleotide Sequence Database under accession numbers DQ056861 and DQ056862, respectively.M. Kandel-Kfir and H. Damari-Weissler contributed equally to this work.     

Putting plant hexokinases in their proper place

Hexokinases (HXKs), catalysts of the first essential step in glucose metabolism, have emerged as important enzymes that mediate sugar sensing in many organisms, including plants. The presence of several types of plant HXK isozymes, located in different intracellular locations, has been suggested. However, recent studies have indicated that most plants have only two types of HXKs, a plastidic stromal isozyme and membrane-associated isozymes located mainly adjacent to the mitochondria, but also in the nucleus. The membrane-associated isozymes are involved in sugar sensing and regulate gene expression. The central role of HXKs in plant development and the increasing interest in their role necessitate the correction of inaccuracies that have spread concerning the substrate specificity and intracellular localization of HXK isozymes, as these inaccuracies are affecting the hypothesized roles presented for these isozymes and shaping future research in this active field.     

Hexokinase from grape berries: its prokaryotic expression, polyclonal antibody preparation and biochemical property analyses

Two full-length hexokinase (HXK, EC 2.7.1.1) cDNAs, VvHXK1 with 1,413 bp and VvHXK2 with 1,458 bp were cloned from grape berries (Vitis vinifera L. Cabernet Sauvignon). VvHXK1 and VvHXK2 genes sequence from grape berries were deposited in GenBank under the accession number JN118544 and JN118545, respectively. The homology of the amino acid of VvHXK1 or VvHXK2 was very similar to ‘Pinot Noir’ grape HXK sequence, their similarties were 99.36 % and 98.97 %, respectively. More intuitive phylogenetic tree showed that the homology of amino acid sequence VvHXK1 with melon CmHXK1 was 86 %, and VvHXK2 homology with rice OsHXK3 was 83 %. The HXK proteins were successfully expressed in plasmid pET-30a (+) vectors in Escherichia coli BL21 (DE3) pLysS. The expressed proteins were purified using Ni-NTA agarose column and used to produce HXK1 antibody and conducted HXK protein blotting analysis. The results,suggested that one polypeptide band of about 51 kDa HXK protein can be detected in grape berries, HXK protein level was the highest during early grape berry development, but the lowest from 50d to 60d during development. Biochemical analysis of two hexokinase isozymes indicated that glucose was the optimal substrate of HXK, The isoelectric points of the two isozymes were 5.8 and 5.6, respectively. And the optimum pH was about 8.0. These results provide a substantial basis for the further studies of functions of grape HXKs to manipulate sugar content of grape berries.     

Spinach SoHXK1 is a mitochondria-associated hexokinase

Hexokinase, a hexose-phosphorylating enzyme, has emerged as a central enzyme in sugar-sensing processes. A few HXK isozymes have been identified in various plant species. These isozymes have been classified into two major groups; plastidic (type A) isozymes located in the plastid stroma and those containing a membrane anchor domain (type B) located mainly adjacent to the mitochondria, but also found in the nucleus. Of all the hexokinases that have been characterized to date, the only exception to this rule is a spinach type B HXK (SoHXK1) that, by means of subcellular fractionation, has been localized to the outer membrane of plastids. However, SoHXK1 has a membrane anchor domain that is almost identical to that of the other type B HXKs. To determine the localization of SoHXK1 enzyme by other means, we expressed SoHXK1::GFP fusion protein in tobacco and Arabidopsis protoplasts and compared its localization with that of the Arabidopsis AtHXK1::GFP fusion protein that shares a similar N-terminal membrane anchor domain. SoHXK1::GFP is localized adjacent to the mitochondria, similar to AtHXK1::GFP and all other previously examined type B HXKs. Proteomic analysis had previously identified AtHXK1 on the outside of the mitochondrial membrane. We, therefore, suggest that SoHXK1 enzyme is located adjacent to the mitochondria like the other type B HXKs that share the same N-terminal membrane anchor domain.     

PCR方法检测水稻中存在G蛋白基因家族

ＰＣＲ方法检测水稻中存在Ｇ蛋白基因家族陈忠英,王钧（中国科学院上海植物生理研究所,２００００３２）关键词Ｇ蛋白;聚合酶链式反应（ＰＣＲ）;水稻苗;ＤＮＡ序列分析植物细胞对各种外源和内源的刺激,如光、重力、病原、激素等都有灵敏复杂的反应,但对植物信息传...     

A large family of class III plant peroxidases

Class III plant peroxidase (POX), a plant-specific oxidoreductase, is one of the many types of peroxidases that are widely distributed in animals, plants and microorganisms. POXs exist as isoenzymes in individual plant species, and each isoenzyme has variable amino acid sequences and shows diverse expression profiles, suggesting their involvement in various physiological processes. Indeed, studies have provided evidence that POXs participate in lignification, suberization, auxin catabolism, wound healing and defense against pathogen infection. Little, however, is known about the signal transduction for inducing expression of the pox genes. Recent studies have provided information on the regulatory mechanisms of wound- and pathogen-induced expression of some pox genes. These studies suggest that pox genes are induced via different signal transduction pathways from those of other known defense-related genes.