The Mechanisms of Brassinosteroids＇ Action： From Signal Transduction to Plant Development

Brassinosteroids play diverse roles in plant growth and development. Plants deficient in brassinosteroid （BR） biosynthesis or defective in signal transduction show many abnormal developmental phenotypes, indicating the importance of both BR biosynthesis and the signaling pathway in regulating these biological processes. Recently, using genetics, proteomics, genomics, cell biology, and many other approaches, more components involved in the BR signaling pathway were identified. Furthermore, the physiological, cellular, and molecular mechanisms by which BRs regulate various aspects of plant development, are being discovered. These include root development, anther and pollen development and formation, stem elongation, vasculature differentiation, and cellulose biosynthesis, suggesting that the biological functions of BRs are far beyond promoting cell elongation, This review will focus on the up-to-date progresses about regulatory mechanisms of the BR signaling pathway and the physiological and molecular mechanisms whereby BRs regulate plant growth and development.

Small G Protein as a Novel Component of the Rice Bmssinosteroid Signal Transduction

Brassinosteroids （BRs） are a class of steroid hormones that are essential for plant growth and development. The BR signal transduction pathway in the dicot model plantArabidopsis is well established, but the components connecting the BR signaling steps in rice have not been fully explored. For example, how the BR signaling is fine-tuned in rice, especially at the BR receptor level, is largely unknown. Here we show that OsPRA2, a rice small G protein, plays a repressive role in the BR signaling pathway. Lamina inclination, coleoptile elongation, and root inhibition assays indicated that rice plants with suppressed expression of OsPRA2 were more sensitive to exogenously applied brassinolide than the wild-type plants. Conversety, rice overexpressing OsPRA2 was less sensitive to exogenous brassinolide. Further study uncovered that OsPRA2 inhibited the dephosphorylation of, and thus inactivated the transcription factor BRASSINAZOLE- RESISTANT 1 （OsBZR1）. More importantly, OsPRA2 was found to co-localize with and directly bind to rice BR receptor BRASSlNOSTEROID-INSENSITIVE 1 （OsBRI1） at the plasma membrane. Additionally, the in vitro assays showed that OsPRA2 inhibits its autophosphorylation. This OsPRA2-OsBRI1 interaction led to the dissociation of OsBRI1 from its co-receptor OsBAK1, and abolished OsBRIl-mediated phosphorylation of OsBAK1. Together, these results reveal a possible working mechanism of OsPRA2 as a novel negative regu- lator on OsBRI1 and OsBZR1 and extend the knowledge about the regulatory mechanism of rice BR signaling.

Origin, evolution, and molecular function of DELLA proteins in plants

Gibberellic acid(GA), a ubiquitous phytohormone, has various effects on regulators of plant growth and development. GAs promote growth by overcoming growth restraint mediated by DELLA proteins(DELLAs). DELLAs, in the GRAS family of plant-specific nuclear proteins, are nuclear transcriptional regulators harboring a unique N-terminal GA perception region for binding the GA receptor GIBBERELLIN INSENSITIVE DWARF1(GID1) and a C-terminal GRAS domain necessary for GA repression activity via interaction with multiple regulatory proteins. The N-terminal conserved region of DELLAs evolved to form a mode of GID1/DELLA-mediated GA signaling originating in bryophytes and ferns. Binding of GA to GID1 increases the affinity between DELLAs and a SCF E3 ubiquitin–ligase complex, thus promoting the eventual destruction of DELLAs by the 26 S proteasome. DELLAs negatively regulate GA response by releasing transcription factors to directly activate downstream genes and indirectly regulate GA biosynthesis genes increasing GA responsiveness and feedback control by promoting GID1 transcription. GA communicates extensively with other plant hormones and uses crosstalk to regulate plant growth and development. In this review, we summarize current understanding of evolutionary DELLA-mediated gibberellin signaling and functional diversification of DELLA, focusing primarily on interactions of DELLAs with diverse phytohormones.

Mutual Information Flow between Beneficial Microorganisms and the Roots of Host Plants Determined the Bio-Functions of Biofertilizers

Modern agriculture is facing new challenges in which ecological and molecular approaches are being integrated to achieve higher crop yields while minimizing negative impacts on the environment. The application of biofertilzers could meet this requirement. Biofertilizer is a natural organic fertilizer that helps to provide all the nutrients required by the plants and helps to increase the quality of the soil with a natural microorganism environment. This paper reviewed the types of biofertilzers, the biological basic of biofertilizers in plant growth promotion. This paper also assayed the bidirectional information exchange between plant-microbes in rhizoshpere and the signal pathway of plant growth- promoting rhizobacteria (PGPR) and plant growth-promoting fungi (PGPF) in the course of plant infection. At last, the challenges of the application and the promising future of biofertilizers were also discussed.

Fibroblast growth factor(FGF)signaling in development and skeletal diseases

Fibroblast growth factors(FGF)and their receptors serve many functions in both the developing and adult organism.Humans contain 18 FGF ligands and four FGF receptors(FGFR).FGF ligands are polypeptide growth factors that regulate several developmental processes including cellular proliferation,differentiation,and migration,morphogenesis,and patterning.FGF-FGFR signaling is also critical to the developing axial and craniofacial skeleton.In particular,the signaling cascade has been implicated in intramembranous ossification of cranial bones as well as cranial suture homeostasis.In the adult,FGFs and FGFRs are crucial for tissue repair.FGF signaling generally follows one of three transduction pathways:RAS/MAP kinase,PI3/AKT,or PLCg.Each pathway likely regulates specific cellular behaviors.Inappropriate expression of FGF and improper activation of FGFRs are associated with various pathologic conditions,unregulated cell growth,and tumorigenesis.Additionally,aberrant signaling has been implicated in many skeletal abnormalities including achondroplasia and craniosynostosis.The biology and mechanisms of the FGF family have been the subject of significant research over the past 30 years.Recently,work has focused on the therapeutic targeting and potential of FGF ligands and their associated receptors.The majority of FGF-related therapy is aimed at age-related disorders.Increased understanding of FGF signaling and biology may reveal additional therapeutic roles,both in utero and postnatally.This review discusses the role of FGF signaling in general physiologic and pathologic embryogenesis and further explores it within the context of skeletal development.

Plant plasma membrane-resident receptors:Surveillance for infections and coordination for growth and development

As sessile organisms, plants are exposed to pathogen invasions and environmental fluctuations. To overcome the challenges of their surroundings, plants acquire the potential to sense endogenous and exogenous cues, resulting in their adaptability. Hence, plants have evolved a large collection of plasma membrane-resident receptors, including RECEPTOR-LIKE KINASEs(RLKs) and RECEPTOR-LIKE PROTEINs(RLPs) to perceive those signals and regulate plant growth,development, and immunity. The ability of RLKs and RLPs to recognize distinct ligands relies on diverse categories of extracellular domains evolved. Co-regulatory receptors are often required to associate with RLKs and RLPs to facilitate cellular signal transduction. RECEPTOR-LIKE CYTOPLASMIC KINASEs(RLCKs) also associate with the complex, bifurcating the signal to key signaling hubs, such as MITOGEN-ACTIVATED PROTEIN KINASE(MAPK) cascades, to regulate diverse biological processes. Here, we discuss recent knowledge advances in understanding the roles of RLKs and RLPs in plant growth, development, and immunity, and their connection with co-regulatory receptors, leading to activation of diverse intracellular signaling pathways.

植物异三聚体G蛋白研究进展

植物细胞中的异三聚体G蛋白信号转导系统包括异三聚体G蛋白、G蛋白偶联受体、类受体激酶、G蛋白信号调节因子等,这些信号转导组分在感受物理及化学刺激、启动细胞内信号级联反应、调控细胞内代谢和基因表达过程中发挥重要作用.异三聚体G蛋白参与调控植物生长发育(如胚胎形成、营养器官生长、有性生殖等)、植物对生物及非生物胁迫的响应、根瘤形成等过程.因此,异三聚体G蛋白信号系统组分参与调控多种农作物的农艺性状,并最终影响农产品的产量和品质.对植物异三聚体G蛋白的结构、活化机制和生理功能等方面近年来取得的研究进展进行了回顾和总结.

油菜素内酯调控植物生长发育的研究进展

油菜素内酯类化合物(brassinosteroids,BRs)是第六大类植物激素,对植物生长发育及逆境胁迫响应具有重要的调控作用。自1970年被发现至今,人们在BRs的生物学功能、结构及生物合成、信号转导通路和其对农作物重要农艺性状调控等方面研究取得一系列重要进展。本文就BRs生物合成途径、BRs信号转导通路及其对植物生长发育的调控机制等方面研究成果进行综述,并对其未来发展和研究方向进行展望。

谷氨酸受体蛋白调控植物生长与胁迫应答的研究进展

植物谷氨酸受体(glutamate receptor-like,GLRs)是动物离子型谷氨酸受体(inotropic glutamate receptors,iGluRs)的同源蛋白,在开花植物中具有多个拷贝,常以功能冗余的基因家族形式共同调节植物生长发育和逆境应答过程。GLRs在植物中发挥作用的机制与其动物同源蛋白既有类似之处,但又表现出植物特异性。iGluRs在哺乳动物的神经系统中发挥重要作用。在iGluRs介导的神经传导中,由突触前膜释放的神经递质识别并结合突触后膜的iGluRs,iGluRs介导的阳离子内流引起突触后膜的去极化,形成动作电位的传递,构成神经传导的基础。过去20多年的研究发现,植物GLRs也可以作为离子通道蛋白,通过调节跨膜离子流行使功能。本文系统综述了植物谷氨酸受体的蛋白结构和演化特征,并对已报道的重要功能位点进行阐释;总结了近些年来对植物谷氨酸受体蛋白在植物生长发育不同时期,以及多种生物和非生物逆境应答中的功能的研究进展,并比较了其与动物iGluRs作用机制的异同;提出并梳理了该领域仍待解决的重要科学问题;最后展望了该蛋白家族在作物耐逆育种中的重要应用前景和价值,以期为改良作物耐逆性状提供线索。

核黄素启动植物生长信号通路的初步研究

报道了核黄素促进植物生长的效应及分子反应。在实验室内对 7种粮食、蔬菜和经济作物使用核黄素后 ,植物生长量增加 2 3 8%～ 85 4 %。在田间试验中 ,烟草使用核黄素后 ,生长量提高 35 9%～ 10 8% ,烤烟叶产量提高 4 4 7%～110 3%。在拟南芥上 ,核黄素处理可以诱导PR 3b、PDF1 2、ETR1和EIN2基因的表达 ;PR 3b和PDF1 2是乙烯信号通路的分子标志 ,乙烯 /茉莉酸信号传导可以调控植物生长发育 ;ETR1和EIN2是乙烯信号通路上、下游的关键调控基因 ,其产物分别作为乙烯的受体和转录调控因子起作用。根据以上这些结果 ,核黄素启动了植物生长信号传导通路的分子反应 。

植物一氧化氮(NO)研究进展

一氧化氮 (NO)是植物的重要生物活性分子 ,它参与植物生长发育的许多过程 ,如种子萌发、下胚轴伸长、叶扩展、根生长、侧根形成、细胞凋亡以及植物抗逆反应等。大量的证据表明 ,植物可以通过与动物NO合酶类似的酶产生NO。此外 ,植物还可通过硝酸还原酶产生NO。NO在植物中的信号传递途径仍不十分清楚 ,植物有可能采用与动物相类似的机制。由于植物的大多数生长发育现象都受到植物激素的调节和控制 ,NO与植物激素之间的关系也受到越来越多的关注。通过激素起作用可能是植物内源NO作用的机理之一。

植物蛋白激酶研究进展

蛋白激酶是一类磷酸转移酶,其在细胞信号转导过程中起到较为重要作用。目前,在不同植物中分离了各种蛋白激酶基因。相关研究报道表明,这一类蛋白酶基因参与了植物的抗逆性、生长发育以及信号转导等一系列生命活动进程。着重从植物蛋白激酶分类、结构及其功能研究几个方面进行综述。

植物的光受体和光控发育研究

Phytochrome has fascinated plant scientists since its discovery in 1959-1960 by the Beltsville research group of the United States Department of Agriculture. Studies in the first 20 years had evidenced that phytochrome acts as an universal regulator in plant life adapting its behavior to the environmental light, and developed widely the physiological understanding of phytochrome action. In the following 20 years, some thirty world_wide major laboratories have published over two hundred papers a year on various aspects of the subject, and they are making steady progress. The authors’ work has also contributed to the following aspects: coaction of phytochrome and phytohormone in photomorphogenesis, phytochrome purification, phytochrome regulation of male fertility, as well as phytochrome A gene analysis and expression in photoperiod sensitive genic male sterile rice. In the recent decade significant advances have been made in studies on phytochrome molecules, genes and signal transduction in phytochrome response. This is largely due to the advances in molecular genetics, where experiments using mutants and transgenic plants, particularly in Arabidopsis, that have led to the significant insights at the molecular level. The topics in this review include:(1) Discovery of phytochrome; (2) Functions of phytochrome; (3) Phytochrome molecules; (4) Phytochrome regulation in gene expression.

油菜素内酯生物合成与功能的研究进展

植物激素油菜素内酯广泛调节植物的生长发育及对外界环境因子变化的反应,在作物上的应用也已引起人们的广泛兴趣。通过遗传学等手段对相关突变体及功能基因的研究为其生物合成与功能研究提供了基础。本文总结了油菜素内酯在植物各组织内的分布、生物合成、相关合成突变体及其编码基因的性质、生理功能以及与其它激素间的相互作用等。

生长素的运输及其在信号转导及植物发育中的作用

生长素作为一种重要的植物激素,参与调节植物生长发育的诸多过程,如器官发生、形态建成、向性反应、顶端优势及组织分化等,其作用机理长期以来备受人们关注。生长素的极性运输能使生长素积累在植物体某些特定部位,从而形成生长素浓度梯度,生长素对植物生长发育的调节主要依赖于这一特性。系统阐述生长素的运输特点、运输机理和相关生长素极性运输载体的研究进展;并对生长素信号转导途径中的重要组分及其机理进行了总结;同时较系统地对生长素参与植物体各器官发育过程及调节情况进行综述。

植物MicroRNA功能的研究进展

MicroRNA(miRNA)是真核生物基因表达的一类负调控因子,植物miRNA主要在转录水平上通过介导靶基因的甲基化、在转录后水平介导靶mRNA的切割或降低靶mRNA的翻译来调节基因的表达,从而调控植物器官的形态建成、生长发育、激素分泌与信号转导以及植物对逆境胁迫因素的应答能力。该文主要综述了近年来植物miRNA在植物生长发育、激素调节与信号转导以及逆境胁迫应答中的重要作用,并针对miRNA的网络调控特征提出了今后miRNA功能研究的方向。

拟南芥油菜素内酯信号转导研究进展

油菜素内酯(brassinosteroid)信号首先被膜上的受体BRI1/BAK1复合体感知,然后在一系列蛋白参与下传递到核内,进一步调控下游基因的表达。本文综述了拟南芥中油菜素内酯信号转导研究的进展,并对今后的研究方向进行了探讨。

植物花粉萌发的研究进展

综述了目前国内外关于植物花粉萌发的研究进展,如在花粉萌发和生长过程中Ca2+通道的开启、信号的转导、Ca2+通道的阻塞、钙调素的作用,另外还有其他重要的矿质元素、植物生长激素对花粉萌发和花粉管生长的作用及其作用机制等。

植物抗逆相关蛋白激酶的结构与功能

植物在遭受外界逆境胁迫时,体内的信号传导系统能够感知和传递逆境胁迫信号,并引起各种生理生化反应以适应环境。植物蛋白激酶在信号感知、传导生长发育以及基因的表达调控中起重要作用。蛋白激酶在信号传导过程的功能是磷酸化修饰目的蛋白,而磷酸化的实现需要蛋白质之间相互作用。本文从植物蛋白激酶的结构、分类、与激素信号传导之间的关系等方面进行了系统的阐述,对蛋白激酶介导的植物抗性与发育的最新研究进展进行了系统的总结,为解析蛋白激酶在植物生长发育中的抗逆机理提供了理论依据。

植物LRR类受体蛋白激酶的研究进展

植物中富亮氨酸重复片断类受体蛋白激酶(LRR-RLK)属于跨膜类受体蛋白激酶,由胞外LRR结构域、单次跨膜区以及胞内激酶结构域三部分组成。在不同植物中,LRR-RLK作为信号识别受体参与CLV、BR、Ax21等信号转导过程,在植物生长发育、激素调节以及逆境应答反应等方面中发挥重要的作用。综述了近年来LRR-RLK的相关调控功能及其作用机制的研究进展,并为进一步探索LRR-RLK的功能及应用提供参考。