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Authors: J. S. Chen, S. T. Wang, Q. Mei, T. Sun, J. T. Hu, G. S. Xiao, H. Chen and Y. H. Xuan.
Plant Molecular Biology (2024)
Abstract: "Plants have a variety of regulatory mechanisms to perceive, transduce, and respond to biotic and abiotic stress. One such mechanism is the calcium-sensing CBL–CIPK system responsible for the sensing of specific stressors, such as drought or pathogens. CBLs perceive and bind Calcium (Ca2+) in response to stress and then interact with CIPKs to form an activated complex. This leads to the phosphorylation of downstream targets, including transporters and ion channels, and modulates transcription factor levels and the consequent levels of stress-associated genes. This review describes the mechanisms underlying the response of the CBL–CIPK pathway to biotic and abiotic stresses, including regulating ion transport channels, coordinating plant hormone signal transduction, and pathways related to ROS signaling. Investigation of the function of the CBL–CIPK pathway is important for understanding plant stress tolerance and provides a promising avenue for molecular breeding."
Authors: Liming He, Liangfan Wu and Jia Li.
Plant Communications (2024)
Short summary: Sulfated peptides and their receptors play critical roles in regulating plant growth, development and environmental fitness. This article provides a comprehensive review for this group of peptides and their receptors, including their discoveries, regulatory components, and revealed biological functions. The authors also put forward a number of key questions for future studies.
Abstract: "Four distinctive types of sulfated peptides have been identified in Arabidopsis thaliana. These peptides play crucial roles in regulating plant development and stress adaptation. Recent studies revealed that Xanthomonas and Meloidogyne can secrete plant-like sulfated peptides, exploiting the plant sulfated signaling pathway to suppress plant immunity. Over the past three decades, receptors of these four types of sulfated peptides have all been identified, all of which belong to the members of leucine-rich repeat receptor-like protein kinase (LRR-RLK) subfamily. A number of regulatory proteins were demonstrated to play important roles in their corresponding signal transduction pathways. In this review, we comprehensively summarize the discoveries of sulfated peptides and their receptors mainly in Arabidopsis thaliana. We also discuss their known biological functions in plant development and stress adaptation. Finally, we put forward a number of questions for the reference of future studies."
Authors: Jiaqi Xiao, Yijie Zhou, Yunyun Xie, Taotao Li, Xinguo Su, Junxian He, Yueming Jiang, Hong Zhu and Hongxia Qu.
Plant Communications (2024)
Abstract: "As the primary form of energy for plants, the shortage of cellular ATP is generally acknowledged to pose a threat to plant growth and development, stress resistance and crop quality. The overall metabolic processes contributing to the ATP pool from its production, dissipation, transportation, and elimination of ATP have been extensively studied. Considerable evidence revealed that in addition to its role in energy supply, ATP also acts as a regulatory signalling molecule to activate global metabolic responses. The identification of eATP receptor DORN1 enables a better understanding of how plants cope with the disruption of ATP homeostasis and the key points at which ATP signalling pathways intersect in a cell or whole organism. Notably, the functions of SnRK1α, the master regulator of the energy management network, in restoring the equilibrium of the ATP pool, and the vast and complex metabolic network that SnRK1α mediates to adapt to fluctuating environments have been demonstrated. This paper reviews recent advances in the regulatory control of the cellular ATP pool, and discusses possible interactions among the key regulators of ATP pool homeostasis and the crosstalk between iATP/eATP signalling pathways. The perception of ATP deficit and modulation of cellular ATP homeostasis mediated by SnRK1α in plants at both physiological and molecular levels are discussed. Finally, this review suggests future research directions for plant cellular ATP homeostasis modulation."
Authors: Run Han, Liang Ma, William Terzaghi, Yan Guo and Jigang Li.
The Plant Journal (2024)
Significance Statement: This review summarizes recent major advances in our understanding of how plants coordinately respond to shade and environmental stresses, and discusses the important questions for future research.
Abstract: "Shade avoidance syndrome (SAS) is triggered by a low ratio of red (R) to far-red (FR) light (R/FR ratio), which is caused by neighbor detection and/or canopy shade. In order to compete for the limited light, plants elongate hypocotyls and petioles by deactivating phytochrome B (phyB), a major R light photoreceptor, thus releasing its inhibition of the growth-promoting transcription factors PHYTOCHROME-INTERACTING FACTORs. Under natural conditions, plants must cope with abiotic stresses such as drought, soil salinity, and extreme temperatures, and biotic stresses such as pathogens and pests. Plants have evolved sophisticated mechanisms to simultaneously deal with multiple environmental stresses. In this review, we will summarize recent major advances in our understanding of how plants coordinately respond to shade and environmental stresses, and will also discuss the important questions for future research. A deep understanding of how plants synergistically respond to shade together with abiotic and biotic stresses will facilitate the design and breeding of new crop varieties with enhanced tolerance to high-density planting and environmental stresses."
Authors: Sampurna Kashyap, Niraj Agarwala and Ramanjulu Sunkar.
Plant Science (2024)
Highlights • Like animals, plants can also memorize past threats and respond robustly to future episodes of the same or similar circumstances. • Stress memory might be generated due to hypersensitive immune responses, epigenetic changes, modulation in hormonal signalling, etc. • The ingenious adaptability of the crop wild relatives (CWRs) in challenging climatic conditions might be due to their peculiar memory functions. • Exploitation of CWRs memory traits may help crop breeders develop more resilient and climate-smart crops. • The ability of plants to modulate root exudation patterns in response to stress conditions can be a component of plant memory.
Abstract: "Being sessile, plants encounter a variety of biotic and abiotic threats in their life cycle. To minimize the damages caused by such threats, plants have acquired sophisticated response mechanisms. One major such response includes memorizing the encountered stimuli in the form of a metabolite, hormone, protein, or epigenetic marks. All of these individually as well as together, facilitate effective transcriptional and post-transcriptional responses upon encountering the stress episode for a second time during the life cycle and in some instances even in the future generations. This review attempts to highlight the recent advances in the area of plant memory. A detailed understanding of plant memory has the potential to offer solutions for developing climate-resilient crops for sustainable agriculture."
Authors: Muhammad Saad Shoaib Khan, Sulaiman Ahmed, Aziz ul Ikram, Fakhir Hannan, Muhammad Umair Yasin, Jin Wang, Biying Zhao, Faisal Islam and Jian Chen.
Physiologia Plantarum (2023)
Highlights: • Melatonin acts as a redox network regulator in plants via regulating secondary messengers signaling. • Melatonin regulates the activity of redox-sensitive proteins and transcription factors. • Melatonin influences gene expression and physiological processes in response to stresses. • Melatonin synergically work with other hormones to confer plant resistance and stress adaptability.
Abstract: "Plants being sessile in nature, are exposed to unwarranted threats as a result of constantly changing environmental conditions. These adverse factors can have negative impacts on their growth, development, and yield. Hormones are key signaling molecules enabling cells to respond rapidly to different external and internal stimuli. In plants, melatonin (MT) plays a critical role in the integration of various environmental signals and activation of stress-response networks to develop defense mechanisms and plant resilience. Additionally, melatonin can tackle the stress-induced alteration of cellular redox equilibrium by regulating the expression of redox homeostasis-related genes and proteins. The purpose of this article is to compile and summarize the scientific research pertaining to MT's effects on plants' resilience to biotic and abiotic stresses. Here, we have summarized that MT exerts a synergistic effect with other phytohormones, for instance, ethylene, jasmonic acid, and salicylic acid, and activates plant defense-related genes against phytopathogens. Furthermore, MT interacts with secondary messengers like Ca2+, nitric oxide, and reactive oxygen species to regulate the redox network. This interaction triggers different transcription factors to alleviate stress-related responses in plants. Hence, the critical synergic role of MT with diverse plant hormones and secondary messengers demonstrates phytomelatonin's importance in influencing multiple mechanisms to contribute to plant resilience against harsh environmental factors."
Authors: Monika Sood.
Journal of Plant Growth Regulation (2023)
Abstract: "Phytohormones are key signalling molecules in developing responses in plants with various biotic and abiotic stresses. From the catalogue of well-known classical plant hormones, Jasmonic acid (JA) and its corresponding precursors and derivatives attract massive research attention by acting as potential methods for improving tolerance in diseased plants. Jasmonates are oxylipins chiefly derived from α-linolenic acids through the octadecanoid pathway. Plants synthesise this hormone in response to growth or defence-linked signs to coordinate plant development, growth or defence against numerous pathogenic microorganisms. Several reports emphasise the contribution of JAs in regulating vital physiological processes such as leaf senescence, tuber formation, photosynthesis, reproduction, seed germination and growth inhibition in plants. In response to pathogen exposure, JAs assume their operational task as a ‘master switch’, in charge of the initiation of signal transduction cascade, participating in the upregulation of genes associated with the production of alkaloids and phytoalexin, synthesis and accumulation of storage proteins, cell wall components and most importunately—stress ameliorative agents. This review focuses on recent findings connected to the structure, biosynthesis, regulation and signalling systems of JAs. In addition to this, the present article gives an essential insight into how the application of this phytohormone is involved in stress amelioration and induction of pathogenesis-resistant genes from an agriculturist, plant physiologist and biotechnologist’s point of view.
Author: Emma Marris
Nature (2023)
Excepts: "Microphones capture ultrasonic crackles from plants that are water-deprived or injured."
"Plants do not suffer in silence. Instead, when thirsty or stressed, plants make “airborne sounds,” according to a study published today in Cell1. Plants that need water or have recently had their stems cut produce up to roughly 35 sounds per hour, the authors found. But well-hydrated and uncut plants are much quieter, making only about one sound per hour. The reason you have probably never heard a thirsty plant make noise is that the sounds are ultrasonic — about 20–100 kilohertz. That means they are so high-pitched that very few humans could hear them. Some animals, however, probably can. Bats, mice and moths could potentially live in a world filled with the sounds of plants, and previous work by the same team has found that plants respond to sounds made by animals, too."
"The team produced a machine-learning model to deduce whether a plant had been cut or was water stressed from the sounds it made, with about 70% accuracy. This result suggests a possible role for the audio monitoring of plants in farming and horticulture. To test the practicality of this approach, the team tried recording plants in a greenhouse. With the aid of a computer program trained to filter out background noise from wind and air-conditioning units, the plants could still be heard. Pilot studies by the authors suggest that tomato and tobacco plants are not outliers. Wheat (Triticum aestivum), corn (Zea mays) and wine grapes (Vitis vinifera) also make noises when they are thirsty.
Authors: Omar A. Hewedy, Nabil I. Elsheery, Ali M. Karkour, Neveen Elhamouly, Ramadan A. Arafa, Ghada Abd-Elmonsef Mahmoud, Mona F.-A. Dawood, Walaa E. Hussein, Abdelaziz Mansour, Dina H. Amin, Suleyman I. Allakhverdiev, Marek Zivcak, Marian Brestic.
Environmental and Experimental Botany (2023)
Highlights • Jasmonic acid (JA) plays crucial roles in crop development, organ formation and functions • There is a high diversity of phytohormone signaling pathways and genes associated with jasmonates • JA crosstalk with other plant hormones and regulates numerous enzymes and proteins associated with plant resistance • An integrated view of JA biosynthesis at the molecular levels, gene expression regulation, and functional role of JA in helping plant species respond to stressful conditions is presented
Abstract: "Jasmonic acid (JA) or methyl jasmonate (MeJA) are master regulators of plant development and stress response against pathogens and environmental fluctuations. Thus, JA is an important stress-associated phytohormone that can promote various defense interactions, regulate stomatal openness, synthesis of antimicrobial substances, or plant cell reprogramming. Numerous studies also demonstrated that plants thriving under environmental fluctuations stresses are linked to the JA response, revealing that JA application can alleviate the damage of abiotic stress by improving plant tolerance. Therefore, jasmonic acid and amino acid conjugate (JA-Ile) represent stress hormones that improve crop resilience under environmental fluctuations. In addition, JA modulates the plant growth and developmental stages by regulating the crosstalk between JA and the main plant hormone groups, balancing plant development and defense mechanism against pathogen attacks. The effects on various processes and plant structures, such as seed germination, primary root/root hair growth, fruit development, pollen maturation, senescence, and regeneration, have been documented for jasmonates. Therefore, we reviewed the functional influence of jasmonates, involving sensing and regulating their signaling under harsh conditions, which is becoming a top priority for agriculture. In addition, the crosstalks with other phytohormones, such as auxin, salicylic acid, ethylene, and the plant-pathogen interactions, are discussed."
Authors: Heike Seybold, Jennifer Bortlik, Xiyuan Jiang, Anja Liese, Benjamin Conrads, Wolfgang Hoehenwarter, Susanne Matschi and Tina Romeis.
bioRxiv (2022)
Abstract: "In nature plants are constantly challenged by simultaneous abiotic and biotic stresses, and under conflicting stress scenarios prioritization of stress responses is required for plant survival. Calcium-dependent protein kinase CPK5 is a central hub in local and distal immune signaling, required for hormone salicylic acid (SA)-dependent immunity and pathogen resistance. Here we show that CPK5-dependent immune responses and pathogen resistance are inhibited upon abscisic acid (ABA) treatment or in genetic mutant backgrounds lacking PP2C phosphatase activities including abi1-2, whereas immune responses are enhanced by co-expression of active ABI1 phosphatase variants. Biochemical studies and mass spectrometry-based phospho-site analysis reveal a direct ABI1 phosphatase-catalyzed de-phosphorylation of CPK5 auto-phosphorylation site T98. Mimicking continuous de-phosphorylation in CPK5T98A leads to enhanced ROS production and more resistant plants, mimicking the auto-phosphorylated status in CPK5T98D, reduces CPK5-mediated immune responses. Mechanistic insight identifies differential phosphorylation at T98 in the N-terminal domain of CPK5 to control the level of interaction between the kinase and its substrate protein rather than CPK5 catalytic activity. Thus, CPK5-catalyzed immune signaling may become discontinued even at an elevated cytoplasmic calcium concentration. Our work reveals an elegant mechanism for stress response prioritization in plants: The ABA-dependent phosphatase ABI1, negative regulator of abiotic responses, functions as positive regulator of biotic stress responses, stabilizing CPK5-dependent immune signaling in the absence of ABA. Continuous pathogen survey activates plant immunity in environmentally friendly conditions, whereas under severe abiotic stress the phosphatase/kinase pair prohibits immune signaling through a direct biochemical switch involving two key regulatory enzymes of these antagonistic pathways."
Authors: Alejandro Fonseca, Tomás Urzúa, Joanna Jelenska, Christopher Sbarbaro, Aldo Seguel, Yorley Duarte, Jean T. Greenberg, Loreto Holuigue, Francisca Blanco-Herrera and Ariel Herrera-Vásquez.
International Journal of Molecular Sciences (2022)
Abstract: "Salicylic acid (SA) is a hormone that modulates plant defenses by inducing changes in gene expression. The mechanisms that control SA accumulation are essential for understanding the defensive process. TGA transcription factors from clade II in Arabidopsis, which include the proteins TGA2, TGA5, and TGA6, are known to be key positive mediators for the transcription of genes such as PR-1 that are induced by SA application. However, unexpectedly, stress conditions that induce SA accumulation, such as infection with the avirulent pathogen P. syringae DC3000/AvrRPM1 and UV-C irradiation, result in enhanced PR-1 induction in plants lacking the clade II TGAs (tga256 plants). Increased PR-1 induction was accompanied by enhanced isochorismate synthase-dependent SA production as well as the upregulation of several genes involved in the hormone’s accumulation. In response to avirulent P. syringae, PR-1 was previously shown to be controlled by both SA-dependent and -independent pathways. Therefore, the enhanced induction of PR-1 (and other defense genes) and accumulation of SA in the tga256 mutant plants is consistent with the clade II TGA factors providing negative feedback regulation of the SA-dependent and/or -independent pathways. Together, our results indicate that the TGA transcription factors from clade II negatively control SA accumulation under stress conditions that induce the hormone production. Our study describes a mechanism involving old actors playing new roles in regulating SA homeostasis under stress."
Author: Philip B. Brewer.
In Book: "Emerging Plant Growth Regulators in Agriculture - Roles in Stress Tolerance" (2022)
Abstract: "Strigolactones are plant hormones that regulate plant growth and development, particularly in response to nutrient deficiency. However, they are also exuded from roots into the rhizosphere to promote symbiosis with beneficial microorganisms. This multimodal action makes the research both interesting and complex, particularly in terms of how strigolactones evolved. Interest has been growing in recent years about whether strigolactones also influence pathogenic organisms and/or plant responses to disease. In general, strigolactones seem to afford a positive effect on plant biotic stress tolerance. Some of this may be by directly inhibiting microbes in the soil, and some by promoting internal plant responses, such as induction of stress hormone pathways and stomata closure. However, the research is still in its infancy. The complex and possibly multimodal actions by strigolactones seem to depend on the type of disease and the species (or even species variety) that are involved. This chapter summarizes the research up until now and expectations for the future."
Authors: Tibo De Coninck and Els J.M. Van Damme.
Plant Science (2021)
Abstract: "For decades, the biological roles of plant lectins remained obscure and subject to speculation. With the advent of technological and scientific progress, researchers have compiled a vast amount of information regarding the structure, biological activities and functionality of hundreds of plant lectins. Data mining of genomes and transcriptome sequencing and high-throughput analyses have resulted in new insights. This review aims to provide an overview of what is presently known about plant lectins, highlighting their versatility and the importance of plant lectins for a multitude of biological processes, such as plant development, immunity, stress signaling and regulation of gene expression. Though lectins primarily act as readers of the glycocode, the multiple roles of plant lectins suggest that their functionality goes beyond carbohydrate-recognition."
Via Jean-Michel Ané
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Author: Daniel J. Cosgrove.
Annual Review of Plant Cell and Development (2024)
Abstract: "Expansins comprise an ancient group of cell wall proteins ubiquitous in land plants and their algal ancestors. During cell growth, they facilitate passive yielding of the wall's cellulose networks to turgor-generated tensile stresses, without evidence of enzymatic activity. Expansins are also implicated in fruit softening and other developmental processes and in adaptive responses to environmental stresses and pathogens. The major expansin families in plants include α-expansins (EXPAs), which act on cellulose-cellulose junctions, and β-expansins, which can act on xylans. EXPAs mediate acid growth, which contributes to wall enlargement by auxin and other growth agents. The genomes of diverse microbes, including many plant pathogens, also encode expansins designated expansin-like X. Expansins are proposed to disrupt noncovalent bonding between laterally aligned polysaccharides (notably cellulose), facilitating wall loosening for a variety of biological roles."
Authors: Yuqing Zhao, Qing Han and Dawei Zhang.
Plant and Cell Physiology (2024)
Abstract: "Due to their sessile lifestyle, plants need to optimize their growth in order to adapt to ever-changing environments. Plants receive stimuli from the environment and convert them into cellular responses. Brassinosteroids (BRs), as growth-promoting steroid hormones, play a significant role in the tradeoff between growth and environmental responses. Here, we provide a comprehensive summary for understanding the crosstalk between BR and various environmental stresses, including water availability, temperature fluctuations, salinization, nutrient deficiencies and diseases. We also highlight the bottlenecks that need to be addressed in future studies. Ultimately, we suppose to improve plant environmental adaptability and crop yield by excavating natural BR mutants or modifying BR signaling and its targets."
Authors: Yuwen Zhang, Xingliang Duan, Yuanming Xie and Wei Xuan.
New Crops (2024)
Abstract: "Plant root systems are critical for absorbing water and nutrients and anchoring plants in the soil, and their development is regulated by phytohormones and complex signaling pathways. Recent studies have identified small peptides as essential players in governing root development, binding to specific receptors on the cell membrane, and triggering signaling processes. In this study, we summarize recent advances in small peptide regulation of root system architecture and tissue organization, as well as the molecular interaction between peptides and canonical hormone signaling. Additionally, we discuss the functions of small peptides in modulating root development responses to environmental forces like nitrogen and phosphate starvation, osmotic stress, and soil microbes through the activation of local and systemic signaling pathways. This review offers a comprehensive overview of peptide signaling during plant root development and prospects for further crop breeding applications."
Authors: Ahmed H. El-Sappah, Kuan Yan and Jia Li.
The Plant Journal (2024)
Significance Statement: To survive, living organisms must sense and respond to their surroundings. Plants sense and respond to various stimuli, such as touch, light, and volatiles. Plants' ability to respond to sound has also been revealed in recent years and their emissions to sounds have been thoroughly documented. In this perspective, we discussed how different types of plants, and their surroundings interact with their responses to environmental stress, whether they emit or receive sounds.
Abstract: "Animals and insects communicate using vibrations that are frequently too low or too high for human ears to detect. Plants and trees can communicate and sense sound. Khait et al. used a dependable recording system to capture airborne sounds produced by stressed plants. In addition to allowing plants to communicate their stress, sound aids in plant defense, development, and resilience. It also serves as a warning that danger is approaching. Demey et al. and others discussed the audit examinations that were conducted to investigate sound discernment in plants at the atomic and biological levels. The biological significance of sound in plants, the morphophysiological response of plants to sound, and the airborne noises that plants make and can hear from a few meters away were all discussed."
Authors: Shiyi Xie, Hongbing Luo, Wei Huang, Weiwei Jin and Zhaobin Dong.
International Journal of Plant Biology (2024)
Abstract: "Maize (Zea mays) cultivation is strongly affected by both abiotic and biotic stress, leading to reduced growth and productivity. It has recently become clear that regulators of plant stress responses, including the phytohormones abscisic acid (ABA), ethylene (ET), and jasmonic acid (JA), together with reactive oxygen species (ROS), shape plant growth and development. Beyond their well-established functions in stress responses, these molecules play crucial roles in balancing growth and defense, which must be finely tuned to achieve high yields in crops while maintaining some level of defense. In this review, we provide an in-depth analysis of recent research on the developmental functions of stress regulators, focusing specifically on maize. By unraveling the contributions of these regulators to maize development, we present new avenues for enhancing maize cultivation and growth while highlighting the potential risks associated with manipulating stress regulators to enhance grain yields in the face of environmental challenges."
Authors: Alessandra Ferrandino, Chiara Pagliarani and Eva Pilar Pérez-Álvarez.
Frontiers in Plant Science (2023)
Abstract: "Abiotic stresses, such as temperature, heat waves, water limitation, solar radiation and the increase in atmospheric CO2 concentration, significantly influence the accumulation of secondary metabolites in grapevine berries at different developmental stages, and in vegetative organs. Transcriptional reprogramming, miRNAs, epigenetic marks and hormonal crosstalk regulate the secondary metabolism of berries, mainly the accumulation of phenylpropanoids and of volatile organic compounds (VOCs). Currently, the biological mechanisms that control the plastic response of grapevine cultivars to environmental stress or that occur during berry ripening have been extensively studied in many worlds viticultural areas, in different cultivars and in vines grown under various agronomic managements. A novel frontier in the study of these mechanisms is the involvement of miRNAs whose target transcripts encode enzymes of the flavonoid biosynthetic pathway. Some miRNA-mediated regulatory cascades, post-transcriptionally control key MYB transcription factors, showing, for example, a role in influencing the anthocyanin accumulation in response to UV-B light during berry ripening. DNA methylation profiles partially affect the berry transcriptome plasticity of different grapevine cultivars, contributing to the modulation of berry qualitative traits. Numerous hormones (such as abscisic and jasmonic acids, strigolactones, gibberellins, auxins, cytokinins and ethylene) are involved in triggering the vine response to abiotic and biotic stress factors. Through specific signaling cascades, hormones mediate the accumulation of antioxidants that contribute to the quality of the berry and that intervene in the grapevine defense processes, highlighting that the grapevine response to stressors can be similar in different grapevine organs. The expression of genes responsible for hormone biosynthesis is largely modulated by stress conditions, thus resulting in the numerous interactions between grapevine and the surrounding environment."
Authors: Jian-Hong Li, Mehtab Muhammad Aslam, Yang-Yang Gao, Lei Dai, Ge-Fei Hao, Zhong Wei, Mo-Xian Chen and Francisco Dini-Andreote.
Highlights: Advancing our understanding of the mechanisms associated with microbial-mediated signal transduction in plants can enhance our ability to precisely manipulate plant physiology to improve tolerance against biotic and abiotic stresses. Long-distance signal transduction in plants can be initiated by the metabolism of specific microbial taxa in association with plants in the rhizosphere and/or phyllosphere. The transduction of specific long-distance signals in plants can be mediated by mobile peptides, RNA, metabolites, and phytohormones, all of which can be translocated via the vascular system. Embracing the complexity of plant physiological responses and regulation in a holobiont context will advance our knowledge of plant–microbe interactions and foster the development of new chemicals to manipulate plant physiological responses.
Abstract: "Microorganisms colonizing the plant rhizosphere and phyllosphere play crucial roles in plant growth and health. Recent studies provide new insights into long-distance communication from plant roots to shoots in association with their commensal microbiome. In brief, these recent advances suggest that specific plant-associated microbial taxa can contribute to systemic plant responses associated with the enhancement of plant health and performance in face of a variety of biotic and abiotic stresses. However, most of the mechanisms associated with microbiome-mediated signal transduction in plants remain poorly understood. In this review, we provide an overview of long-distance signaling mechanisms within plants mediated by the commensal plant-associated microbiomes. We advocate the view of plants and microbes as a holobiont and explore key molecules and mechanisms associated with plant–microbe interactions and changes in plant physiology activated by signal transduction."
Via Jean-Michel Ané
Authors: Ruixi Shi, Jinlan Yu, Xiaorong Chang, Liping Qiao, Xia Liu and Laifeng Lu.
Processes (2023)
Abstract: "Jasmonates (JAs) are phospholipid-derived hormones that regulate plant development and responses to environmental stress. The synthesis of JAs and the transduction of their signaling pathways are precisely regulated at multiple levels within and outside the nucleus as a result of a combination of genetic and epigenetic regulation. In this review, we focus on recent advances in the regulation of JA biosynthesis and their signaling pathways. The biosynthesis of JAs was found to be regulated with an autocatalytic amplification mechanism via the MYC2 regulation pathway and inhibited by an autonomous braking mechanism via the MYC2-targeting bHLH1 protein to terminate JA signals in a highly ordered manner. The biological functions of JAs mainly include the promotion of fruit ripening at the initial stage via ethylene-dependent and independent ways, the regulation of mature coloring via regulating the degradation of chlorophyll and the metabolism of anthocyanin, and the improvement of aroma components via the regulation of fatty acid and aldehyde alcohol metabolism in agricultural crops. JA signaling pathways also function in the enhancement of biotic and abiotic stress resistance via the regulation of secondary metabolism and the redox system, and they relieve cold damage to crops through improving the stability of the cell membrane. These recently published findings indicate that JAs are an important class of plant hormones necessary for regulating plant growth and development, ripening, and the resistance to stress in agricultural crops and products."
Authors: Xianqing Jia, Long Wang, Hongyu Zhao, Yibo Zhang, Zhixiang Chen, Lei Xu and Keke Yi.
Molecular Plant (2023)
Abstract: "Salicylic acid (SA) plays a pivotal role in plant response to biotic and abiotic stress. Several core SA signaling regulators and key proteins in SA biosynthesis have been well charactered. However, much remains unknown about the origin, evolution, and early diversification of core elements in plant SA signaling and biosynthesis. Here, we identified ten core protein families in SA signaling and biosynthesis across green plant lineages. We found that key SA signaling receptors, the nonexpresser of pathogenesis-related proteins (NPRs), originated in the most recent common ancestor (MRCA) of land plants and formed divergent groups in the ancestor of seed plants. However, key transcription factors for SA signaling, TGACG motif-binding proteins (TGAs), originated in the MRCA of streptophytes, arguing for the stepwise evolution of core SA signaling in plants. Different from the assembling of core SA signaling in the ancestor of seed plants, SA extensively exists in green plants, including chlorophytes and streptophyte algae. However, the full isochorismate synthase (ICS)-based SA synthesis pathway was first assembled in the MRCA of land plants. We further uncovered that the ancient abnormal inflorescence meristem 1 (AIM1)-based β-oxidation is crucial for the biosynthesis of SA in Chlorophyte algae, and this biosynthesis pathway may have facilitated the adaptation of early-diverging green algae for the high light intensity environment on land. Taken together, our findings provide significant insights into the early evolution and diversification of plant SA signaling and biosynthesis pathways, and highlight the role of SA in stress tolerance during plant terrestrialization."
Authors: Wei Li, Jinyu He, Xiuzhuo Wang, Matthew Ashline, Zirui Wu, Fengquan Liu, Zheng Qing Fu and Ming Chang.
New Phytologist (2023)
Abstract: "AVRPPHB SUSCEPTIBLE 3 (PBS3) belongs to the GH3 family of acyl acid amido synthetases, which conjugates amino acids to diverse acyl acid substrates. Recent studies demonstrate that PBS3 in Arabidopsis plays a key role in the biosynthesis of plant defense hormone salicylic acid (SA) by catalyzing the conjugation of glutamate to isochorismate to form isochorismate-9-glutamate, which is then used to produce SA through spontaneous decay or ENHANCED PSEUDOMONAS SUSCEPTIBILITY (EPS1) catalysis. Consistent with its function as an essential enzyme for SA biosynthesis, PBS3 is well known to be a positive regulator of plant immunity in Arabidopsis. PBS3 is also involved in the trade-off between abiotic and biotic stress responses in Arabidopsis by suppressing the inhibitory effect of abscisic acid (ABA) on SA-mediated plant immunity. Besides stress responses, PBS3 also plays a role in plant development. Under long-day conditions, PBS3 influences Arabidopsis flowering time by regulating the expression of flowering regulators FLOWERING LOCUS C (FLC) and FLOWERING LOCUS T (FT). Taken together, PBS3 functions in the signaling network of plant development and responses to biotic and/or abiotic stresses, but the molecular mechanisms underlying its diverse roles remain obscure."
Authors: Trang Hieu Nguyen, Alain Goossens and Elia Lacchini.
Current Opinion in Plant Biology (2022)
Highlights: • Jasmonate boosts defense and metabolic processes to increase plant resilience. • Jasmonate is linked to light-regulated processes, HY5 activity, and photomorphogenesis. • Jasmonate connects with the central energy sensor TOR and the SnRK complex. • Like adrenaline in animals, jasmonate boosts plant performances but overexposure can be harmful.
Abstract: "Over the years, jasmonates (JAs) have become recognized as one of the main plant hormones that regulate stress responses by activating defense programs and the production of specialized metabolites. High JA levels have been associated with reduced plant growth, supposedly as a result of the reallocation of carbon sources from primary growth to the biosynthesis of defense compounds. Recent advances suggest however that tight regulatory networks integrate several sensing pathways to steer plant metabolism, and thereby drive the trade-off between growth and defense. In this review, we discuss how JA influences primary metabolism and how it is connected to light-regulated processes, nutrient sensing and energy metabolism. Finally, we speculate that JA, in a conceptual parallelism with adrenaline for humans, overall boosts cellular processes to keep up with an increased metabolic demand during harsh times.
Authors: Qinling Zhong, Hongliang Hu, Baofang Fan, Cheng Zhu, and Zhixiang Chen.
International Journal of Molecular Sciences (2021)
Abstract: "Salicylic acid (SA) is an important plant hormone with a critical role in plant defense against pathogen infection. Despite extensive research over the past 30 year or so, SA biosynthesis and its complex roles in plant defense are still not fully understood. Even though earlier biochemical studies suggested that plants synthesize SA from cinnamate produced by phenylalanine ammonia lyase (PAL), genetic analysis has indicated that in Arabidopsis, the bulk of SA is synthesized from isochorismate (IC) produced by IC synthase (ICS). Recent studies have further established the enzymes responsible for the conversion of IC to SA in Arabidopsis. However, it remains unclear whether other plants also rely on the ICS pathway for SA biosynthesis. SA induces defense genes against biotrophic pathogens, but represses genes involved in growth for balancing defense and growth to a great extent through crosstalk with the growth-promoting plant hormone auxin. Important progress has been made recently in understanding how SA attenuates plant growth by regulating the biosynthesis, transport, and signaling of auxin. In this review, we summarize recent progress in the biosynthesis and the broad roles of SA in regulating plant growth during defense responses. Further understanding of SA production and its regulation of both defense and growth will be critical for developing better knowledge to improve the disease resistance and fitness of crops."
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