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Many organisms evolved strategies to survive desiccation. Plant seeds protect dehydrated embryos from various stressors and can lay dormant for millennia. Hydration is the key trigger to initiate germination, but the mechanism by which seeds sense water remains unresolved. We identified an uncharacterized Arabidopsis thaliana prion-like protein we named FLOE1, which phase separates upon hydration and allows the embryo to sense water stress. We demonstrate that biophysical states of FLOE1 condensates modulate its biological function in vivo in suppressing seed germination under unfavorable environments. We find intragenic, intraspecific, and interspecific natural variation in FLOE1 expression and phase separation and show that intragenic variation is associated with adaptive germination strategies in natural populations. This combination of molecular, organismal, and ecological studies uncovers FLOE1 as a tunable environmental sensor with direct implications for the design of drought-resistant crops, in the face of climate change.
Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/crescimento & desenvolvimento , Germinação , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Príons/metabolismo , Sementes/crescimento & desenvolvimento , Água/metabolismo , Arabidopsis/genética , Arabidopsis/ultraestrutura , Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/ultraestrutura , Desidratação , Imageamento Tridimensional , Peptídeos e Proteínas de Sinalização Intercelular/química , Mutação/genética , Dormência de Plantas , Plantas Geneticamente Modificadas , Domínios Proteicos , Isoformas de Proteínas/metabolismo , Sementes/ultraestruturaRESUMO
Soil salinity impairs plant growth reducing crop productivity. Toxic accumulation of sodium ions is counteracted by the Salt Overly Sensitive (SOS) pathway for Na+ extrusion, comprising the Na+ transporter SOS1, the kinase SOS2, and SOS3 as one of several Calcineurin-B-like (CBL) Ca2 + sensors. Here, we report that the receptor-like kinase GSO1/SGN3 activates SOS2, independently of SOS3 binding, by physical interaction and phosphorylation at Thr16. Loss of GSO1 function renders plants salt sensitive and GSO1 is both sufficient and required for activating the SOS2-SOS1 module in yeast and in planta. Salt stress causes the accumulation of GSO1 in two specific and spatially defined areas of the root tip: in the endodermis section undergoing Casparian strip (CS) formation, where it reinforces the CIF-GSO1-SGN1 axis for CS barrier formation; and in the meristem, where it creates the GSO1-SOS2-SOS1 axis for Na+ detoxification. Thus, GSO1 simultaneously prevents Na+ both from diffusing into the vasculature, and from poisoning unprotected stem cells in the meristem. By protecting the meristem, receptor-like kinase-conferred activation of the SOS2-SOS1 module allows root growth to be maintained in adverse environments.
Assuntos
Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Sódio/metabolismo , Nicho de Células-Tronco , Estresse Salino , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , Trocadores de Sódio-Hidrogênio/genética , Trocadores de Sódio-Hidrogênio/metabolismoRESUMO
Eukaryotic genomes are pervasively transcribed by RNA polymerase II. Yet, the molecular and biological implications of such a phenomenon are still largely puzzling. Here, we describe noncoding RNA transcription upstream of the Arabidopsis thaliana DOG1 gene, which governs salt stress responses and is a key regulator of seed dormancy. We find that expression of the DOG1 gene is induced by salt stress, thereby causing a delay in seed germination. We uncover extensive transcriptional activity on the promoter of the DOG1 gene, which produces a variety of lncRNAs. These lncRNAs, named PUPPIES, are co-directionally transcribed and extend into the DOG1 coding region. We show that PUPPIES RNAs respond to salt stress and boost DOG1 expression, resulting in delayed germination. This positive role of pervasive PUPPIES transcription on DOG1 gene expression is associated with augmented pausing of RNA polymerase II, slower transcription and higher transcriptional burst size. These findings highlight the positive role of upstream co-directional transcription in controlling transcriptional dynamics of downstream genes.
Assuntos
Proteínas de Arabidopsis , Arabidopsis , RNA Longo não Codificante , Animais , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Regulação da Expressão Gênica de Plantas , Germinação/genética , Mutação , RNA Polimerase II/genética , RNA Polimerase II/metabolismo , RNA Longo não Codificante/metabolismoRESUMO
The maintenance of sodium/potassium (Na+ /K+ ) homeostasis in plant cells is essential for salt tolerance. Plants export excess Na+ out of cells mainly through the Salt Overly Sensitive (SOS) pathway, activated by a calcium signal; however, it is unknown whether other signals regulate the SOS pathway and how K+ uptake is regulated under salt stress. Phosphatidic acid (PA) is emerging as a lipid signaling molecule that modulates cellular processes in development and the response to stimuli. Here, we show that PA binds to the residue Lys57 in SOS2, a core member of the SOS pathway, under salt stress, promoting the activity and plasma membrane localization of SOS2, which activates the Na+ /H+ antiporter SOS1 to promote the Na+ efflux. In addition, we reveal that PA promotes the phosphorylation of SOS3-like calcium-binding protein 8 (SCaBP8) by SOS2 under salt stress, which attenuates the SCaBP8-mediated inhibition of Arabidopsis K+ transporter 1 (AKT1), an inward-rectifying K+ channel. These findings suggest that PA regulates the SOS pathway and AKT1 activity under salt stress, promoting Na+ efflux and K+ influx to maintain Na+ /K+ homeostasis.
Assuntos
Proteínas de Arabidopsis , Arabidopsis , Proteínas Serina-Treonina Quinases , Estresse Salino , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Homeostase , Ácidos Fosfatídicos/metabolismo , Potássio/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Estresse Salino/genética , Sódio/metabolismoRESUMO
Lipid polymers such as cutin and suberin strengthen the diffusion barrier properties of the cell wall in specific cell types and are essential for water relations, mineral nutrition, and stress protection in plants. Land plant-specific glycerol-3-phosphate acyltransferases (GPATs) of different clades are central players in cutin and suberin monomer biosynthesis. Here, we show that the GPAT4/6/8 clade in Arabidopsis thaliana, which is known to mediate cutin formation, is also required for developmentally regulated root suberization, in addition to the established roles of GPAT5/7 in suberization. The GPAT5/7 clade is mainly required for abscisic acid-regulated suberization. In addition, the GPAT5/7 clade is crucial for the formation of the typical lamellated suberin ultrastructure observed by transmission electron microscopy, as distinct amorphous globular polyester structures were deposited in the apoplast of the gpat5 gpat7 double mutant, in contrast to the thinner but still lamellated suberin deposition in the gpat4 gpat6 gpat8 triple mutant. Site-directed mutagenesis revealed that the intrinsic phosphatase activity of GPAT4, GPAT6, and GPAT8, which leads to monoacylglycerol biosynthesis, contributes to suberin formation. GPAT5/7 lack an active phosphatase domain and the amorphous globular polyester structure observed in the gpat5 gpat7 double mutant was partially reverted by treatment with a phosphatase inhibitor or the expression of phosphatase-dead variants of GPAT4/6/8. Thus, GPATs that lack an active phosphatase domain synthetize lysophosphatidic acids that might play a role in the formation of the lamellated structure of suberin. GPATs with active and nonactive phosphatase domains appear to have nonredundant functions and must cooperate to achieve the efficient biosynthesis of correctly structured suberin.
Assuntos
Proteínas de Arabidopsis , Arabidopsis , Glicerol-3-Fosfato O-Aciltransferase , Lipídeos , Raízes de Plantas , 1-Acilglicerol-3-Fosfato O-Aciltransferase , Ácido Abscísico/metabolismo , Arabidopsis/enzimologia , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Parede Celular/metabolismo , Regulação da Expressão Gênica de Plantas , Glicerol-3-Fosfato O-Aciltransferase/metabolismo , Glicerol-3-Fosfato O-Aciltransferase/genética , Lipídeos/química , Lipídeos de Membrana/metabolismo , Raízes de Plantas/metabolismo , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/genéticaRESUMO
To ensure optimal growth, plants actively regulate their growth and development based on environmental changes. Among these, salt stress significantly influences growth and yield. In this study, we demonstrate that the growth of root hairs of salt-stressed Arabidopsis thaliana seedlings is regulated by the SALT OVERLY SENSITIVE 2 (SOS2)-GUANOSINE NUCLEOTIDE DIPHOSPHATE DISSOCIATION INHIBITOR 1 (RhoGDI1)-Rho GTPASE OF PLANTS 2 (ROP2) module. We show here that the kinase SOS2 is activated by salt stress and subsequently phosphorylates RhoGDI1, a root hair regulator, thereby decreasing its stability. This change in RhoGDI1 abundance resulted in a fine-tuning of polar localization of ROP2 and root hair initiation followed by polar growth, demonstrating how SOS2-regulated root hair development is critical for plant growth under salt stress. Our results reveal how a tissue-specific response to salt stress balances the relationship of salt resistance and basic growth.
Assuntos
Arabidopsis , Inibidor alfa de Dissociação do Nucleotídeo Guanina rho , Fosforilação , Guanosina Difosfato , Estresse SalinoRESUMO
Soil salinity severely threatens plant growth and crop yields. The utilization of PGPR is an effective strategy for enhancing plant salt tolerance, but the mechanisms involved in this process have rarely been reported. In this study, we investigated the effects of Bacillus subtilis CNBG-PGPR-1 on improving plant salt tolerance and elucidated the molecular pathways involved. The results showed that CNBG-PGPR-1 significantly improved the cellular homeostasis and photosynthetic efficiency of leaves and reduced ion toxicity and osmotic stress caused by salt in tomato. Transcriptome analysis uncovered that CNBG-PGPR-1 enhanced plant salt tolerance through the activation of complex molecular pathways, with plant hormone signal transduction playing an important role. Comparative analysis and pharmacological experiments confirmed that the ethylene pathway was closely related to the beneficial effect of CNBG-PGPR-1 on improving plant salt tolerance. Furthermore, we found that methionine, a precursor of ethylene synthesis, significantly accumulated in response to CNBG-PGPR-1 in tomato. Exogenous L-methionine largely mimicked the beneficial effects of CNBG-PGPR-1 and activated the expression of ethylene pathway-related genes, indicating CNBG-PGPR-1 induces methionine accumulation to regulate the ethylene pathway in tomato. Finally, CNBG-PGPR-1 reduced salt-induced ROS by activating ROS scavenger-encoding genes, mainly involved in GSH metabolism and POD-related genes, which were also closely linked to methionine metabolism. Overall, our studies demonstrate that CNBG-PGPR-1-induced methionine is a key regulator in enhancing plant salt tolerance through the ethylene pathway and ROS scavenging, providing a novel understanding of the mechanism by which beneficial microbes improve plant salt tolerance.
Assuntos
Solanum lycopersicum , Solanum lycopersicum/genética , Bacillus subtilis/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Metionina , Tolerância ao Sal , Etilenos/metabolismo , RacemetioninaRESUMO
Salt glands are the unique epidermal structures present in recretohalophytes, plants that actively excrete excess Na+ by salt secretory structures to avoid salt damage. Here, we describe a transmembrane protein that localizes to the plasma membrane of the recretohalophyte Limonium bicolor. As virus-induced gene silencing of the corresponding gene LbRSG in L. bicolor decreased the number of salt glands, we named the gene Reduced Salt Gland. We detected LbRSG transcripts in salt glands by in situ hybridization and transient transformation. Overexpression and silencing of LbRSG in L. bicolor pointed to a positive role in salt gland development and salt secretion by interacting with Lb3G16832. Heterologous LbRSG expression in Arabidopsis enhanced salt tolerance during germination and the seedling stage by alleviating NaCl-induced ion stress and osmotic stress after replacing or deleting the (highly) negatively charged region of extramembranous loop. After screened by immunoprecipitation-mass spectrometry and verified using yeast two-hybrid, PGK1 and BGLU18 were proposed to interact with LbRSG to strengthen salt tolerance. Therefore, we identified (highly) negatively charged regions in the extramembrane loop that may play an essential role in salt tolerance, offering hints about LbRSG function and its potential to confer salt resistance.
Assuntos
Plumbaginaceae , Tolerância ao Sal , Animais , Tolerância ao Sal/genética , Plumbaginaceae/genética , Plumbaginaceae/metabolismo , Glândula de Sal , Plântula/genética , Germinação , Regulação da Expressão Gênica de Plantas , Plantas Geneticamente ModificadasRESUMO
Salinity is frequently mentioned as a major constraint in worldwide agricultural production. Lint percentage (LP) is a crucial yield-component in cotton lint production. While the genetic factors affect cotton yield in saline soils are still unclear. Here, we employed a recombinant inbred line population in upland cotton (Gossypium hirsutum L.) and investigated the effects of salt stress on five yield and yield component traits, including seed cotton yield per plant, lint yield per plant, boll number per plant, boll weight, and LP. Between three datasets of salt stress (E1), normal growth (E2), and the difference values dataset of salt stress and normal conditions (D-value), 87, 82, and 55 quantitative trait loci (QTL) were detectable, respectively. In total, five QTL (qLY-Chr6-2, qBNP-Chr4-1, qBNP-Chr12-1, qBNP-Chr15-5, qLP-Chr19-2) detected in both in E1 and D-value were salt related QTL, and three stable QTL (qLP-Chr5-3, qLP-Chr13-1, qBW-Chr5-5) were detected both in E1 and E2 across 3 years. Silencing of nine genes within a stable QTL (qLP-Chr5-3) highly expressed in fiber developmental stages increased LP and decreased fiber length (FL), indicating that multiple minor-effect genes clustered on Chromosome 5 regulate LP and FL. Additionally, the difference in LP caused by Gh_A05G3226 is mainly in transcription level rather than in the sequence difference. Moreover, silencing of salt related gene (GhDAAT) within qBNP-Chr4-1 decreased salt tolerance in cotton. Our findings shed light on the regulatory mechanisms underlining cotton salt tolerance and fiber initiation.
Assuntos
Gossypium , Locos de Características Quantitativas , Estresse Salino , Gossypium/genética , Gossypium/fisiologia , Locos de Características Quantitativas/genética , Estresse Salino/genética , Mapeamento Cromossômico , Fibra de Algodão , FenótipoRESUMO
Soil salinity is a major environmental stressor affecting agricultural productivity worldwide. Understanding plant responses to salt stress is crucial for developing resilient crop varieties. Wild relatives of cultivated crops, such as wild tomato, Solanum pimpinellifolium, can serve as a useful resource to further expand the resilience potential of the cultivated germplasm, S. lycopersicum. In this study, we employed high-throughput phenotyping in the greenhouse and field conditions to explore salt stress responses of a S. pimpinellifolium diversity panel. Our study revealed extensive phenotypic variations in response to salt stress, with traits such as transpiration rate, shoot mass, and ion accumulation showing significant correlations with plant performance. We found that while transpiration was a key determinant of plant performance in the greenhouse, shoot mass strongly correlated with yield under field conditions. Conversely, ion accumulation was the least influential factor under greenhouse conditions. Through a Genome Wide Association Study, we identified candidate genes not previously associated with salt stress, highlighting the power of high-throughput phenotyping in uncovering novel aspects of plant stress responses. This study contributes to our understanding of salt stress tolerance in S. pimpinellifolium and lays the groundwork for further investigations into the genetic basis of these traits, ultimately informing breeding efforts for salinity tolerance in tomato and other crops.
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Current climate change brings with it a higher frequency of environmental stresses, which occur in combination rather than individually leading to massive crop losses worldwide. In addition to, for example, drought stress (low water availability), also flooding (excessive water) can threaten the plant, causing, among others, an energy crisis due to hypoxia, which is responded to by extensive transcriptional, metabolic and growth-related adaptations. While signalling during flooding is relatively well understood, at least in model plants, the molecular mechanisms of combinatorial flooding stress responses, for example, flooding simultaneously with salinity, temperature stress and heavy metal stress or sequentially with drought stress, remain elusive. This represents a significant gap in knowledge due to the fact that dually stressed plants often show unique responses at multiple levels not observed under single stress. In this review, we (i) consider possible effects of stress combinations from a theoretical point of view, (ii) summarize the current state of knowledge on signal transduction under single flooding stress, (iii) describe plant adaptation responses to flooding stress combined with four other abiotic stresses and (iv) propose molecular components of combinatorial flooding (hypoxia) stress adaptation based on their reported dual roles in multiple stresses. This way, more future emphasis may be placed on deciphering molecular mechanisms of combinatorial flooding stress adaptation, thereby potentially stimulating development of molecular tools to improve plant resilience towards multi-stress scenarios.
Assuntos
Inundações , Plantas , Estresse Fisiológico , Secas , Hipóxia , ÁguaRESUMO
The roles of clock components in salt stress tolerance remain incompletely characterized in rice. Here, we show that, among OsPRR (Oryza sativa Pseudo-Response Regulator) family members, OsPRR73 specifically confers salt tolerance in rice. Notably, the grain size and yield of osprr73 null mutants were significantly decreased in the presence of salt stress, with accumulated higher level of reactive oxygen species and sodium ions. RNA sequencing and biochemical assays identified OsHKT2;1, encoding a plasma membrane-localized Na+ transporter, as a transcriptional target of OsPRR73 in mediating salt tolerance. Correspondingly, null mutants of OsHKT2;1 displayed an increased tolerance to salt stress. Immunoprecipitation-mass spectrometry (IP-MS) assays further identified HDAC10 as nuclear interactor of OsPRR73 and co-repressor of OsHKT2;1. Consistently, H3K9ac histone marks at OsHKT2;1 promoter regions were significantly reduced in osprr73 mutant. Together, our findings reveal that salt-induced OsPRR73 expression confers salt tolerance by recruiting HDAC10 to transcriptionally repress OsHKT2;1, thus reducing cellular Na+ accumulation. This exemplifies a new molecular link between clock components and salt stress tolerance in rice.
Assuntos
Proteínas CLOCK/genética , Histona Desacetilases/metabolismo , Oryza/crescimento & desenvolvimento , Tolerância ao Sal , Membrana Celular/metabolismo , Regulação da Expressão Gênica de Plantas , Homeostase , Mutação com Perda de Função , Oryza/genética , Oryza/metabolismo , Proteínas de Plantas/genética , Regiões Promotoras Genéticas , Sódio/metabolismoRESUMO
Owing to its detrimental effect on plant growth, salinity is an increasing worldwide problem for agriculture. To understand the molecular mechanisms activated in response to salt in Arabidopsis thaliana, we investigated the Catharanthus roseus receptor-like kinase 1-like family, which contains sensors that were previously shown to be involved in sensing the structural integrity of the cell walls. We found that herk1 the1-4 double mutants, lacking the function of HERKULES1 (HERK1) and combined with a gain-of-function allele of THESEUS1 (THE1), strongly respond to salt application, resulting in an intense activation of stress responses, similarly to plants lacking FERONIA (FER) function. We report that salt triggers pectin methyl esterase (PME) activation and show its requirement for the activation of several salt-dependent responses. Because chemical inhibition of PMEs alleviates these salt-induced responses, we hypothesize a model in which salt directly leads to cell wall modifications through the activation of PMEs. Responses to salt partly require the functionality of FER alone or HERK1/THE1 to attenuate salt effects, highlighting the complexity of the salt-sensing mechanisms that rely on cell wall integrity.
Assuntos
Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Parede Celular/metabolismo , Regulação da Expressão Gênica de Plantas , Pectinas , SalinidadeRESUMO
Population expansion is a global issue, especially for food production. Meanwhile, global climate change is damaging our soils, making it difficult for crops to thrive and lowering both production and quality. Poor nutrition and salinity stress affect plant growth and development. Although the impact of individual plant stresses has been studied for decades, the real stress scenario is more complex due to the exposure to multiple stresses at the same time. Here we investigate using existing evidence and a meta-analysis approach to determine molecular linkages between two contemporaneous abiotic stimuli, phosphate (Pi) deficiency and salinity, on a single plant cell model, the root hairs (RHs), which is the first plant cell exposed to them. Understanding how these two stresses work molecularly in RHs may help us build super-adaptable crops and sustainable agriculture in the face of global climate change.
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Mitogen-activated protein kinase kinases (MAPKKs) play a critical role in the mitogen-activated protein kinase (MAPK) signaling pathway, transducing external stimuli into intracellular responses and enabling plant adaptation to environmental challenges. Most research has focused on the model plant Arabidopsis (Arabidopsis thaliana). The systematic analysis and characterization of MAPKK genes across different plant species, particularly in cotton (Gossypium hirsutum), are somewhat limited. Here, we identified MAPKK family members from 66 different species, which clustered into 5 different sub-groups, and MAPKKs from four cotton species clustered together. Through further bioinformatic and expression analysis, GhMAPKK5 was identified as the most responsive MAPKK member to salt and drought stress among the 23 MAPKKs identified in Gossypium hirsutum. Silencing GhMAPKK5 in cotton through virus-induced gene silencing (VIGS) led to quicker wilting under salt and drought conditions, while overexpressing GhMAPKK5 in Arabidopsis enhanced root growth and seed germination under these stresses, demonstrating GhMAPKK5's positive role in stress tolerance. Transcriptomics and Yeast-Two-Hybrid assays revealed a MAPK cascade signal module comprising GhMEKK (Mitogen-activated protein kinase kinase kinases)3/8/31-GhMAPKK5-GhMAPK11/23. This signaling cascade may play a role in managing drought and salt stress by regulating transcription factor genes, such as WRKYs, which are involved in the biosynthesis and transport pathways of ABA, proline, and RALF. This study is highly important for further understanding the regulatory mechanism of MAPKK in cotton, contributing to its stress tolerance and offering potential in targets for genetic enhancement.
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Understanding phytohormonal signaling is crucial for elucidating plant defense mechanisms against environmental stressors. However, knowledge regarding phytohormone-mediated tolerance pathways under salt stress in Elymus sibiricus, an important species for forage and ecological restoration, remains limited. In this study, transcriptomic and metabolomic approaches uncover the dynamics of phytohormonal signaling in Elymus sibiricus under salt stress. Notably, four hours after exposure to salt, significant activity was observed in the ABA, JA, IAA, and CTK pathways, with ABA, JA, JA-L-Ile, and IAA identified as key mediators in the response of Elymus sibiricus' to salinity. Moreover, SAPK3, Os04g0167900-like, CAT1, MKK2, and MPK12 were identified as potential central regulators within these pathways. The complex interactions between phytohormones and DEGs are crucial for facilitating the adaptation of Elymus sibiricus to saline environments. These findings enhance our understanding of the salt tolerance mechanisms in Elymus sibiricus and provide a foundation for breeding salt-resistant varieties.
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Plants employ various molecular mechanisms to maintain primary root elongation upon salt stress. Identification of key functional genes, therein, is important for improving crop salt tolerance. Through analyzing natural variation of the primary root length of Arabidopsis natural population under salt stress, we identified NIGT1.4, encoding an MYB transcription factor, as a novel contributor to maintained root growth under salt stress. Using both T-DNA knockout and functional complementation, NIGT1.4 was confirmed to have a role in promoting primary root growth in response to salt stress. The expression of NIGT1.4 in the root was shown induced by NaCl treatments in an ABA-dependent manner. SnRK2.2 and 2.3 were shown to interact with and phosphorylate NIGT1.4 individually. The growth of the primary root of snrk2.2/2.3/2.6 triple mutant was shown sensitive to salt stress, which was similar to nigt1.4 plants. Using DNA affinity purification sequencing, ERF1, a known positive regulator for primary root elongation and salt tolerance, was identified as a target gene for NIGT1.4. The transcriptional induction of ERF1 by salt stress was shown absent in nigt1.4 background. NIGT1.4 was also confirmed to bind to the promoter region of ERF1 by yeast one-hybrid experiment and to induce the expression of ERF1 by dual-luciferase analysis. All data support the notion that salt- and ABA-elicited NIGT1.4 induces the expression of ERF1 to regulate downstream functional genes that contribute to maintained primary root elongation. NIGT1.4-ERF1, therefore, acts as a signaling node linking regulators for stress resilience and root growth, providing new insights for breeding salt-tolerant crops.
Assuntos
Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Regulação da Expressão Gênica de Plantas , Melhoramento Vegetal , Plantas Geneticamente Modificadas/genética , Tolerância ao Sal/genética , Estresse Fisiológico/genéticaRESUMO
Salt stress is one of the major causes of reduced crop production, limiting agricultural development globally. Plants have evolved with complex systems to maintain the balance between growth and stress responses, where signaling pathways such as hormone signaling play key roles. Recent studies revealed that hormones are modulated by microRNAs (miRNAs). Previously, two sweet sorghum (Sorghum bicolor) inbred lines with different salt tolerance were identified: the salt-tolerant M-81E and the salt-sensitive Roma. The levels of endogenous hormones in M-81E and Roma varied differently under salt stress, showing a different balance between growth and stress responses. miRNA and degradome sequencing showed that the expression of many upstream transcription factors regulating signal transduction and hormone-responsive genes was directly induced by differentially expressed miRNAs, whose levels were very different between the two sweet sorghum lines. Furthermore, the effects of representative miRNAs on salt tolerance in sorghum were verified through a transformation system mediated by Agrobacterium rhizogenes. Also, miR-6225-5p reduced the level of Ca2+ in the miR-6225-5p-overexpressing line by inhibiting the expression of the Ca2+ uptake gene SbGLR3.1 in the root epidermis and affected salt tolerance in sorghum. This study provides evidence for miRNA-mediated growth and stress responses in sweet sorghum.
Assuntos
MicroRNAs , Sorghum , MicroRNAs/genética , MicroRNAs/metabolismo , Sorghum/metabolismo , Estresse Fisiológico/genética , Estresse Salino/genética , Grão Comestível/genética , Hormônios/metabolismo , Regulação da Expressão Gênica de Plantas/genéticaRESUMO
Salt stress adversely affects the yield and quality of crops and limits their geographical distribution. Studying the functions and regulatory mechanisms of key genes in the salt stress response is important for breeding crops with enhanced stress resistance. Autophagy plays an important role in modulating the tolerance of plants to various types of abiotic stressors. However, the mechanisms underlying salt-induced autophagy are largely unknown. Cation/Ca2+ exchanger proteins enhance apple salt tolerance by inhibiting Na+ accumulation but the mechanism underlying the response to salt stress remains unclear. Here, we show that the autophagy-related gene MdATG18a modulated apple salt tolerance. Under salt stress, the autophagic activity, proline content, and antioxidant enzyme activities were higher and Na+ accumulation was lower in MdATG18a-overexpressing transgenic plants than in control plants. The use of an autophagy inhibitor during the salt treatment demonstrated that the regulatory function of MdATG18a depended on autophagy. The yeast-one-hybrid assay revealed that the homeodomain-leucine zipper (HD-Zip) transcription factor MdHB7-like directly bound to the MdATG18a promoter. Transcriptional regulation and genetic analyses showed that MdHB7-like enhanced salt-induced autophagic activity by promoting MdATG18a expression. The analysis of Na+ efflux rate in transgenic yeast indicated that MdCCX1 expression significantly promoted Na+ efflux. Promoter binding, transcriptional regulation, and genetic analyses showed that MdHB7-like promoted Na+ efflux and apple salt tolerance by directly promoting MdCCX1 expression, which was independent of the autophagy pathway. Overall, our findings provide insight into the mechanism underlying MdHB7-like-mediated salt tolerance in apple through the MdHB7-like-MdATG18a and MdHB7-like-MdCCX1 modules. These results will aid future studies on the mechanisms underlying stress-induced autophagy and the regulation of stress tolerance in plants.
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Malus , Malus/metabolismo , Tolerância ao Sal/genética , Proteínas de Plantas/metabolismo , Saccharomyces cerevisiae/genética , Melhoramento Vegetal , Plantas Geneticamente Modificadas/genética , Autofagia/genética , Regulação da Expressão Gênica de Plantas , Estresse Fisiológico/genéticaRESUMO
Schrenkiella parvula, a leading extremophyte model in Brassicaceae, can grow and complete its lifecycle under multiple environmental stresses, including high salinity. Yet, the key physiological and structural traits underlying its stress-adapted lifestyle are unknown along with trade-offs when surviving salt stress at the expense of growth and reproduction. We aimed to identify the influential adaptive trait responses that lead to stress-resilient and uncompromised growth across developmental stages when treated with salt at levels known to inhibit growth in Arabidopsis and most crops. Its resilient growth was promoted by traits that synergistically allowed primary root growth in seedlings, the expansion of xylem vessels across the root-shoot continuum, and a high capacity to maintain tissue water levels by developing thicker succulent leaves while enabling photosynthesis during salt stress. A successful transition from vegetative to reproductive phase was initiated by salt-induced early flowering, resulting in viable seeds. Self-fertilization in salt-induced early flowering was dependent upon filament elongation in flowers otherwise aborted in the absence of salt during comparable plant ages. The maintenance of leaf water status promoting growth, and early flowering to ensure reproductive success in a changing environment, were among the most influential traits that contributed to the extremophytic lifestyle of S. parvula.