Plant-environment Interactions Research Articles

Glandular trichomes in <i>Connarus suberosus</i> (Connaraceae): distribution, structural organization and probable functions.

Connarus suberosus is a typical species of the Brazilian Cerrado biome, and its inflorescences and young vegetative branches are densely covered by dendritic trichomes. The objective of this study was to report the occurrence of a previously undescribed glandular trichome of this species. The localization, origin and structure of these trichomes were investigated under light, transmission and scanning electron microscopy. Collections were made throughout the year, from five adult specimens of Connarus suberosus near Botucatu, São Paulo, Brazil, including vegetative and reproductive apices, leaves and fruits in different developmental stages, as well as floral buds and flowers at anthesis. Glandular trichomes (GTs) occurred on vegetative and reproductive organs during their juvenile stages. The GTs consisted of a uniseriate, multicellular peduncle, whose cells contain phenolic compounds, as well as a multicellular glandular portion that accumulates lipids. The glandular cell has thin wall, dense cytoplasm (with many mitochondria, plastids and dictyosomes), and a large nucleus with a visible nucleolus. The starch present in the plastids was hydrolyzed during the synthesis phase, reducing the density of the plastid stroma. Some plastids were fused to vacuoles, and some evidence suggested the conversion of plastids into vacuoles. During the final activity stages of the GTs, a darkening of the protoplasm was observed in some of the glandular cells, as a programmed cell death; afterwards, became caducous. The GTs in C. suberosus had a temporal restriction, being limited to the juvenile phase of the organs. Their presence on the exposed surfaces of developing organs and the chemical nature of the reserve products, suggest that these structures are food bodies. Field observations and detailed studies of plant-environment interactions, as well as chemical analysis of the reserve compounds, are still necessary to confirm the role of these GTs as feeding rewards.

Transcriptional Regulation of Plant Secondary MetabolismF

Plant secondary metabolites play critical roles in plant-environment interactions. They are synthesized in different organs or tissues at particular developmental stages, and in response to various environmental stimuli, both biotic and abiotic. Accordingly, corresponding genes are regulated at the transcriptional level by multiple transcription factors. Several families of transcription factors have been identified to participate in controlling the biosynthesis and accumulation of secondary metabolites. These regulators integrate internal (often developmental) and external signals, bind to corresponding cis-elements--which are often in the promoter regions--to activate or repress the expression of enzyme-coding genes, and some of them interact with other transcription factors to form a complex. In this review, we summarize recent research in these areas, with an emphasis on newly-identified transcription factors and their functions in metabolism regulation.

Plant developmental biologists meet on stairways in Matera

The third EMBO Conference on Plant Molecular Biology, which focused on 'Plant development and environmental interactions', was held in May 2012 in Matera, Italy. Here, we review some of the topics and themes that emerged from the various contributions; namely, steering technologies, transcriptional networks and hormonal regulation, small RNAs, cell and tissue polarity, environmental control and natural variation. We intend to provide the reader who might have missed this remarkable event with a glimpse of the recent progress made in this blossoming research field.

Mathematical modeling of plant metabolism-from reconstruction to prediction.

Due to their sessile lifestyle, plants are exposed to a large set of environmental cues. In order to cope with changes in environmental conditions a multitude of complex strategies to regulate metabolism has evolved. The complexity is mainly attributed to interlaced regulatory circuits between genes, proteins and metabolites and a high degree of cellular compartmentalization. The genetic model plant Arabidopsis thaliana was intensely studied to characterize adaptive traits to a changing environment. The availability of genetically distinct natural populations has made it an attractive system to study plant-environment interactions. The impact on metabolism caused by changing environmental conditions can be estimated by mathematical approaches and deepens the understanding of complex biological systems. In combination with experimental high-throughput technologies this provides a promising platform to develop in silico models which are not only able to reproduce but also to predict metabolic phenotypes and to allow for the interpretation of plant physiological mechanisms leading to successful adaptation to a changing environment. Here, we provide an overview of mathematical approaches to analyze plant metabolism, with experimental procedures being used to validate their output, and we discuss them in the context of establishing a comprehensive understanding of plant-environment interactions.

Elemental Profiles Reflect Plant Adaptations to the Environment

Most mineral elements found in plant tissues come exclusively from the soil, necessitating that plants adapt to highly variable soil compositions to survive and thrive. Profiling element concentrations in genetically diverse plant populations is providing insights into the plant-environment interactions that control elemental accumulation, as well as identifying the underlying genes. The resulting molecular understanding of plant adaptation to the environment both demonstrates how soils can shape genetic diversity and provides solutions to important agricultural challenges.

Surveying the plant’s world by magnetic resonance imaging

Understanding the way in which plants develop, grow and interact with their environment requires tools capable of a high degree of both spatial and temporal resolution. Magnetic resonance imaging (MRI), a technique which is able to visualize internal structures and metabolites, has the great virtue that it is non-invasive and therefore has the potential to monitor physiological processes occurring in vivo. The major aim of this review is to attract plant biologists to MRI by explaining its advantages and wide range of possible applications for solving outstanding issues in plant science. We discuss the challenges and opportunities of MRI in the study of plant physiology and development, plant-environment interactions, biodiversity, gene functions and metabolism. Overall, it is our view that the potential benefit of harnessing MRI for plant research purposes is hard to overrate.

Cross-scale multivariate analysis of physiological responses to high temperature in two tropical crops with C3 and C4 metabolism

The concept of hierarchical levels and its implications for biological organisation have been recognised for many years, and various hierarchical models of biological organisation have been proposed. However, the increased tendency to analyse biological systems from the molecular perspective has overshadowed the integrated view of living beings. On the other hand, plant ecophysiological studies have shown that variations in environmental factors can affect the plant from the molecular to the whole-plant level in different ways. The main objective of this study was to demonstrate that a cross-scale multivariate approach is important to support more consistent conclusions about plant–environment interactions. A study with two tropical crops (a C3 and a C4 species) was performed to test the effects, in a single experiment, of high temperatures across different levels of plant organisation from the molecular to the whole-plant level. Simulations using principal component analysis (PCA) on variables grouped according to the nature of the data were performed to investigate the effect of the observational scale on the interpretation of plant responses to high temperature. Despite an efficient photosynthetic response to elevated temperature, indicating an acclimatisation of the photosynthetic apparatus, the results of growth analysis showed a significant reduction in the biomass of both species and in leaf area. The resulting PCAs showed that the distinct differences between the responses of each species to the two temperature regimes were dependent on the specific data set observed. Despite causal associations between the physiological variables in different temperature regimes, the PCA results demonstrate that focusing on specific datasets markedly influences the interpretation of plant environmental response. Thus, we suggest that the multivariate approach could improve the differentiation between a global disruptive disturbance and a local physiological adjustment within a plant.

Characterization and expression analysis of the maize RING-H2 finger protein gene ZmXERICO responsive to plant hormones and abiotic stresses

Really interesting new gene (RING)-H2 proteins are widely represented in plants and play important roles in the regulation of many developmental processes as well as in plant–environment interactions. In the present report, a full-length cDNA encoding a putative RING-H2 protein with high sequence homology to Arabidopsis thaliana RING-H2 gene XERICO, designated as ZmXERICO, was isolated from maize. The full-length cDNA of ZmXERICO contained a 435 bp open reading frame encoding a precursor protein of 145 amino acid residues. Comparative and bioinformatics analyses revealed that ZmXERICO showed a high degree of homology with RING-H2 proteins and contained the transmembrane domain (TM) and RING-H2 motif. In our study, ZmXERICO was analyzed for expression profiles in various organs (root, stem, leaf, stamen, pistil and seed) and responding to exogenous hormone treatment and abiotic stresses using real-time PCR. The results showed that the expression of ZmXERICO was different regulated after treated by gibberellins acid-3 (GA3) and GA biosynthetic inhibitor paclobutrazol between in light and darkness. Moreover, the expression of ZmXERICO under different abiotic stresses was analyzed at different time points. The ZmXERICO was up-regulated in salt, drought, abscisic acid and cold stress. These expression results suggested that ZmXERICO played an important role in plant hormones signal pathways and light signal pathways, and that ZmXERICO might be involved in plant defense system against environmental stresses in maize.

Glucosinolates are produced in trichomes of Arabidopsis thaliana

Glucosinolates (GS) are important plant secondary metabolites in plant resistance to herbivores, bacteria, and fungi, which have been shown to be accumulating in different organs and tissue types at varying concentrations. There are more than 200 GS species found in order Brassicales and presence of these compounds is well documented on organ-specific but not on cell-specific level. We used UPLC/ESI-QTOF-MS to measure the presence of GS and qRT-PCR to analyse the expression of GS biosynthetic and regulatory genes in isolated Arabidopsis thaliana trichomes. Trichomes of Arabidopsis are shown to synthesize chemoprotective aliphatic glucosinolates (AGS) and indolic glucosinolates (IGS), which are known for their biological activities against fungi, bacterial pathogens, or herbivores. UPLC/ESI-QTOF-MS analysis of various IGS mutants reveal increased or decreased levels of IGS in trichomes of gain- and loss-of-function mutants correspondingly. Using pMYB51/HIG1-uidA and pMYB28/PMG1/HAG1-uidA reporter plants we demonstrate that production of these important compounds is activated in trichomes of leaves or inflorescences in response to wounding. Since trichomes represent the first interface in plant-environment interactions, the possible role of GS containing trichomes in plant defense or signaling is discussed.

Chips and tags suggest plant-environment interactions differ for two alpine Pachycladon species

BackgroundExpression profiling has been proposed as a means for screening non-model organisms in their natural environments to identify genes potentially important in adaptive diversification. Tag profiling using high throughput sequencing is a relatively low cost means of expression profiling with deep coverage. However the extent to which very short cDNA sequences can be effectively used in screening for candidate genes is unclear. Here we investigate this question using an evolutionarily distant as well as a closely related transcriptome for referencing tags. We do this by comparing differentially expressed genes and processes between two closely related allopolyploid species of Pachycladon which have distinct altitudinal preferences in the New Zealand Southern Alps. We validate biological inferences against earlier microarray analyses.ResultsStatistical and gene annotation enrichment analyses of tag profiles identified more differentially expressed genes of potential adaptive significance than previous analyses of array-based expression profiles. These include genes involved in glucosinolate metabolism, flowering time, and response to cold, desiccation, fungi and oxidation. In addition, despite the short length of 20mer tags, we were able to infer patterns of homeologous gene expression for 700 genes in our reference library of 7,128 full-length Pachycladon ESTs. We also demonstrate that there is significant information loss when mapping tags to the non-conspecific reference transcriptome of A. thaliana as opposed to P. fastigiatum ESTs but also describe mapping strategies by which the larger collection of A. thaliana ESTs can be used as a reference.ConclusionWhen coupled with a reference transcriptome generated using RNA-seq, tag sequencing offers a promising approach for screening natural populations and identifying candidate genes of potential adaptive significance. We identify computational issues important for the successful application of tag profiling in a non-model allopolyploid plant species.

Climate change impacts on ecosystem functioning: evidence from an Empetrum heathland

• The extent to which plants exert an influence over ecosystem processes, such as nitrogen cycling and fire regimes, is still largely unknown. It is also unclear how such processes may be dependent on the prevailing environmental conditions. • Here, we applied mechanistic models of plant-environment interactions to palaeoecological time series data to determine the most likely functional relationships of Empetrum (crowberry) and Betula (birch) with millennial-scale changes in climate, fire activity, nitrogen cycling and herbivore density in an Irish heathland. • Herbivory and fire activity preferentially removed Betula from the landscape. Empetrum had a positive feedback on fire activity, but the effect of Betula was slightly negative. Nitrogen cycling was not strongly controlled by plant population dynamics. Betula had a greater temperature-dependent population growth rate than Empetrum; thus climate warming promoted Betula expansion into the heathland and this led to reduced fire activity and greater herbivory, which further reinforced Betula dominance. • Differences in population growth response to warming were responsible for an observed shift to an alternative community state with contrasting forms of ecosystem functioning. Self-reinforcing feedback mechanisms--which often protect plant communities from invasion--may therefore be sensitive to climate warming, particularly in arctic regions that are dominated by cold-adapted plant populations.

Ecophysiology of halophytes: questions and challenges

Halophytes are able to tolerate and even benefit from salt concentrations that kill most other plant species and, at the very least, may provide genes that allow transgenic conference of salinity tolerance to crops. In addition, some halophytes have already been tested as vegetable, forage and oilseed crops. However, physiological mechanisms behind the remarkable ability of halophytes to live in highly saline environment are not fully understood. This talk highlights some unanswered questions and challenges in understanding halophyte physiology, with a specific emphasis on complexity of plant-environmental interaction.

Plant genetics, sustainable agriculture and global food security.

The United States and the world face serious societal challenges in the areas of food, environment, energy, and health. Historically, advances in plant genetics have provided new knowledge and technologies needed to address these challenges. Plant genetics remains a key component of global food security, peace, and prosperity for the foreseeable future. Millions of lives depend upon the extent to which crop genetic improvement can keep pace with the growing global population, changing climate, and shrinking environmental resources. While there is still much to be learned about the biology of plant-environment interactions, the fundamental technologies of plant genetic improvement, including crop genetic engineering, are in place, and are expected to play crucial roles in meeting the chronic demands of global food security. However, genetically improved seed is only part of the solution. Such seed must be integrated into ecologically based farming systems and evaluated in light of their environmental, economic, and social impacts-the three pillars of sustainable agriculture. In this review, I describe some lessons learned, over the last decade, of how genetically engineered crops have been integrated into agricultural practices around the world and discuss their current and future contribution to sustainable agricultural systems.

Plant growth and architectural modelling and its applications. Preface.

Over the last decade, a growing number of scientists around the world have invested in research on plant growth and architectural modelling and applications (often abbreviated to plant modelling and applications, PMA). By combining physical and biological processes, spatially explicit models have shown their ability to help in understanding plant–environment interactions. This Special Issue on plant growth modelling presents new information within this topic, which are summarized in this preface. Research results for a variety of plant species growing in the field, in greenhouses and in natural environments are presented. Various models and simulation platforms are developed in this field of research, opening new features to a wider community of researchers and end users. New modelling technologies relating to the structure and function of plant shoots and root systems are explored from the cellular to the whole-plant and plant-community levels.

Leucine-Rich repeat receptor kinases are sporadically distributed in eukaryotic genomes

BackgroundPlant leucine-rich repeat receptor-like kinases (LRR-RLKs) are receptor kinases that contain LRRs in their extracellular domain. In the last 15 years, many research groups have demonstrated major roles played by LRR-RLKs in plants during almost all developmental processes throughout the life of the plant and in defense/resistance against a large range of pathogens. Recently, a breakthrough has been made in this field that challenges the dogma of the specificity of plant LRR-RLKs.ResultsWe analyzed ~1000 complete genomes and show that LRR-RK genes have now been identified in 8 non-plant genomes. We performed an exhaustive phylogenetic analysis of all of these receptors, revealing that all of the LRR-containing receptor subfamilies form lineage-specific clades. Our results suggest that the association of LRRs with RKs appeared independently at least four times in eukaryotic evolutionary history. Moreover, the molecular evolutionary history of the LRR-RKs found in oomycetes is reminiscent of the pattern observed in plants: expansion with amplification/deletion and evolution of the domain organization leading to the functional diversification of members of the gene family. Finally, the expression data suggest that oomycete LRR-RKs may play a role in several stages of the oomycete life cycle.ConclusionsIn view of the key roles that LRR-RLKs play throughout the entire lifetime of plants and plant-environment interactions, the emergence and expansion of this type of receptor in several phyla along the evolution of eukaryotes, and particularly in oomycete genomes, questions their intrinsic functions in mimicry and/or in the coevolution of receptors between hosts and pathogens.

Grand Challenge: Viewing Transporter Function in a Pointillist Landscape

SPECIALTY GRAND CHALLENGE article Front. Plant Sci., 09 May 2011Sec. Plant Membrane Traffic and Transport Volume 2 - 2011 | https://doi.org/10.3389/fpls.2011.00014

HS-SPME method to monitoring „in vivo“ volatile compounds emitted from Achillea collina infested by aphids

Plant leaves normally release small quantities of volatile compounds, but when it is damaged by herbivorous insects, many more volatiles are produced. The emitted volatile fraction plays a key role in plant-environment interaction, being involved in important processes in plant life cycle [1]. Determination of volatile compounds release from living plants are usually performed by enclosing the whole plants or some of its parts in glass o plastic chambers, followed by collection of the emitted compounds in sorbent traps and chromatographic analysis of the adsorbed compounds. This general procedure has some drawbacks for example some material employed as trapping can introduced artifact. This work describes the application of an Headspace Solid Phase Micro-Extraction (HS-SPME) and Gas-Chromatographic Mass-Spectrometric (GC-MS) method to characterize the volatile compounds emitted by leaving leaves of Achillea collina Becker ex Rchb, infested by aphids (Macrosifonella) using a sampling glass chamber specially designed for this task. In particular, the headspaces volatiles were extracted using a divinylbenzene-carboxen-polydimethylsiloxane (DVB/CAR/PDMS, 70/30µm) fiber. The extraction conditions including extraction temperature and time were also optimized using the total peak area as index. The best response was obtained at room temperature for 240min. As a result, many volatile compounds appeared as new compounds after infestation (α-fenchene, aromadendrene and pinocarvone). Other compounds showed an increase trend after infestation by aphid such as camazulene, followed by β-pinene, α-bergamotene and β-phellandrene. In conclusion, the present method is simple and effective and can be used to study the „in vivo“ volatile compound emissions from medicinal plants.

Tools for high-spatial and temporal-resolution analysis of environmental responses in plants

Understanding how plants cope with environmental change requires a spatiotemporal perspective. In this review, we highlight recent work which has led to the development and use of novel tools for the high spatial and temporal-resolution analysis of the plant-environment interaction. FACS-based transcriptome and immunoprecipitation-based translatome data sets have provided an important foundation for the analysis of the transcriptional and translational control of environmental responses in each tissue layer of the plant. Complementary approaches, based on a proteomic toolkit, have provided insight into the biological response of Arabidopsis to NaCl and the relationship between transcript and protein levels. The development and adaptation of biosensors and ion-specific dyes provides the capacity to visualize changes in the transport and accumulation of metabolites and small molecules such as sugars, Na(+) and Ca(2+) at the cellular level. Finally, live-imaging approaches coupled with automated image-analysis algorithms are revealing new levels of dynamism and plasticity in the response to light and gravity. Together, these tools will provide a more comprehensive understanding of environmental responses in plants, which will aide in the development of new crop varieties for sustainable agriculture.

Genetic and metabolic engineering of isoflavonoid biosynthesis

Isoflavonoids are a diverse group of secondary metabolites derived from the phenylpropanoid pathway. These compounds are distributed predominantly in leguminous plants and play important roles in plant-environment interactions and human health. Consequently, the biosynthetic pathway of isoflavonoid compounds has been widely elucidated in the past decades. Up to now, most of the structural genes and some of the regulatory genes involved in this pathway have been isolated and well characterized. Nowadays, the protective effects of the legume isoflavonoids against hormone dependent cancers, cardiovascular disease, osteoporosis, and menopausal symptoms have generated considerable interest within the genetic and metabolic engineering fields to enhance the dietary intake of these compounds for disease prevention. Subsequently, there are some great progresses in genetic and metabolic engineering to improve their yields in leguminous and non-leguminous plants and/or microorganisms. Because of the field of flavonoid biosynthesis has been reviewed fairly extensively in the past, this review concentrates on the more recent development in the isoflavonoid branch of phenylpropanoid pathway, including gene isolation and characterization. In addition, we describe the state-of-the-art research with respect to genetic and metabolic engineering of isoflavonoid biosynthesis.

Proline Metabolism and Its Implications for Plant-Environment Interaction

Proline has long been known to accumulate in plants experiencing water limitation and this has driven studies of proline as a beneficial solute allowing plants to increase cellular osmolarity during water limitation. Proline metabolism also has roles in redox buffering and energy transfer and is involved in plant pathogen interaction and programmed cell death. Some of these unique roles of proline depend on the properties of proline itself, whereas others depend on the "proline cycle" of coordinated proline synthesis in the chloroplast and cytoplasm with proline catabolism in the mitochondria. The regulatory mechanisms controlling proline metabolism, intercellular and intracellular transport and connections of proline to other metabolic pathways are all important to the in vivo functions of proline metabolism. Connections of proline metabolism to the oxidative pentose phosphate pathway and glutamate-glutamine metabolism are of particular interest. The N-acetyl glutamate pathway can also produce ornithine and, potentially, proline but its role and activity are unclear. Use of model systems such as Arabidopsis thaliana to better understand both these long studied and newly emerging functions of proline can help in the design of next-generation experiments testing whether proline metabolism is a promising metabolic engineering target for improving stress resistance of economically important plants.