植物激素对分枝发育的协同调控作用研究进展

植物分枝与其适应环境、生存竞争能力及产量形成密切相关。近年的研究表明植物激素信号在调控植物分枝发育过程中起关键作用。文章主要介绍了生长素、细胞分裂素以及独脚金内酯协同调控植物分枝发育的研究进展,为深入了解植物分枝发育的调控机制提供参考。     

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...     

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。     

植物重力反应的分子调控机制

重力是调节植物生长发育和形态建成的重要环境因子。植物感受到重力刺激后可以通过重力反应来协调自身各个器官的生长方向与重力方向之间的最适角度。植物重力反应过程分为重力信号的感受、重力信号的转导、生长素不对称分布的形成和重力反应器官的弯曲生长4个阶段。近年来,随着大量重力反应缺陷突变体的鉴定及其控制基因的功能解析,重力信号的感受和生长素不对称分布的分子机制等方面的研究取得了重要进展。作为植物适应环境变化的重要手段之一,重力反应还可以通过调节水稻(Oryza sativa L.)的分蘖角度实现对水稻株型和产量的调控。因此,研究植物的重力反应,不仅有助于解析植物生长发育的调控机制,对于作物株型的改良也具有重要的指导意义。然而,重力反应的分子机制及其调控网络仍不清楚。本文综述了近年来植物重力反应的调控机理及其调控水稻分蘖角度的作用机制,并对该领域未来的研究方向和热点进行了展望。     

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.     

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。     

生长素调控植物重力反应的分子机理研究

重力反应是植物对环境的一种适应现象。生长素参与植物环境适应与发育调控的过程,重力反应过程的核心之一是在重力反应器官形成生长素的浓度梯度,诱导下游基因的差异表达。生长素的合成、代谢、极性运输及信号转导在此过程中发挥了关键作用。该文以拟南芥和水稻的研究为基础,综述了近几年对生长素调控植株重力反应的分子机理的研究进展,并对该领域未来的研究进行展望。     

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。     

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.     

樟子松人工林分枝结构的分析

基于对6块樟子松(Pinus sylvestris var. mongolica)人工林固定标准地中的30株样木枝解析调查数据,通过分析不同林分、不同大小林木1级枝和2级枝的分枝概率、分枝格局和分枝角度,揭示了樟子松人工林树冠的分枝结构特点。研究结果表明：樟子松人工林1级枝和2级枝的平均分枝数量分别为3.84个和2.80个,两者分枝概率均呈正态分布;1级和2级枝条在光照条件好的几个区间（方位角46°～225°）分布较多,1级枝条的水平分布遵从均匀分布,而2级枝条则不遵从均匀分布;树冠上层枝条的分枝角度略小于树冠中、下层,上层平均分枝角度为45.6°,而中下层平均分枝角度都为49.4°。不同大小林木的1级枝分枝结构规律表明：Ⅰ级木和Ⅴ级木的每轮平均分枝数非常接近,分别为3.89和3.94个,比Ⅲ级木每轮分枝数大0.5个左右;1级枝水平分布在各区间内(45°间隔)相差在0.24%～2.81%之间,方差分析结果表明枝条水平分布与林木大小无关;不同大小林木的分枝角度有所差别,Ⅰ级木、Ⅲ级木和Ⅴ级木的平均分枝角度分别为48.5°、42.2°和50.7°。     

AtLAZY1 is a signaling component required for gravitropism of the Arabidopsis thaliana inflorescence

The present study identified a family of six A. thaliana genes that share five limited regions of sequence similarity with LAZY1, a gene in Oryza sativa (rice) shown to participate in the early gravity signaling for shoot gravitropism. A T‐DNA insertion into the Arabidopsis gene (At5g14090) most similar to LAZY1 increased the inflorescence branch angle to 81° from the wild type value of 42°. RNA interference lines and molecular rescue experiments confirmed the linkage between the branch‐angle phenotype and the gene consequently named AtLAZY1. Time‐resolved gravitropism measurements of atlazy1 hypocotyls and primary inflorescence stems showed a significantly reduced bending rate during the first hour of response. The subcellular localization of AtLAZY1 protein was investigated to determine if the nuclear localization predicted from the gene sequence was observable and important to its function in shoot gravity responses. AtLAZY1 fused to green fluorescent protein largely rescued the branch‐angle phenotype of atlazy1, and was observed by confocal microscopy at the cell periphery and within the nucleus. Mutation of the nuclear localization signal prevented detectable levels of AtLAZY1 in the nucleus without affecting the ability of the gene to rescue the atlazy1 branch‐angle phenotype. These results indicate that AtLAZY1 functions in gravity signaling during shoot gravitropism, being a functional ortholog of rice LAZY1. The nuclear pool of the protein appears to be unnecessary for this function, which instead relies on a pool that appears to reside at the cell periphery.     

TAC4 controls tiller angle by regulating the endogenous auxin content and distribution in rice

Tiller angle, an important component of plant architecture, greatly influences the grain yield of rice (Oryza sativa L.). Here, we identified Tiller Angle Control 4 (TAC4) as a novel regulator of rice tiller angle. TAC4 encodes a plant‐specific, highly conserved nuclear protein. The loss of TAC4 function leads to a significant increase in the tiller angle. TAC4 can regulate rice shoot gravitropism by increasing the indole acetic acid content and affecting the auxin distribution. A sequence analysis revealed that TAC4 has undergone a bottleneck and become fixed in indica cultivars during domestication and improvement. Our findings facilitate an increased understanding of the regulatory mechanisms of tiller angle and also provide a potential gene resource for the improvement of rice plant architecture.     

Channelling auxin action: modulation of ion transport by indole-3-acetic acid

The growth hormone auxin is a key regulator of plant cell division and elongation. Since plants lack muscles, processes involved in growth and movements rely on turgor formation, and thus on the transport of solutes and water. Modern electrophysiological techniques and molecular genetics have shed new light on the regulation of plant ion transporters in response to auxin. Guard cells, hypocotyls and coleoptiles have advanced to major model systems in studying auxin action. This review will therefore focus on the molecular mechanism by which auxin modulates ion transport and cell expansion in these model cell types.     

Transport of [3H]IAA label in gravistimulated primary roots of maize

The curvature of roots in response to gravity is attributed to the development of a differential concentration gradient of IAA in the top and bottom of the elongation region of roots. The development of the IAA gradient has been attributed to the redistribution of IAA from the stele to cortical tissues in the elongation region. The gravistimulated redistribution of IAA was investigated by applying [³H]IAA to the cut surface of 5 mm apical primary root segments. The movement of label from the stele-associated [³H]IAA into the root, tip, root cap, and cortical tissues on the top and bottom of the elongation region was determined in vertically growing roots and gravistimulated roots. Label from the stele moved into the region of cell differentiation (root tip) prior to accumulating in the elongation region. Little label was observed in the root cap. Gravistimulation did not increase the amount of label moving from the stele; but gravistimulation did increase the amount of label accumulating in cortical tissues on the lower side of the elongation region, and decreased the amount of label accumulating in cortical tissues on the upper side of the elongation region. Removal of the cap prior to or immediately following gravity stimulation rendered the roots partially insensitive to gravity and also prevented gravity-induced asymmetric redistribution of label. However, removal of the root cap following 30 min of gravistimulation did not alter root curvature or the establishment of an IAA asymmetry across the region of root elongation. These results suggest that a signal originating in the root cap directs auxin redistribution in tissues behind the root cap, leading to the development of an asymmetry of IAA concentration in the elongation region that in turn causes the differential growth rate in the elongation region of a graviresponding root.     

园艺作物花青素合成调控研究进展

花青素是一类保护植物免受生物和非生物胁迫的重要次生代谢产物,因其赋予植物丰富的色彩和对人体的保健功能而受到广泛关注。花青素合成调控机理的相关研究是目前园艺作物分子生物学研究的前沿课题,对于园艺作物花青素含量的提高、种质品质的提升等具有重要的意义。结合国内外园艺作物中花青素生物合成调控方面的最新研究进展,介绍了环境因素、酶与激素、DNA甲基化与泛素化和调控基因等对花青素生物合成的作用,以及花青素抵御外界胁迫的功能机制,综述了近年来园艺作物中花青素生物合成调控的研究成果,以期利用基因工程为提升园艺作物的色彩丰富度提供理论参考。     

Changes in IAA responsiveness in the elongation region of graviresponding mung bean roots

IAA responsiveness of sections of root tissue taken from the top and bottom of mung bean roots was assessed prior to and at varying times following gravistimulation. Prior to gravistimulation, root tissue sections from the sides of the elongation zone responded similarly to IAA. After gravistimulation (within 5 min), root sections from the bottom of the elongation zone became more responsive to IAA than sections collected from the upper side of the elongation zone. The change in IAA responsiveness of these tissue sections was transient with root sections from both the top and bottom of the elongation zone again exhibiting similar responsiveness to IAA following 15 minutes of gravistimulation.These studies also examined if the root tip is required for the gravity-induced shift in IAA responsiveness in the tissues of the elongation zone. The IAA responsiveness of top and bottom sections of the elongation zone from decapped mung bean roots was assessed at varying times following gravistimulation. The responsiveness to IAA of top and bottom sections changed rapidly in decapped roots, just as had been previously found for intact roots. Although the alteration in responsiveness was transient in decapped roots (just as intact roots), the time it took for the sections to recover previous responsiveness to IAA was extended.These results suggest that the initial growth response of graviresponding roots may be due to a change in the IAA responsiveness of tissues in the elongation zone and not an asymmetric accumulation of IAA on the lower side of the elongation zone. The results also indicate that the gravity-induced shift in IAA responsiveness in the elongation zone occurs independently of the root cap, suggesting that the cells in the elongation region can perceive and respond to gravity independently of the root cap during the intial phases of the gravity response.     

LAZY3 interacts with LAZY2 to regulate tiller angle by modulating shoot gravity perception in rice

Starch biosynthesis in gravity-sensing tissues of rice shoot determines the magnitude of rice shoot gravitropism and thus tiller angle. However, the molecular mechanism underlying starch biosynthesis in rice gravity-sensing tissues is still unclear. We characterized a novel tiller angle gene LAZY3 (LA3) in rice through map-based cloning. Biochemical, molecular and genetic studies further demonstrated the essential roles of LA3 in gravity perception of rice shoot and tiller angle control. The shoot gravitropism and lateral auxin transport were defective in la3 mutant upon gravistimulation. We showed that LA3 encodes a chloroplast-localized tryptophan-rich protein associated with starch granules via Tryptophan-rich region (TRR) domain. Moreover, LA3 could interact with the starch biosynthesis regulator LA2, determining starch granule formation in shoot gravity-sensing tissues. LA3 and LA2 negatively regulate tiller angle in the same pathway acting upstream of LA1 to mediate asymmetric distribution of auxin. Our study defined LA3 as an indispensable factor of starch biosynthesis in rice gravity-sensing tissues that greatly broadens current understanding in the molecular mechanisms underlying the starch granule formation in gravity-sensing tissues, and provides new insights into the regulatory mechanism of shoot gravitropism and rice tiller angle.