Changes In Tomato Research Articles

Biological Control of Tomato Bacterial Leaf Spots and Its Impact on Some Antioxidant Enzymes, Phenolic Compounds, and Pigment Content.

Tomato bacterial spots, caused by Xanthomonas campestris pv. vesicatoria (Xcv1) and X. euvesicatoria (Xe2), as well as bacterial specks, caused by two strains of Pseudomonas syringae pv. tomato (Pst1 and Pst2), represent significant threats to tomato production in the El-Sharkia governorate, often resulting in substantial yield losses. The objective of this study was to evaluate the efficacy of various biocontrol culture filtrates, including bacteria and fungi agents, in managing the occurrence and severity of these diseases, while also monitoring physiological changes in tomato leaves, including antioxidant enzymes, phenolics, and pigment content. The culture filtrates from examined Trichoderma species (T. viride, T. harzianum, and T. album), as well as the tested bacteria (Bacillus subtilis, Pseudomonas fluorescens, and Serratia marcescens) at concentrations of 25%, 50%, and 100%, significantly inhibited the proliferation of pathogenic bacteria In vitro. For the In vivo experiments, we used specific doses of 5 mL of spore suspension per plant for the fungal bioagents at a concentration of 2.5 × 107 spores/mL. The bacterial bioagents were applied as a 10 mL suspension per plant at a concentration of 1 × 108 CFU/mL. Spraying the culture filtrates of the tested bioagents two days before infection In vivo significantly reduced disease incidence and severity. Trichoderma viride exhibited the highest efficacy among the fungal bioagents, followed by T. harzianum and T. album. Meanwhile, the culture filtrate of B. subtilis emerged as the most potent among the bacterial bioagents, followed by P. fluorescens. Furthermore, applying these culture filtrates resulted in elevated levels of chitinase, peroxidase, and polyphenol oxidase activity. This effect extended to increased phenol contents, as well as chlorophyll a, chlorophyll b, and carotenoids in sprayed tomato plants compared to the control treatment. Overall, these findings underscore the potential of these biocontrol strategies to effectively mitigate disease incidence and severity while enhancing plant defense mechanisms and physiological parameters, thus offering promising avenues for sustainable disease management in tomato production.

Evaluation of Color and Pigment Changes in Tomato after 1-Methylcyclopropene (1-MCP) Treatment.

The Polar Qualification System (PQS) was applied on hue spectra fingerprinting to describe color changes in tomato during storage. The cultivar 'Pitenza' was harvested at six different maturity stages, and half of the samples were subjected to gaseous 1-methylcyclopropene (1-MCP) treatment. Reference color parameters were recorded with a vision system colorimeter instrument, and the fruit pigment concentration was assessed with the DA-index®. Additionally, acoustic firmness (Stiffness) was measured. All acquired reference parameters were used to grade fruit in the supply chain. The applied 1-MCP treatments were used to control the ripening of climacteric horticultural produce. Both the DA-index® and stiffness values, presented as chlorophyll concentration and acoustic firmness, showed significant differences among maturity stages and treated and control samples and in their kinetics during storage. The machine vision parameter PQS-X was significantly affected by 1-MCP treatment (F = 10.18, p < 0.01), while PQS-Y was primarily affected by storage time (F = 18.18, p < 0.01) and maturity stage (F = 11.15, p < 0.01). A significant correlation was achieved for acoustic firmness with normalized color (r > 0.78) and PQS-Y (r > 0.80), as well as for the DA-index® (r > 0.9). The observed color changes agreed with the reference measurements. The significant statistical effect on the PQS coordinates suggests that hue spectra fingerprinting with this data compression technique is suitable for quality assessment based on color.

Biophysical and biochemical changes in tomato (Solanum lycopersicum) genotypes at different fruit developmental stages under protected cultivation

An experiment was conducted during 2020–21 and 2021–22 to evaluate the biophysical and biochemical characteristics of tomato [Solanum lycopersicum (L.)] genotypes (Pusa Rohini, Pusa Cherry-1, S-22, PKM-1 and Pusa Protected-1) grown at Centre for Protected Cultivation Technology (CPCT), ICAR-Indian Agricultural Research Institute, New Delhi. Tomato fruits were harvested at 14 different fruit developmental stages (DS01-DS14) starting from 4 days after post anthesis to the final red riped stage. Fruit size (length and width), biomass, firmness, total soluble solids (TSS), titratable acids (T.A), β-carotene, ascorbic acid and lycopene content were analysed for all the developmental stages. The highest value of fruit length, breadth, biomass, TSS, β-carotene and lycopene content was observed at full ripe tomatoes and the lowest in the early immature green stage. However, parameters like fruit firmness,T.A and ascorbic acid content were higher in early immature to mature green stage and decreased once the fruit entered the ripening stage. Thus, irrespective of the genotypes considered in this study, all the above parameters except fruit firmness, ascorbic acid and T.A were found to increase gradually with the advancement of ripening process. This clearly showed a significant relationship between the biochemical and biophysical parameters of the tomatoes with their fruit developmental stages, hence could be used as an indicator to characterize the fruit developmental stages.

Phosphate deprivation-induced changes in tomato are mediated by an interaction between brassinosteroid signaling and zinc.

Inorganic phosphate (Pi) is a necessary macronutrient for basic biological processes. Plants modulate their root system architecture (RSA) and cellular processes to adapt to Pi deprivation albeit with a growth penalty. Excess application of Pi fertilizer, on the contrary, leads to eutrophication and has a negative environmental impact. We compared RSA, root hair elongation, acid phosphatase activity, metal ion accumulation, and brassinosteroid hormone levels of Solanum lycopersicum (tomato) and Solanum pennellii, which is a wild relative of tomato, under Pi sufficiency and deficiency conditions to understand the molecular mechanism of Pi deprivation response in tomato. We showed that S. pennellii is partially insensitive to phosphate deprivation. Furthermore, it mounts a constitutive response under phosphate sufficiency. We demonstrate that activated brassinosteroid signaling through a tomato BZR1 ortholog gives rise to the same constitutive phosphate deficiency response, which is dependent on zinc overaccumulation. Collectively, these results reveal an additional strategy by which plants can adapt to phosphate starvation.

The Oomycete Microbe-Associated Molecular Pattern, Arachidonic Acid, and an Ascophyllum nodosum-Derived Plant Biostimulant Induce Defense Metabolome Remodeling in Tomato.

Arachidonic acid (AA) is an oomycete-derived microbe-associated molecular pattern (MAMP) capable of eliciting robust defense responses and inducing resistance in plants. Similarly, Ascophylum nodosum extract (ANE) from the brown seaweed A. nodosum, a plant biostimulant that contains AA, can also prime plants for defense against pathogen challenges. A previous parallel study comparing the transcriptomes of AA- and ANE-root-treated tomatoes demonstrated significant overlap in transcriptional profiles, a shared induced resistance phenotype, and changes in the accumulation of various defense-related phytohormones. In this work, untargeted metabolomic analysis via liquid chromatography-mass spectrometry was conducted to investigate the local and systemic metabolome-wide remodeling events elicited by AA and ANE root treatment in tomatoes. Our study demonstrated AA and ANE's capacity to locally and systemically alter the metabolome of tomatoes with enrichment of chemical classes and accumulation of metabolites associated with defense-related secondary metabolism. AA- and ANE-root-treated plants showed enrichment of fatty acyl-glycosides and strong modulation of hydroxycinnamic acids and derivatives. Identification of specific metabolites whose accumulation was affected by AA and ANE treatment revealed shared metabolic changes related to ligno-suberin biosynthesis and the synthesis of phenolic compounds. This study highlights the extensive local and systemic metabolic changes in tomatoes induced by treatment with a fatty acid MAMP and a seaweed-derived plant biostimulant with implications for induced resistance and crop improvement.

Physiological changes in tomato colonized by dark septate endophytic fungi

As is customary in mycorrhizae, the interaction between plant and dark septate endophytic (DSE) fungi can result in physiological changes in the host plant, which are still poorly understood. This study aimed to evaluate the physiological changes in tomato plants colonized by DSE fungi. Four DSE isolates previously identified through ITS phylogeny were inoculated on tomato seeds and compared to non-inoculated plants (control). Kinetic parameters (Vmax and Km) were calculated measuring the nitrate content in the nutrient solution. The contents of NO3--N, NH4+-N, amino-N, soluble sugars in the root, petiole, stem and leaf, and the contents of macronutrients in the shoot were determined. The plants inoculated with A101 and A105 exhibited (i) significant increases in the soluble sugar contents; (ii) increases in the contents of P, K, Mg and S; and (iii) increased dry biomass compared to control. The A103 inoculation was antagonistic when compared to the other treatments, leading to a higher influx of NO3--N in the plants, resulting in a higher amino-N and the lower soluble sugar content in the shoot. The physiological parameters of tomato varied depending on the inoculation, and the changes ranged from positive to negative depending on each isolate involved in the interaction.

Impairment of the photorespiratory pathway on tomato leaves during the infection process of Septoria lycopersici

Septoria leaf spot, caused by Septoria lycopersici, is a destructive disease on tomato that reduces fruit quality and yield. Plants infected by pathogens display profound changes in photosynthesis, photorespiration, and respiration that affect defense responses. This study investigated the impacts caused by S. lycopersici infection on the photorespiration of tomato plants. Infected leaves showed a remarkable reduction in photosynthesis and in the pool of photosynthetic pigments. The respiration and photorespiration-to-gross photosynthesis ratio increased in the infected leaves. Reduction in photosynthesis on infected leaves was mainly associated with biochemical limitations. Infection by S. lycopersici resulted in increased concentrations of malonaldehyde, superoxide anion, and hydrogen peroxide indicating great oxidative damage. Genes involved in the photorespiratory pathway (GOX1, GOX2, SHMT2, SMHT3, and GLYK), nitrogen metabolism (Fd-GOGAT), and stress acclimatization (mMDH1, mMDH2, and CAT) were up-regulated during the infection process of S. lycopersici. A better comprehension of the physiological changes in tomato leaves infected by S. lycopersici at the photorespiration level may contribute to breeding cultivars with increased resistance to cope with Septoria leaf spot.

Novel mechanistic insights of selenium induced microscopic, histochemical and physio-biochemical changes in tomato (Solanum lycopersicum L.) plant. An account of beneficiality or toxicity

Selenium (Se) is a well-known beneficial element in plants. The window of Se between toxic and optimal concentration is narrow and uneven which fluctuates with plants species. This experiment was aimed to investigate the morpho-physiological, microscopic and histochemical responses of two different varieties of tomato (S-22 and PKM-1), exposed to different concentrations of Se (0, 10, 40 or 80 µM), applied to soil at 30 days after transplantation (DAT). At 40 DAT, it was observed that high concentrations (40 or 80 µM) of Se radically increased oxidative stress examined by elevated reactive oxygen species (ROS), malondialdehyde (MDA) content, cell death, electrolyte leakage and decreased chlorophyll content leading phenotypic symptoms of Se-induced toxicity like stunted growth and chlorosis. Furthermore, high doses of Se altered the chloroplast and stomatal organisation, and adversely affected the photosynthetic performance of plants. But low concentration of Se improved the plant dry mass, photosynthesis, Rubisco activity, protein content and maintained the steady-state equilibrium among ROS generation and antioxidant enzymes like catalase, peroxidase and superoxide dismutase. Our outcomes proposed that high concentration of Se generated toxicity (phyto-selenosis), whereas lower concentration of Se-triggered positive impact by improving growth, photosynthetic traits and maintaining steady-state equilibrium between scavenging-system and ROS generation.

Essential Oils Prime Epigenetic and Metabolomic Changes in Tomato Defense Against Fusarium oxysporum.

In this work, we studied the direct and indirect plant protection effects of an Artemisia absinthium essential oil (AEO) on tomato seedlings against Fusarium oxysporum sp. oxysporum radicis lycopersici (Fol). AEO exhibited a toxic effect in vitro against Fol. Additionally, tomato seedlings germinated from seeds pretreated with AEO and grown hydroponically were protected against Fol. Plant disease symptoms, including, water and fresh weight loss, tissue necrosis, and chlorosis were less pronounced in AEO-treated seedlings. AEO also contributed to plant defenses by increasing callose deposition and the production of reactive oxygen species (ROS) on seed surfaces without affecting seed germination or plant development. The essential oil seed coating also primed a durable tomato seedling defense against the fungus at later stages of plant development. RNA-seq and metabolomic analysis performed on seedlings after 12 days showed that the AEO treatment on seeds induced transcriptomic and metabolic changes. The metabolomic analysis showed an induction of vanillic acid, coumarin, lycopene, oleamide, and an unknown metabolite of m/z 529 in the presence of Fol. The StNRPD2 gene, the second largest component of RNA polymerases IV and V directly involved in de novo cytosine methylation by RNA-directed DNA methylation (RdDM), was highly induced in the presence of AEO. The host methionine cycle (MTC) controlling trans-methylation reactions, was also altered by AEO through the high induction of S-adenosyl methionine transferases (SAMts). Our results suggest that AEO treatment could induce de novo epigenetic changes in tomato, modulating the speed and extent of its immune response to Fol. The EO-seed coating could be a new strategy to prime durable tomato resistance, compatible with other environmentally friendly biopesticides.

Examination of morphological and molecular changes in tomato (Solanum lycopersicum L.) seedlings with the application of tebuconazole

This study aims to determine the effects of tebuconazole substance used at different doses on the quality of tomato seedlings, retrotransposon mobility caused by this substance in the plants and its genotoxic effects and to determine the optimum dose to be used in practice in seedling production. Tebuconazole applied different concentrations (25, 50, 75, 100, 125 and 150 ppm) were tested. According to the study results, the seedling length and stem length significantly according to the applied doses. The study found out that the stem, leaf and root dry matter contents and leaf chlorophyll content (SPAD values) also statistically significantly changed based on the applied doses. According to the data obtained, the lowest seedling length (12.68 cm) and stem length (4.75 cm) were obtained from a dose of 150 ppm. The highest dry matter content in seedlings was obtained at a dose of 50 ppm in stem (22%) and at 0 ppm (control) in leaves (25.01%) and root. In the study, the highest leaf chlorophyll content (SPAD values) was determined at doses of 150 ppm, 125 ppm and 75 ppm, respectively. This study revealed that various doses of tebuconazole had a positive effect on controlling the height of tomato seedlings and specific quality characteristics of seedlings. In addition, molecular analyzes showed that polymorphism ratios in plants that were applied the substance at different doses varied between 4.70% and 38.09% and the GTS (genomic template stability) value varied between 61.91% and 95.30%. Analyses indicated that the polymorphism ratio increased depending on the increase in dose whereas the GTS value decreased.

Anti-Herbivore Resistance Changes in Tomato with Elevation.

Local adaptations of host plants to climatic conditions along an elevation gradient can affect insect-plant interactions. Using local accessions sampled from different elevations within South America, plant defense responses and herbivore growth were evaluated on two host plants: a) cherry tomato, Solanum lycopersicum var. cerasiforme, and b) wild tomato, Solanum pimpinellifolium. The elevational origin of the accessions ranged from 100 to 3000m above sea level. We hypothesized a higher level of defensive compounds in plants originating from lower elevations and, consequently, stronger resistance to insect herbivory. Interestingly, plant resistance to insect herbivory, as demonstrated by a reduction in Helicoverpa zea growth, was stronger for middle and high-elevation accessions. Total phenolic content increased with elevation in both herbivore-damaged and undamaged leaves, augmenting plant resistance. However, an elevational gradient was not evident for plant defensive proteins (polyphenol oxidase and trypsin protease inhibitors) or the density of leaf trichomes. Tradeoffs between constitutive and induced defenses were evident in both tomato genotypes. Future studies should test the role of plasticity in plant defense systems in restricting or facilitating range expansion of insect herbivores with climate change.

Effects of Green Light on Elongation Do Not Interact with Far-Red, Unless the Phytochrome Photostationary State (PSS) Changes in Tomato.

Simple SummaryThis paper focuses on the role of phytochromes (phys) in the interaction between green light and far-red light effects on “shade avoidance syndrome”. We grew wild type and phy mutants of tomato under a set of light conditions with different combinations of green, blue, red, and far-red light. Partial (20%) replacement of red/blue by green light in the absence of far-red light hardly affected the tomato plant morphology. However, when the spectrum contained far-red light, partially replacing red/blue by green light resulted in more elongation, which was associated with a lower phytochrome photostationary state (PSS) value. There was no effect of partial substitution of red/blue with green light when the PSS was kept constant. Thus, this study has revealed an interaction between green and far-red light effects on elongation unless PSS was kept constant. Green light was often a bit neglected in photobiology, but now an increasing number of researchers are realizing that green light deserves more attention. This study advances the understanding of light quality and plant growth and finding the optimal spectrum when growing plants under LED lighting in controlled environment agriculture.Green light (G) could trigger a “shade avoidance syndrome” (SAS) similarly to far-red light. We aimed to test the hypothesis that G interacts with far-red light to induce SAS, with this interaction mediated by phytochromes (phys). The tomato (Solanum lycopersicum cv. Moneymaker) wild-type (WT) and phyA, phyB1B2, and phyAB1B2 mutants were grown in a climate room with or without 30 µmol m−2 s−1 G on red/blue and red/blue/far-red backgrounds, maintaining the same photosynthetically active radiation (400–700 nm) of 150 µmol m−2 s−1 and red/blue ratio of 3. G hardly affected the dry mass accumulation or leaf area of WT, phyA, and phyB1B2 with or without far-red light. A lower phytochrome photostationary state (PSS) by adding far-red light significantly increased the total dry mass by enhancing the leaf area in WT plants but not in phy mutants. When the background light did not contain far-red light, partially replacing red/blue with G did not significantly affect stem elongation. However, when the background light contained far-red light, partially replacing red/blue with G enhanced elongation only when associated with a decrease in PSS, indicating that G interacts with far-red light on elongation only when the PSS changes.

Effect of Postharvest Transport and Storage on Color and Firmness Quality of Tomato

Transport duration affects the vibration level generated which has adverse effects on fresh produce during transportation. Furthermore, temperature affects the quality of fresh commodities during storage. This study evaluated physical changes in tomatoes during transportation and storage. Tomatoes were transported at three distances (100, 154, and 205 km) from a local farm and delivered to the Postharvest Laboratory where vibration acceleration was recorded per distance. Tomato was stored at two different temperatures (10 °C and 22 °C) for 12 days. The physical qualities like weight loss and firmness of all tomato samples were evaluated. RGB image acquisition system was used to assess the color change of tomato. The results of vibration showed that over 40% of accelerations occurred in the range of 0.82–1.31 cm/s2 of all transport distances. Physical quality analyses like weight loss and firmness were highly affected by transportation distance, storage temperature, and storage period. The reduction in weight loss and firmness was the highest in tomatoes transported from the farthest distance and stored at 22 °C. Lightness, yellowness, and hue values showed a high reduction as transport distance increased particularly in tomatoes stored at 22 °C. Redness, total color difference, and color indices increased significantly on tomatoes transported from 205 km and stored at 10 °C and 22 °C. The study indicated that the increase in transportation distance and storage temperature cause higher changes in the physical qualities of tomatoes.

Chemical and nutritional quality changes of tomato during postharvest transportation and storage

Transportation over longer distances could accelerate the chemical changes of fresh produce. Moreover, fresh produce quality is also influenced by temperature conditions during storage. The present study aims to explore the postharvest quality chemical and nutritional changes in tomatoes as affected by transportation distance and storage conditions. Tomato fruit was transported from a local farm to three distances (100, 154, and 205 km) and delivered to the laboratory to undergo chemical and nutritional quality analysis. Tomatoes were stored at two storage temperature conditions at10°C (95 ± 1% relative humidity) and 22 °C (65 ± 5% relative humidity) for 12 days. To record all vibration data signals, a 3-Axis USB vibration/acceleration data logger was used during transportation. The changes in chemical properties of tomato including total soluble solids (TSS), titratable acidity (TA), sugar:acid ratio (TSS:TA), and pH were measured. Furthermore, nutritional changes (i.e., total lycopene and carotenoids) were determined. Vibration data results recorded 41% of acceleration occurrence in the range interval of 0.0099 -0.0116 m/s 2 in the longest distance of road travel. Chemical quality indicators like total soluble solids and sugar/acid ratio were mostly affected (p < 0.05) by storage condition and duration but not (p > 0.05) by transportation distance. However, TA was significantly affected by all investigated factors and was lower (0.25%) in tomatoes transported from the farthest distance compared to medium and shortest distances (0.26%) stored at 22 °C. Lycopene and carotenoids were highly affected by all studied factors. The highest amount of lycopene and carotenoids was observed in tomato transported from a long distance and stored at 22 °C on day12 with 1.21 and 1.55 mg.100 g −1 FW, respectively. The temperature during storage and long-distance transportation is critical in reducing postharvest chemical and nutritional quality losses of tomatoes.

Zinc oxide nanoparticles mediated substantial physiological and molecular changes in tomato.

There has long been debate about how nanoproducts meet agricultural requirements. This study aimed to investigate tomato responses to the long-time foliar application of zinc oxide nanoparticles (ZnO-NP; 0 and 3 mgl-1) or bulk type (BZnO). Both ZnO-NP and BZnO treatments, especially the nanoform, were significantly capable of improving growth, biomass, and yield. The ZnO-NP treatment upregulated the expression of the R2R3MYB transcription factor by 2.6 folds. The BZnO and ZnO-NP treatments transcriptionally up-regulated WRKY1 gene by 2.5 and 6.4 folds, respectively. The bHLH gene was also upregulated in response to BZnO (2.3-fold) or ZnO-NP (4.7-fold). Moreover, the ZnO-NP application made a contribution to upregulation in the EREB gene whereas the bulk compound did not make a significant change. Upregulation in the HsfA1a gene also resulted from the ZnO-NP (2.8-fold) or BZnO (1.6-fold) supplementation. The MKK2 and CAT genes displayed a similar upregulation trend in response to the supplements by an average of 3-folds. While the application of ZnO-NP slightly down-regulated the histone deacetylases (HDA3) gene by 1.9-fold, indicating epigenetic modification. The supplements, especially the nano-product, enhanced concentrations of K, Fe, and Zn in both leaves and fruits. The concentrations of Chla, Chlb, and carotenoids were increased in response to the BZnO or ZnO-NP treatments. Likewise, BZnO or ZnO-NP mediated an increase in activity of nitrate reductase and proline content in leaves. These treatments increased soluble phenols and phenylalanine ammonia-lyase activity. With a similar trend, the BZnO or ZnO-NP application improved the activities of catalase and peroxidase enzymes. The reinforcement in metaxylem and secondary tissues resulted from the applied supplements. This study provides comprehensive comparative evidence on how ZnO-NPs may remodel the chromatin ultrastructure and transcription program, and confer stress tolerance in crops. This study also underlines the necessity of providing integrated transcriptome and proteome data in future studies.

SIMULASI TRANSPORTASI TOMAT DAN PERUBAHAN MUTU TOMAT SELAMA PENYIMPANAN

Chemical, physical, and microbiological damage of fruits and vegetables can occur during the transportation process. The percentage of damage can reach 30-50% if the treatment during transportation is not carried out properly. The research objective was to determine the quality changes in tomatoes after transportation simulation based on the arrangement of the fruit in cardboard packaging. The treatment in this research is tomato arrangement patterns: the face centered cubic (FCC) arrangement, the traditional arrangement and the jumble (farmer) arrangement. The research begins with a transportation simulation using a vibrating table in a vertical direction, using a frequency range of 3.9 Hz and an amplitude of 5.2 cm. The simulation is carried out in 1 hour. After the simulation at the 1st hour, amount of mechanical damage (bruising) on ​​every package was carried out. The results showed that the pattern of arranging tomatoes in cardboard packaging that gave the least damage was the FCC arrangement pattern. The FCC pattern only causes shrinkage of 0.11% and the smallest amount of mechanical damage (bruising) is 0.64%.

Pseudomonas koreensis promotes tomato growth and shows potential to induce stress tolerance via auxin and polyphenol‐related pathways

Pseudomonas koreensis, a subgroup of the P. fluorescens complex, is a potential plant growth-promoting rhizobacterium. This study explored the mechanisms of plant growth promotion by P. koreensis and its potential to induce stress tolerance in tomato. Tomato plants in pots were inoculated with P. koreensis GS and cultured for 60 days. RNA sequencing and gas chromatography-mass spectrometry were used to detect global transcriptomic and metabolomic changes in tomato leaves. Liquid chromatography-mass spectrometry was used for quantification of plant hormones. The inoculated plants showed more vigorous growth, with higher leaf chlorophyll content and shoot biomass compared with uninoculated controls. The activities of several defense enzymes (e.g., phenylalanine ammonia-lyase) were enhanced in the leaves of inoculated plants. A total of 737 differentially expressed genes were identified, which were related to plant hormone biosynthesis, MAPK signaling transduction, and polyphenol biosynthesis. The contents of specific metabolites related to plant growth and stress tolerance, including polyphenols (phenylpropanoids) and amino acids (tryptophanand and proline), were increased after inoculation. Plant hormones such as indole-3-acetic acid participated in plant growth promotion by P. koreensis. P. koreensis promoted plant growth and showed potential to induce stress tolerance in tomato by enhancing auxin and polyphenol-related pathways.

Multifaceted roles of nitric oxide in tomato fruit ripening: NO-induced metabolic rewiring and consequences for fruit quality traits.

Nitric oxide (NO) has been implicated as part of the ripening regulatory network in fleshy fruits. However, very little is known about the simultaneous action of NO on the network of regulatory events and metabolic reactions behind ripening-related changes in fruit color, taste, aroma and nutritional value. Here, we performed an in-depth characterization of the concomitant changes in tomato (Solanum lycopersicum) fruit transcriptome and metabolome associated with the delayed-ripening phenotype caused by NO supplementation at the pre-climacteric stage. Approximately one-third of the fruit transcriptome was altered in response to NO, including a multilevel down-regulation of ripening regulatory genes, which in turn restricted the production and tissue sensitivity to ethylene. NO also repressed hydrogen peroxide-scavenging enzymes, intensifying nitro-oxidative stress and S-nitrosation and nitration events throughout ripening. Carotenoid, tocopherol, flavonoid and ascorbate biosynthesis were differentially affected by NO, resulting in overaccumulation of ascorbate (25%) and flavonoids (60%), and impaired lycopene production. In contrast, the biosynthesis of compounds related to tomato taste (sugars, organic acids, amino acids) and aroma (volatiles) was slightly affected by NO. Our findings indicate that NO triggers extensive transcriptional and metabolic rewiring at the early ripening stage, modifying tomato antioxidant composition with minimal impact on fruit taste and aroma.

Phytophthora Effectors Modulate Genome-wide Alternative Splicing of Host mRNAs to Reprogram Plant Immunity

Alternative splicing (AS) of pre-mRNAs increases transcriptome and proteome diversity, regulates gene expression through multiple mechanisms, and plays important roles in plant development and stress responses. However, the prevalence of genome-wide plant AS changes during infection and the mechanisms by which pathogens modulate AS remain poorly understood. Here, we examined the global AS changes in tomato leaves infected with Phytophthora infestans, the infamous Irish famine pathogen. We show that more than 2000 genes exhibiting significant changes in AS are not differentially expressed, indicating that AS is a distinct layer of transcriptome reprogramming during plant–pathogen interactions. Furthermore, our results show that P. infestans subverts host immunity by repressing the AS of positive regulators of plant immunity and promoting the AS of susceptibility factors. To study the underlying mechanism, we established a luminescence-based AS reporter system in Nicotiana benthamiana to screen pathogen effectors modulating plant AS. We identified nine splicing regulatory effectors (SREs) from 87 P. infestans effectors. Further studies revealed that SRE3 physically binds U1-70K to manipulate the plant AS machinery and subsequently modulates AS-mediated plant immunity. Our study not only unveils genome-wide plant AS reprogramming during infection but also establishes a novel AS screening tool to identify SREs from a wide range of plant pathogens, providing opportunities to understand the splicing regulatory mechanisms through which pathogens subvert plant immunity.

Physicochemical Quality Changes in Tomatoes during Delayed Cooling and Storage in a Controlled Chamber

The exposure of tomato fruits to unfavorable environments during the postharvest could result in severe losses along the supply chain. In this research, four tomato cultivars were stored in a controlled chamber under three levels of postharvest conditions to investigate the effects of delayed cooling on selected physicochemical quality parameters of the tomatoes. The tomato cultivars were subjected to three postharvest treatments: Immediate storage (IS) at harvest day; delayed storage (DS), leaving tomatoes without cover for one day; and under cover (DSC), separately in a greenhouse, and then stored in a controlled chamber at a temperature of 10 ± 1 °C and relative humidity of 90% ± 3%. Fresh weight, firmness, total soluble solids (TSS), and hue angle (h°) were examined over 15 days, every 5 days. Among the tomato cultivars, Cherry (7160), treated under DS showed the highest weight loss (13.01%) and firmness loss (42.14%) after 15 days of storage. Dabol (large) tomatoes treated with DS showed higher changes in TSS (°Bx) values (4.79 to 5.76). Low changes in hue angle values were found in IS-treated Cherry (7160) tomatoes at the end of the storage period. Overall quality changes were slower for all tomato cultivars treated with IS than with other treatments throughout the storage period. This study indicated the importance of reducing cooling delays to maintain the quality during the postharvest and prolong storage of harvested tomatoes.