Aims: This study aims to characterise the molecular properties and structural features of the non-specific lipid transfer protein (CsnsLTP) gene family and to analyse its expression patterns in cucumber. Candidate CsnsLTP genes that may contribute to resistance to Corynespora cassiicola infection will be identified and may provide valuable genetic resources for molecular breeding against cucumber target leaf spot disease. Study Design: The resistant cultivar Jinyou 38 and the susceptible cultivar Xintaimici were used as plant materials. Seedlings at the two-leaf and one-bud stage were inoculated with C. cassiicola. Samples were collected at eight time points spanning 0–144 h post-inoculation. CsnsLTP family members were identified through a combination of bioinformatic and expression analyses, and their infection-responsive characteristics were subsequently characterised. Methodology: Thirteen CsnsLTP genes were retrieved from the NCBI database. Multiple bioinformatic tools, including ExPASy, CELLO, MEGA, MEME, NCBI Batch CD-Search, and TBtools, were used to systematically characterise the deduced proteins, including their physicochemical properties, subcellular localisation, phylogenetic relationships, chromosomal distribution, conserved motifs, conserved domains, and exon–intron gene structures. Reverse transcription quantitative PCR (RT-qPCR) was then used to quantify the relative transcript abundance of all target genes in resistant and susceptible cucumber cultivars at distinct time points after C. cassiicola inoculation. Results: The 13 CsnsLTP genes were unevenly distributed across chromosomes 1, 3, 4, 5, and 7 and exhibited significant variation in their physicochemical properties. Subcellular localisation predictions indicated that most encoded proteins were localised to the plasma membrane, although some were also predicted to reside in the cell wall, chloroplasts, and other compartments. Phylogenetic analysis classified the family members into three subfamilies, with Motif 1 identified as a conserved motif shared by subfamilies II and III. Expression profiling revealed that CsnsLTP1, CsnsLTP4, CsnsLTP5, CsnsLTP7, CsnsLTP8, CsnsLTP9, CsnsLTP10, CsnsLTP12, and CsnsLTP13 were significantly differentially expressed between resistant and susceptible cultivars following C. cassiicola infection, suggesting that they are candidate genes associated with resistance to target leaf spot in cucumber. Conclusions: This study identified 13 CsnsLTPs in cucumber and systematically characterised their molecular and structural features. Pathogen-induced expression screening identified nine candidate resistance-associated genes. These findings provide candidate genes and a theoretical basis for the molecular genetic improvement of target leaf spot resistance in cucumber.

Carbohydrates are crucial for plant growth and serve as fundamental energy sources, regulated by multiple factors. In tomato, development is closely linked to hormone-mediated sugar metabolism. Although jasmonic acid (JA) is known to function in signaling and growth regulation, its specific role in sugar metabolism remains unclear. This study demonstrated that JA signaling negatively regulates tomato seedling growth. Exogenous application of the JA activator MeJA suppressed growth, whereas the JA inhibitor DIECA and the JA synthesis mutant spr2 promoted it. Further analysis revealed that JA impaired growth by inhibiting photosynthesis-reducing photosynthetic pigment content and efficiency. MeJA treatment increased fructose and glucose levels but decreased sucrose and starch. These changes resulted from downregulated sucrose synthase (SlSS, SlSPS) activity and expression, alongside upregulated acid invertase (SlAI, SlNI) activity and SlTIV1 expression. Thus, JA restricted tomato seedling growth by suppressing photosynthesis and promoting soluble sugar accumulation. Transcriptome analysis identified SlEXPA8, a JA-responsive expansin gene. JA signaling downregulated SlEXPA8 expression; silencing SlEXPA8 impaired photosynthesis, reduced activities of sucrose-metabolizing enzymes, and lowered sucrose and starch levels, inhibiting seedling growth. Overexpression of SlEXPA8, however, enhanced growth. EMSA, ChIP, GUS, and LUC assays confirmed that SlMYC2 directly bound the SlEXPA8 promoter and regulated its transcription. These findings uncovered a mechanism by which JA signaling modulated sugar metabolism via expansin proteins, offering insights for targeted genetic improvement of tomato seedling vigor.

Background: Tomato (Solanum lycopersicum) stress responses are strongly regulated by jasmonic acid signaling—especially via MYB transcription factors—yet key regulators like SlMYB83 in JA-deficient spr2 mutants remain largely uncharacterized. Aims: Based on the tomato SlMYB83 gene previously identified through transcriptome screening, this study aims to elucidate its protein structural characteristics, tissue‑specific expression patterns, and responsive relationship to jasmonic acid (JA) signaling, thereby providing a foundation for subsequent functional studies. Study Design: A research design integrating bioinformatics prediction with gene expression analysis was adopted to systematically characterize the protein properties of SlMYB83 and its expression changes in a mutant and under exogenous hormone treatment. Methods: Bioinformatics analyses were performed using tools such as ProtParam, SignalP-5.0, TMHMM, SOPMA, SWISS-MODEL, Plant-mPLoc, PLANTCARE, and STRING. Quantitative real‑time PCR (qRT‑PCR) was used to examine tissue‑specific expression as well as expression differences in the spr2 mutant and under MeJA treatment. Results: SlMYB83 was characterized as a hydrophilic protein lacking signal peptide and transmembrane domains, localized to the nucleus, and containing a SANT domain. Its promoter harbored stress‑responsive elements including MeJA and ABA. The gene exhibited the highest expression in leaves and the lowest in fruits. SlMYB83 expression was significantly upregulated in the spr2 mutant but markedly downregulated following exogenous MeJA treatment. Conclusions: This study elucidated the fundamental characteristics of the SlMYB83 protein and revealed that JA negatively regulates its expression, thereby laying a foundation for subsequent functional research.

As plant-specific transcription factors (TFs), growth-regulating factors (GRFs) play pivotal roles in regulating plant growth, development, and stress responses. Previous RNA-seq analysis revealed differential expression of CsGRF1 and CsGRF7 in cucumber under Podosphaera xanthii stress, suggesting their potential involvement in powdery mildew (PM) resistance. However, the functions and regulatory mechanisms of CsGRF1 and CsGRF7 in cucumber's defense remain unclear. In this study, we investigated the functional divergence of CsGRF1 and CsGRF7 in cucumber's PM defense. Subcellular localization, transcriptional activity, and protein interaction assays confirmed that both are typical members of the GRF TF family. Functional analyses demonstrated that CsGRF1 positively regulates cucumber resistance to P. xanthii, whereas CsGRF7 suppresses it. Further studies revealed that CsGRF1 enhances disease resistance by maintaining reactive oxygen species (ROS) homeostasis, while CsGRF7 negatively regulates lignin biosynthesis by directly interacting with CsODO1 (an MYB TF that inhibits PM resistance), thereby reducing defense responses. This study elucidates distinct regulatory roles of GRF family members in PM resistance and provides a theoretical foundation for improving cucumber disease resistance.

We resolved that SlMYC2 positively regulated tomato leaf senescence by inhibiting ROS scavenging capacity and exacerbating oxidative damage and PSII functional decline using a darkness-induced senescence model. Tomato leaf senescence seriously affects its yield and quality. Jasmonic acid (JA) signaling can promote tomato leaf senescence, but the mechanism is unclear. SlMYC2, as a core transcription factor in JA signaling, may play a role in regulating leaf senescence. Therefore, this study used SlMYC2 overexpression and silencing lines to systematically analyze the mechanism of SlMYC2 regulation of leaf senescence through a darkness-induced senescence model. The results showed SlMYC2 accelerated the leaf senescence process in tomato by increased chlorophyll degradation and malondialdehyde accumulation in SlMYC2-OE lines after dark treatment, and the expressions of senescence-related genes SlSGR1, SlSAG12, and SlSAG15 were significantly upregulated. At the photosynthetic physiological level, SlMYC2-OE caused damage to photosystem II (PSII) function, with a significant decrease in maximum photochemical efficiency (Fv/Fm) and performance index (PIABS), and exacerbated damage to the donor side (Wk). Further studies found SlMYC2 accelerated programmed cell death (PCD) by promoting the accumulation of reactive oxygen species (ROS). The contents of superoxide anion (O₂⁻·) and hydrogen peroxide (H₂O₂) significantly increased in the SlMYC2-OE lines, while the contents of ascorbic acid (AsA) and glutathione (GSH), as well as the activities and gene expressions of key antioxidant enzymes such as SOD, POD, CAT, APX, and GR were all inhibited. In summary, SlMYC2 has been shown to inhibit the removal of reactive oxygen species (ROS), exacerbate oxidative damage and photosystem II (PSII) function decline, and positively regulate the process of leaf senescence in tomato. This study will provide a theoretical foundation for targeting the JA signaling pathway to regulate tomato senescence.

CsnsLTP6 may participate in balancing ROS signaling and scavenging by enhancing ROS content and antioxidant enzyme activity, thereby mediating the defense response of cucumber. Target leaf spot, caused by Corynespora cassiicola, poses a significant threat to economically important crops such as cucumber (Cucumis sativus). To combat this stress, plants have evolved a range of defense mechanisms that ultimately enhance their resistance. CsnsLTP6, a non-specific lipid transfer protein, has previously been shown to be highly associated with the cucumber’s response to attack by C. cassiicola. Here, we investigated the precise role of CsnsLTP6 in the defense of cucumber against C. cassiicola infection. Comprehensive sequence alignment revealed that CsnsLTP6 harbors a highly conserved nsLTP1 domain. Subcellular localization and tissue-specific expression profiling revealed that CsnsLTP6 is localized to the cell wall and functions primarily in cucumber leaves. Functional assays demonstrated that transient silencing of CsnsLTP6 significantly compromised resistance against C. cassiicola, whereas its overexpression markedly enhanced resistance to this pathogen. Investigation of ROS metabolism in transient transgenic plants indicated that CsnsLTP6 participates in ROS homeostasis via a dual mechanism: it first promotes transient ROS accumulation to activate downstream signaling pathways, then rapidly up-regulates the activities of key antioxidant enzymes and the contents of non-enzymatic antioxidants to scavenge the excess ROS. This coordinated action sustains cellular redox balance and ultimately enhances stress tolerance. Our findings not only identify a promising gene target for breeding stress-resilient cucumber cultivars but also provide new insights into ROS-centered strategies for controlling plant diseases.

Cold stress significantly impairs plant growth and development, making the study of cold resistance mechanisms a critical research focus. Oreorchis patens (Lindl.) exhibits strong cold hardiness, yet its molecular and physiological adaptations to cold stress remain unclear. This study utilized microscopy, physiological assays, and RNA sequencing to comprehensively investigate O. patens’s responses to cold stress. The results reveal that cold stress altered leaf anatomy, leading to irregular mesophyll cells, deformed chloroplasts, and variable epidermal thickness. Physiologically, SOD and POD activities peaked at 5 °C/−10 °C, while CAT activity declined; osmotic regulators (soluble sugars, proline) increased with decreasing temperatures. Compared to the reference plants (e.g., Erigeron canadensis, Allium fistulosum), O. patens exhibited lower SOD and POD but markedly higher CAT activities, alongside reduced MDA, soluble sugars, proline, and proteins, underscoring its distinctive tolerance strategy. Low temperature stress (≤10 °C/5 °C) significantly decreased the SPAD index; the net photosynthetic rate (Pn) initially increased and then approached zero within the temperature range from 30 °C/25 °C to 25 °C/20 °C; transpiration rate (Tr) and stomatal conductance (Gs) changed synchronously, accompanied by an increase in intercellular CO2 concentration (Ci). RNA sequencing identified 1139 cold-responsive differentially expressed genes, which were primarily enriched in flavonoid/lignin biosynthesis, jasmonic acid synthesis, and ROS scavenging pathways. qRT-PCR analysis revealed the role of secondary metabolites in O. patens response to cold stress. This study was the first to discuss the physiological, biochemical, and molecular regulatory mechanisms of O. patens resistance to cold stress, which provides foundational insights into its overwintering mechanisms and informs breeding strategies for cold-hardy horticultural crops in northern China.

Transcription factors MYB, WRKY, bHLH, bZIP and NAC were identified as key candidate genes for JA and TOR regulation of tomato seedling growth and development. Jasmonic acid (JA) and Target of Rapamycin (TOR) signaling pathways interact to regulate plant growth, development, and stress responses. In this study, transcriptomic and weighted gene co-expression network analysis (WGCNA) were conducted on tomato wild-type (WT) and spr2 mutant lines treated with the TOR inhibitor RAP and activator MHY1485. We identified key roles of MAPK kinase and ethylene signaling in mediating JA–TOR interaction. Core transcription factors, including MYB, WRKY, bHLH, bZIP, and NAC, were highlighted as central regulators within the interaction between JA and TOR signaling network. These findings advance our understanding of how JA and TOR signaling coordinate plant growth and stress adaptation.

Cucumber (Cucumis sativus) is an economically important vegetable but powdery mildew (caused by Podosphaera xanthii) limits cucumber production. The WALLS ARE THIN1 (WAT1) gene is crucial for regulating secondary cell wall thickness and is pivotal in plant immune responses. However, the role of WAT1 in cucumber defense against P. xanthii remains poorly characterized. In this study, we identified 47 CsWAT1 genes in the C. sativus genome and classified them into five clusters. Comprehensive analyses of the chromosome location, gene structure, and protein motifs revealed both conserved evolutionary and functional characteristics across plant species, as well as novel features specific to cucumber. Promoter analysis suggested that nine CsWAT1 genes may participate in the cucumber response to P. xanthii stress. Further expression profiling and functional analysis indicated that CsWAT1-20 positively regulates cucumber defense against P. xanthii stress. Our results provide fundamental insights into the characterization of CsWAT1 genes and the function of CsWAT1-20 in P. xanthii defense, laying the groundwork for further studies on the roles of the CsWAT1 gene family in cucumber plants.

Target leaf spot (TLS), caused by Corynespora cassiicola, is a prevalent leaf disease that significantly impacts cucumber yield and quality. Breeding disease-resistant cucumber varieties is a key strategy for managing this disease, and identifying critical resistance genes is essential for genetic improvement. In this study, we identified a highly susceptible mutant to TLS in the Tnt1 retrotransposon mutant library. Bulked segregation analysis sequencing (BSA-seq) further pinpointed a candidate gene for TLS resistance, encoding the Mildew Resistance Locus O (MLO) protein, CsMLO4. Expression analysis revealed that CsMLO4 is strongly induced by C. cassiicola infection. Functional analyses revealed that loss of function and silencing of CsMLO4 attenuated resistance to TLS and exhibited reduced reactive oxygen species (ROS) accumulation, while transient overexpression of CsMLO4 enhanced both disease resistance and ROS levels. These findings suggest that CsMLO4 mediates cucumber defense against C. cassiicola by modulating ROS levels. Additionally, transcriptome analysis identified multiple disease-resistance-related pathways affected by the loss of function of CsMLO4. Overexpression of CsMYB, a potential candidate gene regulated by CsMLO4, showed enhanced resistance to C. cassiicola. This study expands insights into the functional role of MLO family beyond their association with powdery mildew resistance and offers new perspectives on the mechanisms underlying TLS resistance in cucumber.

Tomato (Solanum lycopersicum) is a vital crop in China, yet its growth and quality are compromised by environmental stresses. This study investigated the role of myelocytomatosis (MYC) transcription factors (SlMYCs) in tomato stress tolerance. We identified 23 potential SlMYC genes and analyzed their physicochemical properties, evolutionary relationships, gene structures, conserved domains, expression profiles, interaction networks, promoter sequences, and 3D models using bioinformatics. Phylogenetic analysis classified the SlMYCs into three groups with similar structural characteristics. Protein interaction networks revealed significant connections between SlMYCs and proteins involved in drought, chilling, and salt tolerance, particularly emphasizing the jasmonic acid signaling pathway. Experimental treatments with methyl jasmonate (MeJA) and simulated stress conditions showed that several SlMYC genes were responsive to these stimuli, with SlMYC1 and SlMYC2 demonstrating consistent expression patterns across various tissues. Further network analyses and molecular docking studies indicated potential binding interactions for these two genes. The findings confirmed that SlMYC1 and SlMYC2 contributed to tomato’s abiotic stress tolerance, highlighting their potential for breeding programs aimed at improving stress resilience in tomato varieties. This research laid the groundwork for enhancing tomato varieties under environmental stressors.

Epicuticular wax is the first barrier to protect higher plants from adverse external environments and is affected by light intensity. Meanwhile, the epicuticular wax can affect photosynthesis by influencing the absorption and reflection of light. Hosta 'Halcyon' and Hosta ensata were two genotypes of Hosta differing in the glaucousness of leaf surface. In this research, pot experiments were conducted to study the effects of different light intensities on photosynthetic physiological characteristics and the epicuticular wax content on the leaf surface of two genotypes of Hosta. The results showed that the contents of chlorophyll of two genotypes of Hosta decreased and the chlorophyll a/b increased significantly with the increase of light intensity. The chlorophyll contents of H. 'Halcyon' were more than that of H. ensata. The Pn of two genotypes of Hosta reached the maximum in 50 % relative light intensity. The Fv/Fm of two genotypes of Hosta in sun light were significant higher than those in shade treatments, indicating that strong light inhibited photosynthesis and resulted to light inhibition. H. 'Halcyon' was more adaptable to light intensity than H. ensata. With the increase of light intensity, the epicuticular wax content of H. 'Halcyon' decreased first and reached the minimum in 50 % relative light intensity and then increased, while that of H. ensata decreased gradually. Pn showed a significant negative correlation with the epicuticular max content.

Tomato production in northern China is often susceptible to chilling stress, which seriously affects the growth and development, yield and quality of tomato. Recently, we found that the target of rapamycin (TOR) might be involved in the response to chilling of tomato. So we exogenously applied TOR inhibitor AZD8055 and activator MHY1485 to clarify the role of TOR signaling in tomato response to chilling stress. The research results showed that the damage caused by chilling stress was relieved due to the TOR signaling was inhibited by AZD8055. The development degree of seedlings and root activity increased compared with the control group, while the chilling injury index decreased. At the same time, after the AZD8055 treatment, the REC and MDA contents were significantly decreased, and membrane lipid damage was reduced. NBT and DAB staining results showed that the color was lighter, and the area was smaller under AZD8055 treatment while the contents of O2− and H2O2 increased. Under chilling stress, the application of AZD8055 increased the activity of the antioxidases SOD, CAT, POD, GR, and APX and improved the expression of the SOD, CAT, POD, GR, and APX antioxidase genes. Photosynthetic efficiency, chlorophyll content, energy dissipation and Fv/Fm also improved. The GSH content was reduced, and the GSSG content was increased. In addition, the contents of ASA and soluble protein also increased. Therefore, TOR signaling played a negative regulatory role in tomato response to chilling stress.

Trichomes, which are special structures on the surfaces of plants, play an important role in plant defense. Trichomes in tomatoes are composed of multiple cells that are divided into glandular and non-glandular trichomes. Glandular trichomes can secrete a diverse array of specialized metabolites and terpenes are the main types. Previous studies have shown that JA and TOR signaling are associated with trichomes, and there may be an interaction between these, but the mechanism remains unclear. In this study, JA signaling and its key transcription factor SlMYC1 were shown to regulate the transcript levels of terpene synthesis precursor-related genes (MEP/MVA pathways). SlTOR positively regulated the formation of type VI trichomes through GC-MS, qRT-PCR, and transient transgenic assays, and the synthesis and accumulation of monoterpenes and sesquiterpenes were positively regulated through the expression of key genes for terpene synthesis. Subsequently, SlTOR was the direct target of SlMYC1 by yeast one-hybrid, GUS, and transient expression assays. Collectively, this study revealed that tomato trichomes were regulated by SlTOR, and SlMYC1 mediated the growth and development of trichomes and the synthesis of terpenes by directly binding the promoter of SlTOR to activate its expression. This lays the foundation for the molecular regulatory mechanism of multicellular trichomes.

Main conclusionMYB transcription factors are essential for diverse biology processes in plants. This review has focused on the potential molecular actions of MYB transcription factors in plant immunity.Plants possess a variety of molecules to defend against disease. Transcription factors (TFs) serve as gene connections in the regulatory networks controlling plant growth and defense against various stressors. As one of the largest TF families in plants, MYB TFs coordinate molecular players that modulate plant defense resistance. However, the molecular action of MYB TFs in plant disease resistance lacks a systematic analysis and summary. Here, we describe the structure and function of the MYB family in the plant immune response. Functional characterization revealed that MYB TFs often function either as positive or negative modulators towards different biotic stressors. Moreover, the MYB TF resistance mechanisms are diverse. The potential molecular actions of MYB TFs are being analyzed to uncover functions by controlling the expression of resistance genes, lignin/flavonoids/cuticular wax biosynthesis, polysaccharide signaling, hormone defense signaling, and the hypersensitivity response. MYB TFs have a variety of regulatory modes that fulfill pivotal roles in plant immunity. MYB TFs regulate the expression of multiple defense genes and are, therefore, important for increasing plant disease resistance and promoting agricultural production.

Resistance to disease in plants requires the coordinated action of multiple functionally related genes, as it is difficult to improve disease resistance with a single functional gene. Therefore, the use of transcription factors to regulate the expression of multiple resistance genes to improve disease resistance has become a recent focus in the field of gene research. The basic leucine zipper (bZIP) transcription factor family plays vital regulatory roles in processes, such as plant growth and development and the stress response. In our previous study, CsbZIP90 (Cucsa.134370) was involved in the defense response of cucumber to Podosphaera xanthii, but the relationship between cucumber and resistance to powdery mildew remained unclear. Herein, we detected the function of CsbZIP90 in response to P. xanthii. CsbZIP90 was localized to the cytoplasm and nucleus, and its expression was significantly induced during P. xanthii attack. Transient overexpression of CsbZIP90 in cucumber cotyledons resulted in decreased resistance to P. xanthii, while silencing CsbZIP90 increased resistance to P. xanthii. CsbZIP90 negatively regulated the expression of reactive oxygen species (ROS)-related genes and activities of ROS-related kinases. Taken together, our results show that CsbZIP90 suppresses P. xanthi resistance by modulating ROS. This study will provide target genes for breeding cucumbers resistant to P. xanthii.

Cucumber is a warm climate vegetable that is sensitive to chilling reactions. Chilling can occur at any period of cucumber growth and development and seriously affects the yield and quality of cucumber. Hydrogen (H2) is a type of antioxidant that plays a critical role in plant development and the response to stress. Hydrogen-rich water (HRW) is the main way to use exogenous hydrogen. This study explored the role and mechanism of HRW in the cucumber defense response to chilling stress. The research results showed that applying 50% saturated HRW to the roots of cucumber seedlings relieved the damage caused by chilling stress. The growth and development indicators, such as plant height, stem diameter, leaf area, dry weight, fresh weight, and root length, increased under the HRW treatment. Photosynthetic efficiency, chlorophyll content, and Fv/Fm also improved and reduced energy dissipation. In addition, after HRW treatment, the REC and MDA content were decreased, and membrane lipid damage was reduced. NBT and DAB staining results showed that the color was lighter, and the area was smaller under HRW treatment. Additionally, the contents of O2− and H2O2 also decreased. Under chilling stress, the application of HRW increased the activity of the antioxidases SOD, CAT, POD, GR, and APX and improved the expression of the SOD, CAT, POD, GR, and APX antioxidase genes. The GSSG content was reduced, and the GSH content was increased. In addition, the ASA content also increased. Therefore, exogenous HRW is an effective measure for cucumber to respond to chilling stress.

Nucleotide-binding leucine-rich repeat sequence (NBS-LRR) protein is the main immune receptor in plants and participates in plant resistance to pathogens. When the NBS-LRR protein is activated by the pathogen’s effector protein, its conformation changes from an inhibitory state to an activated state, then it activates downstream signal transduction and initiates defense responses to inhibit the growth of pathogens. The NBS-LRR protein has major three domains: NBS, LRR and TIR/CC, which all play a certain role in the immune response induced by it. In this paper, the NBS-LRR protein domains and their functions, molecular mechanism of the induced immune response and its application in disease resistance breeding are reviewed.

Lignin is a complex phenolic compound that can enhance the stiffness, hydrophobicity, and antioxidant capacity of the cell wall; it thus provides a critical barrier against pathogen and insect invaders. Caffeoyl shikimate esterase (CSE) is a key novel enzyme involved in lignin biosynthesis that is associated with genetic improvements in lignocellulosic biomass; however, no research thus far have revealed the role of CSE in resistance to pathogenic stress. CsCSE1 (Cucsa.134370) has previously been shown to highly associated with the response of cucumber to attack by Podosphaera xanthii through RNA sequencing. Here, we detected the exactly role of CsCSE1 in the defence of cucumber to P. xanthii infection. Homologous sequence alignment revealed that CsCSE1 contains two highly conserved lyase domains (GXSXG), suggesting that CsCSE1 possesses CSE activity. Subcellular localization analysis manifested that CsCSE1 was localized to the plasma membrane and endoplasmic reticulum (ER). Functional analysis demonstrated that the transient silencing of CsCSE1 in cucumber dramatically attenuated resistance to P. xanthii, whereas overexpression of CsCSE1 in cucumber markedly increased resistance to P. xanthii. Further investigation of the abundance of lignin in transient transgenic plants revealed that CsCSE1 might actively mediate the disease resistance of cucumber by promoting lignin biosynthesis. CsCSE1 also affects the expression of its downstream lignin biosynthesis-related genes, like CsLAC, CsCOMT, CsCCR, and CsCAD. The results of this study provide targets for the genetic breeding of tolerant cucumber cultivars as well as new insights that could aid the control of plant diseases.

Tomato (Solanum lycopersicum) is a major vegetable crop cultivated worldwide. The regulation of tomato growth and fruit quality has long been a popular research topic. MYC2 is a key regulator of the interaction between jasmonic acid (JA) signaling and other signaling pathways, and MYC2 can integrate the interaction between JA signaling and other hormone signals to regulate plant growth and development. TOR signaling is also an essential regulator of plant growth and development. However, it is unclear whether MYC2 can integrate JA signaling and TOR signaling during growth and development in tomato. Here, MeJA treatment and SlMYC2 overexpression inhibited the growth and development of tomato seedlings and photosynthesis, but increased the sugar-acid ratio and the contents of lycopene, carotenoid, soluble sugar, total phenol and flavonoids, indicating that JA signaling inhibited the growth of tomato seedlings and altered fruit quality. When TOR signaling was inhibited by RAP, the JA content increased, and the growth and photosynthesis of tomato seedlings decreased, indicating that TOR signaling positively regulated the growth and development of tomato seedlings. Further yeast one-hybrid assays showed that SlMYC2 could bind directly to the SlTOR promoter. Based on GUS staining analysis, SlMYC2 regulated the transcription of SlTOR, indicating that SlMYC2 mediated the interaction between JA and TOR signaling by acting on the promoter of SlTOR. This study provides a new strategy and some theoretical basis for tomato breeding.