Search

Auxin regulates flower and fruit abscission, but how developmental signals mediate auxin transport in abscission remains unclear. Here, we reveal the role of the transcription factor BEL1‐LIKE HOMEODOMAIN11 (SlBEL11) in regulating auxin transport during abscission in tomato (Solanum lycopersicum). SlBEL11 is highly expressed in the fruit abscission zone, and its expression increases during fruit development. Knockdown of SlBEL11 expression by RNA interference (RNAi) caused premature fruit drop at the breaker (Br) and 3 d post‐breaker (Br+3) stages of fruit development. Transcriptome and metabolome analysis of SlBEL11‐RNAi lines revealed impaired flavonoid biosynthesis and decreased levels of most flavonoids, especially quercetin, which functions as an auxin transport inhibitor. This suggested that SlBEL11 prevents premature fruit abscission by modulating auxin efflux from fruits, which is crucial for the formation of an auxin response gradient. Indeed, quercetin treatment suppressed premature fruit drop in SlBEL11‐RNAi plants. DNA affinity purification sequencing (DAP‐seq) analysis indicated that SlBEL11 induced expression of the transcription factor gene SlMYB111 by directly binding to its promoter. Chromatin immunoprecipitation‐quantitative polymerase chain reaction and electrophoretic mobility shift assay showed that S. lycopersicum MYELOBLASTOSIS VIRAL ONCOGENE HOMOLOG111 (SlMYB111) induces the expression of the core flavonoid biosynthesis genes SlCHS1, SlCHI, SlF3H, and SlFLS by directly binding to their promoters. Our findings suggest that the SlBEL11–SlMYB111 module modulates flavonoid biosynthesis to fine‐tune auxin efflux from fruits and thus maintain an auxin response gradient in the pedicel, thereby preventing premature fruit drop. [ABSTRACT FROM AUTHOR]

Fruit locule number is an important agronomic trait that affects fruit appearance, quality, and yield. CLAVATA3 (SlCLV3) is a candidate gene of the fasciated (fas) locus that plays a role in controlling the number of flower organs and fruit locules in tomato. The SlCLV3 encoding signal peptide mainly acts by inhibiting the expression of WUSCHEL (WUS) but there is little research about how the receptor transmits the CLV3 signal to WUS and inhibits its expression. The CRISPR/Cas9 method was employed to edit the first exon of tomato SlCLV3 in this study, leading to the functional deletion of SlCLV3. As a result, flowers with a high number of organs and fruits with a high number of locules were produced. We screened six candidate genes using the transcriptome of clv3 mutants, analyzed expression variations in these genes between the cultivated allele and wild-type allele of fas, and showed that only SlLET6 and SlGIF1 (GRF1-interacting factor 1) were influenced by the fas locus. SlLET6 overexpression resulted in an increase in flower carpels and fruit locules. These results suggest that SlLET6 may be the downstream gene of SlCLV3 regulating the number of carpels and fruit locules in tomato. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Low nocturnal temperature (LNT) is a major constraint for protected tomato production in China during winter and spring, which leads to tomato phosphorus (P) deficiency symptoms. The soil P fractions reflect soil P availability. The foliar and root P fractions reflect the adaptation strategies of tomatoes to LNT. However, the relationship between plant P fractions and soil P fractions under LNT is not well understood. Therefore, we conducted a 40-day indoor incubation experiment with four nocturnal temperatures (15, 12, 9 and 6 °C). Tomato growth status, plant P fractions and soil P fractions were determined. Then, structural equation model (SEM) was used to analyze the direct and/or indirect effects of LNT on soil P fractions, plant P fractions and tomato shoot dry weight (SDW). The results showed that LNT decreased soil P availability by decreasing soil labile P and increasing soil moderately labile P. The foliar inorganic P, metabolite P, nucleic acid P and residual P were decreased under 9 and 6 °C. The root nucleic acid P and lipid P were decreased, while metabolite P was increased under 9 and 6 °C. Tomato foliar and root P fraction allocation was directly influenced by the increase in soil moderately labile P, while the decline in SDW was directly influenced by the decrease in soil labile P. In conclusion, LNT affects tomato P fractions allocation by reducing soil P availability, which limits the shoot dry matter production in tomatoes. [ABSTRACT FROM AUTHOR]

Melatonin is a direct free radical scavenger that has been demonstrated to increase plants' resistance to a variety of stressors. Here, we sought to examine the effect of melatonin on tomato seedlings subjected to low night temperatures using an integrated physiological, transcriptomic, and proteomic approach. We found that a pretreatment with 100 μM melatonin increased photosynthetic and transpiration rates, stomatal apertures, and peroxidase activity, and reduced chloroplast damage of the tomato plant under a low night temperature. The melatonin pretreatment reduced the photoinhibition of photosystem I by regulating the balance of both donor- and acceptor-side restriction of PSI and by increasing electron transport. Furthermore, the melatonin pretreatment improved the photosynthetic performance of proton gradient regulation 5 (SlPGR5) and SlPGR5-like photosynthetic phenotype 1 (SlPGRL1)-suppressed transformants under a low night temperature stress. Transcriptomic and proteomic analyses found that the melatonin pretreatment resulted in the upregulation of genes and proteins related to transcription factors, signal transduction, environmental adaptation, and chloroplast integrity maintenance in low night temperature-stressed tomato plants. Collectively, our results suggest that melatonin can effectively improve the photosynthetic efficiency of tomato plants under a low night temperature and provide novel insights into the molecular mechanism of melatonin-mediated abiotic stress resistance. [ABSTRACT FROM AUTHOR]

Plants often need to withstand multiple types of environmental stresses (e.g., salt and low temperature stress) because of their sessile nature. Although the physiological responses of plants to single stressor have been well-characterized, few studies have evaluated the extent to which pretreatment with non-lethal stressors can maintain the photosynthetic performance of plants in adverse environments (i.e., acclimation-induced cross-tolerance). Here, we studied the effects of sodium chloride (NaCl) pretreatment on the photosynthetic performance of tomato plants exposed to low temperature stress by measuring photosynthetic and chlorophyll fluorescence parameters, stomatal aperture, chloroplast quality, and the expression of stress signaling pathway-related genes. NaCl pretreatment significantly reduced the carbon dioxide assimilation rate, transpiration rate, and stomatal aperture of tomato leaves, but these physiological acclimations could mitigate the adverse effects of subsequent low temperatures compared with non-pretreated tomato plants. The content of photosynthetic pigments decreased and the ultra-microstructure of chloroplasts was damaged under low temperature stress, and the magnitude of these adverse effects was alleviated by NaCl pretreatment. The quantum yield of photosystem I (PSI) and photosystem II (PSII), the quantum yield of regulatory energy dissipation, and non-photochemical energy dissipation owing to donor-side limitation decreased following NaCl treatment; however, the opposite patterns were observed when NaCl-pretreated plants were exposed to low temperature stress. Similar results were obtained for the electron transfer rate of PSI, the electron transfer rate of PSII, and the estimated cyclic electron flow value (CEF). The production of reactive oxygen species induced by low temperature stress was also significantly alleviated by NaCl pretreatment. The expression of ion channel and tubulin-related genes affecting stomatal aperture, chlorophyll synthesis genes, antioxidant enzyme-related genes, and abscisic acid (ABA) and low temperature signaling-related genes was up-regulated in NaCl-pretreated plants under low temperature stress. Our findings indicated that CEF-mediated photoprotection, stomatal movement, the maintenance of chloroplast quality, and ABA and low temperature signaling pathways all play key roles in maintaining the photosynthetic capacity of NaCl-treated tomato plants under low temperature stress. [ABSTRACT FROM AUTHOR]

Low night temperature (LNT) causes environmental stress and has a severe and negative impact on plant growth and productivity. Synthetic elicitors can regulate plant growth and induce defense mechanisms from this type of stress. Here, we evaluated the effect of the exogenous growth regulator diethyl aminoethyl hexanoate (DA-6) in tomato leaf response to LNT stress. Our results showed that exogenous DA-6 activates the expression of chlorophyll synthesis and photosystem-related genes, and results in higher photosynthetic activity and chlorophyll production. Furthermore, DA-6 can regulate the synthesis of endogenous cytokinin (CTK) and the expression of decomposition genes to stabilize chloroplast structure, reduce oxidative damage, and maintain the photochemical activity of tomato leaves under LNT stress. DA-6 maintains a high level of ABA content and induces the expression of CBF genes, indicating that DA-6 may participate in the cold response signaling pathway and induce the expression of downstream low temperature response genes and accumulation of compatible osmolytes. This study unravels a mode of action by which plant growth regulators can improve low temperature tolerance and provides important considerations for their application to alleviate the harmful effects of cold stress. [ABSTRACT FROM AUTHOR]

Soluble carbohydrates not only directly affect plant growth and development but also act as signal molecules in processes that enhance tolerance to cold stress. Raffinose family oligosaccharides (RFOs) are an example and play an important role in abiotic stress tolerance. This study aimed to determine whether galactinol, a key limiting factor in RFO biosynthesis, functions as a signal molecule in triggering cold tolerance. Exposure to low temperatures induces the expression of galactinol synthase (AnGolS1) in Ammopiptanthus nanus , a desert plant that survives temperatures between −30 °C to 47 °C. AnGolS1 has a greater catalytic activity than tomato galactinol synthase (SlGolS2). Moreover, SlGolS2 is expressed only at low levels. Expression of AnGolS1 in tomato enhanced cold tolerance and led to changes in the sugar composition of the seeds and seedlings. AnGolS1 transgenic tomato lines exhibited an enhanced capacity for ethylene (ET) signaling. The application of galactinol abolished the repression of the ET signaling pathway by 1-methylcyclopropene during seed germination. In addition, the expression of ERF transcription factors was increased. Galactinol may therefore act as a signal molecule affecting the ET pathway. [ABSTRACT FROM AUTHOR]

Melatonin (MT) can protect plants against abiotic stress. In order to explore whether melatonin can improve photosynthetic function under NaCl stress, Solanum lycopersicum L. cv. Liaoyuanduoli were exposed to 150 mmol L−1 NaCl stress with or without pretreatment with 150 μmol L−1 melatonin. The results showed that NaCl stress can lead to reduced chlorophyll content, lower photosynthetic function, increased reaction oxygen species (ROS) levels, and decreased PSII activity. These changes were mainly due to the reduction in oxygen-evolving complex (OEC) activity on the donor side of PSII and the blockage of electron transfer from QA to QB on receptor side of PSII. The donor side of PSII was more sensitive to NaCl stress relative to the receptor side of PSII. Interestingly, application of MT enhanced tomato NaCl tolerance. MT reduced the production of ROS by balancing the distribution of photosynthetic electron flux, facilitated the repair of PSII by maintaining the abundance of Psb O and D1, and promoting the ability of the donor and acceptor sides of PSII to deliver electrons. MT also enhanced the scavenging ability of ROS by stimulating the activity of enzymes involved in the AsA-GSH cycle. [ABSTRACT FROM AUTHOR]

Food availability represents a major worldwide concern due to climate change and population growth. Low-temperature stress (LTS) severely restricts the growth of tomato seedlings. Exogenous 5-aminolevulinic acid (ALA) can alleviate the harm of abiotic stress including LTS; however, data on its protective mechanism on tomato seedling roots, the effects of organelle structure, and the regulation of metabolic pathways under LTS are lacking. In this study, we hope to fill the above gaps by exploring the effects of exogenous ALA on morphology, mitochondrial ultrastructure, reactive oxygen species (ROS) enrichment, physiological indicators, related gene expression, and metabolic pathway in tomato seedlings root under LTS. Results showed that ALA pretreatment could increase the activity of antioxidant enzymes and the content of antioxidant substances in tomato seedlings roots under LTS to scavenge the massively accumulated ROS, thereby protecting the mitochondrial structure of roots and promoting root development under LTS. Combined transcriptomic and metabolomic analysis showed that exogenous ALA pretreatment activated the glutathione metabolism and β-alanine metabolism of tomato seedling roots under LTS, further enhanced the scavenging ability of tomato seedling roots to ROS, and improved the low-temperature tolerance of tomato seedlings. The findings provide a new insight into the regulation of the low-temperature tolerance of tomato by exogenous ALA. • Exogenous 5-aminolevulinic acid (ALA) significantly improved low-temperature tolerance in tomatoes. • Exogenous ALA could protect root mitochondria of tomato seedlings under low-temperature stress (LTS). • Exogenous ALA could improve the scavenging ability of tomato seedling roots to reactive oxygen species under LTS. • Exogenous ALA could regulating the glutathione metabolism and β-alanine metabolism of tomato seedling roots under LTS. [ABSTRACT FROM AUTHOR]

Nano-TiO 2 has been reported to promote photosynthesis in some crops; however, the mechanism behind this action remains unknown. In this research, the effects of nano-TiO 2 on leaf photosynthesis under mild heat stress were investigated. Results showed that the net photosynthetic rate, conductance to H 2O, and transpiration rate of tomato leaves increased after application of an appropriate concentration of nano-TiO 2. Nano-TiO 2 also significantly decreased the minimum chlorophyll fluorescence and relative electron transport in leaves. Under mild heat stress, Nano-TiO 2 increased regulated photosystem II (PS II) energy dissipation and decreased non-regulated PS II energy dissipation. These results indicate that nano-TiO 2 plays a positive role in promoting photosynthesis in tomato leaves under mild heat stress. [ABSTRACT FROM AUTHOR]

The number of locules in tomato affects fruit size, shape, and the incidence of malformation. Low temperature increases locule number and the incidences of malformation in tomato plants. In this study, three flower bud developmental stages (pre-flower bud differentiation, sepal and petal primordium formation, and carpel primordium formation) under different night temperatures (10, 15, and 20 °C) were used to analyze the reason behind locule number change using an RNA sequencing (RNA-seq) approach, Quantitative real-time PCR (qRT-PCR), and ultra-performance liquid chromatography–tandem mass spectrometry (UPLC-MS). The results showed that the "plant hormone signal transduction", "starch and sucrose metabolism", and "diterpenoid biosynthesis" categories were remarkably activated during flower bud differentiation. Transcripts of gibberellin (GA)-related genes and endogenous levels of GAs were analyzed, and it was discovered that SlGA2ox genes were significantly downregulated and bioactive GA1 and GA4 accumulated at lower overnight temperature. Exogenous application of bioactive GA1, GA4, and PAC (paclobutrazol) showed that GA1 and GA4 increased the locule number, while PAC decreased the locule number. Taken together, our results suggest that lower overnight temperature reduced the expression of SlGA2ox genes, leading to GA1 and GA4 accumulation, thereby increasing locule number in tomato. [ABSTRACT FROM AUTHOR]

5-Aminolevulinic acid (ALA), an antioxidant existing in plants, has been widely reported to participate in the process of coping with cold stress of plants. In this study, exogenous ALA promoted the growth of tomato plants and alleviated the appearance of purple tomato leaves under low-temperature stress. At the same time, exogenous ALA improved antioxidant enzyme activities, SlSOD gene expression, Fv/Fm, and proline contents and reduced H 2 O 2 contents, SlRBOH gene expression, relative electrical conductivity, and malondialdehyde contents to alleviate the damage caused by low temperature to tomato seedlings. Compared with low-temperature stress, spraying exogenous ALA before low-temperature stress could restore the indicators of photochemical quenching, actual photochemical efficiency, electron transport rate, and nonphotochemical quenching to normal. Exogenous ALA could increase the total contents of the xanthophyll cycle pool, the positive de-epoxidation rate of the xanthophyll cycle and improved the expression levels of key genes in the xanthophyll cycle under low-temperature stress. In addition, we found that exogenous ALA significantly enhanced the absorption of mineral nutrients, promoted the transfer and distribution of mineral nutrients to the leaves, and improved the expression levels of mineral nutrient absorption-related genes, which were all conducive to the improved adaptation of tomato seedlings under low-temperature stress. In summary, the application of exogenous ALA can increase tomato seedlings' tolerance to low-temperature stress by improving the xanthophyll cycle and the ability of the absorption of mineral nutrients in tomato seedlings. • Exogenous 5-aminolevulinic acid (ALA) significantly improved low temperature tolerance in tomatoes. • ALA could improve the xanthophyll cycle ability of tomato seedlings under low-temperature stress. • Exogenous ALA could improve nutrient uptake by tomato seedlings under low-temperature stress. • Exogenous ALA could promote the transformation of mineral nutrition to leaves under low-temperature stress. [ABSTRACT FROM AUTHOR]

Tomato is an important horticultural cash crop, and low-temperature stress has seriously affected the yield and quality of tomato. 5-Aminolevulinic acid (ALA) is widely used in agriculture as an efficient and harmless growth regulator. It is currently unclear whether exogenous ALA can cope with low-temperature stress by regulating tomato starch content and phenylalanine metabolism. In this study, exogenous ALA remarkably improved the low-temperature tolerance of tomato seedlings. RNA-sequencing results showed that exogenous ALA affected starch metabolism and phenylalanine metabolism in tomato seedling leaves under low-temperature stress. Subsequently, we used histochemical staining, observation of chloroplast microstructure, substance content determination, and qRT-PCR analysis to demonstrate that exogenous ALA could improve the low-temperature tolerance of tomato seedlings by regulating starch content and phenylalanine metabolism (SlPAL , SlPOD1 , and SlPOD2). Simultaneously, we found that exogenous ALA induced the expression of SlMYBs and SlWRKYs under low-temperature stress. In addition, dual luciferase, yeast one hybrid, and electrophoretic mobility shift assays indicate that SlMYB4 and SlMYB88 could regulate the expression of SlPOD2 in phenylalanine metabolism. We demonstrated that exogenous ALA could improve the low-temperature tolerance of tomato seedlings by regulating starch content and phenylalanine metabolism. • Exogenous 5-aminolevulinic acid (ALA) significantly improved low temperature tolerance in tomatoes. • ALA could regulating starch content and phenylalanine metabolism of tomato seedlings under low-temperature stress. • SlMYB4 and SlMYB88 could regulate the expression of SlPOD2 in phenylalanine metabolism. [ABSTRACT FROM AUTHOR]

As bivalent cation transporters, UPF0016 family is widely expressed in eukatyotes. UPF0016 family has been shown to regulate plants growth, development and photosynthesis. However, studies of UPF0016 family have not been reported in tomato (Solanum lycopersicum L.), and the biological function of this family is still unclear. In this study, we performed the first comprehensive genome-wide characterization and expression in the UPF0016 family in tomato with 5 UPF0016 family members being identified, named as SlPML1, SlPML2, SlPML3, SlPML4 and SlPML5, which were regulated in a tissue-specific manner. Based on phylogenetic analysis, 5 SlPMLs could be divided into 3 groups, with the character of their chromosome distribution, gene structure and conserved protein motifs of 5 SlPMLs were characterized. RT-qPCR analysis indicated that SlPML may aid regulation of tomato in response to abiotic stress. Among these 5 members, SlPML3 was selected and utilized for further experiments, which might be localized in endomembrane compartments. It was found that SlPML3 could relieve membrane lipid peroxidation and reduce the damage of photosynthesis under drought stress, and further efforts need to be explored on its regulatory mechanism. Thus, this study provides an overview of the UPF0016 family in tomato and lays on valuable resource for further analysis on their function and regulatory mechanisms. • In this study, we performed the first comprehensive genome-wide characterization and expression in the UPF0016 family in tomato. • RT-qPCR analysis indicated that SlPML may aid regulation of tomato in response to abiotic stress (high temperature, low temperature, high-salt stress and drought stress). • SlPML3 could relieve membrane lipid peroxidation and reduce the damage of photosynthesis under drought stress. [ABSTRACT FROM AUTHOR]

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. • Identification of the whole family of tomato PLC, including PI-PLC and NPC. • Whole family analysis of tomato PLC. • Solanum PLCs are sensitive to abiotic stress. • Silencing of SlPLC3 decreased the tolerance of tomato to salt stress. • Silencing of SlPLC4 decreased the tolerance of tomato to low temperature stress. [ABSTRACT FROM AUTHOR]

Vermicompost has great commercial potential in the horticultural industry and its effectiveness is affected by soil water regimes. The effects of vermicompost (VM) on tomato yield and quality and soil fertility were compared with chick compost (CM), horse compost (HM) and chemical fertilizer (CF) in a greenhouse under the three soil water regimes (50–60, 60–70 and 70–80% θ f , θ f i s field capacity). Additionally a control treatment (CK, no fertilization) was included. Under 60–70% θ f , VM increased the yield by 16.3, 9.6, 52.0 and 69.3%, and the vitamin C (V C ) content by 8.2, 59.2, 15.2 and 80.3% when compared to CM, HM, CF and CK, respectively. However, VM decreased the soluble solids and total acidity under three soil water regimes. Total acidity in VM was 17.8, 4.8, 26.4 and 9.1% lower than that in CM, HM, CF and CK, respectively, and the sugar/acid ratio (the ratio of soluble solids to total acidity) in VM was also lower than the other two composts, but higher than CF and CK. VM had the highest sugar/acid ratio under 50–60% θ f . The sugar/acid ratio in VM decreased with the increase of soil water content. VM had lower soil organic matter content than CM and HM, but higher than CF and CK under the three soil water regimes. The soil organic matter content in VM was 17.0 and 12.7% lower than that in CM and HM, but 12.9 and 10.1% higher than that in CF and CK. VM had higher available N and P contents in soil than the other treatments under 70–80% θ f . VM increased the activities of acid phosphatase, catalase and urease in soil compared to the other treatments under the three soil water regimes. Thus vermicompost increased tomato yield and V C under 60–70% of field capacity and the effects of vermicompost on soil fertility varied with soil water regime. [ABSTRACT FROM AUTHOR]

Tomato is often exposed to high temperature stress during summer cultivation. Stomatal movement plays important roles in photosynthesis and transpiration which restricts the quality and yield of tomato under environmental stress. To elucidate the mechanism of stomatal movement in high temperature tolerance, SlSnRK2s (sucrose non-fermenting 1-related protein kinases) silenced plants were generated in tomato with CRISPR-Cas 9 gene editing techniques. Through the observation of stomatal parameters, SlSnRK2.3 regulated stomatal closure which was responded to ABA (abscisic acid) and activated signaling pathway of ROS (reactive oxygen species) in high temperature stress. Based on the positive functions of SlSnRK2.3, the cDNA library was generated to investigate interaction proteins of SlSnRK2s. The interaction between SlSnRK2.3 and SlSUI1 (protein translation factor SUI1 homolog) was employed by Yeast two hybrid assay (Y2H), Luciferase (LUC), and Bimolecular fluorescence complementation (BiFC). Finally, the specific interactive sites between SlSnRK2.3 and SlSUI1 were verified by site-directed mutagenesis. The consistent mechanism of SlSnRK2.3 and SlSUI1 in stomatal movement, indicating that SlSUI1 interacted with SlSnRK2.3 through ABA-dependent signaling pathway in high temperature stress. Our results provided evidence for improving the photosynthetic capacity of tomato under high temperature stress, and support the breeding and genetic engineering of tomato over summer facility cultivation. • SlSnRK2.3 interacts with SlSUI1 in vitro and vivo. • SlSnRK2.3-SlSUI1 interaction proteins enhance the high temperature tolerance via ABA-dependent signaling pathway. • SlSnRK2.3-SlSUI1 interaction proteins mediate stomatal movement and development with ROS scavenging under high temperature stress. [ABSTRACT FROM AUTHOR]

• PGR5/PGRL1-dependent CEF plays an important role in the response to low night temperature stress in tomato leaves. • PGR5/PGRL1-dependent CEF induces NPQ via lumen acidification to protect the donor and acceptor side of PSII. • PGR5/PGRL1-dependent CEF protects the donor side of PSI under low night temperature stress. • PGR5/PGRL1-dependent CEF enhances ROS scavenging by increasing the activity of antioxidant enzymes, and affects the expression of genes encoding key photosystem complex proteins and antioxidant enzymes. Cyclic electron flow (CEF) around photosystem I (PSI) is an important photoprotective mechanism, mediated mainly by PGR5/PGRL1 proteins and the chloroplast NAD(P)H dehydrogenase (NDH) complex. Here, chemical inhibition of PGR5/PGRL1- or NDH-dependent CEF was performed to determine their roles in preventing photoinhibition in tomato leaves under low night temperature (LNT) stress. Experimental treatments were with either antimycin A (A) or rotenone (R) to inhibit PGR5/PGRL1- or NDH-dependent CEF, respectively. The results showed that net photosynthetic rate (P n), antioxidant enzyme activity, maximal photochemistry efficiency (F v / F m), effective photochemical quantum yield of PSII [Y(II)], non-photochemical quenching (NPQ), coefficient of photochemical fluorescence quenching (qP), and effective photochemical quantum yield of PSI [Y(I)] decreased more under LNT following A treatment than following R treatment. In A-treated plants, analysis of the normalized relative variable fluorescence at the K step (V k) and the relative variable fluorescence at the J step (VJ) showed that both the donor and acceptor sides of PSII were severely damaged under LNT. Moreover, the donor side limitation of PSI [Y(ND)] increased whereas the acceptor side limitation of PSI [Y(NA)] decreased and the expression of genes encoding photosystem core subunits was significantly reduced. A treatment also resulted in increased ROS content and inhibition of SOD and APX activities under LNT. These data suggest that PGR5/PGRL1-dependent CEF plays a more important role than NDH-dependent CEF regarding resistance to LNT stress in tomato. [ABSTRACT FROM AUTHOR]