The YABBY Transcription Factor, SlYABBY2a, Positively Regulates Fruit Septum Development and Ripening in Tomatoes.

The tomato fruit is a complex organ and is composed of various structures from the inside out, such as columella, septum, and placenta. However, our understanding of the development and function of these internal structures remains limited. In this study, we identified a plant-specific YABBY protein, SlYABBY2a, in the tomato (Solanum lycopersicum). SlYABBY2a exhibits relatively high expression levels among the nine YABBY genes in tomatoes and shows specific expression in the septum of the fruit. Through the use of a gene-editing technique performed by CRISPR/Cas9, we noticed defects in septum development in the Slyabby2a mutant fruits, leading to the inward concavity of the fruit pericarp and delayed septum ripening. Notably, the expression levels of key genes involved in auxin (SlFZY4, SlFZY5, and SlFZY6) and ethylene (SlACS2) biosynthesis were significantly downregulated in the septum of the Slalkbh10b mutants. Furthermore, the promoter activity of SlYABBY2a was regulated by the ripening regulator, SlTAGL1, in vivo. In summary, these discoveries provide insights into the positive regulation of SlYABBY2a on septum development and ripening and furnish evidence of the coordinated regulation of the auxin and ethylene signaling pathways in the ripening process, which expands our comprehension of septum development in the internal structure of the fruit.

Clinical Observation of Posterior-Chamber Phakic Implantable Collamer Lens V4c Implantation in Myopic Patients with Shallow Anterior Chamber Depth: A Retrospective, Consecutive Observational Study.

Purpose: The reference range for the preoperative anterior chamber angle width for ICL surgery is unclear. Our objective was to assess the clinical effect and the range of anterior chamber angle width of posterior-chamber implantable collamer lens V4c (ICL V4c) implantation in patients with anterior chamber depth (ACD) < 2.8 mm. Methods: Patients who underwent ICL V4c implantation with shallow ACD were included in this retrospective study. The patients' uncorrected and corrected distance visual acuity, angle of trabecular-iris (TIA), angle-opening distance (AOD500), trabecular-iris space area (TISA500), corneal endothelial cell density, vault, retinal nerve fiber layer thickness, intraocular pressure, visual field, and complications were analyzed. Results: Forty-one patients (68 eyes) completed at least 12 months of follow-up (median follow-up, 30 months). The effectiveness and safety indices were 1.09 ± 0.13 and 1.04 ± 0.21, respectively. The preoperative TIA values on the nasal and temporal sides were 39.78 ± 7.68 degree (range, 25.8-65.1 degree) and 41.54 ± 8.03 degree (range, 28.5-63.00 degree). Forty-seven eyes had uncorrected distance visual acuity ≥1.0, and 55 had corrected distance visual acuity ≥1.0 at the last follow-up visit. The TIA, AOD500, and TISA500 on the nasal and temporal sides were significantly reduced compared to those before surgery (all P < 0.01); no eye had an angle closure or elevated intraocular pressure. The ICL V4c vault was 290.88 ± 153.36 µm (range, 60.0-880.0 µm). No severe complications occurred in any patient. Conclusions: In patients with myopia with shallow ACD (2.55-2.79 mm), a preoperative TIA >25.8° is safe and effective for a relatively long time after surgery; however, an extended long-term close follow-up is needed.

A SEPALLATA MADS-Box Transcription Factor, SlMBP21, Functions as a Negative Regulator of Flower Number and Fruit Yields in Tomato.

MADS-box transcription factors act as the crucial regulators in plant organ differentiation. Crop yields are highly influenced by the flower number and fruit growth. However, flower identification is a very complex biological process, which involves many cascade regulations. The molecular mechanisms underlying the genetic regulation of flower identification in cultivated plants, such as tomato, are intricate and require further exploration. In this study, we investigated the vital function of a SEPALLATA (SEP) MADS-box gene, SlMBP21, in tomato sympodial inflorescence meristem (SIM) development for the conversion from SIMs to floral meristems (FMs). SlMBP21 transcripts were primarily accumulated in young inflorescence meristem, flowers, sepals, and abscission zones. The Ailsa Craig (AC++) tomato plants with suppressed SlMBP21 mRNA levels using RNAi exhibited a large increase in flower number and fruit yields in addition to enlarged sepals and inhibited abscission zone development. Scanning electron microscopy (SEM) revealed that the maturation of inflorescence meristems (IMs) was repressed in SlMBP21-RNAi lines. RNA-seq and qRT-PCR analyses showed that numerous genes related to the flower development, plant hormone signal transduction, cell cycle, and cell proliferation et al. were dramatically changed in SlMBP21-RNAi lines. Yeast two-hybrid assay exhibited that SlMBP21 can respectively interact with SlCMB1, SFT, JOINTLESS, and MC, which play key roles in inflorescence meristems or FM development. In summary, our data demonstrate that SlMBP21 functions as a key regulator in SIM development and the conversion from SIMs to FMs, through interacting with other regulatory proteins to control the expression of related genes.

Two SEPALLATA MADS-Box Genes, SlMBP21 and SlMADS1, Have Cooperative Functions Required for Sepal Development in Tomato.

MADS-box transcription factors have crucial functions in numerous physiological and biochemical processes during plant growth and development. Previous studies have reported that two MADS-box genes, SlMBP21 and SlMADS1, play important regulatory roles in the sepal development of tomato, respectively. However, the functional relationships between these two genes are still unknown. In order to investigate this, we simultaneously studied these two genes in tomato. Phylogenetic analysis showed that they were classified into the same branch of the SEPALLATA (SEP) clade. qRT-PCR displayed that both SlMBP21 and SlMADS1 transcripts are preferentially accumulated in sepals, and are increased with flower development. During sepal development, SlMBP21 is increased but SlMADS1 is decreased. Using the RNAi, tomato plants with reduced SlMBP21 mRNA generated enlarged and fused sepals, while simultaneous inhibition of SlMBP21 and SlMADS1 led to larger (longer and wider) and fused sepals than that in SlMBP21-RNAi lines. qRT-PCR results exhibited that the transcripts of genes relating to sepal development, ethylene, auxin and cell expansion were dramatically changed in SlMBP21-RNAi sepals, especially in SlMBP21-SlMADS1-RNAi sepals. Yeast two-hybrid assay displayed that SlMBP21 can interact with SlMBP21, SlAP2a, TAGL1 and RIN, and SlMADS1 can interact with SlAP2a and RIN, respectively. In conclusion, SlMBP21 and SlMADS1 cooperatively regulate sepal development in tomato by impacting the expression or activities of other related regulators or via interactions with other regulatory proteins.

Overexpression of SlCRF6 in tomato inhibits leaf development and affects plant morphology.

Cytokinin response factors (CRFs) are transcription factors (TFs) that are specific to plants and have diverse functions in plant growth and stress responses. However, the precise roles of CRFs in regulating tomato plant architecture and leaf development have not been comprehensively investigated. Here, we identified a novel CRF, SlCRF6, which is involved in the regulation of plant growth via the gibberellin (GA) signaling pathway. SlCRF6-overexpressing (SlCRF6-OE) plants displayed pleiotropic phenotypic changes, including reduced internode length and leaf size, which caused dwarfism in tomato plants. This dwarfism could be alleviated by application of exogenous GA3. Remarkably, quantitative real-time PCR (qRTPCR), a dual luciferase reporter assay and a yeast one-hybrid (Y1H) assay revealed that SlCRF6 promoted the expression of SlDELLA (a GA signal transduction inhibitor) in vivo. Furthermore, transgenic plants displayed variegated leaves and diminished chlorophyll content, resulting in decreased photosynthetic efficiency and less starch than in wild-type (WT) plants. The results of transient expression assays and Y1H assays indicated that SlCRF6 suppressed the expression of SlPHAN (leaf morphology-related gene). Collectively, these findings suggest that SlCRF6 plays a crucial role in regulating tomato plant morphology, leaf development, and the accumulation of photosynthetic products.

Suppression of a hexokinase gene SlHXK1 in tomato affects fruit setting and seed quality.

Hexokinase is considered to be the key molecule in sugar signaling and metabolism. Here, we reported that silencing SlHXK1 resulted in a decrease in flower number, increased rate of flower dropping, abnormal thickening of the anther wall, and reduced pollen and seed viability. An anatomical analysis revealed the loss of small cells and abnormal thickening of anther walls in SlHXK1-RNAi lines. Treatment with auxin and 1-methylcyclopropene inhibited flower dropping from the pedicel abscission zone. qRT-PCR analysis revealed that the effect of SlHXK1 on abscission was associated with the expression levels of genes related to key meristem, auxin, ethylene, cell wall metabolism and programmed cell death. Pollen germination and pollen staining experiments showed that pollen viability was significantly reduced in the SlHXK1-RNAi lines. Physiological and biochemical analyses showed that hexokinase activity and starch content were markedly decreased in the transgenic lines. The expression of genes related to tomato pollen development was also suppressed in the transgenic lines. Although the RNAi lines eventually produced some viable seeds, the yield and quality of the seeds was lower than that of wild-type plants. Yeast two-hybrid and bimolecular fluorescence complementation assays showed that SlHXK1 interacted with SlKINγ. Furthermore, SlPIF4 inhibited the transcriptional expression of SlHXK1. In conclusion, our results demonstrate that SlHXK1 may play important roles in pollen, anther, seed and the pedicel abscission zone by affecting starch accumulation or cell wall synthesis, as well as by regulating the number of the transcripts of genes that are involved in auxin, ethylene and cell wall degradation.

Overexpression of SlPRE3 alters the plant morphologies in Solanum lycopersicum.

KEY MESSAGE: Overexpression of SlPRE3 is detrimental to the photosynthesis and alters plant morphology and root development. SlPRE3 interacts with SlAIF1/SlAIF2/SlPAR1/SlIBH1 to regulate cell expansion. Basic helix-loop-helix (bHLH) transcription factors play crucial roles as regulators in plant growth and development. In this study, we isolated and characterized SlPRE3, an atypical bHLH transcription factor gene. SlPRE3 exhibited predominant expression in the root and moderate expression in the senescent leaves. Comparative analysis with the wild type revealed significant differences in plant morphology in the 35S:SlPRE3 lines. These differences included increased internode length, rolling leaves with reduced chlorophyll accumulation, and elongated yet fewer adventitious roots. Additionally, 35S:SlPRE3 lines displayed elevated levels of GA3 (gibberellin A3) and reduced starch accumulation. Furthermore, utilizing the Y2H (Yeast two-hybrid) and the BiFC (Bimolecular Fluorescent Complimentary) techniques, we identified physical interactions between SlPRE3 and SlAIF1 (ATBS1-interacting factor 1)/SlAIF2 (ATBS1-interacting factor 2)/SlPAR1 (PHYTOCHROME RAPIDLY REGULATED 1)/SlIBH1 (ILI1-binding bHLH 1). RNA-seq analysis of root tissues revealed significant alterations in transcript levels of genes involved in gibberellin metabolism and signal transduction, cell expansion, and root development. In summary, our study sheds light on the crucial regulatory role of SlPRE3 in determining plant morphology and root development.

Down-regulation of SlGT-26 gene confers dwarf plants and enhances drought and salt stress resistance in tomato.

Plant architecture, an important agronomic trait closely associated with yield, is governed by a highly intricate molecular network. Despite extensive research, many mysteries surrounding this regulation remain unresolved. Trihelix transcription factor family plays a crucial role in the development of plant morphology and abiotic stresses. Here, we identified a novel trihelix transcription factor named SlGT-26, and its down-regulation led to significant alterations in plant architecture, including dwarfing, reduced internode length, smaller leaves, and shorter petioles. The dwarf phenotype of SlGT-26 silenced transgenic plants could be recovered after spraying exogenous GA3, and the GA3 content were decreased in the RNAi plants. Additionally, the expression levels of gibberellin-related genes were affected in the RNAi lines. These results indicate that the dwarf of SlGT-26-RNAi plants may be a kind of GA3-sensitive dwarf. SlGT-26 was response to drought and salt stress treatments. SlGT-26-RNAi transgenic plants demonstrated significantly enhanced drought resistance and salt tolerance in comparison to their wild-type tomato counterparts. SlGT-26-RNAi transgenic plants grew better, had higher relative water content and lower MDA and H2O2 contents. The expression of multiple stress-related genes was also up-regulated. In summary, we have discovered a novel gene, SlGT-26, which plays a crucial role in regulating plant architecture and in respond to drought and salt stress.

Trihelix transcription factor SlGT31 regulates fruit ripening mediated by ethylene in tomato.

Trihelix proteins are plant-specific transcription factors that are classified as GT factors due to their binding specificity for GT elements, and they play crucial roles in development and stress responses. However, their involvement in fruit ripening and transcriptional regulatory mechanisms remains largely unclear. In this study, we cloned SlGT31, encoding a trihelix protein in tomato (Solanum lycopersicum), and determined that its relative expression was significantly induced by the application of exogenous ethylene whereas it was repressed by the ethylene-inhibitor 1-methylcyclopropene. Suppression of SlGT31 expression resulted in delayed fruit ripening, decreased accumulation of total carotenoids, and reduced ethylene content, together with inhibition of expression of genes related to ethylene and fruit ripening. Conversely, SlGT31-overexpression lines showed opposite results. Yeast one-hybrid and dual-luciferase assays indicated that SlGT31 can bind to the promoters of two key ethylene-biosynthesis genes, ACO1 and ACS4. Taken together, our results indicate that SlGT31 might act as a positive modulator during fruit ripening.

SlERF.J2 reduces chlorophyll accumulation and inhibits chloroplast biogenesis and development in tomato leaves.

Chlorophyll metabolism and chloroplast biogenesis in tomato (Solanum lycopersicum) leaves contribute to photosynthesis; however, their molecular mechanisms are poorly understood. In this study, we found that overexpression of SlERF.J2 (ethylene transcription factor) resulted in a decrease in leaf chlorophyll content and reduced accumulation of starch and soluble sugar. The slerf.j2 knockout mutant showed no apparent change. Further observation of tissue sections and transmission electron microscopy (TEM) showed that SlERF.J2 was involved in chlorophyll accumulation and chloroplast formation. RNA-seq of mature SlERF.J2-OE leaves showed that many genes involved in chlorophyll biosynthesis and chloroplast formation were significantly downregulated compared with those in WT leaves. Genome global scanning of the ERF TF binding site combined with RNA-seq differential gene expression and qRT-PCR detection analysis showed that COP1 was a potential target gene of SlERF.J2. Tobacco transient expression technology, a dual-luciferase reporter system and Y1H technology were employed to verify that SlERF.J2 could bind to the COP1 promoter. Notably, overexpression of SlERF.J2 in Nr mutants resulted in impaired chloroplast biogenesis and development. Taken together, our findings demonstrated that SlERF.J2 plays an essential role in chlorophyll accumulation and chloroplast formation, laying a foundation for enhancing plant photosynthesis.

A tomato HD-zip I transcription factor, VAHOX1, acts as a negative regulator of fruit ripening.

Homeodomain-leucine zipper (HD-Zip) transcription factors are only present in higher plants and are involved in plant development and stress responses. However, our understanding of their participation in the fruit ripening of economical plants, such as tomato (Solanum lycopersicum), remains largely unclear. Here, we report that VAHOX1, a member of the tomato HD-Zip I subfamily, was expressed in all tissues, was highly expressed in breaker+4 fruits, and could be induced by ethylene. RNAi repression of VAHOX1 (VAHOX1-RNAi) resulted in accelerated fruit ripening, enhanced sensitivity to ethylene, and increased total carotenoid content and ethylene production. Conversely, VAHOX1 overexpression (VAHOX1-OE) in tomato had the opposite effect. RNA-Seq results showed that altering VAHOX1 expression affected the transcript accumulation of a series of genes involved in ethylene biosynthesis and signal transduction and cell wall modification. Additionally, a dual-luciferase reporter assay, histochemical analysis of GUS activity and a yeast one-hybrid (Y1H) assay revealed that VAHOX1 could activate the expression of AP2a. Our findings may expand our knowledge about the physiological functions of HD-Zip transcription factors in tomato and highlight the diversities of transcriptional regulation during the fruit ripening process.

Anthocyanin accumulation and transcriptional regulation in purple flowering stalk (Brassica campestris L. var. purpurea Bailey).

KEY MESSAGE: 1. Purple flowering stalk (Brassica campestris L. ssp. chinensis L. var. purpurea Bailey) is a crop with the high-level anthocyanin. 2. Increased abundance of LBGs promoted the synthesis of anthocyanin. 3. TTG2 (WRKY) interacted with TTG1 (WD40), probably regulating anthocyanin accumulation by shaping a MBWW complex. Brassica crops are a class of nutrient-rich vegetables. Here, two Brassica Crops-Flowering Stalk cultivars, purple flowering stalk (Brassica campestris L. var. purpurea Bailey) and pakchoi (Brassica campestris ssp. chinensis var. communis) were investigated. HPLC-ESI-MS/MS analysis demonstrated that Cy 3-p-coumaroylsophoroside-5-malonylglucoside and Cy 3-diferuloylsophoroside-5-malonylglucoside were identified as the major anthocyanin in peel of purple flowering stalk. The transcript level of structural genes including C4H, CHS, F3H, DFR, ANS and UFGT, and regulatory genes such as TT8, TTG1, Bra004162, Bra001917 and TTG2 in peel of purple flowering stalk were significantly higher than that in peel of pakchoi. In addition, the TTG2(WRKY) interacted only with TTG1(WD40) and the interaction between TT8 (bHLH) and TTG1/Bra004162(MYB)/Bra001917(MYB) were identified. Else, the WD40-WRKY complex (TTG1-TTG2) could activate the transcript of TT12. Our study laid a foundation for the research on the anthocyanin accumulation in Brassica crops.

The AP2/ERF transcription factor SlERF.J2 functions in hypocotyl elongation and plant height in tomato.

KEY MESSAGE: Our findings indicated that the SlERF.J2-IAA23 module integrates hormonal signals to regulate hypocotyl elongation and plant height in tomato. Light and phytohormones can synergistically regulate photomorphogenesis-related hypocotyl elongation and plant height in tomato. AP2/ERF family genes have been extensively demonstrated to play a role in light signaling and various hormones. In this study, we identified a novel AP2/ERF family gene in tomato, SlERF.J2. Overexpression of SlERF.J2 inhibits hypocotyl elongation and plant height. However, the plant height in the slerf.j2ko knockout mutant was not significantly changed compared with the WT. we found that hypocotyl cell elongation and plant height were regulated by a network involving light, auxin and gibberellin signaling, which is mediated by regulatory relationship between SlERF.J2 and IAA23. SlERF.J2 protein could bind to IAA23 promoter and inhibit its expression. In addition, light-dark alternation can activate the transcription of SlERF.J2 and promote the function of SlERF.J2 in photomorphogenesis. Our findings indicated that the SlERF.J2-IAA23 module integrates hormonal signals to regulate hypocotyl elongation and plant height in tomato.

The AlkB Homolog SlALKBH10B Negatively Affects Drought and Salt Tolerance in Solanum lycopersicum.

ALKBH proteins, the homologs of Escherichia coli AlkB dioxygenase, constitute a single-protein repair system that safeguards cellular DNA and RNA against the harmful effects of alkylating agents. ALKBH10B, the first discovered N6-methyladenosine (m6A) demethylase in Arabidopsis (Arabidopsis thaliana), has been shown to regulate plant growth, development, and stress responses. However, until now, the functional role of the plant ALKBH10B has solely been reported in arabidopsis, cotton, and poplar, leaving its functional implications in other plant species shrouded in mystery. In this study, we identified the AlkB homolog SlALKBH10B in tomato (Solanum lycopersicum) through phylogenetic and gene expression analyses. SlALKBH10B exhibited a wide range of expression patterns and was induced by exogenous abscisic acid (ABA) and abiotic stresses. By employing CRISPR/Cas9 gene editing techniques to knock out SlALKBH10B, we observed an increased sensitivity of mutants to ABA treatment and upregulation of gene expression related to ABA synthesis and response. Furthermore, the Slalkbh10b mutants displayed an enhanced tolerance to drought and salt stress, characterized by higher water retention, accumulation of photosynthetic products, proline accumulation, and lower levels of reactive oxygen species and cellular damage. Collectively, these findings provide insights into the negative impact of SlALKBH10B on drought and salt tolerance in tomato plant, expanding our understanding of the biological functionality of SlALKBH10B.

Transcription and Metabolism Pathways of Anthocyanin in Purple Shamrock (Oxalis triangularis A.St.-Hil.).

Anthocyanins are water-soluble pigments that can impart various colors to plants. Purple shamrock (Oxalis triangularis) possesses unique ornamental value due to its purple leaves. In this study, three anthocyanins, including malvidin 3-O-(4-O-(6-O-malonyl-glucopyranoside)-rhamnopyranosyl)-5-O-(6-O-malonyl-glucopyranoside), delphinidin-3-O-rutinoside and malvidin-3,5-di-O-glucoside, were characterized with ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS) in purple shamrock. To investigate the molecular mechanism of anthocyanin biosynthesis in green shamrock (Oxalis corymbosa) and purple shamrock, RNA-seq and qRT-PCR were performed, and the results showed that most of the anthocyanin biosynthetic and regulatory genes were up-regulated in purple shamrock. Then, dark treatment and low temperature treatment experiments in purple shamrock showed that both light and low temperature can induce the biosynthesis of anthocyanins.

Silencing of SlMYB50 affects tolerance to drought and salt stress in tomato.

High salinity and drought stresses often cause plants to produce ROS, including hydrogen peroxide (H2O2) and superoxide (O2-), which interfere with plant growth and affect crop yield. The transcription factors of the MYB family are involved in responses to biotic and abiotic stresses. Here, we isolated the R2R3-MYB transcription factor gene SlMYB50 and found that silencing of SlMYB50 increased resistance to PEG 6000, mannitol and salt. In addition, the resistance of transgenic tomatoes increased under high salt and drought stress. After stress treatment, the relative water content, chlorophyll content (critical for carbon fixation) and root vitality of the SlMYB50-RNAi lines were higher than those of the wild-type (WT). The opposite was true the water loss rate, relative conductivity, and MDA (as a sign of cell wall disruption). Under drought stress conditions, SlMYB50-silenced lines exhibited less H2O2 and less O2- accumulation, as well as higher CAT enzyme activity, than were exhibited by the WT. Notably, after stress treatment, the expression levels of chlorophyll-synthesis-related, flavonoid-synthesis-related, carotenoid-related, antioxidant-enzyme-related and ABA-biosynthesis-related genes were all upregulated in SlMYB50-silenced lines compared to those of WT. A dual-luciferase reporter system was used to verify that SlMYB50 could bind to the CHS1 promoter. In summary, this study identified essential roles for SlMYB50 in regulating drought and salt tolerance.

SlJAZ10 and SlJAZ11 mediate dark-induced leaf senescence and regeneration.

During evolutionary adaptation, the mechanisms for self-regulation are established between the normal growth and development of plants and environmental stress. The phytohormone jasmonate (JA) is a key tie of plant defence and development, and JASMONATE-ZIM DOMAIN (JAZ) repressor proteins are key components in JA signalling pathways. Here, we show that JAZ expression was affected by leaf senescence from the transcriptomic data. Further investigation revealed that SlJAZ10 and SlJAZ11 positively regulate leaf senescence and that SlJAZ11 can also promote plant regeneration. Moreover, we reveal that the SlJAV1-SlWRKY51 (JW) complex could suppress JA biosynthesis under normal growth conditions. Immediately after injury, SlJAZ10 and SlJAZ11 can regulate the activity of the JW complex through the effects of electrical signals and Ca2+ waves, which in turn affect JA biosynthesis, causing a difference in the regeneration phenotype between SlJAZ10-OE and SlJAZ11-OE transgenic plants. In addition, SlRbcs-3B could maintain the protein stability of SlJAZ11 to protect it from degradation. Together, SlJAZ10 and SlJAZ11 not only act as repressors of JA signalling to leaf senescence, but also regulate plant regeneration through coordinated electrical signals, Ca2+ waves, hormones and transcriptional regulation. Our study provides critical insights into the mechanisms by which SlJAZ11 can induce regeneration.

The role of melatonin in tomato stress response, growth and development.

Melatonin has attracted widespread attention after its discovery in higher plants. Tomato is a key model economic crop for studying fleshy fruits. Many studies have shown that melatonin plays important role in plant stress resistance, growth, and development. However, the research progress on the role of melatonin and related mechanisms in tomatoes have not been systematically summarized. This paper summarizes the detection methods and anabolism of melatonin in tomatoes, including (1) the role of melatonin in combating abiotic stresses, e.g., drought, heavy metals, pH, temperature, salt, salt and heat, cold and drought, peroxidation hydrogen and carbendazim, etc., (2) the role of melatonin in combating biotic stresses, such as tobacco mosaic virus and foodborne bacillus, and (3) the role of melatonin in tomato growth and development, such as fruit ripening, postharvest shelf life, leaf senescence and root development. In addition, the future research directions of melatonin in tomatoes are explored in combination with the role of melatonin in other plants. This review can provide a theoretical basis for enhancing the scientific understanding of the role of melatonin in tomatoes and the improved breeding of fruit crops.

Genome-Wide Identification, Classification and Expression Analysis of m6A Gene Family in Solanum lycopersicum.

Advanced knowledge of messenger RNA (mRNA) N6-methyladenosine (m6A) and DNA N6-methyldeoxyadenosine (6 mA) redefine our understanding of these epigenetic modifications. Both m6A and 6mA carry important information for gene regulation, and the corresponding catalytic enzymes sometimes belong to the same gene family and need to be distinguished. However, a comprehensive analysis of the m6A gene family in tomato remains obscure. Here, 24 putative m6A genes and their family genes in tomato were identified and renamed according to BLASTP and phylogenetic analysis. Chromosomal location, synteny, phylogenetic, and structural analyses were performed, unravelling distinct evolutionary relationships between the MT-A70, ALKBH, and YTH protein families, respectively. Most of the 24 genes had extensive tissue expression, and 9 genes could be clustered in a similar expression trend. Besides, SlYTH1 and SlYTH3A showed a different expression pattern in leaf and fruit development. Additionally, qPCR data revealed the expression variation under multiple abiotic stresses, and LC-MS/MS determination exhibited that the cold stress decreased the level of N6 2'-O dimethyladenosine (m6Am). Notably, the orthologs of newly identified single-strand DNA (ssDNA) 6mA writer-eraser-reader also existed in the tomato genome. Our study provides comprehensive information on m6A components and their family proteins in tomato and will facilitate further functional analysis of the tomato N6-methyladenosine modification genes.

Knockout of SlALKBH2 weakens the DNA damage repair ability of tomato.

During the growth and evolution of plants, genomic DNA is subject to constant assault from endogenous and environmental DNA damage compounds, which will result in mutagenic or genotoxic covalent adducts. Whether for prokaryotes, eukaryotes or even viruses, maintaining genome integrity is critical for the continuation of life. Escherichia coli and mammals have evolved the AlkB family of Fe(II)/alpha-ketoglutarate-dependent dioxygenases that repair DNA alkylation damage. We identified a functional homologue with EsAlkB and HsALKBH2 in tomatoes, and named it SlALKBH2. In our study, the SlALKBH2 knockout mutant showed hypersensitivity to the DNA mutagen MMS and displayed more severe growth abnormalities than wild-type plants under mutagen treatment, such as slow growth, leaf deformation and early senescence. Additionally, genes with high transcriptional activity, such as rDNA, have increased methylation under MMS treatment. In conclusion, this study shows that the tomato SlALKBH2 gene may play an important role in ensuring the integrity of the genome.