The genetic basis and improvement of photosynthesis in tomato

Photosynthesis is one the most important chemical reaction in plants,and it is the ultimate energy source of any living organisms.The light and dark reactions are two essential phases of photosynthesis.Light reaction harvests light energy to synthesize ATP and NADPH through an electron transport chain,and as well as giving out O_(2);dark reaction fixes CO_(2) into six carbon sugars by utilizing NADPH and energy from ATP.Subsequently,plants convert optical energy into chemical energy for maintaining growth and development through absorbing light energy.Here,firstly,we highlighted the biological importance of photosynthesis,and hormones and metabolites,photosynthetic and regulating enzymes,and signaling components that collectively regulate photosynthesis in tomato.Next,we reviewed the advances in tomato photosynthesis,including two aspects of genetic basis and genetic improvement.Numerous genes regulating tomato photosynthesis are gradually uncovered,and the interaction network among those genes remains to be constructed.Finally,the photosynthesis occurring in fruit of tomato and the relationship between photosynthesis in leaf and fruit were discussed.Leaves and fruits are photosynthate sources and sinks of tomato respectively,and interaction between photosynthesis in leaf and fruit exists.Additionally,future perspectives that needs to be addressed on tomato photosynthesis were proposed.

Finding the balance: Modifying the cholesterol and steroidal glycoalkaloid synthesis pathway in tomato(Solanum lycopersicum L.) for human health, fruit flavor, and plant defense

Unlike most plants, members of the genus Solanum produce cholesterol and use this as a precursor for steroidal glycoalkaloids. The production of the compounds begins as a branch from brassinosteroid biosynthesis, which produces cholesterol that is further modified to produce steroidal glycoalkaloids. During the cholesterol biosynthesis pathway, genetic engineering could alter the formation of cholesterol from provitamin D3(7-dehydrocholesterol) and produce vitamin D3. Cholesterol is a precursor for many steroidal glycoalkaloids, including a-tomatine and esculeoside A. Alpha-tomatine is consumed by mammals and it can reduce cholesterol content and improve LDL:HDL ratio. When there is a high a-tomatine content, the fruit will have a bitter flavor, which together with other steroidal glycoalkaloids serving as protective and defensive compounds for tomato against insect, fungal, and bacterial pests. These compounds also affect the rhizosphere bacteria by recruiting beneficial bacteria. One of the steroidal glycoalkaloids, esculeoside A increases while fruit ripening. This review focuses on recent studies that uncovered key reactions of the production of cholesterol and steroidal glycoalkaloids in tomato connecting to human health, fruit flavor, and plant defense and the potential application for tomato crop improvement.

A PHYB-PIF4-auxin module promotes tomato graft formation in response to elevated ambient temperature

Grafting is an effective technique for increasing the resistance of vegetables to biotic and abiotic stresses.It has been widely applied to produce solanaceous and melon vegetables.Temperature is an important external factor affecting graft formation.However,the molecular mechanism by which external ambient temperature affects tomato graft formation remains unclear.In this study,we demonstrated that elevating ambient temperature during grafting to 35℃ for more than 24 h after grafting accelerated vascular reconnection.We generated self-or heterografted combinations between phyB1B2 and pif4 loss-of-function mutant and wild-type plants,and were mutants unresponsive to graft formation at elevated ambient temperature.In addition,elevated ambient temperature induced SlPIF4 expression during grafting.SlPIF4 directly binds the promoters of auxin biosynthesis genes SlYUCCAs and activates their expression.Further investigation revealed auxin accumulation in the graft junction under elevated ambient temperature.The results illuminate the mechanism by which the PHYB-PIF4-auxin module promotes tomato graft formation in response to elevated ambient temperature.

Heat shock transcription factors regulate thermotolerance gene networks in tomato(Solanum lycopersicum)flower buds

Tomato(Solanum lycopersicum)is an important fruit and vegetable crop in worldwide.The fertility of tomato reproductive organs can be dramatically decreased when ambient temperatures rise above 35°C,reducing tomato fruit yield.It is necessary to identify transcription factors(TFs)and target genes involved in heat stress response(HSR)signaling cascades in tomato flower buds to improve tomato plant thermotolerance.In this study,we profiled genes expressed in three developmental stages of tomato flower buds.Red and turquoise modules for heat stress(HS)were identified through gene co-expression network analysis,and the genes within these modules were enriched in HS-related pathways.By focusing on the TFs in the two modules,we identified several novel HSR-related TFs,including SlWRKY75,SlMYB117,and SlNAM.Furthermore,homology analysis illustrated a conserved signaling cascade in tomato.Lastly,we identified and experimentally validated four HSF-regulated genes,namely SlGrpE,SlERDJ3A,SlTIL,and SlPOM1,that likely modulate thermotolerance in plants.These results provide a high-resolution atlas of gene expression during tomato flower bud development under HS conditions,which is a valuable resource for uncovering potential regulatory networks associated with the HSR in tomato.

TKN3 affects cell expansion to regulate fruit development in tomato

Tomato is a model system for studying fleshy fruit development.After fertilization,cell division and expansion in the pericarp are crucial for fruit development and determine the final fruit size.TKN3 was found to be expressed in the tomato ovary wall/pericarp of zero to two days post-anthesis fruits as a KNOX I class member,but its function in fruit development was elusive.Here,we found that mutations of TKN3 by CRISPR/Cas9 caused fruit developmental defects,and fruit weight was dramatically reduced in the tkn3cr mutant.Histological observation of fruit pericarps revealed that mutation of TKN3 repressed cell expansion after fertilization,leading to flattened cells in the mesocarp and thereby thinner pericarps in red fruits.Moreover,tkn3cr mutants also displayed pleiotropic phenotypes including enlarged leaves and floral organs,indicating conserved functions in meristem maintenance and leaf development.Yeast two-hybrid and BiFC assays further showed that TKN3 could interact with Solyc10g086640(a homolog of Arabidopsis PNY),which has a similar expression pattern as TKN3.Genome-wide identification of genes regulated by TKN3 indicated that the auxin and gibberellin(GA)pathways might mediate the function of TKN3.Our works revealed that TKN3 controls cell expansion in pericarps,and provides new insights into the roles of KNOX proteins in fruit development.

Effects of Chlorine-Based Fertilizers on Tomato Growth under Soilless Culture

This study investigated the effects of chlorine-based fertilizers under varying nitrogen solution concentrations in a soilless culture system. The experiment included four nitrogen solution concentration levels, with nitrogen concentrations of 6 mmol/L (C1), 12 mmol/L (C2), 18 mmol/L (C3), and 24 mmol/L (C4). Each nutrient concentration level was further divided into four chloride ion treatments (R1, R2, R3, and R4), where 100%, 60%, 33%, and 0% of the NH4+ and K+ ions were derived from NH4Cl and KCl, respectively. The length, surface area and volume of root were significantly higher by 25.3%~136.9%, 40.1%~173.1%, 27.9%~178.0%, respectively, in the R4 treatment than in the R1 and R2 treatments at flowering stage. The aboveground biomass and yield in the R4 treatment were significantly higher, by approximately 15.6%~43.5% and 16.6%~28.6%, respectively, than in the R1, R2, and R3 treatments at the picking stage. The C3 and C4 treatments significantly decreased biomass and yield by 31.9%~50.2% and 20.7%~50.5%, respectively, compared to the C1 and C2 treatments at the picking stage. Besides, the higher nutrient solution increased the incidence of blossom-end rot. In conclusion, high concentrations of chloride ions in nutrient solutions, especially when the Cl− concentration exceeded 10 mmol/L, have been shown to inhibit tomato growth in soilless culture systems. Therefore, replacing sulfur-based fertilizers by chlorine-based fertilizers is not recommended for tomato production under the studied conditions.

SlPGR5/SlPGRL1 pathway-dependent cyclic electron transport regulates photoprotection and chloroplast quality in tomato plants

The essential photoprotective role of proton gradient regulation 5(PGR5)-dependent cyclic electron flow(CEF)has been reported in Arabidopsis,rice,and algae.However,its functional assessment has not been performed in tomato yet.In this study,we focused on elucidate the function of SlPGR5 and SlPGR5-like photosynthetic phenotype 1(PGRL1)in tomato.We performed RNA interference and found that SlPGR5/SlPGRL1-suppressed transformants exhibited extremely low CO_(2)assimilation capacity,their photosystem I(PSI)and PSII were severely photoinhibited and chloroplasts were obviously damaged.The SlPGR5/SlPGRL1-suppressed plants almost completely inhibited CEF and Y(ND),and PSII photoinhibition may be directly related to the inability to produce sufficient proton motive force to induce NPQ.The transgenic plants overexpressing SlPGR5 and SlPGRL1 driven by 35S promoter capable alleviate photoinhibition of plants under low night temperature.The transcriptomic and proteomic analyses suggested that the nuclear gene transcription and turnover of chloroplast proteins,including the plastoglobule-related proteins,were closely related to SlPGR5/SlPGRL1 pathway dependent CEF.The bridge relationship between CEF and chloroplast quality maintenance was a novel report to our knowledge.In conclusion,these results revealed the regulatory mechanism of the SlPGR5/SlPGRL1 pathway in photoprotection and maintenance of chloroplast function in tomato,which is crucial for reduce yield loss,especially under adverse environmental conditions.

Histological,transcriptomic,and gene functional analyses reveal the regulatory events underlying gibberellin-induced parthenocarpy in tomato

Gibberellin(GA)is one of the major plant hormones that promote parthenocarpy,a highly valuable agronomic trait.Here,we demonstrated that exogenous GA3application triggered the formation of parthenocarpic fruits with smaller size but unchanged shape in tomato(Solanum lycopersicum).These fruits exhibited a thicker pericarp,undeveloped ovules,and few jelly tissues,leading to smaller locules with empty cavities.Histological investigation showed that GA treatment produced more cell layers with larger cells in the pericarp,suggesting its promotion in both cell division and expansion.Transcriptomic analyses between GA-3and mock-treated unpollinated ovaries/fruits identified a large number of differentially expressed genes related to hormones,cell division,cell expansion,and transcription factors,implying that they coordinately regulated parthenocarpy conferred by GA.In particular,the downregulation of five reported repressors of tomato parthenocarpy,including two auxin signaling components,AUXIN RESPONSE FACTOR5(SlARF5)and Sl ARF7,and three MADS-box genes,TOMATO APETALA3(TAP3),TOMATO PISTILLATA(TPI),and AGAMOUS-LIKE6(SlAGL6),after GA treatment might play a key role in this process.Furthermore,we found that the knockdown of a GA signaling factor SlMYB33,which was depressed by GA treatment,induced parthenocarpic fruit set in tomato,an effect that might have been achieved by enhancing GA biosynthesis and decreasing the expression of some repressors of tomato parthenocarpy.Thus,our results provide a basis for understanding the regulatory mechanism of GA in tomato parthenocarpy.

Phytoene synthases 1 modulates tomato fruit quality through influencing the metabolic flux between carotenoid and flavonoid pathways

The deterioration in fruit quality of commercial tomatoes is a major concern of modern tomato breeding.However,the metabolism and genetics of fruit quality are poorly understood.Here,we performed transgenic and molecular biology experiments to reveal that tomato phytoene synthase 1(SlPSY1)is responsible for the accumulation of an important flavor chemical,6-methyl-5-hepten-2-one(MHO).To dissect the function of SlPSY1 in regulating fruit quality,we generated and analyzed a dataset encompassing over 2000 compounds detected by GC-MS and LC-MS/MS along with transcriptomic data.The combined results illustrated that SlPSY1 deficiency imparts novel flavor to yellow tomatoes with 236 volatiles significantly changed and improves fruit firmness,possibly due to accumulation of seven cutins.Further analysis indicated SlPSY1 is essential for carotenoid-derived metabolite biosynthesis by catalyzing prephytoene-PP(PPPP)to 15-cis-phytoene.Notably,we showed that SlPSY1 can influence the metabolic flux between carotenoid and flavonoid pathways,and this metabolic flux was confirmed by silencing SlCHS1.Our study provided insights into the multiple effects of SlPSY1 on tomato fruit metabolome and highlights the potential to produce high-quality fruit by rational design of SlPSY1 expression.

Dynamic regulation of the irrigation-nitrogen-biochar nexus for the synergy of yield,quality,carbon emission and resource use efficiency in tomato

Integrated water and fertilizer management is important for promoting sustainable development of facility agriculture,and biochar plays an important role in guaranteeing food production,as well as alleviating water shortages and the overuse of fertilizers.The field experiment had twelve treatments and a control(CK)trial including two irrigation amounts(I1,100%ETm;I2,60%ETm;where ETm is the maximum evapotranspiration),two nitrogen applications(N1,360 kg ha^(−1);N2,120 kg ha^(−1))and three biochar application levels(B1,60 t ha^(−1);B_(2),30 t ha^(−1)and B3,0 t ha^(−1)).A multi-objective synergistic irrigation-nitrogen-biochar application system for improving tomato yield,quality,water and nitrogen use efficiency,and greenhouse emissions was developed by integrating the techniques of experimentation and optimization.First,a coupled irrigation-nitrogen-biochar plot experiment was arranged.Then,tomato yield and fruit quality parameters were determined experimentally to establish the response relationships between irrigation-nitrogen-biochar dosage and yield,comprehensive quality of tomatoes(TCQ),irrigation water use efficiency(IWUE),partial factor productivity of nitrogen(PFPN),and net greenhouse gas emissions(NGE).Finally,a multi-objective dynamic optimization regulation model of irrigation-nitrogen-biochar resource allocation at different growth stages of tomato was constructed which was solved by the fuzzy programming method.The results showed that the application of irrigation and nitrogen to biochar promoted increase in yield,IWUE and PFPN,while it had an inhibitory effect on NGE.In addition,the optimal allocation amounts of water and fertilizer were different under different scenarios.The yield of the S1 scenario increased by 8.31%compared to the B_(1)I_(1)N_(2) treatment;TCQ of the S2 scenario increased by 5.14%compared to the B_(2)I_(2)N_(1) treatment;IWUE of the S3 scenario increased by 10.01%compared to the B1I2N2 treatment;PFPN of the S4 scenario increased by 9.35%compared to the B_(1)I_(1)N_(2) treatment;and NGE of the S5 scenario decreased by 11.23%compared to the B_(2)I1N1 treatment.The optimization model showed that the coordination of multiple objectives considering yield,TCQ,IWUE,PFPN,and NGE increased on average from 4.44 to 69.02%compared to each treatment when the irrigation-nitrogen-biochar dosage was 205.18 mm,186 kg ha^(−1)and 43.31 t ha^(−1),respectively.This study provides a guiding basis for the sustainable management of water and fertilizer in greenhouse tomato production under drip irrigation fertilization conditions.

Time and Space Efficient Multi-Model Convolution Vision Transformer for Tomato Disease Detection from Leaf Images with Varied Backgrounds

A consumption of 46.9 million tons of processed tomatoes was reported in 2022 which is merely 20%of the total consumption.An increase of 3.3%in consumption is predicted from 2024 to 2032.Tomatoes are also rich in iron,potassium,antioxidant lycopene,vitamins A,C and K which are important for preventing cancer,and maintaining blood pressure and glucose levels.Thus,tomatoes are globally important due to their widespread usage and nutritional value.To face the high demand for tomatoes,it is mandatory to investigate the causes of crop loss and minimize them.Diseases are one of the major causes that adversely affect crop yield and degrade the quality of the tomato fruit.This leads to financial losses and affects the livelihood of farmers.Therefore,automatic disease detection at any stage of the tomato plant is a critical issue.Deep learning models introduced in the literature show promising results,but the models are difficult to implement on handheld devices such as mobile phones due to high computational costs and a large number of parameters.Also,most of the models proposed so far work efficiently for images with plain backgrounds where a clear demarcation exists between the background and leaf region.Moreover,the existing techniques lack in recognizing multiple diseases on the same leaf.To address these concerns,we introduce a customized deep learning-based convolution vision transformer model.Themodel achieves an accuracy of 93.51%for classifying tomato leaf images with plain as well as complex backgrounds into 13 categories.It requires a space storage of merely 5.8 MB which is 98.93%,98.33%,and 92.64%less than stateof-the-art visual geometry group,vision transformers,and convolution vision transformermodels,respectively.Its training time of 44 min is 51.12%,74.12%,and 57.7%lower than the above-mentioned models.Thus,it can be deployed on(Internet of Things)IoT-enabled devices,drones,or mobile devices to assist farmers in the real-time monitoring of tomato crops.The periodicmonitoring promotes timely action to prevent the spread of diseases and reduce crop loss.

Tomato detection method using domain adaptive learning for dense planting environments

This study aimed to address the challenge of accurately and reliably detecting tomatoes in dense planting environments,a critical prerequisite for the automation implementation of robotic harvesting.However,the heavy reliance on extensive manually annotated datasets for training deep learning models still poses significant limitations to their application in real-world agricultural production environments.To overcome these limitations,we employed domain adaptive learning approach combined with the YOLOv5 model to develop a novel tomato detection model called as TDA-YOLO(tomato detection domain adaptation).We designated the normal illumination scenes in dense planting environments as the source domain and utilized various other illumination scenes as the target domain.To construct bridge mechanism between source and target domains,neural preset for color style transfer is introduced to generate a pseudo-dataset,which served to deal with domain discrepancy.Furthermore,this study combines the semi-supervised learning method to enable the model to extract domain-invariant features more fully,and uses knowledge distillation to improve the model's ability to adapt to the target domain.Additionally,for purpose of promoting inference speed and low computational demand,the lightweight FasterNet network was integrated into the YOLOv5's C3 module,creating a modified C3_Faster module.The experimental results demonstrated that the proposed TDA-YOLO model significantly outperformed original YOLOv5s model,achieving a mAP(mean average precision)of 96.80%for tomato detection across diverse scenarios in dense planting environments,increasing by 7.19 percentage points;Compared with the latest YOLOv8 and YOLOv9,it is also 2.17 and 1.19 percentage points higher,respectively.The model's average detection time per image was an impressive 15 milliseconds,with a FLOPs(floating point operations per second)count of 13.8 G.After acceleration processing,the detection accuracy of the TDA-YOLO model on the Jetson Xavier NX development board is 90.95%,the mAP value is 91.35%,and the detection time of each image is 21 ms,which can still meet the requirements of real-time detection of tomatoes in dense planting environment.The experimental results show that the proposed TDA-YOLO model can accurately and quickly detect tomatoes in dense planting environment,and at the same time avoid the use of a large number of annotated data,which provides technical support for the development of automatic harvesting systems for tomatoes and other fruits.

A chorismate mutase from Radopholus similis plays an essential role in pathogenicity

In the process of infecting plants, plant parasitic nematodes release a series of proteins that play an essential role in the successful infection and pathogenesis of plant cells and tissues through stylets or body walls. In this study,based on transcriptome data, a chorismate mutase gene of Radopholus similis(RsCM) was identified and cloned,which is a single copy gene specifically expressed in the oesophageal gland and highly expressed in juveniles and females. Transient expression of RsCM in tobacco leaves showed that it was localised in the cytoplasm and nucleus of tobacco leaf cells, which inhibited the pattern-triggered immunity(PTI) induced by flg22, including callose deposition and defence gene expression, and cell death induced by immune elicitors BAX, but could not inhibit cell death induced by immune elicitors Gpa2/RBP-1. The RNA interference(RNAi) transgenic tomato of RsCM obviously inhibited the infection, pathogenicity, and reproduction of R. similis. However, the resistance of the overexpression transgenic tomato of RsCM to R. similis infection was significantly reduced, and the expression levels of two salicylic acid(SA) pathway genes(PR1 and PR5) in roots infected by the nematode were significantly down-regulated,which indicated that RsCM might be involved in the inhibition of SA pathway. The results of this study demonstrate that RsCM suppresses the host immune system and might be a new target for the control of R. similis, which also provides new data for the function and mechanism of CM genes of migratory parasitic plant nematodes.

Functional prediction of tomato PLATZ family members and functional verification of Sl PLATZ17

PLATZ is a novel zinc finger DNA-binding protein that plays an important role in regulating plant growth and development and resisting abiotic stress.However,there has been very little research on the function of this family gene in tomatoes,which limits its application in germplasm resource improvement.Therefore,the PLATZ gene family was identified and analyzed in tomato,and its roles were predicted and verified to provide a basis for in-depth research on SlPLATZ gene function.In this study,the PLATZ family members of tomato were identified in the whole genome,and 19 SlPLATZ genes were obtained.Functional prediction was conducted based on gene and promoter structure analysis and RNA-seq-based expression pattern analysis.SlPLATZ genes that responded significantly under different abiotic stresses or were significantly differentially expressed among multiple tissues were screened as functional gene resources.SlPLATZ17 was selected for functional verification by experiment-based analysis.The results showed that the downregulation of SlPLATZ17 gene expression reduced the drought and salt tolerance of tomato plants.Tomato plants overexpressing SlPLATZ17 had larger flower sizes and long,thin petals,adjacent petals were not connected at the base,and the stamen circumference was smaller.This study contributes to understanding the functions of the SlPLATZ family in tomato and provides a reference for functional gene screening.

Genome-wide analyses of mi RNAs in mycorrhizal plants in response to late blight and elucidation of the role of miR319c in tomato resistance

Tomato(Solanum lycopersicum), an economically important vegetable crop cultivated worldwide, often suffers massive financial losses due to Phytophthora infestans(P. infestans) spread and breakouts. Arbuscular mycorrhiza(AM) fungi mediated biocontrol has demonstrated great potential in plant resistance. However, little information is available on the regulation of mycorrhizal tomato resistance against P. infestans.Therefore, microRNAs(miRNAs) sequencing technology was used to analyse miRNA and their targets in the mycorrhizal tomato after P.infestans infection. Our study showed a lower severity of necrotic lesions in mycorrhizal tomato than in nonmycorrhizal controls. We investigated 35 miRNAs that showed the opposite expression tendency in mycorrhizal and nonmycorrhizal tomato after P. infestans infection when compared with uninfected P. infestans. Among them, miR319c was upregulated in mycorrhizal tomato leaves after pathogen infection. Overexpression of miR319c or silencing of its target gene(TCP1) increased tomato resistance to P. infestans, implying that miR319c acts as a positive regulator in tomato after pathogen infection. Additionally, we examined the induced expression patterns of miR319c and TCP1 in tomato plants exposed to salicylic acid(SA) treatment, and SA content and the expression levels of SA-related genes were also measured in overexpressing transgenic plants. The result revealed that miR319c can not only participates in tomato resistance to P. infestans by regulating SA content, but also indirectly regulates the expression levels of key genes in the SA pathway by regulating TCP1. In this study, we propose a novel mechanism in which the miR319c in mycorrhizal tomato increases resistance to P. infestans.

Spatio-temporal dynamics of phytohormones in the tomato graft healing process

Graft healing involves a series of cytological and molecular events including wound responses, callus formation and vascular bundle remodelling. Hormones are important signalling molecules regulating plant development and responses to environmental stimuli. However,the detailed dynamics of phytohormones in graft healing remain elusive. In this research, internodes above and below the graft site were harvested from 0 to 168 h after grafting(HAG), and liquid chromatography tandem mass spectrometry(LC-MS/MS) was used to determinate jasmonic acid, auxin, cytokinin, ethylene, salicylic acid, abscisic acid and gibberellin levels during the graft healing process. Uniform manifold approximation and projection(UMAP) and k-means analyses were performed to explore hormone spatio-temporal dynamics. We found the stage-specific and asymmetric accumulation of phytohormones in the tomato graft healing process. At the early healing stage(before vascular bundle reconnection), IAA, cZ, ABA, JA and SA mainly accumulated above the graft site, while tZ and ACC mainly accumulated below the graft site. MEIAA, ICAld and IP mainly accumulated at the later stage. Comminated with the healing process, we suggested that JA is mainly involved in wound responses, IAA is beneficial to the formation of callus and vascular cell development, tZ promotes cell division, and IP is linked to vascular bundle remodelling. In addition, expression of JA-related genes SlMYC2 and SlJAZ2, IAA-related gene SlIAA1, tZ-related genes SlHP2 and SlRR8, and IP-related gene SlRR9 correlated with hormone accumulation. The findings provide important information about the hormones and genes involved in the tomato graft healing process.

Enzymatic Characterization of Pectinex XXL,a Pectinase Produced by Aspergillus niger,and Its Application in Fruit Juice Production

Pectinex XXL,a commercially prepared pectinase,was investigated for its potential application in the fruit juice industry.Polygalacturonic acid was used as the substrate for determining the enzymatic properties of Pectinex XXL using the DNS method.According to the results,the optimal pH for Pectinex XXL activity was 4.5,and the enzyme was stable in the pH range of 3.0~4.5.The optimal pH and pH stability range are consistent with those of some tropical and subtropical fruits.The optimal temperature for Pectinex XXL activity was 60℃,and the enzyme remained stable after one hour in a water bath set at 40℃.Additionally,the enzymatic activity was not inhibited in the presence of 1 mmol/L of Na^(+),Mg^(2+),Ba^(2+),Co^(2+),Zn^(2+),and Fe^(2+),whereas it was slightly inhibited in the presence of 2 mmol/L of K^(+)and Fe^(2+)and partially inhibited in the presence of 1 and 2 mmol/L of Ca^(2+)and Mn^(2+),demonstrating its good stability in acids and excellent thermal catalytic performance.Based on the above experimental results,depectinization experiments were performed on plantain and cherry tomato juices using different amounts of Pectinex XXL.After one hour reaction with 16 U/mL of the enzyme,the yields of the plantain and cherry tomato juices were substantially increased by 119.03%and 15.97%,respectively,while their light transmittance was remarkably enhanced by 37.65%and 12.35%,respectively.Furthermore,the enzyme reduced the viscosity of the plantain and cherry tomato juices by 88.29%and 29.50%,respectively.The juice production experiments confirmed that this enzyme can significantly improve the yield and light transmittance of plantain juice,while effectively reducing its viscosity.These findings indicate the potential of Pectinex XXL in the industrial production of plantain juice.

Heat-inducible SlWRKY3 confers thermotolerance by activating the SlGRXS1 gene cluster in tomato

High temperature stress is one of the major environmental factors that affect the growth and development of plants. Although WRKY transcription factors play a critical role in stress responses, there are few studies on the regulation of heat stress by WRKY transcription factors,especially in tomato. Here, we identified a group I WRKY transcription factor, SlWRKY3, involved in thermotolerance in tomato. First, SlWRKY3 was induced and upregulated under heat stress. Accordingly, overexpression of SlWRKY3 led to an increase, whereas knock-out of SlWRKY3 resulted in decreased tolerance to heat stress. Overexpression of SlWRKY3 accumulated less reactive oxygen species(ROS), whereas knock-out of SlWRKY3 accumulated more ROS under heat stress. This indicated that SlWRKY3 positively regulates heat stress in tomato. In addition,SlWRKY3 activated the expression of a range of abiotic stress-responsive genes involved in ROS scavenging, such as a SlGRXS1 gene cluster.Further analysis showed that SlWRKY3 can bind to the promoters of the SlGRXS1 gene cluster and activate their expression. Collectively, these results imply that SlWRKY3 is a positive regulator of thermotolerance through direct binding to the promoters of the SlGRXS1 gene cluster and activating their expression and ROS scavenging.

Response of Bacterial Community and Enzyme Activity of Greenhouse Tomato under Different Irrigation Systems

The micro-sprinkler irrigation mulched(MSM)has been suggested as a novel water-saving approach in con-trolled environment agriculture.However,the effects of microbial community structure and enzyme activity in the rhizosphere soil on crop growth under MSM remain unclear.This study conducted a randomized experimen-tal design using greenhouse tomatoes to investigate changes in bacterial community structure and enzyme activity in rhizosphere soil under different irrigation frequencies(F)and amounts(I)of MSM.Thefindings revealed that with the increase of F or I,The total count of soil bacteria in tomatoesfirst rose and then fell in terms of Opera-tional Taxonomic Units(OTUs)classification.Compared to other F,the most abundance of nitrogen and phos-phorus metabolism genes and enzyme activities were observed with a 5-day F.Moreover,the diversity of soil bacterial community structure initially rose before eventually declining with the increase of the I.Applying 1.00 Epan(cumulative evaporation of a 20 cm standard pan)under MSM helped boost the abundance of nitrogen and phosphorus metabolism functional genes in soil bacteria,ensuring higher enzyme activities related to nitro-gen,carbon,and phosphorus metabolism in the rhizosphere soil of tomatoes.Tomatoes’yield initially rose before eventually declining with the increase in F or I,whereas I had a more significant effect on yield.A 1.00%increase in I yielded a minimum of 39.24%increase in tomato yield.The study showed a positive correlation between soil bacterial community,soil enzyme activity,and greenhouse tomato yield under MSM.Considering the results comprehensively,the combined irrigation mode of F of 5 d and I of 1.00 Epan was recommended for greenhouse tomatoes under MSM.This conclusion provides theoretical support for water-saving practices and yield improve-ment in facility agriculture,especially tomato cultivation.

Genome-Wide Identification of Tomato (Solanum lycopersicum L.) CKX Gene Family and Expression Analysis in the Callus Tissue under Zeatin Treatment

The cytokinin oxidase/dehydrogenase(CKX)enzyme is essential for controlling thefluctuating levels of endogen-ous cytokinin(CK)and has a significant impact on different aspects of plant growth and development.Nonethe-less,there is limited knowledge about CKX genes in tomato(Solanum lycopersicum L.).Here we performed genome-wide identification and analysis of nine SlCKX family members in tomatoes using bioinformatics tools.The results revealed that nine SlCKX genes were unevenly distributed onfive chromosomes(Chr.1,Chr.4,Chr.8,Chr.10,and Chr.12).The amino acid length,isoelectric points,and molecular weight of the nine SlCKX proteins ranged from 453 to 553,5.77 to 8.59,and 51.661 to 62.494 kD,respectively.Subcellular localization analysis indi-cated that SlCKX2 proteins were located in both the vacuole and cytoplasmic matrix;SlCKX3 and SlCKX5 pro-teins were located in the vacuole;and SlCKX1,4,6,7,8,and 9 proteins were located in the cytoplasmic matrix.Furthermore,we observed differences in the gene structures and phylogenetic relationships of SlCKX proteins among different members.SlCKX1-9 were positioned on two out of the three branches of the CKX phylogenetic tree in the multispecies phylogenetic tree construction,revealing their strong conservation within phylogenetic subgroups.Unique patterns of expression of CKX genes were noticed in callus cultures exposed to varying con-centrations of exogenous ZT,suggesting their roles in specific developmental and physiological functions in the regeneration system.These results may facilitate subsequent functional analysis of SlCKX genes and provide valu-able insights for establishing an efficient regeneration system for tomatoes.