RESUMO
As a plant-specific transcription factor, lateral organ boundaries domain (LBD) protein was reported to regulate plant growth and stress response, but the functional research of subfamily II genes is limited. SlMYC2, a master regulator of Jasmonic acid response, has been found to exhibit high expression levels in fruit and has been implicated in the regulation of fruit ripening and resistance to Botrytis. However, its role in fruit expansion remains unknown. In this study, we present evidence that a subfamily II member of LBD, namely SlLBD40, collaborates with SlMYC2 in the regulation of fruit expansion. Overexpression of SlLBD40 significantly promoted fruit growth by promoting mesocarp cell expansion, while knockout of SlLBD40 showed the opposite result. Similarly, SlMYC2 knockout resulted in a significant decrease in cell expansion within the fruit. Genetic analysis indicated that SlLBD40-mediated cell expansion depends on the expression of SlMYC2. SlLBD40 bound to the promoter of SlEXPA5, an expansin gene, but did not activate its expression directly. While, the co-expression of SlMYC2 and SlLBD40 significantly stimulated the activation of SlEXPA5, leading to an increase in fruit size. SlLBD40 interacted with SlMYC2 and enhanced the stability and abundance of SlMYC2. Furthermore, SlMYC2 directly targeted and activated the expression of SlLBD40, which is essential for SlLBD40-mediated fruit expansion. In summary, our research elucidates the role of the interaction between SlLBD40 and SlMYC2 in promoting cell expansion in tomato fruits, thus providing novel insights into the molecular genetics underlying fruit growth.
Assuntos
Frutas , Regulação da Expressão Gênica de Plantas , Proteínas de Plantas , Solanum lycopersicum , Fatores de Transcrição , Solanum lycopersicum/genética , Solanum lycopersicum/crescimento & desenvolvimento , Solanum lycopersicum/metabolismo , Frutas/genética , Frutas/crescimento & desenvolvimento , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Fatores de Transcrição/metabolismo , Fatores de Transcrição/genética , Plantas Geneticamente Modificadas , Regiões Promotoras Genéticas/genéticaRESUMO
Drought is the most severe form of stress experienced by plants worldwide. Cucumber is a vegetable crop that requires a large amount of water throughout the growth period. In our previous study, we identified that overexpression of CsHSFA1d could improve cold tolerance and the content of endogenous jasmonic acid in cucumber seedlings. To explore the functional diversities of CsHSFA1d, we treat the transgenic plants under drought conditions. In this study, we found that the heat shock transcription factor HSFA1d (CsHSFA1d) could improve drought stress tolerance in cucumber. CsHSFA1d overexpression increased the expression levels of galactinol synthase (CsGolS3) and raffinose synthase (CsRS) genes, encoding the key enzymes for raffinose family oligosaccharide (RFO) biosynthesis. Furthermore, the lines overexpressing CsHSFA1d showed higher enzymatic activity of GolS and raffinose synthase to increase the content of RFO. Moreover, the CsHSFA1d-overexpression lines showed lower reactive oxygen species (ROS) accumulation and higher ROS-scavenging enzyme activity after drought treatment. The expressions of antioxidant genes CsPOD2, CsAPX1 and CsSOD1 were also upregulated in CsHSFA1d-overexpression lines. The expression levels of stress-responsive genes such as CsRD29A, CsLEA3 and CsP5CS1 were increased in CsHSFA1d-overexpression lines after drought treatment. We conclude that CsHSFA1d directly targets and regulates the expression of CsGolS3 and CsRS to promote the enzymatic activity and accumulation of RFO to increase the tolerance to drought stress. CsHSFA1d also improves ROS-scavenging enzyme activity and gene expression indirectly to reduce drought-induced ROS overaccumulation. This study therefore offers a new gene target to improve drought stress tolerance in cucumber and revealed the underlying mechanism by which CsHSFA1d functions in the drought stress by increasing the content of RFOs and scavenging the excessive accumulation of ROS.
Assuntos
Cucumis sativus , Galactosiltransferases , Regulação da Expressão Gênica de Plantas , Oligossacarídeos , Proteínas de Plantas , Plantas Geneticamente Modificadas , Rafinose , Espécies Reativas de Oxigênio , Cucumis sativus/genética , Cucumis sativus/fisiologia , Cucumis sativus/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Rafinose/metabolismo , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Oligossacarídeos/metabolismo , Galactosiltransferases/metabolismo , Galactosiltransferases/genética , Secas , Fatores de Transcrição de Choque Térmico/metabolismo , Fatores de Transcrição de Choque Térmico/genética , Estresse Fisiológico/genéticaRESUMO
There is often a trade-off effect between different agronomic traits due to gene pleiotropy, leading to a negative correlation between yield and resistance. Consequently, using gene-editing techniques to develop superior traits becomes challenging. Genetic resources that defy this constraint are scarce but hold great potential as targets for improvement through the utilisation of CRISPR. Transcription factors are critical in modulating numerous gene expressions across diverse biological processes. Here, we found that the trihelix transcription factor SlGT30 plays a role in drought resistance and tomato fruit development. We edited the SlGT30 gene with CRISPR/Cas9 technology and found that the knockout lines showed decreased stomata density in the leaves and large fruits. Subsequent examination revealed that cell ploidy was impacted in the leaves and fruits of SlGT30 knockout lines. SlGT30 knockout affected cell size through the endoreduplication pathway, manifested in decreased stomata density and reduced water loss. Consequently, this resulted in an enhancement of drought resistance. For the fruit, both cell size and cell number increased in the fruit pericarp of knockout lines, improving the fruit size and weight accordingly. Therefore, SlGT30 represents a promising candidate gene for gene editing in breeding practice.
RESUMO
Cucumber (Cucumis sativus) originated in tropical areas and is very sensitive to low temperatures. Cold acclimation is a universal strategy that improves plant resistance to cold stress. In this study, we report that heat shock induces cold acclimation in cucumber seedlings, via a process involving the heat-shock transcription factor HSFA1d. CsHSFA1d expression was improved by both heat shock and cold treatment. Moreover, CsHSFA1d transcripts accumulated more under cold treatment after a heat-shock pre-treatment than with either heat shock or cold treatment alone. After exposure to cold, cucumber lines overexpressing CsHSFA1d displayed stronger tolerance for cold stress than the wild type, whereas CsHSFA1d knockdown lines obtained by RNA interference were more sensitive to cold stress. Furthermore, both the overexpression of CsHSFA1d and heat-shock pre-treatment increased the endogenous jasmonic acid (JA) content in cucumber seedlings after cold treatment. Exogenous application of JA rescued the cold-sensitive phenotype of CsHSFA1d knockdown lines, underscoring that JA biosynthesis is key for CsHSFA1d-mediated cold tolerance. Higher JA content is likely to lead to the degradation of CsJAZ5, a repressor protein of the JA pathway. We also established that CsJAZ5 interacts with CsICE1. JA-induced degradation of CsJAZ5 would be expected to release CsICE1, which would then activate the ICE-CBF-COR pathway. After cold treatment, the relative expression levels of ICE-CBF-COR signaling pathway genes, such as CsICE1, CsCBF1, CsCBF2 and CsCOR1, in CsHSFA1d overexpression lines were significantly higher than in the wild type and knockdown lines. Taken together, our results help to reveal the mechanism underlying heat shock-induced cold acclimation in cucumber.
Assuntos
Cucumis sativus , Aclimatação/genética , Temperatura Baixa , Cucumis sativus/genética , Regulação da Expressão Gênica de Plantas , Resposta ao Choque Térmico , Plântula/genética , Transdução de SinaisRESUMO
Melon (Cucumis melo L.) represents an agriculturally significant horticultural crop that is widely grown for its flavorful fruits. Downy mildew (DM), a pervasive foliar disease, poses a significant threat to global melon production. Although several quantitative trait loci related to DM resistance have been identified, the comprehensive genetic underpinnings of this resistance remain largely uncharted. In this study, we utilized integrative transcriptomics and metabolomics approaches to identify potential resistance-associated genes and delineate the strategies involved in the defense against DM in two melon cultivars: the resistant 'PI442177' ('K10-1') and the susceptible 'Huangdanzi' ('K10-9'), post-P. cubensis infection. Even in the absence of the pathogen, there were distinctive differentially expressed genes (DEGs) between 'K10-1' and 'K10-9'. When P. cubensis was infected, certain genes, including flavin-containing monooxygenase (FMO), receptor-like protein kinase FERONIA (FER), and the HD-ZIP transcription factor member, AtHB7, displayed pronounced expression differences between the cultivars. Notably, our data suggest that following P. cubensis infection, both cultivars suppressed flavonoid biosynthesis via the down-regulation of associated genes whilst concurrently promoting lignin production. The complex interplay of transcriptomic and metabolic responses elucidated by this study provides foundational insights into melon's defense mechanisms against DM. The robust resilience of 'K10-1' to DM is attributed to the synergistic interaction of its inherent transcriptomic and metabolic reactions.
Assuntos
Cucurbitaceae , Oomicetos , Peronospora , Cucurbitaceae/genética , Oomicetos/genética , Perfilação da Expressão Gênica , Mecanismos de Defesa , Doenças das Plantas/genéticaRESUMO
Cucumber (Cucumis sativus L.) is an important vegetable crop that carries on vegetative growth and reproductive growth simultaneously. Indeterminate growth is favourable for fresh market under protected environments, whereas determinate growth is preferred for pickling cucumber in the once-over mechanical harvest system. The genetic basis of determinacy is largely unknown in cucumber. In this study, map-based cloning of the de locus showed that the determinate growth habit is caused by a non-synonymous SNP in CsTFL1CsTFL1 is expressed in the subapical regions of the shoot apical meristem, lateral meristem and young stems. Ectopic expression of CsTFL1 rescued the terminal flower phenotype in the Arabidopsis tfl1-11 mutant and delayed flowering in wild-type Arabidopsis Knockdown of CsTFL1 resulted in determinate growth and formation of terminal flowers in cucumber. Biochemical analyses indicated that CsTFL1 interacts with a homolog of the miRNA biogenesis gene CsNOT2a; CsNOT2a interacts with FDP. Cucumber CsFT directly interacts with CsNOT2a and CsFD, and CsFD interacts with two 14-3-3 proteins. These data suggest that CsTFL1 competes with CsFT for interaction with CsNOT2a-CsFDP to inhibit determinate growth and terminal flower formation in cucumber.
Assuntos
Cucumis sativus , Flores/crescimento & desenvolvimento , Flores/genética , Fatores Genéricos de Transcrição/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Sequência Conservada , Cucumis sativus/genética , Cucumis sativus/crescimento & desenvolvimento , Flores/metabolismo , Regulação da Expressão Gênica de Plantas , Redes Reguladoras de Genes , Genes de Plantas , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Proteínas de Plantas/fisiologia , Plantas Geneticamente Modificadas , Polimorfismo de Nucleotídeo Único , Ligação ProteicaRESUMO
In acidic soils, aluminum (Al) toxicity is the main factor inhibiting plant root development and reducing crops yield. STOP1 (SENSITIVE TO PROTON RHIZOTOXICITY 1) was a critical factor in detoxifying Al stress. Under Al stress, STOP1 expression was not induced, although STOP1 protein accumulated, even in the presence of RAE1 (STOP1 DEGRADATION E3-LIGASE). How the Al stress triggers and stabilises the accumulation of STOP1 is still unknown. Here, we characterised SlSTOP1-interacting zinc finger protein (SlSZP1) using a yeast-two-hybrid screening, and generated slstop1, slszp1 and slstop1/slszp1 knockout mutants using clustered regularly interspaced short palindromic repeats (CRISPR) in tomato. SlSZP1 is induced by Al stress but it is not regulated by SlSTOP1. The slstop1, slszp1 and slstop1/slszp1 knockout mutants exhibited hypersensitivity to Al stress. The expression of SlSTOP1-targeted genes, such as SlRAE1 and SlASR2 (ALUMINUM SENSITIVE), was inhibited in both slstop1 and slszp1 mutants, but not directly regulated by SlSZP1. Furthermore, the degradation of SlSTOP1 by SlRAE1 was prevented by SlSZP1. Al stress increased the accumulation of SlSTOP1 in wild-type (WT) but not in slszp1 mutants. The overexpression of either SlSTOP1 or SlSZP1 did not enhance plant Al resistance. Altogether, our results show that SlSZP1 is an important factor for protecting SlSTOP1 from SlRAE1-mediated degradation.
Assuntos
Proteínas de Arabidopsis , Arabidopsis , Alumínio/metabolismo , Alumínio/toxicidade , Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Regulação da Expressão Gênica de Plantas , Raízes de Plantas/metabolismo , Fatores de Transcrição/metabolismo , Dedos de ZincoRESUMO
Initiation and progression of leaf senescence are triggered by various environmental stressors and phytohormones. Jasmonic acid (JA) and darkness accelerate leaf senescence in plants. However, the mechanisms that integrate these two factors to initiate and regulate leaf senescence have not been identified. Here, we report a transcriptional regulatory module centred on a novel tomato WRKY transcription factor, SlWRKY37, responsible for both JA- and dark-induced leaf senescence. The expression of SlWRKY37, together with SlMYC2, encoding a master transcription factor in JA signalling, was significantly induced by both methyl jasmonate (MeJA) and dark treatments. SlMYC2 binds directly to the promoter of SlWRKY37 to activate its expression. Knock out of SlWRKY37 inhibited JA- and dark-induced leaf senescence. Transcriptome analysis and biochemical experiments revealed SlWRKY53 and SlSGR1 (S. lycopersicum senescence-inducible chloroplast stay-green protein 1) as direct transcriptional targets of SlWRKY37 to control leaf senescence. Moreover, SlWRKY37 interacted with a VQ motif-containing protein SlVQ7, and the interaction improved the stability of SlWRKY37 and the transcriptional activation of downstream target genes. Our results reveal the physiological and molecular functions of SlWRKY37 in leaf senescence, and offer a target gene to retard leaf yellowing by reducing sensitivity to external senescence signals, such as JA and darkness.
Assuntos
Solanum lycopersicum , Solanum lycopersicum/genética , Solanum lycopersicum/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Reguladores de Crescimento de Plantas/metabolismo , Senescência Vegetal , Regulação da Expressão Gênica de Plantas , Oxilipinas/metabolismo , Ciclopentanos/metabolismo , Folhas de Planta/metabolismoRESUMO
Phytomelatonin is a small multifunctional molecule found ubiquitously in plants, which plays an important role in plant growth, development, and biotic and abiotic stress responses. The classical biosynthetic and metabolic pathways of phytomelatonin have been elucidated, and uncovering alternative pathways has deepened our understanding of phytomelatonin synthesis. Phytomelatonin functions mainly via two pathways. In the direct pathway, phytomelatonin mediates the stress-induced reactive oxygen species burst through its strong antioxidant capacity. In the indirect pathway, phytomelatonin acts as a signal to activate signaling cascades and crosstalk with other plant hormones. The phytomelatonin receptor PMTR1/CAND2 was discovered in 2018, which enhanced our understanding of phytomelatonin function. This review summarizes the classical and potential pathways involved in phytomelatonin synthesis and metabolism. To elucidate the functions of phytomelatonin, we focus on the crosstalk between phytomelatonin and other phytohormones. We propose two models to explain how PMTR1 transmits the phytomelatonin signal through the G protein and MAPK cascade. This review will facilitate the identification of additional signaling molecules that function downstream of the phytomelatonin signaling pathway, thus improving our understanding of phytomelatonin signal transmission.
Assuntos
Melatonina , Reguladores de Crescimento de Plantas , Antioxidantes , Melatonina/metabolismo , Reguladores de Crescimento de Plantas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais/fisiologia , Estresse FisiológicoRESUMO
Tuber shape is one of the most important quality traits in potato appearance. Since poor or irregular shape results in higher costs for processing and influences the consumers' willingness to purchase, breeding for shape uniformity and shallow eye depth is highly important. Previous studies showed that the major round tuber shape controlling locus, the Ro locus, is located on chromosome 10. However, fine mapping and cloning of tuber shape genes have not been reported. In this study, the analyses of tissue sectioning and transcriptome sequencing showed that the developmental differences between round and elongated tuber shapes begin as early as the hook stage of the stolon. To fine map tuber shape genes, a high-density genetic linkage map of the Ro region on chromosome 10 based on a diploid segregating population was constructed. The total length of the genetic linkage map was 25.8 cM and the average marker interval was 1.98 cM. Combined with phenotypic data collected from 2014 to 2017, one major quantitative trait locus (QTL) for tuber shape was identified, which explained 61.7-72.9% of the tuber shape variation. Through the results of genotyping and phenotypic investigation of recombinant individuals, Ro was fine mapped in a 193.43 kb interval, which contained 18 genes. Five candidate genes were preliminarily predicted based on tissue sections and transcriptome sequencing. This study provides an important basis for cloning Ro gene(s).
Assuntos
Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Loci Gênicos , Tubérculos , Solanum tuberosum , Tubérculos/genética , Tubérculos/metabolismo , Solanum tuberosum/genética , Solanum tuberosum/metabolismoRESUMO
Jasmonic acid (JA) is a key regulator of plant defense responses. Although the transcription factor MYC2, the master regulator of the JA signaling pathway, orchestrates a hierarchical transcriptional cascade that regulates the JA responses, only a few transcriptional regulators involved in this cascade have been described. Here, we identified the basic helix-loop-helix (bHLH) transcription factor gene in tomato (Solanum lycopersicum), METHYL JASMONATE (MeJA)-INDUCED GENE (SlJIG), the expression of which was strongly induced by MeJA treatment. Genetic and molecular biology experiments revealed that SlJIG is a direct target of MYC2. SlJIG knockout plants generated by gene editing had lower terpene contents than the wild type from the lower expression of TERPENE SYNTHASE (TPS) genes, rendering them more appealing to cotton bollworm (Helicoverpa armigera). Moreover, SlJIG knockouts exhibited weaker JA-mediated induction of TPSs, suggesting that SlJIG may participate in JA-induced terpene biosynthesis. Knocking out SlJIG also resulted in attenuated expression of JA-responsive defense genes, which may contribute to the observed lower resistance to cotton bollworm and to the fungus Botrytis cinerea. We conclude that SlJIG is a direct target of MYC2, forms a MYC2-SlJIG module, and functions in terpene biosynthesis and resistance against cotton bollworm and B. cinerea.
Assuntos
Proteínas de Arabidopsis , Solanum lycopersicum , Animais , Proteínas de Arabidopsis/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Ciclopentanos/metabolismo , Ciclopentanos/farmacologia , Regulação da Expressão Gênica de Plantas , Insetos , Solanum lycopersicum/genética , Solanum lycopersicum/metabolismo , Oxilipinas/metabolismo , Oxilipinas/farmacologia , TerpenosRESUMO
BACKGROUND: TLPs (Tubby-like proteins) are widespread in eukaryotes and highly conserved in plants and animals. TLP is involved in many biological processes, such as growth, development, biotic and abiotic stress responses, while the underlying molecular mechanism remains largely unknown. In this paper we characterized the biological function of cucumber (Cucumis sativus L.) Tubby-like protein 8 (CsTLP8) in Arabidopsis. RESULTS: In cucumber, the expression of the tubby-like protein CsTLP8 was induced by NaCl treatment, but reduced by PEG (Polyethylene Glycol) and ABA (Abscisic Acid) treatment. Subcellular localization and transcriptional activation activity analysis revealed that CsTLP8 possessed two characteristics of classical transcription factors: nuclear localization and trans-activation activity. Yeast two-hybrid assay revealed interactions of CsTLP8 with CsSKP1a and CsSKP1c, suggesting that CsTLP8 might function as a subunit of E3 ubiquitin ligase. The growth activity of yeast with ectopically expressed CsTLP8 was lower than the control under NaCl and mannitol treatments. Under osmotic and salt stresses, overexpression of CsTLP8 inhibited seed germination and the growth of Arabidopsis seedlings, increased the content of MDA (Malondialdehyde), and decreased the activities of SOD (Superoxide Dismutase), POD (Peroxidase) and CAT (Catalase) in Arabidopsis seedlings. Overexpression of CsTLP8 also increased the sensitivity to ABA during seed germination and ABA-mediated stomatal closure. CONCLUSION: Under osmotic stress, CsTLP8 might inhibit seed germination and seedling growth by affecting antioxidant enzymes activities. CsTLP8 acts as a negative regulator in osmotic stress and its effects may be related to ABA.
Assuntos
Ácido Abscísico/metabolismo , Cucumis sativus/metabolismo , Germinação , Pressão Osmótica , Proteínas de Plantas/metabolismo , Sementes , Transdução de Sinais , Antioxidantes/metabolismo , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Cucumis sativus/efeitos dos fármacos , Cucumis sativus/crescimento & desenvolvimento , Plântula/metabolismo , Sementes/embriologia , Cloreto de Sódio , Fatores de Transcrição/metabolismo , Ubiquitina-Proteína Ligases/metabolismoRESUMO
As crucial signal transducers, G-proteins and G-protein-coupled receptors (GPCRs) have attracted increasing attention in the field of signal transduction. Research on G-proteins and GPCRs has mainly focused on animals, while research on plants is relatively rare. The mode of action of G-proteins is quite different from that in animals. The G-protein α (Gα) subunit is the most essential member of the G-protein signal cycle in animals and plants. The G-protein is activated when Gα releases GDP and binds to GTP, and the relationships with the GPCR and the downstream signal are also achieved by Gα coupling. It is important to study the role of Gα in the signaling pathway to explore the regulatory mechanism of G-proteins. The existence of a self-activated Gα in plants makes it unnecessary for the canonical GPCR to activate the G-protein by exchanging GDP with GTP. However, putative GPCRs have been found and proven to play important roles in G-protein signal transduction. The unique mode of action of G-proteins and the function of putative GPCRs in plants suggest that the same definition used in animal research cannot be used to study uncanonical GPCRs in plants. This review focuses on the different functions of the Gα and the mode of action between plants and animals as well as the functions of the uncanonical GPCR. This review employs a new perspective to define uncanonical GPCRs in plants and emphasizes the role of uncanonical GPCRs and Gα subunits in plant stress resistance and agricultural production.
Assuntos
Subunidades alfa de Proteínas de Ligação ao GTP/metabolismo , Plantas/metabolismo , Estresse Fisiológico , Animais , Regulação da Expressão Gênica de Plantas , Guanosina Difosfato/metabolismo , Guanosina Trifosfato/metabolismo , Humanos , Desenvolvimento Vegetal , Proteínas de Plantas/metabolismo , Transdução de SinaisRESUMO
The SNAT enzyme participates in the biosynthesis of melatonin, which is reported to regulate thermotolerance in many plants. However, the mechanistic basis of this regulation remains unclear. In this study, we identified the SlSNAT gene, which is responsible for melatonin biosynthesis in tomato. SlSNAT expression levels were 3- and 5-fold higher in SlSNAT overexpression lines OX-2 and OX-6, respectively. The melatonin levels were 3- and 4-fold higher than those in wild type. The melatonin levels decreased by 50% when the expression of SlSNAT was downregulated to 40%. Overexpression of SlSNAT in tomato plants provided significantly enhanced thermotolerance with better growth performance in Photosystem II (PSII) maximum photochemical quantum yield (Fv/Fm) and alleviated heat injury. Both exogenous melatonin treatment and endogenous melatonin manipulation by SlSNAT overexpression decreased the levels of reactive oxygen species�accumulation and Fv/Fm. The SlSNAT overexpression line showed protected ribulose bisphosphate carboxylase oxygenase proteins and upregulated response of heat transcription factors and heat shock proteins under heat stress. HSP40, a DnaJ-type chaperone, was found to interact with SlSNAT in the chloroplast. Downregulation of HSP40 showed lower melatonin synthesis under heat stress. HSP40 functions as a chaperone to protect the SNAT enzyme during melatonin synthesis under heat stress. HSP40 interacted with SlSNAT and together participated in melatonin-related thermotolerance regulation in tomato.
Assuntos
Proteínas de Choque Térmico HSP40/metabolismo , Melatonina/biossíntese , Proteínas de Plantas/metabolismo , Solanum lycopersicum/fisiologia , Termotolerância/fisiologia , Regulação da Expressão Gênica de Plantas , Proteínas de Choque Térmico HSP40/genética , Resposta ao Choque Térmico/genética , Solanum lycopersicum/genética , Modelos Biológicos , Proteínas de Plantas/genética , Ligação Proteica , Espécies Reativas de Oxigênio/metabolismo , Ribulose-Bifosfato Carboxilase/metabolismo , Termotolerância/genéticaRESUMO
Improving plant water-use efficiency (WUE) is important to plant survival and crop yield in the context of water limitation. In this study, SlTLFP8 (Tubby-like F-box protein 8) was identified as an osmotic-induced gene in tomato. Transgenic tomato with up-regulated expression of SlTLFP8 showed enhanced water-deficient resistance, whereas knockout mutants generated by CRISPR/Cas9 were more sensitive to water deficit. SlTLFP8 overexpression significantly enhanced WUE by suppressing transpiration under both water-sufficient and water-deficient conditions. Further study showed that overexpressing SlTLFP8 significantly increased leaf epidermal cell size and thereby decreased stomatal density 10-20%, conversely SlTLFP8 knockout resulted in decreased cell size and thereby increased stomatal density 20-50%. SlTLFP8 overexpression and knockout modulated ploidy levels in leaf cells. Changes in expression of cell cycle related genes also indicated that SlTLFP8 affected cell size and stomatal density through endocycle transition. Despite changes in stomata density and transpiration, altering the expression of SlTLFP8 did not change photosynthesis. Additionally, biomass was not altered and there was little difference in fruit yield for transgenic and wild type lines under water-sufficient and water-deficient conditions. Our results demonstrate the effect of SlTLFP8 on endoreduplication and the potential of SlTLFP8 for improvement of WUE. BRIEF SUMMERY: This work found a new mechanism of TLP (Tubby like protein) response to water-deficient stress. SlTLFP8, a member of TLP family, regulates water-deficient resistance by modulating water loss via affecting stomatal density. Expression of SlTLFP8 was induced by osmotic stress. Transgenic tomato lines with SlTLFP8 overexpression or SlTLFP8 knockout showed significantly differences in water-use efficiency (WUE) and water-deficient resistance. The difference of leaf water loss caused by transpiration is the main explanation of the difference in WUE and water-deficient resistance. Additionally, overexpressing SlTLFP8 significantly decreased stomatal density, while SlTLFP8 knockout resulted in increased stomatal density, and SlTLFP8 affected stomatal density through endoreduplication and altered epidermal cell size. Despite changes in stomata density, altering the expression of SlTLFP8 did not result in distinct changes in photosynthesis, biomass and yield of tomato.
Assuntos
Endorreduplicação , Proteínas F-Box/fisiologia , Proteínas de Plantas/fisiologia , Estômatos de Plantas/anatomia & histologia , Transpiração Vegetal , Água/metabolismo , Proteína 9 Associada à CRISPR , Sistemas CRISPR-Cas , Tamanho Celular , Proteínas F-Box/metabolismo , Técnicas de Silenciamento de Genes , Solanum lycopersicum/genética , Solanum lycopersicum/fisiologia , Proteínas de Plantas/metabolismo , Estômatos de Plantas/fisiologia , Reação em Cadeia da Polimerase em Tempo RealRESUMO
Melatonin plays an important role in stress tolerance in plants. In this study, exogenous melatonin significantly alleviated the dwarf phenotype and inhibited the decrease of plant fresh weight induced by excess copper (Cu2+). Our results indicated that melatonin alleviated Cu2+ toxicity by improving Cu2+ sequestration, carbon metabolism and ROS (reactive oxygen species) scavenging, rather than by influencing the Cu2+ uptake under excess Cu2+ conditions. Transcriptome analysis showed that melatonin broadly altered gene expression under Cu2+ stress. Melatonin increased the levels of glutathione and phytochelatin to chelate excess Cu2+ and promoted cell wall trapping, thus keeping more Cu2+ in the cell wall and vacuole. Melatonin inhibited ROS production and enhanced antioxidant systems at the transcriptional level and enzyme activities, thus building a line of defense in response to excess Cu2+. The distribution of nutrient elements was recovered by melatonin which was disturbed by Cu2+. In addition, melatonin activated carbon metabolism, especially glycolysis and the pentose phosphate pathway, to generate more ATP, an intermediate for biosynthesis. Taken together, melatonin alleviated Cu2+ toxicity in cucumber via multiple mechanisms. These results will help to resolve the toxic effects of Cu2+ stress on plant growth and development. These results can be used for new strategies to solve problems associated with Cu2+ stress.
Assuntos
Cucumis sativus/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Peroxidação de Lipídeos/genética , Peroxidação de Lipídeos/fisiologia , Melatonina/metabolismo , Melatonina/farmacologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Transcriptoma/genéticaRESUMO
The NAC transcription factors play vital roles in responding to drought stress in plants; however, the molecular mechanisms remain largely unknown in cucumber. Suppression of CsATAF1 via RNA interference (RNAi) weakened drought stress tolerance in cucumber due to a higher water loss rate in leaves, a higher level of hydrogen peroxide (H2O2) and superoxide radicals (O2·-), increased malondialdehyde (MDA) content, lower Fv/Fm ratios and lower antioxidant enzyme activity. The analysis of root length and stomatal apertures showed that CsATAF1-RNAi cucumber plants were less responsive to ABA. In contrast, CsATAF1-overexpression (OE) plants showed increased drought stress tolerance and sensitivity to ABA. Quantitative PCR (qPCR) analysis showed that expression of several stress-responsive genes was significantly up-regulated in CsATAF1-OE transformants and down-regulated in CsATAF1-RNAi transformants. CsABI5, CsCu-ZnSOD and CsDREB2C were verified as direct target genes of CsATAF1. Yeast one-hybrid analysis and electrophoretic mobility shift assay (EMSA) further substantiated that CsATAF1 bound to the promoters of CsABI5, CsCu-ZnSOD and CsDREB2C. Transient expression in tobacco leaves and cucumber protoplasts showed that CsATAF1 directly up-regulated the expression of CsABI5, CsCu-ZnSOD and CsDREB2C. Our results demonstrated that CsATAF1 functioned as a positive regulator in response to drought stress by an ABA-dependent pathway and decreasing reactive oxygen species (ROS) accumulation in cucumber.
Assuntos
Ácido Abscísico/farmacologia , Adaptação Fisiológica , Cucumis sativus/fisiologia , Secas , Espécies Reativas de Oxigênio/metabolismo , Estresse Fisiológico , Adaptação Fisiológica/efeitos dos fármacos , Núcleo Celular/efeitos dos fármacos , Núcleo Celular/metabolismo , Cucumis sativus/genética , Cucumis sativus/crescimento & desenvolvimento , Sequestradores de Radicais Livres/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Genes de Plantas , Germinação/efeitos dos fármacos , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Transporte Proteico/efeitos dos fármacos , Interferência de RNA , Análise de Sequência de DNA , Estresse Fisiológico/efeitos dos fármacos , Ativação Transcricional/efeitos dos fármacos , Ativação Transcricional/genéticaRESUMO
To better understand the function of melatonin in tomato fruit ripening and quality improvement, a label-free quantitation method was used to investigate the proteins that differ between the control (CK) and 50 µm melatonin treatment (M50) fruits. Proteomics data identified 241 proteins that were significantly influenced by melatonin. These proteins were involved in several ripening-related pathways, including cell wall metabolism, oxidative phosphorylation, carbohydrate, and fatty acid metabolism. Moreover, the application of exogenous melatonin increased eight proteins that are related to anthocyanin accumulation during fruit ripening. Additionally, the affected protein levels correlated with the corresponding gene transcript levels. Further, the total anthocyanin content from M50 increased by 52%, 48%, and 50% at 5, 8, and 13 DAT (day after melatonin treatment), respectively. The melatonin-mediated promotion of fruit ripening and quality might be due to the altered proteins involved in processes associated with ripening. In this work, we indicated that a senescence-related protein was downregulated in the M50 fruit, while a cell apoptosis inhibitor (API5) protein was upregulated. In addition, peroxidases (POD9, POD12, peroxidase p7-like) and catalase (CAT3) significantly increased in the M50 fruits. Based on the previous studies and our data, we inferred that melatonin might be positively related to fruit ripening but negatively related to fruit senescence. This research provides insights into the physiological and molecular mechanisms underlying melatonin-mediated fruit ripening as well as the anthocyanin formation process in tomato fruit at the protein concentration level, and we reveal possible candidates for regulation of anthocyanin formation during fruit ripening.
Assuntos
Antocianinas/biossíntese , Frutas/metabolismo , Melatonina/farmacologia , Proteínas de Plantas/metabolismo , Proteômica , Solanum lycopersicum/metabolismoRESUMO
In recent years melatonin has emerged as a research highlight in plant studies. Melatonin has different functions in many aspects of plant growth and development. The most frequently mentioned functions of melatonin are related to abiotic stresses such as drought, radiation, extreme temperature, and chemical stresses. This review mainly focuses on the regulatory effects of melatonin when plants face harsh environmental conditions. Evidence indicates that environmental stress can increase the level of endogenous melatonin in plants. Overexpression of the melatonin biosynthetic genes elevates melatonin levels in transgenic plants. The transgenic plants show enhanced tolerance to abiotic stresses. Exogenously applied melatonin can also improve the ability of plants to tolerate abiotic stresses. The mechanisms by which melatonin alleviates abiotic stresses are discussed.
Assuntos
Melatonina/genética , Reguladores de Crescimento de Plantas/genética , Fenômenos Fisiológicos Vegetais , Estresse Fisiológico , Secas , Regulação da Expressão Gênica de Plantas , Melatonina/metabolismo , Reguladores de Crescimento de Plantas/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/metabolismoRESUMO
In this study, the effect of melatonin on the postharvest ripening and quality improvement of tomato fruit was carried out. The tomatoes were immersed in exogenous melatonin for 2h, and then the related physiological indicators and the expression of genes during post-harvest life were evaluated. Compared with control check (CK), the 50 µM melatonin treatment significantly increased lycopene levels by 5.8-fold. Meanwhile, the key genes involved in fruit colour development, including phytoene synthase1 (PSY1) and carotenoid isomerase (CRTISO), showed a 2-fold increase in expression levels. The rate of water loss from tomato fruit also increased 8.3%, and the expression of aquaporin genes, such as SlPIP12Q, SlPIPQ, SlPIP21Q, and SlPIP22, was up-regulated 2- to 3-fold under 50 µM melatonin treatment. In addition, 50 µM melatonin treatment enhanced fruit softening, increased water-soluble pectin by 22.5%, and decreased protopectin by 19.5%. The expression of the cell wall modifying proteins polygalacturonase (PG), pectin esterase1 (PE1), ß-galactosidase (TBG4), and expansin1 (Exp1) was up-regulated under 50 µM melatonin treatment. Melatonin increased ethylene production by 27.1%, accelerated the climacteric phase, and influenced the ethylene signalling pathway. Alteration of ethylene production correlated with altered 1-aminocyclopropane-1-carboxylic acid (ACC) synthase (ACS4) expression. The expression of ethylene signal transduction-related genes such as NR, SlETR4, SlEIL1, SlEIL3, and SlERF2, was enhanced by 50 µM melatonin. The effect of melatonin on ethylene biosynthesis, ethylene perception, and ethylene signalling may contribute to fruit ripening and quality improvement in tomato. This research may promote the application of melatonin on postharvest ripening and quality improvement of tomato fruit as well as other horticultural productions in the future.