叶发育的遗传调控机理研究进展

叶是植物进行光合作用的主要器官。高等植物叶原基起始于顶端分生组织的周边区,在一系列基因精确调控下,叶原基建立近一远轴、基一顶轴和中．侧轴极性,引导原基细胞朝着特定的方向分裂和分化,最终发育戍一定形态和大小的叶片。近年来分子遗传学研究结果表明,数个转录因子家族基因、小分子RNA和细胞增殖相关因子组成一个复杂的遗传控制网络,调节叶片极性建成过程。此外,复叶的形态建成还受到另外一些转录因子的调控。本文对近年来叶发育遗传调控机理研究的新进展做简要介绍。     

miR319在植物器官发育中的调控作用

microRNAs(miRNAs)是一类内源性的、21~25个碱基长度的小分子非编码RNA,它通过指导剪切或者抑制翻译等方式调节植物基因的表达,参与调控植物生长发育各个方面。大量研究表明,miR319通过靶向TCPs转录因子控制植物叶、花等器官的生长命运,并参与调控部分激素生物合成和信号传导通路,在植物发育过程中发挥重要生物学功能。文章综述了miR319在植物叶形态建成、生长发育以及叶衰老和花器官发育等过程中的重要调控作用。     

大豆microRNA基因GmMIR160A负调控植物叶片衰老进程

:叶片衰老是受内外多种因子影响的遗传发育进程.生长素、细胞分裂素和乙烯等多种植物激素是调 控叶片衰老的重要内部因子,它们通过长或短距离运输形成叶片组织内特定的区域分布和浓度梯度,从而直 接或间接参与植物叶片衰老过程.分子遗传学表明,细胞分裂素和乙烯分别是叶片衰老的抑制子和正调节 子,而生长素如何参与叶片衰老的分子机制目前还不清晰.植物体内成熟小分子RNA 由小RNA 基因转录 并通过特定酶加工形成的２１~２３bp的双链RNA分子.这些小分子通过不完全配对方式抑制其靶基因转录 和/或表达,参与植物生长发育多个过程,然而这类小RNA 分子如何调控植物叶片衰老发育过程目前则还鲜 有报告.大豆是重要的油料作物,具有典型的单次结实性衰老特征.研究大豆叶片衰老具有重要的科学意义 和深远的应用价值.该文采用实时荧光定量PCR(qPCR)技术分析大豆(Glycinemax)microRNA基因Gm- MIR１６０A 的表达模式,发现大豆第一复叶中GmMIR１６０A 表达受外源生长素和黑暗处理的诱导,暗示该基 因是生长素快速响应的叶片衰老相关基因.为进一步探究GmMIR１６０A 在大豆叶片发育中的功能,构建了 肾上腺皮质激素(Glucocorticoid,GR)类似物地塞米松(Dexamethasone,DEX)诱导表达GmMIR１６０A 双元表 达载体并通过农杆菌介导的子叶节方法转化野生型大豆.通过抗性筛选和基因组PCR 鉴定并结合表型分 析,共获得了４株诱导表达的稳定遗传转基因植株(株系OXＧ３、OXＧ５、OXＧ７和OXＧ８).GmMIR１６０A 过表达 植株根、茎、叶、花和果实在形态学上与野生型相比无显著差异,但叶片的叶绿素含量增加、最大光量子效率 (Fv/Fm)增强.进一步分子分析发现,转基因大豆叶片中GmARFs 和衰老标记基因(GmCYSP１)表达明显下 降,表明大豆Gma-miR１６０通过抑制靶基因GmARFs 的表达来负调控植物叶片的衰老进程.该文揭示了生 长素通过小分子RNA调控叶片发育一条新途径,为研究植物激素调控植物叶片衰老提供了新的思路.     

大豆microRNA基因GmMIR160A负调控植物叶片衰老进程

叶片衰老是受内外多种因子影响的遗传发育进程。生长素、细胞分裂素和乙烯等多种植物激素是调控叶片衰老的重要内部因子,它们通过长或短距离运输形成叶片组织内特定的区域分布和浓度梯度,从而直接或间接参与植物叶片衰老过程。分子遗传学表明,细胞分裂素和乙烯分别是叶片衰老的抑制子和正调节子,而生长素如何参与叶片衰老的分子机制目前还不清晰。植物体内成熟小分子RNA由小RNA基因转录并通过特定酶加工形成的21~23bp的双链RNA分子。这些小分子通过不完全配对方式抑制其靶基因转录和/或表达,参与植物生长发育多个过程,然而这类小RNA分子如何调控植物叶片衰老发育过程目前则还鲜有报告。大豆是重要的油料作物,具有典型的单次结实性衰老特征。研究大豆叶片衰老具有重要的科学意义和深远的应用价值。该文采用实时荧光定量PCR(qPCR)技术分析大豆(Glycine max)micro RNA基因GmMIR160A的表达模式,发现大豆第一复叶中GmMIR160A表达受外源生长素和黑暗处理的诱导,暗示该基因是生长素快速响应的叶片衰老相关基因。为进一步探究GmMIR160A在大豆叶片发育中的功能,构建了肾上腺皮质激素(Glucocorticoid,GR)类似物地塞米松(Dexamethasone,DEX)诱导表达GmMIR160A双元表达载体并通过农杆菌介导的子叶节方法转化野生型大豆。通过抗性筛选和基因组PCR鉴定并结合表型分析,共获得了4株诱导表达的稳定遗传转基因植株(株系OX-3、OX-5、OX-7和OX-8)。GmMIR160A过表达植株根、茎、叶、花和果实在形态学上与野生型相比无显著差异,但叶片的叶绿素含量增加、最大光量子效率(Fv/Fm)增强。进一步分子分析发现,转基因大豆叶片中GmARFs和衰老标记基因(GmCYSP1)表达明显下降,表明大豆Gma-miR160通过抑制靶基因GmARFs的表达来负调控植物叶片的衰老进程。该文揭示了生长素通过小分子RNA调控叶片发育一条新途径,为研究植物激素调控植物叶片衰老提供了新的思路。     

植物叶脉发育的分子机制

叶脉在高等植物发育过程中扮演着为叶片输送水分和营养及支撑叶片的重要角色。植物叶片的形态构造看起来简单,而叶脉发育的分子机理却十分复杂。大量研究表明,植物叶脉发育与生长素的极性运输紧密相关,此外,还受到众多转录因子、小分子RNA以及细胞分裂素、油菜素内酯等因素的调控。综述了近年来叶脉发育的分子机制研究进展,以期了解叶脉发育的调控网络。     

植物叶发育的分子机理

叶是植物进行光合作用和蒸腾作用的主要场所, 对植物的生长发育具有重要的作用。叶的发育包括叶原基的形成和极性的建立, 大量研究表明, 叶发育建成受到众多转录因子、小分子RNA以及生长素等因子的调控。文章综述了近年来叶发育和形态建成的分子机制研究进展, 以期了解叶发育的调控网络。     

microRNA在植物生长发育中的研究进展

microRNA(miRNA)是一类广泛存在于植物体内,长约20-25个核苷酸的内源性非编码小分子RNA,通过定向降解靶基因mRNA和抑制其翻译,从而在转录后水平控制靶向基因的表达来调控多种多样的生物功能,包括植物的生长发育、生殖和对逆境胁迫的响应。已有的研究表明,miRNA及其靶基因不仅在植物的时序转换中是一个关键调控因子,也在茎尖发育、叶形态建成、花器官发育和开花时间等过程中发挥着重要调控作用。重点介绍mi RNA在调控植物生长发育过程以及发育可塑性过程中的研究进展,并对植物miRNA研究中有待进一步阐明的问题进行了探讨和展望,以期为深入解析miRNA在调节植物组织和器官模式中的功能,以及植物形态多样性中的作用和分子调控网络提供参考。     

植物叶缘和叶脉发育调控的研究进展

通常可通过植物叶片的形态来区分不同植物的种类。叶片由茎顶端分生组织侧翼发育而成,为多种多样大小和形状的扁平结构。叶片的结构看似简单,但调控叶片形态和结构发育的分子机理错综复杂,叶片的发育受植物激素、转录因子、一系列蛋白因子及环境的共同调控。本文回顾了叶片边缘形态和叶脉发育研究的最新进展。在叶边缘形态方面,Aux/IAA生长素响应抑制家族蛋白通过调节生长素浓度最大点的离散分布影响小叶的起始和生长以及叶边缘结构;NAM/CUC转录因子促进叶边缘锯齿的分离以及复叶中小叶的分离和分化,NAM/CUC和Aux/IAA通过不同通路实现对生长素的调控;拟南芥RAX1基因/番茄Potato-leaf基因和拟南芥JAG基因/番茄LYR基因促进叶边缘锯齿发育;RCO调控复叶小叶的发育不通过改变生长素的分布来实现;在番茄中反式小干扰RNA途径中的因子参与叶边缘形态发育;另外,在拟南芥中,mir164A、CUC2、PIN1、DPA4、SVR9-1及SVR9L-1构成复杂的调控网络影响叶边缘锯齿的发育。在叶脉发育方面,PIN1能否正确的定位会影响叶脉发育;AS1和AS2共同参与叶片远近轴极性的分化;另外AXR6、MP、BDL、CVP因子功能的缺失影响叶脉发育;生长素、PIN1、Aux/IAA、MP、ATHB8构成反馈循环调控子叶叶脉的形成。     

水稻OsYABBY6基因参与叶片发育的初步研究

水稻YABBY基因家族在植物侧生器官发育过程中起着重要调控作用。在研究中,采用合成型转录因子的方法将转录抑制结构域EAR融合于OsYABBY6的C-端,获得转基因株系CE-OsYABBY6。表型分析发现,转基因株系CE-OsYABBY6-16和CE-OsYABBY6-19成熟期的剑叶均明显表现出朝近轴面卷曲,其卷曲指数相比于野生型均显著提高(P0.05),说明OsYABBY6参与了水稻叶的发育调控。进一步的细胞组织学分析发现,与野生型相比,CE-OsYABBY6-16叶片横切面中的泡状细胞束的总数、非正常泡状细胞束的数量和比率均显著增加,说明OsYABBY6蛋白与泡状细胞的发育相关。同时,转基因株系CE-OsYABBY6中细胞周期及细胞伸长相关基因的转录水平显著升高,说明OsYABBY6对细胞分裂及生长产生了影响,最终导致了叶片发育的异常。总之,水稻转录因子OsYABBY6参与了叶的近-远轴发育调控,尤其是叶片近轴面的发育调控,而且是泡状细胞发育和叶片伸展所必需的。     

MicroRNAs在棕色脂肪细胞分化过程中的作用

MicroRNA(miRNA)是一种非编码的小分子RNA,负性调控转录后基因表达。miRNA在个体时序性发育、细胞增殖分化和凋亡、器官发育、脂肪代谢等许多生物发育过程中起着重要作用。近年来对miRNA的研究证实,miRNA直接或间接影响棕色脂肪组织发育过程中重要转录因子的表达。综述了miRNA调节棕色脂肪细胞分化的最新研究进展。     

Characterization of novel small RNAs from tea (<Emphasis Type="Italic">Camellia sinensis</Emphasis> L.)

Small RNAs play important roles in plant development, metabolism, signal transduction and responses to biotic and abiotic stresses by affecting gene expression. Tea (Camellia sinensis L.) is an important commercial crop in the world. To understand the regulatory mechanisms involving small RNAs in tea metabolism, we constructed a small RNA (sRNA) library from its tea drink manufacturing tissue part i.e. topmost two leaves and a bud. For the first time, we isolated and cloned six novel small RNAs candidates from tea. These were predicted to target 67 genes responsible for various important plant functions. Isolated small RNAs were validated through expression analysis in young leaf and old leaf during non-dormant and dormant growth phases of tea. Results suggest the probable role of isolated small RNAs in development and seasonal variations of tea.     

Sensitivity of soybean leaf development to water deficits

Abstract. Drought effects on the final leaf area of individual leaves were hypothesized to depend on the leaf developmental stage at which drought occurred. To evaluate this hypothesis, final leaf area and cell number were measured for soybean ( Glycine max (L.) Merr.) leaves that were at different stages of development when single or cyclical drought treatment was imposed. Leaf emergence rate from the meristem, as depicted by changes in the plastochron index, was not as sensitive as leaf expansion to cyclical droughts. For leaf expansion, small leaves, once they emerged from the meristem, suffered larger decreases in growth than leaves undergoing rapid leaf area expansion. Decreases in final leaf area as a result of a cyclical drought were correlated with decreases in final cell number. Decreases resulting from a single 8-d drought were dependent on the age of the leaf at the time of drought, because small leaves were found to have proportionately larger decreases in final cell number and area than larger leaves. These results indicated that age-dependent leaf responses to drought are based on the relative activity of cell division and expansion at the time stress was imposed.     

Small RNAs in tomato fruit and leaf development

Tomato fruit and leaf development offers excellent systems to study the evolution of gene regulation underlying development of different organs. We have identified over 350 and 700 small RNAs from tomato fruit and leaf, respectively. Except for conserved microRNAs, more than 90% of the small RNAs are unique to tomato. We confirmed expression of some conserved as well as novel putative microRNAs by Northern hybridization. Our results help form a basis for comparative studies on how small RNA-mediated gene expression has contributed to the evolution of common and distinct developmental pathways of fruits and leaves. We have established a website (http://ted.bti.cornell.edu/digital/sRNA/) for public access to all of our small RNA sequences, their expression patterns in respective tissues, and their matching genes or predicted target genes in a searchable manner.     

Mutation in a novel gene SMALL AND CORDATE LEAF 1 affects leaf morphology in cucumber

Plant species exhibit substantial variation in leaf morphology.VWe isolated a recessive mutant gene termed small and cordate leaf 1(sclh)that causes alteration in both leaf size and shape of cucumber.Compared to wild type leaves,the sclh mutant had fewer numbers of epidermal pavement cells.A single nucleotide polymorphism was associated with this leaf phenotype,which occurred in a putative nucleoside bisphosphate phosphatase.RNA-seq analysis of the wild type and sclh mutant leaves suggested that SCL_1 regulation may not involve known hormonal pathways.Our work identified a candidate gene for SCL_1 that may play a role in leaf development.     

A triangular relationship between leaf size and seed size among woody species: allometry, ontogeny, ecology and taxonomy

 A hypothesized relationship between seed weight and leaf size was investigated for 58 diverse British (semi-)woody species. Interspecific variation in leaf size of adult plants corresponded allometrically with interspecific variation in the weight of an infructescence (seed-bearing inflorescence). The relationship between seed size and leaf size of adult plants was triangular. The corners of the triangle were interpreted in terms of ecological strategy. Medium-sized infructescences, small seeds and large leaves were seen among medium-sized, fast-growing, earlier-successional, mostly deciduous shrubs and trees; small infructescences, small seeds and small leaves mostly among low, slow-growing evergreens from stress-prone, proclimax habitats; and large infructescences, large seeds and large leaves among slow-growing, later-successional trees of potential competitive vigour. The hypothesis that the combination of large seeds and small leaves is allometrically unlikely was supported by the data. The roles of ontogeny and taxonomic relatedness in the seed size-leaf size relationship were examined by correlative and taxonomic analyses of seed, plant and leaf size during the unfolding of the life history from seed through two seedling phases to adulthood. Deciduous versus evergreen leaf habit was a source of deviation from the otherwise linear allometric relationships during ontogenetic development, none of which were, individually, confounded significantly with taxonomy. Received: 2 March 1998 / Accepted: 15 October 1998