Showing papers in "Journal of Experimental Botany in 2023"
TL;DR: Recent advances in understanding the intersection of auxin and abiotic stress in plants are summarized and discussed, with a focus on temperature, salt, and drought stresses.
Abstract: Plants are exposed to a variety of abiotic stresses; these stresses have profound effects on plant growth, survival, and productivity. Tolerance and adaptation to stress require sophisticated stress sensing, signaling, and various regulatory mechanisms. The plant hormone auxin is a key regulator of plant growth and development, playing pivotal roles in the integration of abiotic stress signals and control of downstream stress responses. In this review, we summarize and discuss recent advances in understanding the intersection of auxin and abiotic stress in plants, with a focus on temperature, salt, and drought stresses. We also explore the roles of auxin in stress tolerance and opportunities arising for agricultural applications.
39 citations
TL;DR: In this paper , the authors distinguish seven inherent capacities that enable plants to respond to abiotic stresses and continue growing, although at a reduced rate, to achieve a productive yield, and show how these capacities are important for reproductive success of major crop species during drought, salinity, temperature extremes, flooding, and nutrient stress.
Abstract: Abiotic stresses like drought and heat continue to impact crop production in a warming world. This paper distinguishes seven inherent capacities that enable plants to respond to abiotic stresses and continue growing, although at a reduced rate, to achieve a productive yield. These are the capacities to selectively take up essential resources, store them and supply them to different plant parts, generate the energy required for cellular functions, conduct repairs to maintain plant tissues, communicate between plant parts, manage existing structural assets in the face of changed circumstances, and shape-shift through development to be efficient in different environments. By illustration we show how all seven plant capacities are important for reproductive success of major crop species during drought, salinity, temperature extremes, flooding, and nutrient stress. Confusion about the term 'oxidative stress' is explained. This allows us to focus on the strategies that enhance plant adaptation by identifying key responses that can be targets for plant breeding.
39 citations
TL;DR: In this paper , the authors describe the current knowledge on the different modalities of signaling, from the well-characterized canonical nuclear auxin pathway, to the more recently discovered or re-discovered non-canonical modes of auxin signaling.
Abstract: As auxin is a major regulator of plant development, studying the signaling mechanisms by which auxin influences cellular activities is of primary importance. In this review, we describe the current knowledge on the different modalities of signaling, from the well-characterized canonical nuclear auxin pathway, to the more recently discovered or re-discovered non-canonical modes of auxin signaling. In particular, we discuss how both the modularity of the nuclear auxin pathway and the dynamic regulation of its core components allow to trigger specific transcriptomic responses. We highlight the fact that the diversity of modes of auxin signaling allows for a wide range of timescales of auxin responses, from second-scale cytoplasmic responses to minute/hour-scale modifications of gene expression. Finally, we question the extent to which the temporality of auxin signaling and responses contributes to development in both the shoot and the root meristems. We conclude by stressing the fact that future investigations should allow to build an integrative view not only of the spatial control, but also of the temporality of auxin-mediated regulation of plant development, from the cell to the whole organism.
34 citations
TL;DR: In this article , the role of arbuscular mycorrhizal fungi (AMF) in maintaining water supply to plants from drying soils and the underlying biophysical mechanisms were reviewed.
Abstract: Arbuscular mycorrhizal fungi (AMF) have been presumed to ameliorate crop tolerance to drought. Here, we review the role of AMF in maintaining water supply to plants from drying soils and the underlying biophysical mechanisms. We used a soil-plant hydraulic model to illustrate the impact of several AMF mechanisms on plant responses to edaphic drought. The AMF enhance soil's capability to transport water and extend the effective root length, thereby attenuating the drop in matric potential at the root surface during soil drying. The synthesized evidence and the corresponding simulations demonstrate that symbiosis with AMF postpones the stress onset limit, which is defined as the disproportionality between transpiration rates and leaf water potentials, during soil drying. The symbiosis can thus help crops survive extended intervals of limited water availability. We also provide our perspective on future research needs and call for reconciling the dynamic changes in soil and root hydraulics in order to better understand the role of AMF in plant water relations in the face of climate changes.
33 citations
TL;DR: In this paper , the authors used male and female full-sibs of Populus deltoides to investigate whether the two plant sexes will present sexual differences in the phyllosphere microbiome structure and associated pathogen resistance against a leaf pathogenic fungus after soil cadmium (Cd) exposure.
Abstract: Phyllosphere associated microorganisms play a crucial role in protecting plants from diseases, while their composition and diversity are strongly influenced by heavy metal contaminants. As dioecious plants exhibited sexual dimorphism in metal accumulation and tolerance between male and female individuals, in this study we used male and female full-sibs of Populus deltoides to investigate whether the two plant sexes will present sexual differences in the phyllosphere microbiome structure and associated pathogen resistance against a leaf pathogenic fungus after soil cadmium (Cd) exposure. We found that Cd-treated male plants grew better and accumulated more leaf Cd than females. Cd stress reduced leaf lesion area of both plant sexes after leaf pathogen infection, whereas male plants exhibited better resistance than females. More importantly, Cd exposure differentially altered the structure and function of phyllosphere microbiomes between male and female plants, with more abundant ecologically beneficial microbes but decreased pathogenic fungal taxa harbored in male plants. Further in vitro toxicity tests suggested that such sexual difference in pathogen resistance between the two plant sexes could attribute to direct Cd toxicity and indirect shifts in the phyllosphere microbiome. This study provides implication for understanding the underlying mechanism of heavy metals involved in plant-pathogen interactions.
31 citations
TL;DR: The published information on how modifying genes related to potassium homeostasis in plants affects abiotic stress tolerance at the whole plant level is reviewed.
Abstract: Potassium is the major cation responsible for the maintenance of the ionic environment in plant cells. Stable potassium homeostasis is indispensable for virtually all cellular functions, and, concomitantly, viability. Plants must cope with environmental changes such as salt or drought that can alter ionic homeostasis. Potassium fluxes are required to regulate the essential process of transpiration, so a constraint on potassium transport may also affect the plant's response to heat, cold, or oxidative stress. Sequencing data and functional analyses have defined the potassium channels and transporters present in the genomes of different species, so we know most of the proteins directly participating in potassium homeostasis. The still unanswered questions are how these proteins are regulated and the nature of potential cross-talk with other signaling pathways controlling growth, development, and stress responses. As we gain knowledge regarding the molecular mechanisms underlying regulation of potassium homeostasis in plants, we can take advantage of this information to increase the efficiency of potassium transport and generate plants with enhanced tolerance to abiotic stress through genetic engineering or new breeding techniques. Here, we review current knowledge of how modifying genes related to potassium homeostasis in plants affect abiotic stress tolerance at the whole plant level.
29 citations
TL;DR: A review on different types of cyanobacterial-plant associations, both endophytic and epiphytic, and insights from a structural viewpoint, as well as our current understanding of the mechanisms involved in the symbiotic crosstalk are provided in this paper .
Abstract: Nitrogen-fixing cyanobacteria from the order Nostocales are able to establish symbiotic relationships with diverse plant species. They are promiscuous symbionts as the same strain of cyanobacterium is able to form symbiotic biological nitrogen fixing (BNF) relationships with different plants species. This review will focus on the different types of cyanobacterial-plant associations, both endophytic and epiphytic, and provide insights from a structural viewpoint, as well as our current understanding of the mechanisms involved in the symbiotic crosstalk. In all these symbioses, the benefit for the plant is clear; they obtain from the cyanobacterium, fixed-nitrogen and other bioactive compounds, such as phytohormones, polysaccharides, siderophores or vitamins, leading to enhanced plant growth and productivity. Additionally, there is increasing use of different cyanobacterial species as bio-inoculants for BNF to improve soil fertility and crop production, thus providing an eco-friendly, alternative, and sustainable approach to reduce the over-reliance on synthetic chemical fertilizers.
29 citations
TL;DR: A review of the current understanding of GSH/GS-conjugate degradation and its overall picture is presented in this article , which aims to build a foundation for future studies.
Abstract: Glutathione (GSH) is a ubiquitous, abundant, and indispensable thiol for plants that participates in various biological processes, such as the scavenging of oxidative stress, redox signaling, storage and transport of sulfur, detoxification of harmful substances, and the metabolisms of several compounds; therefore, knowledge of GSH metabolism is essential for plant science. Nevertheless, elucidation of GSH degradation is insufficient, which has hampered our understanding of plant life. Over the last five decades, the idea of the γ-glutamyl cycle has been dominant in GSH studies, and the exoenzyme γ-glutamyl transpeptidase (GGT) has been regarded as the major GSH degradation enzyme. However, recent studies have shown that GSH is degraded in cells by cytosolic enzymes such as γ-glutamyl cyclotransferase (GGCT) or γ-glutamyl peptidase (GGP). Meanwhile, a portion of GSH is degraded after conjugation with other molecules, which has also been found to be carried out by vacuolar GGT, GGP, or phytochelatin synthase (PCS). These findings are now displacing the assumption of the γ-glutamyl cycle, and a novel overview of the plant GSH degradation pathways is essential. This review aims to build a foundation for future studies by summarizing the current understanding of GSH/GS-conjugate degradation and presenting its overall picture.
25 citations
TL;DR: The role of sugars in apical dominance has been investigated for more than a century as mentioned in this paper , with different approaches over time with first the physiology era, the genetic era, and then the multidisciplinary era.
Abstract: The process of apical dominance by which the apical bud/shoot tip of the plant inhibits the outgrowth of axillary buds located below has been studied for more than a century. Different approaches were used over time with first the physiology era, the genetic era, and then the multidisciplinary era. During the physiology era, auxin was thought of as the master regulator of apical dominance acting indirectly to inhibit bud outgrowth via unknown secondary messenger(s). Potential candidates were cytokinin (CK) and abscisic acid (ABA). The genetic era with the screening of shoot branching mutants in different species revealed the existence of a novel carotenoid-derived branching inhibitor and led to the significant discovery of strigolactones (SLs) as a novel class of plant hormones. The re-discovery of the major role of sugars in apical dominance emerged from modern physiology experiments and involves ongoing work with genetic material affected in sugar-signalling. As crops and natural selection rely on the emergent properties of networks such as this branching network, future work should explore the whole network, the details of which are critical but not individually sufficient to solve the wicked problems of sustainable food supply and climate change.
25 citations
TL;DR: In this paper , the authors discuss the underlying physical mechanisms and significance of structural/functional dynamics of photosystem II, as reflected by chlorophyll-a fluorescence induction kinetics (ChlF) and variations of the novel parameter Δτ1/2.
Abstract: Photosystem II (PSII) uses solar energy to oxidize water and delivers electrons to fix CO2. Although the atomic resolution structure and basic photophysical and photochemical functions of PSII are well understood, many important questions remain. The activity of PSII in vitro and in vivo is routinely monitored by recording chlorophyll-a fluorescence induction kinetics (ChlF). According to the 'mainstream' model, the rise from the minimum level (Fo) to the maximum (Fm) of ChlF of dark-adapted PSII reflects the closure of all functionally active reaction centers, and the Fv/Fm ratio is equated with the maximum photochemical quantum yield of PSII (Fv=Fm-Fo). However, this model has never been free of controversies. A range of recent experimental data confirmed that the first single-turnover saturating flash (STSF), generating closed state (PSIIC), produces F1
25 citations
TL;DR: This work discusses how changes in the root growth rate, lateral root formation, density and growth angle of non-flood adapted plant species (mainly Arabidopsis) could contribute to avoiding and enduring critical hypoxic conditions.
Abstract: Abstract Plant submergence is a major abiotic stress that impairs plant performance. Under water, reduced gas diffusion exposes submerged plant cells to an environment that is enriched in gaseous ethylene and is limited in oxygen (O2) availability (hypoxia). The capacity for plant roots to avoid and/or sustain critical hypoxia damage is essential for plants to survive waterlogging. Plants use spatiotemporal ethylene and O2 dynamics as instrumental flooding signals to modulate potential adaptive root growth and hypoxia stress acclimation responses. However, how non-adapted plant species modulate root growth behaviour during actual waterlogged conditions to overcome flooding stress has hardly been investigated. Here we discuss how changes in the root growth rate, lateral root formation, density, and growth angle of non-flood adapted plant species (mainly Arabidopsis) could contribute to avoiding and enduring critical hypoxic conditions. In addition, we discuss current molecular understanding of how ethylene and hypoxia signalling control these adaptive root growth responses. We propose that future research would benefit from less artificial experimental designs to better understand how plant roots respond to and survive waterlogging. This acquired knowledge would be instrumental to guide targeted breeding of flood-tolerant crops with more resilient root systems.
TL;DR: In this paper , the authors summarize classic and recent studies on the accumulation profile and role of ABA and other important hormones in the regulation of non-climacteric fruit development and ripening, as well as their cross-talk, paying special attention to the two main non-carcinogenic plant models, strawberry and grape, and discuss the importance of the transcriptional and environmental regulation of fruit ripening.
Abstract: Fruit ripening involves numerous physiological, structural and metabolic changes that result in the formation of edible fruits. This process is controlled at different molecular levels, with essential roles for phytohormones, transcription factors and epigenetic modifications. Fleshy fruits are classified as either climacteric or non-climacteric species. Climacteric fruits are characterized by a burst in respiration and ethylene production at the onset of ripening, while regulation of non-climacteric fruit ripening has been commonly attributed to abscisic acid (ABA). However, there is controversy as to whether mechanisms regulating fruit ripening are shared between non-climacteric species, and to what extent other hormones contribute alongside ABA. In this review, we summarize classic and recent studies on the accumulation profile and role of ABA and other important hormones in the regulation of non-climacteric fruit development and ripening, as well as their cross-talk, paying special attention to the two main non-climacteric plant models, strawberry and grape. We highlight both the common and different roles of these regulators in these two crops, and discuss the importance of the transcriptional and environmental regulation of fruit ripening, as well as the need to optimize genetic transformation methodologies to facilitate gene functional analyses.
TL;DR: Grafting is a traditional horticultural technique that makes use of plant wound healing mechanisms to join two different genotypes together to form one plant as discussed by the authors , and it is used to control the vigour of the scion and/or provides tolerance to deleterious soil conditions such as the presence of soil pests or pathogens, limited or excessive water or mineral nutrient supply.
Abstract: Grafting is a traditional horticultural technique that makes use of plant wound healing mechanisms to join two different genotypes together to form one plant. In many agricultural systems, grafting with rootstocks controls the vigour of the scion and/or provides tolerance to deleterious soil conditions such as the presence of soil pests or pathogens, limited or excessive water or mineral nutrient supply. Much of our knowledge about the limits to grafting different genotypes together comes from empirical knowledge of horticulturalists. Until recently, researchers believed that grafting monocotyledonous plants was impossible, because they lack a vascular cambium, and that graft compatibility between different scion/rootstock combinations was restricted to closely related genotypes. Recent papers have overturned these ideas and open up the possibility of new research directions and applications for grafting in agriculture. The objective of this review is to describe and assess these recent advances in the field of grafting, and in particular, the molecular mechanisms underlining graft union formation and graft compatibility between different genotypes. The challenges of characterizing the different stages of graft union formation and phenotyping graft compatibility are examined.
TL;DR: Technological advances have helped unravel crucial plant and microbial genes and pathways that control beneficial, pathogenic, and commensal plant–microbe interactions, and holistic approaches are recommended in integrating host and microbial omics datasets to achieve precision and efficiency in data analysis.
Abstract: Advances in high throughput- omics techniques provide avenues to decipher plant microbiomes. However, there is limited information on how integrated informatics can help provide deeper insights into plant-microbe interactions in a concerted way. Integrating multi-omic datasets can transform our understanding of the plant microbiome from unspecified genetic influences on interacting species to specific gene-by-gene interactions. Here, we highlight recent progress and emerging strategies in crop microbiome omics research and review key aspects of how the integration of host and microbial omics-based datasets can be used to provide a comprehensive outline of the complex crop microbe interactions. We describe how these technological advances have helped unravel crucial plant and microbial genes and pathways that control beneficial, pathogenic, and commensal plant-host interactions. We identify crucial knowledge gaps and synthesize current limitations in our understanding of crop microbiome omics approaches. We highlight recent studies in which multi-omics-based approaches have led to improved models of crop microbial community structure and function. Finally, we recommend holistic approaches in integrating host and microbial omics datasets to achieve precision and efficiency in data analysis which is crucial for biotic and abiotic stress control and in understanding the contribution of the microbiota in shaping plant fitness.
TL;DR: For many years, research has been carried out to understand the mechanism of auxin action, its biosynthesis, catabolism, perception, and transport, and one central interest is understanding the auxindependent gene expression regulation mechanism involving AUXIN RESPONSE Factor (ARF) transcription factors and their repressors, the AUXin/INDOLE-3-ACETIC ACID (Aux/IAA) proteins as mentioned in this paper .
Abstract: For many years, research has been carried out to understand the mechanism of auxin action, its biosynthesis, catabolism, perception, and transport. One central interest is understanding the auxin-dependent gene expression regulation mechanism involving AUXIN RESPONSE FACTOR (ARF) transcription factors and their repressors, the AUXIN/INDOLE-3-ACETIC ACID (Aux/IAA) proteins. Numerous studies have been focused on the MONOPTEROS (MP)/ARF5, an activator of auxin-dependent gene expression with a crucial impact on plant development. This review paper summarizes over thirty years of research on MP/ARF5. We indicate the available analytical tools to study MP/ARF5 and point out the known mechanism of MP/ARF5-dependent regulation of gene expression during various developmental processes, i.e., embryogenesis, leaf formation, vascularization, and shoot and root meristem formation. However, many questions remain about the auxin-dose-dependent regulation of gene transcription by MP/ARF5 and its isoforms in plant cells, the composition of the MP/ARF5 protein complex, and finally, the list of genes under its direct control. In addition, the information on post-translational modifications of MP/ARF5 protein is marginal, and knowledge about their consequences on MP/ARF5 function is limited. Moreover, the epigenetic factors and other regulators that act upstream of MP/ARF5 are poorly understood. Their identification will be a challenge in the coming years.
TL;DR: A review of plastid morphological and functional diversity in both model and non-model plants can be found in this article , which highlights important advances in the field that can also impact future agricultural and biotechnological improvement in plants.
Abstract: Plastids are a group of essential, heterogenous semiautonomous organelles characteristic of plants that perform photosynthesis and a diversity of metabolic pathways that impact growth and development. Plastids are remarkably dynamic and can interconvert in response to specific developmental and environmental cues functioning as central metabolic hub in plant cells. By far the best studied plastid is the chloroplast, but in recent years the combination of modern techniques and genetic analyses has expanded our current understanding of plastid morphological and functional diversity in both model and non-model plants. These studies have provided evidence of an unexpected diversity of plastid subtypes with specific characteristics. In this review we describe recent findings that provide insights into the characteristics of these specialized plastids and their functions. We concentrate on the emerging evidence that supports the model that signals derived from particular plastid types play pivotal roles in plant development, environmental, and defense responses. Furthermore, we provide examples of how new technologies are illuminating the functions of these specialized plastids and the overall complexity of their differentiation processes. Finally, we discuss future research directions such as the use of ectopic plastid differentiation as a valuable tool to characterize factors involved in plastid differentiation. Collectively, we highlight important advances in the field that can also impact future agricultural and biotechnological improvement in plants.
TL;DR: In this paper , the emerging roles of TRXs and GRXs in redoxregulated processes interacting with other cell signalling systems such as organellar retrograde communication and gene expression, especially in plants during their development and under stressful environments.
Abstract: Integration of reactive oxygen species (ROS)-mediated signal transduction pathways via redox sensors and the thiol-dependent signalling network is of increasing interest in cell biology for their implications in plant growth and productivity. Redox regulation is an important point of control in the protein structure, interactions, cellular location and function, thioredoxins (TRXs) and glutaredoxins (GRXs) being key players in the maintenance of cellular redox homeostasis. The crosstalk between second messengers, ROS, thiol redox signalling and redox homeostasis-related genes, controls almost every aspect of plant development and stress response. We review the emerging roles of TRXs and GRXs in redox-regulated processes interacting with other cell signalling systems such as organellar retrograde communication and gene expression, especially in plants during their development and under stressful environments. This approach will throw light on the specific role of these proteins as redox signalling components, and their importance in different developmental processes during abiotic stress.
TL;DR: In this paper , the role of hydrogen sulfide (H2S) during drought was analyzed, focused on the underlying mechanism of H2S. The role of protein persulfidation in alleviating ROS accumulation and balancing redox homeostasis under drought stress was highlighted.
Abstract: Hydrogen sulfide (H2S) is a signaling molecule that regulates essential plant processes. In this study, the role of H2S during drought was analyzed, focused on the underlying mechanism. Pretreatments with H2S before imposing drought on plants significantly improved the characteristic stressed phenotypes under drought and decreases the levels of typical biochemical stress markers such as, anthocyanin, proline and hydrogen peroxide. H2S also regulated drought-responsive genes, amino acid metabolism, and repressed drought-induced bulk autophagy and protein ubiquitination, demonstrating the protective effect of H2S pretreatments. Quantitative proteomic analysis identified 887 significantly different persulfidated proteins in plants under control and drought stress. Bioinformatic analyses of the proteins more persulfidated in drought revealed that the most enriched biological processes were cellular response to oxidative stress and hydrogen peroxide catabolism. Protein degradation, abiotic stress responses, and the phenylpropanoid pathway were also highlighted, suggesting the importance of persulfidation to cope with drought-induced stress. Our findings emphasize the role of H2S as a promoter of enhanced tolerance to drought, enabling plants to respond more rapidly and efficiently. Furthermore, the main role of protein persulfidation in alleviating ROS accumulation and balancing redox homeostasis under drought stress is highlighted.
TL;DR: In this paper , a review of chemical signals and their mechanisms of action is presented, enhancing our understanding of plant-microbe interactions and providing references for the comprehensive development and utilization of these active components in agricultural production.
Abstract: Every living organism on Earth depends on its interactions with other organisms to live. In the rhizosphere, plants and microorganisms constantly exchange signals and influence each other's behavior. Recent studies have shown that many beneficial rhizosphere microbes can produce specific signaling molecules that affect plant root architecture and may therefore have substantial effects on aboveground growth. This review sorts out these chemical signals and summarizes their mechanisms of action, enhancing our understanding of plant-microbe interactions and providing references for the comprehensive development and utilization of these active components in agricultural production. Finally, we have pointed out future research directions and challenges, such as the searching of microbial signals to induce the primary root development.
TL;DR: Protoplasts have been used for decades in plant research and have been instrumental in genetic transformation and the study of various aspects of plant physiology and genetics as discussed by the authors , but despite their potential, challenges remain to expand the use of protoplasts in synthetic biology.
Abstract: Protoplasts, which are plant cells with their cell walls removed, have been used for decades in plant research and have been instrumental in genetic transformation and the study of various aspects of plant physiology and genetics. With the advent of synthetic biology, these individualized plant cells are fundamental to accelerate the "design-build-test-learn" cycle, which is relatively slow in plant research. Despite their potential, challenges remain to expanding the use of protoplasts in synthetic biology. The capacity of individual protoplasts to hybridize to form new varieties, and to regenerate from single cells, creating individuals with new features is underexplored. The main objective of this review is to discuss the use of protoplasts in plant synthetic biology and to highlight the challenges to exploiting protoplast technologies in this new "age of synthetic biology".
TL;DR: Progress is summarized in the understanding of phytohormone-regulated primary metabolism under water-limited conditions, especially in Arabidopsis thaliana, and recent findings concerning the amino acids associated with ABA metabolism and signaling are highlighted.
Abstract: Phytohormones are essential signaling molecules globally regulating many processes of plants, including their growth, development and stress responses. The promotion of growth and the enhancement of stress resistance have to be balanced, especially under adverse conditions such as drought stress, because of limited resources. Plants cope with drought stress via various strategies, including the transcriptional regulation of stress-responsive genes and the adjustment of metabolism, and phytohormones play roles in these processes. However, besides abscisic acid (ABA) is an important signal under drought, less attention has been paid to other phytohormones. In this review, we summarize progress in the understanding of phytohormone-regulated primary metabolism under water-limited conditions, especially in Arabidopsis thaliana, and highlight recent findings concerning the amino acids associated with ABA metabolism and signaling. We also discuss how phytohormones function antagonistically and synergistically in order to balance growth and stress responses.
TL;DR: In this paper , a light-responsive regulatory module was proposed to regulate anthocyanin biosynthesis in rose petals, which involves the transcription factors RhHY5, RhMYB114a, and RhmyB3b.
Abstract: Roses are significant botanical species with both ornamental and economic value, displaying diverse floral traits, particularly an extensive array of petal colors. The red pigmentation of rose petals is predominantly attributed to anthocyanin accumulation. However, the underlying regulatory mechanism of anthocyanin biosynthesis in roses remains elusive. This study presents a novel light-responsive regulatory module governing anthocyanin biosynthesis in rose petals, which involves the transcription factors RhHY5, RhMYB114a, and RhMYB3b. Under light conditions, RhHY5 represses RhMYB3b expression, and induces RhMYB114a expression that positively regulates anthocyanin biosynthesis in rose petals through the direct activation of anthocyanin structural genes via the MYB114a-bHLH3-WD40 complex. Notably, this function likely involves an interaction and synergy between RhHY5 and the MYB114a-bHLH3-WD40 complex. Additionally, RhMYB3b is activated by RhMYB114a to prevent excessive accumulation of anthocyanin. Conversely, in low light conditions, the degradation of RhHY5 leads to down-regulation of RhMYB114a and up-regulation of RhMYB3b, which in turn inhibits the expression of both RhMYB114a and anthocyanin structural genes. Additionally, RhMYB3b competes with RhMYB114a for binding to RhbHLH3 and the promoters of anthocyanin-related structural genes. Overall, our study uncovers a complex light-mediated regulatory network that governs anthocyanin biosynthesis in the rose, thereby advancing our understanding of the underlying molecular mechanisms of anthocyanin biosynthesis in rose flowers.
TL;DR: In this article , the authors summarize typical transpiration response patterns to soil and atmospheric drying and the sensitivity to plant hydraulic traits using a soil-plant hydraulic framework, showing that a low plant hydraulic conductance triggers an earlier restriction in transpiration during increasing VPD.
Abstract: The water deficit experienced by crops is a function of atmospheric water demand (vapor pressure deficit, VPD) and soil water supply over the whole crop cycle. We summarize typical transpiration response patterns to soil and atmospheric drying and the sensitivity to plant hydraulic traits. We explain the transpiration response patterns using a soil-plant hydraulic framework. In both cases of drying, stomatal closure is triggered by limitations in soil-plant hydraulic conductance. However, traits impacting the transpiration response differ between the two drying processes and act at different time scales. A low plant hydraulic conductance triggers an earlier restriction in transpiration during increasing VPD. During soil drying, the impact of the plant hydraulic conductance is less obvious. It is rather a decrease in the belowground hydraulic conductance (related to soil hydraulic properties and root length density) that is involved in transpiration downregulation. The transpiration response to increasing VPD has a daily time scale. In the case of soil drying, it acts on a seasonal scale. Varieties that are conservative in water use on a daily scale may not be conservative over larger time scales (e.g. during soil drying). This potential independency of strategies needs to be considered in environmental-specific breeding for yield-based drought tolerance.
TL;DR: In this paper , the authors review and discuss current knowledge about the contribution of the three levels of plant hormonal pathways in providing spatial specificity to plant hormone action and explore how new technological developments, such as plant hormone sensors based on FRET or single-cell RNA-seq, can provide an unprecedented level of resolution in defining the spatial domains of plant hormone activity and its dynamics.
Abstract: Although many plant cell types are capable of producing hormones and plant hormones can in most cases act in the same cells in which they are produced, they also act as signaling molecules that coordinate physiological responses between different parts of the plant, indicating that their action is subject to spatial regulation. Numerous publications have reported that all levels of plant hormonal pathways, i.e., metabolism, transport, and perception/signal transduction, can help determine the spatial ranges of hormone action. For example, polar auxin transport or localized auxin biosynthesis contribute to creating a differential hormone accumulation across tissues that is instrumental for specific growth and developmental responses. On the other hand, tissue specificity of cytokinin actions has been proposed to be regulated by mechanisms operating at the signaling stages. Here, we review and discuss current knowledge about the contribution of the three levels mentioned above in providing spatial specificity to plant hormone action. We also explore how new technological developments, such as plant hormone sensors based on FRET or single-cell RNA-seq, can provide an unprecedented level of resolution in defining the spatial domains of plant hormone action and its dynamics.
TL;DR: The white fly Bemisia tabaci is a piercing-sucking herbivore that reduces the yields of crops both by feeding on plants and transmitting plant viruses as discussed by the authors . But the nature of B. tabaci salivary effectors is incompletely understood.
Abstract: The whitefly Bemisia tabaci is a piercing-sucking herbivore that reduces the yields of crops both by feeding on plants and transmitting plant viruses. Like most plant feeders, B. tabaci has evolved ways to avoid plant defense responses. For example, B. tabaci is known to secrete salivary effectors to suppress host defenses. However, the nature of B. tabaci effectors is incompletely understood. In this study, we used B. tabaci genomic and salivary gland transcriptomic data and an overexpression system to identify a previously unknown B. tabaci salivary effector, BtE3. BtE3 is specifically expressed in the head (containing primary salivary glands) and is secreted into hosts during B. tabaci feeding. In planta overexpression of BtE3 blocked Burkholderia glumae-induced hypersensitive response (HR) in both Nicotiana benthamiana and Solanum lycopersicum. Silencing of BtE3 by plant-mediated RNAi prevented whiteflies from continuously ingesting phloem sap and reduced whitefly survival and fecundity. Moreover, over-expression of BtE3 in planta upregulated the salicylic acid- (SA-) signaling pathway but suppressed the downstream jasmonic acid- (JA-) mediated defenses. Taken together, these results indicate that BtE3 is a whitefly-specific novel effector involved in whitefly-plant interactions. These findings increase our understanding of whitefly effectors and suggest novel strategies for whitefly pest management.
TL;DR: In this paper , the authors provide an overview of key aspects of ARF DNA-binding such as auxin response elements (TGTCNN) and tandem repeat motifs, and consider how structural biology and in vitro studies help us understand ARFs DNA preferences.
Abstract: Most plant growth and development processes are regulated one way or another by auxin. The best-studied mechanism by which auxin exerts its regulatory effects is through the nuclear auxin pathway (NAP). In this pathway, AUXIN RESPONSE FACTORs (ARFs) are the transcription factors that ultimately determine which genes become auxin-regulated by binding to specific DNA sequences. ARFs have primarily been studied in Arabidopsis thaliana, but recent studies in other species have revealed family-wide DNA-binding specificities for different ARFs and the minimal functional system of the NAP system, consisting in a duo of competing ARFs of the A and B classes. In this review, we provide an overview of key aspects of ARF DNA-binding such as auxin response elements (TGTCNN) and tandem repeat motifs, and consider how structural biology and in vitro studies help us understand ARF DNA preferences. We also highlight some recent aspects related to the regulation of ARF levels inside a cell, which may alter the DNA-binding profile of ARFs in different tissues. We finally emphasize on the need to study minimal NAP systems to understand fundamental aspects of ARF function, the need to characterize algal ARFs to understand how ARFs evolved, how cutting-edge techniques can increase our understanding of ARFs, and which remaining questions can only be answered by structural biology.
TL;DR: It is argued that variation in root architecture in crops has important implications for root exudation, microbial recruitment and function, and the decomposition and fate of root tissues and exudates.
Abstract: Root architectural phenotypes are promising targets for crop breeding, but root architectural effects on microbial associations in agricultural fields are not well understood. Architecture determines the location of microbial associations within root systems, which when integrated with soil vertical gradients, determines the functions and the metabolic capability of rhizosphere microbial communities. We argue that variation in root architecture in crops has important implications for root exudation, microbial recruitment and function, and the decomposition and fate of root tissues and exudates. Recent research has shown that the root microbiome changes along root axes and among root classes, that root tips have a unique microbiome, and that root exudates change within the root system depending on soil physicochemical conditions. Although fresh exudates are produced in larger amounts in root tips, the rhizosphere of mature root segments also plays a role in influencing soil vertical gradients. We argue that more research is needed to understand specific root phenotypes that structure microbial associations and discuss candidate root phenotypes that may determine the location of microbial hotspots within root systems with relevance to agricultural systems.
TL;DR: Zhang et al. as discussed by the authors identified a CLas effector, SDE4405 (CLIBASIA_04405), which contributes to Huanglongbing (HLB)-associated intracellular bacterium asiaticus (CLas) to manipulate autophagy.
Abstract: Autophagy functions in plant host immunity responses to pathogen infection. The molecular mechanisms and functions used by the citrus Huanglongbing (HLB)-associated intracellular bacterium 'Candidatus Liberibacter asiaticus' (CLas) to manipulate autophagy are unknown. We identified a CLas effector, SDE4405 (CLIBASIA_04405), which contributes to HLB progression. Transgenic SDE4405 in Wanjincheng orange (Citrus sinensis) promotes CLas proliferation and symptom expression via suppressing host immunity response. SDE4405 interacts with ATG8-family proteins (ATG8s) and their interactions activate autophagy in Nicotiana benthamiana. The occurrence of autophagy is also significantly enhanced in SDE4405-transgenic citrus plants. Interrupting NbATG8s-SDE4405 interaction by silencing NbATG8s reduces Pseudomonas syringae pv. tomato strain DC3000ΔhopQ1-1 (Pst DC3000ΔhopQ1-1) proliferation in N. benthamiana, and transient overexpression of CsATG8c and SDE4405 in citrus promotes Xanthomonas citri subsp. citri (Xcc) multiplication, suggesting SDE4405-ATG8s interaction negatively regulates plant defense. These data show the role of the CLas effector protein in manipulating autophagy and provide new insights into the molecular interaction between CLas and citrus.
TL;DR: This review examines the intentional consequences of strigolactone exudation, and also the unintentional consequences caused by eavesdroppers, and attempts to understand the enigma of the strigolactone molecular diversity synthesized and exuded into the rhizosphere by plants.
Abstract: Abstract The rhizosphere is a complex physical and chemical interface between plants and their underground environment, both biotic and abiotic. Plants exude a large number of chemicals into the rhizosphere in order to manipulate these biotic and abiotic components. Among such chemicals are strigolactones, ancient signalling molecules that in flowering plants act as both internal hormones and external rhizosphere signals. Plants exude strigolactones to communicate with their preferred symbiotic partners and neighbouring plants, but at least some classes of parasitic organisms are able to ‘crack’ these private messages and eavesdrop on the signals. In this review, we examine the intentional consequences of strigolactone exudation, and also the unintentional consequences caused by eavesdroppers. We examine the molecular mechanisms by which strigolactones act within the rhizosphere, and attempt to understand the enigma of the strigolactone molecular diversity synthesized and exuded into the rhizosphere by plants. We conclude by looking at the prospects of using improved understanding of strigolactones in agricultural contexts.
TL;DR: In this article , a framework for categorizing the different components of synthetic gene circuits is proposed to facilitate the exchange of DNA parts and information in plant synthetic biology, thus facilitating the access of DNA information.
Abstract: This review aims to provide a framework for categorizing the different components of synthetic gene circuits, thus facilitating the exchange of DNA parts and information in plant synthetic biology.