作物分枝的分子调控研究进展

分枝的数量及角度是决定作物株型的重要农艺性状.有效分枝数决定着作物的穗数或荚果数,进而决定着作物的产量;而分枝角度与光合效率、种植密度和抗病性密切相关,不仅影响作物的产量,也会影响作物的品质.由于分枝在作物生产中具有十分重要的作用,吸引了越来越多的研究者的注意,多个与分枝性状相关的关键基因被鉴定,分枝数目调控的分子机制...     

独脚金内酯调控侧枝发育的研究进展

植物通过内源激素或环境信号调控叶腋内腋芽的形成和发育,从而控制其分枝特性。独脚金内酯(strigolactones,SLs),一种产生于植物根部的类胡萝卜素衍生物,具有刺激寄生植物种子的萌发和促进丛枝菌根真菌菌丝分枝的作用,最近的研究表明,它还可以沿茎干向上运输,与生长素和细胞分裂素一起直接或间接抑制植物分枝,目前已经作为一种新的植物激素受到广泛认可。本文综述了独脚金内酯的结构、合成途径和生物活性,以及调控植物分枝的分子机理,并展望了其在抑制杂草或新型除草剂的研发、促进植物和有益真菌的共生,以及调控作物的分枝和株型等方面的应用前景。     

独脚金内酯调控植物侧枝发育的分子机制及其与生长素交互作用的研究进展

对独脚金内酯（strigolactones,SLs）调控植物侧枝发育的分子机制及其与生长素相互作用的相关研究结果进行了总结和归纳,在此基础上提出今后的重点研究方向。相关的研究结果显示：在拟南芥[Arabidops~thaliana（Linn．）Heynh．]、豌豆（Pisum sativum Linn．）和水稻（Oryza sativa Linn．）等植物多枝突变体中SLs作为可转导信号参与侧枝发育的分子调控,从这些植物中已克隆获得参与SLs生物合成及信号应答途径的一些基因。作为一种植物激素,SLs在侧枝发育调控网络中与生长素相互作用;腋芽发育与其中生长素的输出密切相关,SLs通过调控芽中生长素的输出间接抑制腋芽发育和侧枝生长,而生长素则在SLs生物合成中起调节作用。     

独脚金内酯调控植物根系发育的分子机制研究的进展

独脚金内酯(strigolactones,SLs)是近年来发现的新型植物激素,参与调控植物生长发育过程,SLs在调控根系形态方面具有重要的作用。该文重点综述了SLs对植物主根、侧根、根毛及不定根的调节,特别是SLs与其他信号分子如生长素、乙烯、NO等的相互作用,以及SLs在氮磷胁迫条件下对根系调控的研究进展,为进一步深入了解SLs对植物生长和发育的调节奠定基础。     

作物抗倒伏相关性状及其信号转导调控机理的研究进展

倒伏是影响作物品种选育和产业化推广的重要限制因子,会使作物籽粒与秸秆的产量和品质显著降低且易引发病虫害,不利于机械化收割使作物经济效益显著降低.株高、茎秆强度、壁厚、分蘖数、分蘖夹角等性状同作物茎秆抗倒伏特性密切相关.倒伏主要分为为根倒伏和茎倒伏,茎倒伏与茎秆特性相关,其中株高与分蘖数分别受赤霉素信号转导和独脚金内酯信...     

水稻分蘖的分子机理研究进展

分蘖是水稻等禾谷类作物生产的关键农艺性状,也是单子叶植物一种特殊的分枝现象.水稻分蘖的形成是一个复杂的过程,其间受遗传、植物激素、栽培环境等因素的综合影响.近年来,对水稻分蘖数改变的突变体研究取得令人瞩目的研究成果,本综述总结水稻分蘖的调控机理的最新研究进展.     

植物激素对几种禾本科植物外植体的胚胎发生及形态发生途径的影响(简报)

2,4-D对胚胎发生起着关键的作用;单独使用细胞分裂素时,外植体不能脱分化,与2,4-D配合时,抑制双穗雀稗外植体愈伤组织的诱导,而1～5mg/L的2,4-D对苏丹草有促进影响:马唐对其不敏感。细胞分裂素与2,4-D配合使用,对苏丹草胚状体的分化亦有显著的促进效果。     

黄芪幼苗根系生长发育与GR24和IAA的关系北大核心CSCD

为探究独脚金内酯和生长素对黄芪根系生长发育的影响,该研究以膜荚黄芪和蒙古黄芪幼苗为材料,在种子萌发袋中添加不同浓度GR24和IAA(2μmol·L^(-1) GR24、5μmol·L^(-1) IAA和2μmol·L^(-1) GR24+5μmol·L^(-1) IAA),7 d后检测黄芪幼苗主根长和侧根数,并测定内源激素含量、生长素和独脚金内酯相关基因表达量的变化。结果表明:(1)GR24处理显著促进黄芪主根生长。(2)IAA处理下主根生长受到抑制,侧根数明显增加。(3)GR24+IAA处理下主根的生长同样受到抑制,膜荚黄芪侧根数较IAA处理下减少,说明GR24有抑制IAA对侧根发育的诱导作用,但不能缓解IAA对黄芪主根生长的抑制。(4)3种处理下黄芪幼苗根系内源激素含量、生长素和独脚金内酯相关基因表达量发生了显著变化,说明GR24和IAA对黄芪幼苗主根长和侧根数的影响可能与生长素和独脚金内酯相关基因表达及内源激素水平的变化有关。该研究结果初步阐明了黄芪幼苗根系生长发育与GR24和IAA之间的关系,为黄芪规范化育苗和幼苗质量控制提供理论依据,对进一步探索独脚金内酯和生长素调控黄芪根系生长发育的分子机制具有一定的意义。     

壳寡糖、一氧化氮和植物激素在烟草气孔运动中的作用及其相互关系

本文研究了壳寡糖（COS）、一氧化氮（NO）和植物激素对烟草气孔运动的作用及其相互关系,结果表明,COS、NO、脱落酸（ABA）能诱导烟草气孔开度减小;ABA合成抑制剂钨酸钠（Na2WO4）和NO合成酶抑制剂L-NAME具有清除COS、ABA或NO诱导烟草气孔开度减小的作用。说明COS通过诱导ABA和NO产生,进而诱导烟草气孔开度减小,而且ABA和NO之间有相互作用。另外,细胞分裂素和生长素能够诱导烟草气孔开度增大,也能够逆转COS诱导的气孔开度减小。     

独角金内酯能抑制植物的分枝并介导植物与枞枝真菌及寄生植物间的相互作用

植物激素在植物生长发育中起着重要的调控作用;一种激素往往调控多个生理过程,而植物的某一生理过程则受制于多种激素的协同作用．独角金内酯（strigolactones）是新近发现的一种植物激素或其前体,能够抑制植物的分枝和侧芽的生长,与生长素和细胞分裂素一起调控植物的分枝数量．独角金内酯类化合物还能促进可与植物共生的真菌（枞枝真菌,Arbucular Mycorrhizal Fungi）菌丝分枝生长以促进共生关系的建立,而枞枝真菌则可帮助植物吸收土壤中的营养物质特别是无机磷．独角金内酯还能刺激寄生植物如独角金（striga）和列当（orobanche）等的种子的萌发．这种激素在植物的根中合成,它既可以向地上部位输送以调节植物的生长,也可直接释放到土壤中以介导植物与土壤微生物及寄生植物的信号交换．其生物合成还受到植物营养水平的调节,当植物处于磷饥饿状态时,它的合成水平会升高．根据独角金内酯已知的功能,可以预测其广泛的应用前景．     

植物茎分枝的分子调控

植物茎分枝结构决定了不同植物的不同形态结构.本文从腋生分生组织的发生、腋芽的生长两个方面综述了近年来植物分枝发生发育相关的分子机理研究及其进展.发现在不同植物中腋分生组织形成的基本机制是相似的,LS（lateral suppressor）及其同源基因在不同植物中都参与腋生分生组织的形成,而BL(blind)及其同源基因也参与调控腋生分生组织的形成.腋生分生组织的形成可能也是受激素调控的.目前,对腋芽生长的分子调控机制的认识主要集中于生长素通过二级信使的作用调控腋芽的生长.而生长素调控腋芽生长的机制已经较为清楚的有两条途径：一是生长素通过抑制细胞分裂素合成来调控腋芽的生长;另一途径是一种类胡萝卜素衍生的信号物质参与生长素的运输调控(MAX途径)来调控腋芽的生长.最新研究表明,TB1的拟南芥同源基因在MAX途径的下游负调控腋芽的生长.此外,增强表达OsNAC2也促进腋芽的生长.     

The Roles of Phytohormones in Development as Studied in Transgenic Plants

The study of transgenic plants has greatly advanced our understanding of the control of development and metabolism. The ability to isolate and modify genes greatly extends the range of what is technically feasible. In the area of hormone biology, transgenic plants have helped to elucidate the pathways of synthesis, the metabolic control points, and the biological functions of the various phytohormones. This review covers the available genes that modulate the metabolism and perception of the phytohormones. One of the most significant conclusions coming out of transgenic plant work is the complex interaction among the different classes of phytohormones. For example, increasing the level of the auxin indole-3-acetic acid (IAA) in a plant has the secondary effect of inducing ethylene biosynthesis. This complication can be circumvented by combining transgenic plants modulating multiple hormones or through the use of available mutants. In this manner, transgenic plants have been utilized to unambiguously define the roles of auxin, cytokinin, and ethylene in the control of apical dominance. The power of transgenic plants as tools in hormone biology is perhaps best illustrated by work on ethylene. In this case, the modular characterization of genes led to elucidation of the biosynthetic pathway. Availability of the biosynthetic genes has permitted detailed analysis of the regulation of synthesis, definition of the role of ethylene in the control of several developmental processes, and the application of that knowledge for agricultural improvement.     

Research Progress and Application of Plant Branching

Plant branching development plays an important role in plant morphogenesis (aboveground plant type), the number and angle of branches are important agronomic characters that determine crop plant type. Effective branches determine the number of panicles or pods of crops and then control the yield of crops. With the rapid development of plant genomics and molecular genetics, great progress has been made in the study of branching development. In recent years, a series of important branching-related genes have been validated from Arabidopsis thaliana, rice, pea, tomato and maize mutants. It is reviewed that plant branching development is controlled by genetic elements and plant hormones, such as auxin, cytokinin and lactones (or lactone derivatives), as well as by environment and genetic elements. Meanwhile, shoot architecture in crop breeding was discussed in order to provide theoretical basis for the study of crop branching regulation.     

Toward Molecular Understanding of In Vitro and In Planta Shoot Organogenesis

Shoot organogenesis, one of the in vitro plant regeneration processes that occur during in vitro micropropagation, is used in the study of plant development. Morphological, physiological, and molecular aspects of in vitro shoot organogenesis have been extensively studied for over 50 years. Because of the research progress in plant genetics and molecular biology, our understanding of in planta and in vitro shoot meristem development, the cell cycle and cytokinin signal transduction has advanced significantly. These research advances provide useful information as well as molecular tools to study further the genetic and molecular aspects of shoot organogenesis. A number of key molecular markers, genes, and pathways have been shown to play a critical role in the process of in vitro shoot organogenesis. Furthermore, these studies reveal that in vitro shoot organogenesis, as with in planta shoot development, is a complex, well-coordinated developmental process, given that the induction of a single molecular event is likely to be insufficient to induce the entire process. Continued study is required to identify additional molecular events that trigger dedifferentiation and act as developmental switches for de novo shoot development.     

The control of shoot branching: an example of plant information processing

Throughout their life cycle, plants adjust their body plan to suit the environmental conditions in which they are growing. A good example of this is in the regulation of shoot branching. Axillary meristems laid down in each leaf formed from the primary shoot apical meristem can remain dormant, or activate to produce a branch. The decision whether to activate an axillary meristem involves the assessment of a wide range of external environmental, internal physiological and developmental factors. Much of this information is conveyed to the axillary meristem via a network of interacting hormonal signals that can integrate inputs from diverse sources, combining multiple local signals to generate a rich source of systemically transmitted information. Local interpretation of the information provides another layer of control, ensuring that appropriate decisions are made. Rapid progress in molecular biology is uncovering the component parts of this signalling network, and combining this with physiological studies and mathematical modelling will allow the operation of the system to be better understood.     

Phytohormones in Japanese Mugwort Gall Induction by a Gall-Inducing Gall Midge

A variety of insect species induce galls on host plants. Liquid chromatographic/tandem mass spectrometric analyses showed that a gall midge (Rhopalomyia yomogicola) that induces galls on Artemisia princeps contained high levels of indole-3-acetic acid and cytokinins. The gall midge larvae also synthesized indole-3-acetic acid from tryptophan. Close observation of gall tissue sections indicated that the larval chamber was surrounded by layers of cells having secondary cell walls with extensive lignin deposition, except for the part of the gall that constituted the feeding nutritive tissue which was composed of small cells negatively stained for lignin. The differences between these two types of tissue were confirmed by an expression analysis of the genes involved in the synthesis of the secondary cell wall. Phytohormones may have functioned in maintaining the feeding part of the gall as fresh nutritive tissue. Together with the results in our previous study, those presented here suggest the importance of phytohormones in gall induction.