生长素介导环境信号调控植物的生长发育

植物是一类营固着生活的自养型生物, 如何更好地适应周围环境对植物的生存至关重要。生长素是调控植物生长发育的重要激素之一。近年来的研究发现, 生长素不仅能够响应内在的发育信号, 而且能够介导各种环境信号, 参与植物生长发育和生长反应的调控。该文主要从光信号、温度信号、重力信号、营养元素和金属离子信号等方面重点阐述生长素如何介导上述各种不同的环境信号, 从而调控植物的生长发育。     

Retrograde signaling and plant stress: plastid signals initiate cellular stress responses

Retrograde signaling coordinates the expression of nuclear genes encoding organellar proteins with the metabolic and developmental state of the organelle. These plastid signals are essential not only for coordinating photosynthetic gene expression in both the nucleus and in the chloroplasts but also for mediating plant stress responses. The chloroplasts therefore act as sensors of environmental changes and complex networks of plastid signals coordinate cellular activities and assist the cell during plant stress responses. Recent work suggests that information from both cytosolic-signaling and plastid-signaling networks must be integrated for the plant cell to respond optimally to environmental stress.     

Auxin cross-talk: integration of signalling pathways to control plant development

Plants sense and respond to endogenous signals and environmental cues to ensure optimal growth and development. Plant cells must integrate the myriad transduction events into a comprehensive network of signalling pathways and responses. The phytohormone auxin occupies a central place within this transduction network, frequently acting in conjunction with other signals, to co-ordinately regulate cellular processes such as division, elongation and differentiation. As a non-cell autonomous signal, auxin also interacts with other signalling pathways to regulate inter-cellular developmental processes. As part of this especially themed edition of Plant Molecular Biology, we will review examples of `cross-talk' between auxin and other signalling pathways. Given the current state of knowledge, we have deliberately focused our efforts reviewing auxin interactions with other phytohormone and light signalling pathways. We conclude by discussing how new genomic approaches and the Arabidopsis genome sequence are likely to impact this area of research in the future.     

Flowering responses to light and temperature

Light and temperature signals are the most important environmental cues regulating plant growth and development. Plants have evolved various strategies to prepare for, and adapt to environmental changes. Plants integrate environmental cues with endogenous signals to regulate various physiological processes, including flowering time. There are at least five distinct pathways controlling flowering in the model plant Arabidopsis thaliana: the photoperiod pathway, the vernalization/thermosensory pathway, the autonomous floral initiation, the gibberellins pathway, and the age pathway. The photoperiod and temperature/vernalization pathways mainly perceive external signals from the environment, while the autonomous and age pathways transmit endogenous cues within plants. In many plant species, floral transition is precisely controlled by light signals(photoperiod) and temperature to optimize seed production in specific environments. The molecular mechanisms by which light and temperature control flowering responses have been revealed using forward and reverse genetic approaches. Here we focus on the recent advances in research on flowering responses to light and temperature.     

Of light and length: regulation of hypocotyl growth in Arabidopsis

At all stages, plant development results from a complex integration of multiple endogenous and environmental signals. The sedentary nature of plants strongly enhances the impact of the environment on plant development as compared to animal development. The embryonic and postembryonic seedling stem, called the hypocotyl, of the model species Arabidopsis (thale cress) has proved to be an excellent system for studying such signal interplay in the regulation of growth and developmental responses. The extension of the hypocotyl, which is regulated by a network of interacting factors, including light and plant hormones, is such a process. These regulatory factors often reciprocally regulate their biosynthesis and/or signalling. Here we present the current state of knowledge about the regulation of hypocotyl growth by a large repertoire of internal and external cues.     

Determination of sex by jasmonate

正Jasmonic acid (JA) and some of its derivatives are important signals in plant stress responses such as biotic or abiotic stresses during alteration of the environment and are signals in several developmental processes such as trichome development, growth/defense balance, root growth, senescence, or light signaling m entary     

Integration of Light and Auxin Signaling

Light is vital for plant growth and development: It provides energy for photosynthesis, but also reliable information on seasonal timing and local habitat conditions. Light sensing is therefore of paramount importance for plants. Thus, plants have evolved sophisticated light receptors and signaling networks that detect and respond to changes in light intensity, duration, and spectral quality. Environmental light signals can drive developmental transitions such as germination and flowering, but they also continuously shape development to allow adaptation to the local habitat and microclimate. The ability to respond to a changing and sometimes unfavorable environment underlies the huge success of plants. Much of this growth and developmental plasticity is achieved by light modulation of auxin signaling systems. In this article, we examine the connections between light and auxin that elicit local responses, long distance signaling, and coordinated growth between the shoot and root.     

ABA and sugar interactions regulating development: cross-talk or voices in a crowd?

Plant growth and development are controlled by the concerted action of many signaling pathways that integrate information from environmental signals with that from developmental and metabolic cues. Physiological studies have demonstrated that abscisic acid and sugars have both similar and antagonistic effects on diverse processes, including seed development, germination, and seedling growth. Recent genetic studies have identified several loci that are involved in both sugar and hormonal responses. It is rarely clear whether these apparent linkages reflect direct or indirect interactions between sugar and hormone signaling pathways, but the identification of gene products that are encoded at these loci is allowing these possibilities to be tested.     

Light signaling and UV‐B‐mediated plant growth regulation

Light plays an important role in plants’ growth and development throughout their life cycle. Plants alter their morphological features in response to light cues of varying intensity and quality. Dedicated photoreceptors help plants to perceive light signals of different wavelengths. Activated photoreceptors stimulate the downstream signaling cascades that lead to extensive gene expression changes responsible for physiological and developmental responses. Proteins such as ELONGATED HYPOCOTYL5 (HY5) and CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1) act as important factors which modulate light‐regulated gene expression, especially during seedling development. These factors function as central regulatory intermediates not only in red, far‐red, and blue light pathways but also in the UV‐B signaling pathway. UV‐B radiation makes up only a minor fraction of sunlight, yet it imparts many positive and negative effects on plant growth. Studies on UV‐B perception, signaling, and response in plants has considerably surged in recent times. Plants have developed different strategies to use UV‐B as a developmental cue as well as to withstand high doses of UV‐B radiation. Plants’ responses to UV‐B are an integration of its cross‐talks with both environmental factors and phytohormones. This review outlines the current developments in light signaling with a major focus on UV‐B‐mediated plant growth regulation.     

Long-distance stress and developmental signals associated with abscisic acid signaling in environmental responses

Flowering plants consist of highly differentiated organs, including roots, leaves, shoots and flowers, which have specific roles: root system for water and nutrient uptake, leaves for photosynthesis and gas exchange and reproductive organs for seed production. The communication between organs through the vascular system, by which water, nutrient and signaling molecules are transported, is essential for coordinated growth and development of the whole plant, particularly under adverse conditions. Here, we highlight recent progress in understanding how signaling pathways of plant hormones are associated with long-distance stress and developmental signals, with particular focus on environmental stress responses. In addition to the root-to-shoot peptide signal that induces abscisic acid accumulation in leaves under drought stress conditions, we summarize the diverse stress-responsive peptide signals reported to date to play a role in environmental responses.     

Complexity of SMAX1 signaling during seedling establishment

Karrikins (KARs) are small butenolide compounds identified in the smoke of burning vegetation. Along with the stimulating effects on seed germination, KARs also regulate seedling vigor and adaptive behaviors, such as seedling morphogenesis, root hair development, and stress acclimation. The pivotal KAR signaling repressor, SUPPRESSOR OF MAX2 1 (SMAX1), plays central roles in these developmental and morphogenic processes through an extensive signaling network that governs seedling responses to endogenous and environmental cues. Here, we summarize the versatile roles of SMAX1 reported in recent years and discuss how SMAX1 integrates multiple growth hormone signals into optimizing seedling establishment. We also discuss the evolutionary relevance of the SMAX1-mediated signaling pathways during the colonization of aqueous plants to terrestrial environments.     

Environmental and Genetic Determinants of Colony Morphology in Yeast

Nutrient stresses trigger a variety of developmental switches in the budding yeast Saccharomyces cerevisiae. One of the least understood of such responses is the development of complex colony morphology, characterized by intricate, organized, and strain-specific patterns of colony growth and architecture. The genetic bases of this phenotype and the key environmental signals involved in its induction have heretofore remained poorly understood. By surveying multiple strain backgrounds and a large number of growth conditions, we show that limitation for fermentable carbon sources coupled with a rich nitrogen source is the primary trigger for the colony morphology response in budding yeast. Using knockout mutants and transposon-mediated mutagenesis, we demonstrate that two key signaling networks regulating this response are the filamentous growth MAP kinase cascade and the Ras-cAMP-PKA pathway. We further show synergistic epistasis between Rim15, a kinase involved in integration of nutrient signals, and other genes in these pathways. Ploidy, mating-type, and genotype-by-environment interactions also appear to play a role in the controlling colony morphology. Our study highlights the high degree of network reuse in this model eukaryote; yeast use the same core signaling pathways in multiple contexts to integrate information about environmental and physiological states and generate diverse developmental outputs.     

Developmental plasticity and maternal effects of reproductive characteristics in the frog,Bombina orientalis

Summary Life history theory suggests that reproductive characteristics such as ovum size and clutch size should be well buffered against vararies of the environment. However, studies which demonstrate environmental sensitivity of reproductive characteristics are increasing in number, as are studies which find that maternal effects are responsible for much of the variation in developmental and growth rates in embryonic and larval fish and amphibians. The data reported here demonstrate that the environment, in terms of temperature and food availability that a specific individual encounters during vitellogenesis, exerts a strong influence on both egg size and number. Warmer temperatures and less food decrease ovum size, while colder temperatures and less food decrease clutch size. The variation in ovum size that is induced by the environment can exert a strong influence on variation in offspring development and growth and serve as an excellent model for studies on the evolution of developmental plasticity.     

类受体激酶调控根生长发育的研究进展

类受体激酶是一类具有激酶活性的单次跨膜受体,通过接收和传递胞外信号调控细胞的生理反应,参与植物生长发育过程。植物根在生长发育过程中受到大量的外部刺激和内源性发育信号的影响,植物必须通过整合这些信号并转化为细胞反应,才能适应不断变化的环境条件;植物类受体激酶作为细胞膜上的信息监测者,通过与外源和内源信号的通讯调控根的生长发育。该文对近年来国内外有关类受体激酶的结构、分类及其作用机制,特别是植物类受体激酶在根发育信号转导途径中的功能和作用等方面的研究进展进行综述,为进一步揭示植物类受体激酶在根生长发育中的功能及其作用机制提供参考。     

AP2/ERF转录因子调控植物非生物胁迫响应研究进展

低温、干旱、高盐和缺氧等多种不良环境影响植物的生长发育, 植物通过长期进化形成复杂的调节机制来适应这些不利条件。AP2/ERF是植物特有的转录因子, 在各种胁迫响应过程中发挥关键调控作用。近年来, 越来越多的研究表明, 植物激素介导的信号级联通路与逆境胁迫响应关系密切, AP2/ERF转录因子可与激素信号转导协同形成交叉调控网络。许多AP2/ERF转录因子通过响应植物激素脱落酸和乙烯, 激活依赖或不依赖于脱落酸和乙烯的胁迫响应基因的表达。此外, AP2/ERF转录因子参与赤霉素、细胞分裂素和油菜素内酯介导的生长发育和胁迫应答。该文简要综述了AP2/ERF转录因子的结构特征、转录调控、翻译后修饰、结合位点、协同互作蛋白及其参与调控依赖或不依赖激素信号转导途径的非生物胁迫响应研究进展, 为解析不同AP2/ERF转录因子在调控激素和胁迫响应网络中的作用提供理论依据。     

Plant target of rapamycin signaling network: Complexes,conservations, and specificities

Target of rapamycin (TOR) is an evolutionarily conserved protein kinase that functions as a central signaling hub to integrate diverse internal and external cues to precisely orchestrate cellular and organismal physiology. During evolution, TOR both maintains the highly conserved TOR complex compositions, and cellular and molecular functions, but also evolves distinctive roles and strategies to modulate cell growth, proliferation, metabolism, survival, and stress responses in eukaryotes. Here, we review recent discoveries on the plant TOR signaling network. We present an overview of plant TOR complexes, analyze the signaling landscape of the plant TOR signaling network from the upstream signals that regulate plant TOR activation to the downstream effectors involved in various biological processes, and compare their conservation and specificities within different biological contexts. Finally, we summarize the impact of dysregulation of TOR signaling on every stage of plant growth and development, from embryogenesis and seedling growth, to flowering and senescence.     

Factors influencing seaweed responses to eutrophication: some results from EU-project EUMAC

Seaweed responses to eutrophication and their role in coastal eutrophication processes were compared at 8 different sites along the European coasts from the Baltic to the Mediterranean as part of the EU-ENVIRONMENT Project Marine Eutrophication and benthic Macrophytes (EUMAC). Structural and functional changes of marine benthic vegetation typical of eutrophic waters, in particular mass development (blooms) of certain seaweeds, are not merely the result of increased nutrient loading, but must be attributed to complex interactions of primary and secondary effects during the eutrophication process. Due to species-specific physiological properties of the algae (nutrient kinetics, growth potential, light, temperature requirements), the combined effects of abiotic and biotic factors on juvenile or adult developmental stages control the development of algal blooms in different ways. In particular the role of light, temperature, water motion and oxygen depletion, as well as of grazers, on early and adult developmental stages of the algae are considered. The result are discussed in the context of coastal eutrophication control and management. This revised version was published online in June 2006 with corrections to the Cover Date.