IntroductionClass III peroxidase (PRX) functions as a pivotal enzyme in lignin polymerization and participates in the regulation of cell wall hardening and elongation. Nevertheless, comprehensive investigations on PRX involvement in the rind cracking of melon (Cucumis melo) remain absent.MethodsIn this study, melon was used as experimental material. Physiological analyses were performed to compare peroxidase activity and lignin accumulation between cracking-susceptible and resistant cultivars, as well as between cracked and non-cracked rinds. Genome-wide identification, phylogenetic analysis, chromosome localization, collinearity analysis, and cis-acting element prediction were conducted to characterize the melon PRX gene family. Transcriptome sequencing was used to analyze CmPRX expression patterns across different rind types, and quantitative real-time polymerase chain reaction (qRT-PCR) was performed for validation. Protein-protein interaction networks were predicted to explore the functional associations of candidate genes.Results and discussionPeroxidase activity and lignin accumulation were significantly higher in cracking-susceptible cultivars compared to cracking-resistant cultivars, with cracked rinds displaying elevated levels relative to intact rinds. Sixty-four PRX genes were identified in the melon genome, and phylogenetic analysis categorized them into six subgroups. The CmPRX genes were unevenly distributed across 12 chromosomes, and collinearity analysis uncovered eight duplicated gene pairs within the melon genome. Comparative synteny analysis revealed that the number of collinear PRX gene pairs between melon and other Cucurbitaceae species, specially cucumber and watermelon, was greater than that observed with the more distantly related Arabidopsis. Promoter cis-acting element examination revealed that the 64 CmPRX genes harbored 25 classes of elements associated with hormones, stress responses, and growth and development. Transcriptome data from melon rinds revealed that the CmPRX genes could be clustered into six groups based on expression patterns across different rind types. Among these, CmPRX genes in clusters 1 and 6 exhibited higher transcript levels in cracked rinds compared to non-cracked rinds. Moreover, quantitative real-time polymerase chain reaction analyses confirmed that CmPRX39, CmPRX48, and CmPRX51 were expressed at significantly elevated levels in cracked rinds compared with those of non-cracked rinds. Protein interaction network prediction showed that these three candidate genes interacted with multiple proteins involved in the lignin synthesis pathway, suggesting their potential regulatory roles in rind cracking of melon through mediating lignin polymerization. These findings identified candidate genes influencing rind cracking in melon, thereby offering potential molecular targets for the breeding of cracking-resistant cultivars.

Capsaicinoids are a class of unique alkaloids that confer the pungent taste to pepper fruits. However, it remains largely unknown how light regulates the biosynthesis of capsaicinoids. We conducted a metabolic analysis on light- and dark-adapted pepper fruits. The results showed that dark-adapted pepper fruits had lower capsaicinoid contents and correspondingly downregulated transcription of capsaicinoid biosynthetic genes (CBGs), indicating that light plays a crucial role in capsaicinoid biosynthesis. Furthermore, silencing of CaHY5, a pivotal transcription factor gene in the light signaling pathway, decreased the content of capsaicinoid and suppressed the expression of CBGs, whereas transient overexpression of CaHY5 generated exactly opposite results. CaHY5 can bind to the G-box motif in the promoters of CaBBX2 and CaACS8, thereby enhancing their transcriptional levels. The activated CaBBX2 then binds to the T/G-box in the CaACS8 promoter to stimulate its expression. CaBBX2 or CaACS8 silencing led to decreased levels of capsaicinoids, while their transient overexpression produced increased capsaicinoid contents. Collectively, our results indicated that the light-activated CaHY5-CaBBX2-CaACS8 regulatory module plays a pivotal role in capsaicinoid biosynthesis. These findings provide new insights into the influence of light on capsaicinoid biosynthesis and potential targets for activation of this biosynthetic pathway in pepper.

Summary statement Chenopodium quinoa 's long terminal repeat retrotransposons (LTR‐RTs) drive genome expansion, Subgenome B/A divergence, and highland‐lowland ecotype differentiation; key subfamilies (Ogre, CRM) refine polyploidization timing and LTR‐RT insertions in genes enhance environmental adaptation.

As one of the grave environmental hazards, soil salinization seriously limits crop productivity, growth, and development. When plants are exposed to salt stress, they suffer a sequence of damage mainly caused by osmotic stress, ion toxicity, and subsequently oxidative stress. As sessile organisms, plants have developed many physiological and biochemical strategies to mitigate the impact of salt stress. These strategies include altering root development direction, shortening the life cycle, accelerating dormancy, closing stomata to reduce transpiration, and decreasing biomass. Apart from being a prime energy source, light is an environmental signal that profoundly influences plant growth and development and also participates in plants' response to salt stress. This review summarizes the regulatory network of salt tolerance by light signals in plants, which is vital to further understanding plants' adaptation to high salinity. In addition, the review highlights potential future uses of genetic engineering and light supplement technology by light-emitting diode (LED) to improve crop growth in saline-alkali environments in order to make full use of the vast saline land.

Abscisic acid (ABA) plays a key role in promoting the growth and development of plants, as well as mediating the responses of plants to adverse environmental conditions. Here, we measured the photosynthetic capacity of wild-type RR, mutant sitiens (sit), and ABA-pretreated sit tomato seedlings following exposure to low-temperature (LT) stress. We found that the net photosynthetic rate, intercellular carbon dioxide concentration, transpiration rate, and stomatal conductance of sit seedlings were lower than those of RR seedlings under LT stress. The chloroplast width, area, and number of osmiophilic granules were significantly larger in sit seedlings than in RR seedlings, while the chloroplast length/width ratio was significantly lower in sit seedlings than in RR seedlings. The photochemical activity of sit seedlings was lower, and the expression of photosynthesis-related genes in sit seedlings was altered following exposure to LT stress. ABA pretreatment significantly alleviated the above phenomenon. We also conducted an RNA sequencing analysis and characterized the expression patterns of genes in tomato seedlings following exposure to LT stress. We constructed 15 cDNA libraries and identified several differentially expressed genes involved in photosynthesis, plant hormone signaling transduction, and primary and secondary metabolism. Additional analyses of genes encoding transcription factors and proteins involved in photosynthesis-related processes showed pronounced changes in expression under LT stress. Luciferase reporter assay and electrophoretic mobility shift assay revealed that WRKY22 regulates the expression of PsbA. The PSII of WRKY22 and PsbA-silenced plants was inhibited. Our findings indicate that ABA plays a role in regulating the process of photosynthesis and protecting PSII in tomato under LT stress through the WRKY22–PsbA complex.

Stomata are tiny pores on the plant leaf surface that regulate the exchange of water and gases between the plant and the external environment. They are crucial for photosynthesis, water use efficiency (WUE), and the plant’s ability to adapt to environmental changes. Stomatal movement is vital for understanding how plants adapt to environmental stress and optimize resource utilization. Changes in environmental conditions, especially the quality and intensity of light throughout the day, affect stomatal dynamics and diurnal behavior, which in turn impact photosynthetic efficiency and water-use efficiency. In this review, we summarize the biophysical principles and mechanisms of stomatal movement regulated by ion transport at the plasma membrane, vacuolar membrane and metabolic activity through persulfidation or S-nitrosylation modifications. Specifically, we focus on recent progress in the regulation of stomatal movement by different light qualities, and summarize the photochemical and biochemical events underlying photoreceptors as well as the knowledge of novel regulatory functions and signaling in the multilayer control of stomatal movement and environmental adaptation. Furthermore, as rising global temperatures and increased water needs of farming methods are expected to escalate future crop losses, we explore the potential of smart LED lighting and gene editing technology in enhancing photosynthetic efficiency and water-use efficiency, leading to increased crop biomass and higher crop yields.

Nocturnal starch remobilization is critical for plant carbon allocation and stress adaptation. While β-amylase 3 (BAM3) serves as the primary catalyst for starch degradation at night, its regulation mechanisms under stress remain to be fully characterized. The chloroplast vesiculation (CV) protein is crucial for maintaining chloroplast homeostasis during stress conditions, though its potential involvement in starch metabolic processes remains unexplored. Herein, we show that low night temperature (LNT) stress induces starch accumulation in tomato leaves, with SlCV overexpression exacerbating this phenotype and compromising LNT tolerance, whereas SlCV silencing promotes starch catabolism. RNA-seq and metabolome analyses detected lower levels of starch metabolites and amylase activity in SlCV overexpression plants. Strikingly, we have confirmed the physical interaction between SlCV and SlBAM3, and SlCV overexpression significantly accelerated the degradation of SlBAM3 under LNT stress, while SlCV knockout enhanced the stability of SlBAM3. Genetic validation confirmed that SlBAM3-silenced plants accumulate excessive starch and exhibit LNT-sensitive phenotypes, and SlBAM3 overexpression enhances cold tolerance. Furthermore, SlBAM3 complementation rescues the starch overaccumulation and LNT hypersensitivity of SlCV overexpression plants. These results elucidate the regulatory mechanism of starch metabolism mediated by SlCV and associated with SlBAM3 protein stability, providing novel insights into the starch metabolic pathway under cold stress.

PsbS protein is essential for the rapid induction of non-photochemical quenching (NPQ) under low night temperatures (LNTs), but its stability is often affected by adverse environmental conditions. However, the regulatory mechanism for the stability of PsbS or chloroplast proteins remains to be fully characterized. We show that LNT decreases NPQ levels and SlPsbS protein abundance in tomato leaves. LNT-activated chloroplast vesicles (SlCVs) targeting the chloroplasts induce the formation of CV-containing vesicles (CCVs) containing SlPsbS, exported from the chloroplasts. Subsequently, SlCV and SlPsbS contact COP9 signalosome subunit 5A (SlCSN5A) in the cytosol and are ubiquitinated and degraded. Genetic evidence demonstrates that the overexpression of SlCV aggravates SlPsbS protein degradation, whereas silencing of SlCSN5 and SlCV delays LNT-induced NPQ reduction and SlPsbS protein turnover. This study reveals a ubiquitin-dependent degradation pathway of chloroplast proteins co-mediated by CV and CSN5A, thereby providing a basic reference for the regulation of chloroplast protein stability under stress conditions.

FBNs are lipid-associated proteins that play a critical role in plant growth and stress response. However, the mechanisms of how FBNs proteins participate in the low night temperature response in tomato still unclear. Here we conducted a comprehensive genome-wide analysis of the FBN gene family in Solanum lycopersicum. In total, 14 SlFBN genes were identified, and information on their gene structures, protein motifs, phylogenetic relationships, and stress-related cis-regulatory elements (CREs) was provided. Among these, SlFBN11 was selected as a promising candidate for further functional characterization. The silencing of SlFBN11 destroys the redox balance of the PSI reaction center under low night temperature (LNT) stress, which led to increased ROS accumulation. Surprisingly, we found that the silencing of SlFNR2 also displayed an imbalance in electron transport of the PSI under LNT stress. Further experiments showed SlFBN11 can interact with SlFNR2 to positively response electron transport low night temperature. Collectively, the study provides a comprehensive analysis of the FBN genes family in Solanum lycopersicum and provides a theoretical basis for our understanding of the function of FBN genes in adaptation to LNT stresses.

INTRODUCTION:The yield and quality of tomato (Solanum lycopersicum. L) are often decreased when plants suffer from low light intensity and short-photoperiod in winter. Manipulation of the artificial light environment is a feasible technology to promote off-seasonal production and improve fruit nutritional quality in the greenhouse. OBJECTIVES:Here we aim to investigate the appropriate balance between red (R) and blue (B) light to improve tomato yield and quality traits. METHODS:Biochemical, molecular and genetic analysis were used to study the photosynthetic traits, pigments, sugar and volatile accumulation pathway genes. RESULTS:Tomato plants subjected to R1B0.8, a ratio between monochromatic red (R) and blue (B) light, for 16 h photoperiod showed significantly increased chlorophyll and biomass accumulation compared to white (W) light treatment. R1B0.8 light treatment enhanced electron transfer efficiency and photosynthetic capacity by improving the light energy utilization rate and inducing photosystem core subunit genes (SlPsaC, SlPsaB, SlPsaA) and light-harvesting complex genes (SlLHCB/A). Compared to W light, R1B0.8 light also induced carotenoid accumulation and accelerated fruit ripening, which was associated with the upregulation of carotenoid biosynthesis genes (SlPSY1, SlPDS) and ethylene biosynthesis genes (SlACS2, SlACO2) in tomato fruits. Moreover, fruits exposed to R1B0.8 light treatments significantly improved fructose and glucose accumulation and the expression of the volatile-related gene (SlAADC1a) and flavor-related gene (SlGORKY). CONCLUSION:Our results showed that R1B0.8 light with a 16 h photoperiod could prominently promote photosynthetic traits, pigments, sugar and volatile accumulation in tomato. Our findings on the manipulation of artificial light environments in protected horticulture offer possibilities for enhancing crop yield and quality to meet the increasing global demand for food.

Soluble sugar accumulation in fruit ripening determines fleshy fruit quality. However, the molecular mechanism for this process is not yet understood. Here, we showed a transcriptional repressor, CmMYB44 regulates sucrose accumulation and ethylene synthesis in oriental melon (Cucumis. melo var. makuwa Makino) fruit. Overexpressing CmMYB44 suppressed sucrose accumulation and ethylene production. Furthermore, CmMYB44 repressed the transcriptional activation of CmSPS1 (sucrose phosphate synthase 1) and CmACO1 (ACC oxidase 1), two key genes in sucrose and ethylene accumulation, respectively. During the later stages of fruit ripening, the repressive effect of CmMYB44 on CmSPS1 and CmACO1 could be released by overexpressing CmERFI-2 (ethylene response factor I-2) and exogenous ethylene in “HS” fruit (high sucrose accumulation fruit). CmERFI-2 acted upstream of CmMYB44 as a repressor by directly binding the CmMYB44 promoter region, indirectly stimulating the expression level of CmSPS1 and CmACO1. Taken together, we provided a molecular regulatory pathway mediated by CmMYB44, which determines the degree of sucrose and ethylene accumulation in oriental melon fruit and sheds light on transcriptional responses triggered by ethylene sensing that enable the process of fruit ripening.

MicroRNAs (miRNAs) mediate the degradation of target mRNA and inhibit mRNA translation to regulate gene expression at the transcriptional and post-transcriptional levels in response to environmental stress in plants. We characterized the post-transcriptional mechanism by deep sequencing small RNA (sRNA) to examine how miRNAs were involved in low night temperature (LNT) stress in tomato and whether the molecular mechanism depended on the abscisic acid (ABA) signaling pathway. We annotated conserved miRNAs and novel miRNAs with four sRNA libraries composed of wild-type (WT) tomato plants and ABA-deficient mutant (sit) plants under normal growth and LNT stress conditions. Reverse genetics analysis suggested that miR162 participated in LNT resistance and the ABA-dependent signaling pathway in tomato. miR162-overexpressing (pRI-miR162) and miR162-silenced (pRNAi-miR162) transgenic tomato plants were generated to evaluate miR162 functions in response to LNT stress. miR162 deficiency exhibited high photosynthetic capacity and regulated stomatal opening, suggesting negative regulation of miR162 in the ABA-dependent signaling pathway in response to LNT stress. As feedback regulation, miR162 positively regulated ABA to maintain homeostasis of tomato under diverse abiotic stresses. The mRNA of DICER-LIKE1 (DCL1) was targeted by miR162, and miR162 inhibited DCL1 cleavage in LNT response, including the regulation of miRNA160/164/171a and their targets. The DCL1-deficient mutants (dcl1) with CRISPR/Cas9 prevented stomatal opening to influence photosynthesis in the ABA signaling pathway under LNT stress. Finally, we established the regulatory mechanism of ABA-miR162-DCL1, which systematically mediated cold tolerance in tomato. This study suggests that post-transcriptional modulators acted as systemic signal responders via the stress hormone signaling pathway, and the model at the post-transcriptional level presents a new direction for research in plant abiotic stress resistance.

Auxin is a vital phytohormone, but its synthesis pathway is poorly understood. This study used bioinformatic analysis to identify and analyze the gene family members that encode tomato auxin biosynthesis. The FZY gene family members encoding flavin-containing monooxygenases were retrieved from the tomato genome database. DNAMAN analysis revealed nine genes within the landmark domain WL(I/V)VATGENAE, between the FAD and NADPH domains. Phylogenetic analysis showed that the FZY gene family in tomato is closely related to the YUC gene family in Arabidopsis thaliana. A qRT-PCR showed that SlFZY2, SlFZY3, SlFZY4-1, and SlFZY5 were highly expressed in tomato flower organs. The analysis of promoter cis-acting elements revealed light-responsive elements in the promoters of all nine members in tomato, indicating their sensitivity to light signals. Furthermore, the promoters of SlFZY4-2, SlFZY5, and SlFZY7 contain low-temperature-responsive elements. This study demonstrated that SlTAA5 expression was 2.22 times that of SlTAA3 in the roots, and SlTAA3 expression in the pistils was 83.58 times that in the stamens during the tomato flowering stage. Therefore, various members of the tomato FZY gene family are involved in regulating the development of tomato floral organs and are responsive to abiotic stresses, such as low temperature and weak light.

Cold stress is a key environmental constraint that dramatically affects the growth, productivity, and quality of tomato (Solanum lycopersicum); however, the underlying molecular mechanisms of cold tolerance remain poorly understood. In this study, we identified REDUCED CHLOROPLAST COVERAGE 2 (SlREC2) encoding a tetratricopeptide repeat protein that positively regulates tomato cold tolerance. Disruption of SlREC2 largely reduced abscisic acid (ABA) levels, photoprotection, and the expression of C-REPEAT BINDING FACTOR (CBF)-pathway genes in tomato plants under cold stress. ABA deficiency in the notabilis (not) mutant, which carries a mutation in 9-CIS-EPOXYCAROTENOID DIOXYGENASE 1 (SlNCED1), strongly inhibited the cold tolerance of SlREC2-silenced plants and empty vector control plants and resulted in a similar phenotype. In addition, foliar application of ABA rescued the cold tolerance of SlREC2-silenced plants, which confirms that SlNCED1-mediated ABA accumulation is required for SlREC2-regulated cold tolerance. Strikingly, SlREC2 physically interacted with β-RING CAROTENE HYDROXYLASE 1b (SlBCH1b), a key regulatory enzyme in the xanthophyll cycle. Disruption of SlBCH1b severely impaired photoprotection, ABA accumulation, and CBF-pathway gene expression in tomato plants under cold stress. Taken together, this study reveals that SlREC2 interacts with SlBCH1b to enhance cold tolerance in tomato via integration of SlNCED1-mediated ABA accumulation, photoprotection, and the CBF-pathway, thus providing further genetic knowledge for breeding cold-resistant tomato varieties.

Phospholipase C (PLC) can hydrolyze phospholipids to produce phospholipid signals and participate in plant stress response. In this study, we used the HMM method to identify PLC family members in the whole genome of tomato (Solanum lycopersicum L.). Based on the 7 known phosphatidylinositol-specific phospholipase C (SlPI-PLC) genes, 3 nonspecific phospholipase C (NPC) were newly identified. We found that SlPLCs contained a classical conserved domain and high homology with dicotyledonous Arabidopsis PLCs through the domain and evolutionary relationship of 10 genes. A variety of abiotic stress- and hormone-related elements were identified through cis-acting element analysis. Quantitative real-time polymerase chain reaction showed that most of the PLC members expressed differentially under abiotic stresses (low temperature, high temperature, drought, and high salt) and various developmental stages with condition/stage-specific expression and overlapping expression. The expression of SlPLC4 and SlPLC3 increased under low-temperature treatment and salt treatment. Under low temperature and salt stress, net photosynthetic rate and Fv/Fm decreased and electrical leakage increased in TRV-SlPLC4- or TRV-SlPLC3-silenced plants, indicating that PLC gene silencing can decrease abiotic stress resistance in tomato plants. Yeast Two-Hybrid experiment showed that 8 pairs of PLCs interact with each other, which may form dimer polymers within the family to perform specific functions. This study contributes to the understanding of the genome and function of SLPLCs and provides a foundation for further elucidation of the potential mechanism underlying the role of PLC in abiotic stress in tomatoes.

Light signals and plant hormones are involved in regulating the growth, development and stress resistance of plants; however, it remains unclear whether light affects hormones and thus pathogen resistance in oriental melon. Here, we found that red light promoted salicylic acid (SA) accumulation and powdery mildew resistance by activating the transcription of CmICS, the key gene for SA biosynthesis, and silencing CmICS seriously weakened the induction effect of red light on powdery mildew resistance in oriental melon leaves. Further studies showed that red light induced the expression of CmWRKY42 under powdery mildew stress, and CmWRKY42 directly bound to the CmICS promoter to activate its expression and promote the accumulation of SA under red light. Furthermore, we found that PHYTOCHROME INTERACTING FACTOR 8 (PIF8), as a negative regulator of SA biosynthesis, inhibits CmWRKY42 transcriptional activation by binding to the CmWRKY42 promoter, and thus inhibits transcriptional activation of CmICS by CmWRKY42. Also, CmPIF8 binds to the CmICS promoter and directly inhibits its transcription. In conclusion, our study revealed a new molecular mechanism of the relationship between red light-SA-powdery mildew resistance and provided a theoretical basis for resistance breeding of oriental melon.

Cold stress usually causes the abscission of floral organs and a decline in fruit setting rate, seriously reducing tomato yield. Auxin is one of the key hormones that affects the abscission of plant floral organs; the YUCCA (YUC) family is a key gene in the auxin biosynthesis pathway, but there are few research reports on the abscission of tomato flower organs. This experiment found that, under low temperature stress, the expression of auxin synthesis genes increased in stamens but decreased in pistils. Low temperature treatment decreased pollen vigor and pollen germination rate. Low night temperature reduced the tomato fruit setting rate and led to parthenocarpy, and the treatment effect was most obvious in the early stage of tomato pollen development. The abscission rate of tomato pTRV-Slfzy3 and pTRV-Slfzy5 silenced plants was higher than that of the control, which is the key auxin synthesis gene affecting the abscission rate. The expression of Solyc07g043580 was down-regulated after low night temperature treatment. Solyc07g043580 encodes the bHLH-type transcription factor SlPIF4. It has been reported that PIF4 regulates the expression of auxin synthesis and synthesis genes, and is a key protein in the interaction between low temperature stress and light in regulating plant development.

Increasing photosynthesis and light capture offers possibilities for improving crop yield and provides a sustainable way to meet the increasing global demand for food. However, the poor light transmittance of transparent plastic films and shade avoidance at high planting density seriously reduce photosynthesis and alter fruit quality in vegetable crops, and therefore it is important to investigate the mechanisms of light signaling regulation of photosynthesis and metabolism in tomato (Solanum lycopersicum). Here, a combination of red, blue, and white (R1W1B0.5) light promoted the accumulation of chlorophyll, carotenoid, and anthocyanin, and enhanced photosynthesis and electron transport rates by increasing the density of active reaction centers and the expression of the genes LIGHT-HARVESTING COMPLEX B (SlLHCB) and A (SlLHCA), resulting in increased plant biomass. In addition, R1W1B0.5 light induced carotenoid accumulation and fruit ripening by decreasing the expression of LYCOPENE β-CYCLASE (SlCYCB). Disruption of SlCYCB largely induced fruit lycopene accumulation, and reduced chlorophyll content and photosynthesis in leaves under red, blue, and white light. Molecular studies showed that ELONGATED HYPOCOTYL 5 (SlHY5) directly activated SlCYCB, SlLHCB, and SlLHCA expression to enhance chlorophyll accumulation and photosynthesis. Furthermore, R1W1B0.5 light-induced chlorophyll accumulation, photosynthesis, and SlHY5 expression were largely decreased in the slphyb1cry1 mutant. Collectively, R1W1B0.5 light noticeably promoted photosynthesis, biomass, and fruit quality through the photoreceptor (SlPHYB1 and SlCRY1)-SlHY5-SlLHCA/B/SlCYCB module in tomato. Thus, the manipulation of light environments in protected agriculture is a crucial tool to regulate the two vital agronomic traits related to crop production efficiency and fruit nutritional quality in tomato.

Melatonin (MT) functions in removing reactive oxygen species (ROS) and delaying plant senescence, thereby acting as an antioxidant; however, the molecular mechanism underlying the specific action of MT is unclear. Herein, we used the mutant plants carrying the MT decomposition gene melatonin 3‐hydroxylase ( M3H ) in tomato to elucidate the specific mechanism of action of MT. Sl M3H‐OE accelerated senescence by decreasing the content of endogenous MT in plants. Sl M3H is a senescence‐related gene that positively regulates aging. MT inhibited the expression of the senescence‐related gene SlCV to scavenge ROS, induced stable chloroplast structure, and delayed leaf senescence. Simultaneously, MT weakened the interaction between Sl CV and Sl PsbO /Sl CAT3 , reduced ROS production in photosystem II, and promoted ROS elimination. In conclusion, MT regulates ROS homeostasis and delays leaf aging in tomato plants through Sl CV expression modulation.

Plants have evolved sophisticated regulatory networks to cope with dynamically changing light and temperature environments during day-night and seasonal cycles. However, the integration mechanisms of light and low temperature remain largely unclear. Here, we show that low red : far-red ratio (LR : FR) induces FAR-RED ELONGATED HYPOCOTYL3 (SlFHY3) transcription under cold stress in tomato (Solanum lycopersicum). Reverse genetic approaches revealed that knocking out SlFHY3 decreases myo-inositol accumulation and increases cold susceptibility, whereas overexpressing SlFHY3 induces myo-inositol accumulation and enhances cold tolerance in tomato plants. SlFHY3 physically interacts with ELONGATED HYPOCOTYL5 (SlHY5) to promote the transcriptional activity of SlHY5 on MYO-INOSITOL-1-PHOSPHATE SYNTHASE 3 (SlMIPS3) and induce myo-inositol accumulation in tomato plants under cold stress. Disruption of SlHY5 and SlMIPS3 largely suppresses the cold tolerance of SlFHY3-overexpressing plants and myo-inositol accumulation in tomato. Furthermore, silencing of SlMIPS3 drastically reduces myo-inositol accumulation and compromises LR : FR-induced cold tolerance in tomato. Together, our results reveal a crucial role of SlFHY3 in LR : FR-induced cold tolerance in tomato and unravel a novel regulatory mechanism whereby plants integrate dynamic environmental light signals and internal cues (inositol biosynthesis) to induce and control cold tolerance in tomato plants.