Tomato Fruit Ripening Research Articles

The transcription factor EMB1444-like affects tomato fruit ripening by regulating YELLOW-FRUITED TOMATO 1, a core component of ethylene signaling transduction.

The fleshy fruit of tomato (Solanum lycopersicum) are climacteric and, as such, ethylene plays a pivotal role in their ripening and quality traits. In this study, a basic helix-loop-helix transcription factor, EMB1444-like, was found to induce the expression of YELLOW-FRUITED TOMATO 1 (YFT1), which encodes the SlEIN2 protein, a key element in the ethylene signaling pathway. Yeast one-hybrid and EMSA analyses revealed that EMB1444-like binds to the E-box motif (CACTTG, -1295 bp to -1290 bp upstream of the ATG start codon) of the YFT1 promoter (pYFT1). Suppression of EMB1444-like expression in tomato lines (sledl) using RNAi reduced ethylene production by lowering the expression of 1-AMINOCYCLOPROPANE-1-CARBOXYLATE SYNTHASE 2/4 (ACS2/4) and ACC OXIDASE1 (ACO1) in a positive feedback loop. sledl tomato also showed differences in numerous quality traits related to fruit ripening, compared with the wild type, such as delayed chromoplast differentiation, a decrease in carotenoid accumulation, and delayed fruit ripening in an ethylene-independent manner, or at least upstream of ripening mediated by YFT1/SlEIN2. This study elucidates the regulatory framework of fruit ripening in tomato, providing information that may be used to breed tomato hybrid cultivars with an optimal balance of shelf-life, durability, and high quality.

An Integrative Transcriptomics and Proteomics Approach to Identify Putative Genes Underlying Fruit Ripening in Tomato near Isogenic Lines with Long Shelf Life.

The elucidation of the ripening pathways of climacteric fruits helps to reduce postharvest losses and improve fruit quality. Here, we report an integrative study on tomato ripening for two near-isogenic lines (NIL115 and NIL080) with Solanum pimpinellifolium LA0722 introgressions. A comprehensive analysis using phenotyping, molecular, transcript, and protein data were performed. Both NILs show improved fruit firmness and NIL115 also has longer shelf life compared to the cultivated parent. NIL115 differentially expressed a transcript from the APETALA2 ethylene response transcription factor family (AP2/ERF) with a potential role in fruit ripening. E4, another ERF, showed an upregulated expression in NIL115 as well as in the wild parent, and it was located physically close to a wild introgression. Other proteins whose expression levels changed significantly during ripening were identified, including an ethylene biosynthetic enzyme (ACO3) and a pectate lyase (PL) in NIL115, and an alpha-1,4 glucan phosphorylase (Pho1a) in NIL080. In this study, we provide insights into the effects of several genes underlying tomato ripening with potential impact on fruit shelf life. Data integration contributed to unraveling ripening-related genes, providing opportunities for assisted breeding.

A BAHD-type acyltransferase concludes the biosynthetic pathway of non-bitter glycoalkaloids in ripe tomato fruit

Tomato is the highest value fruit and vegetable crop worldwide, yet produces α-tomatine, a renowned toxic and bitter-tasting anti-nutritional steroidal glycoalkaloid (SGA) involved in plant defense. A suite of modifications during tomato fruit maturation and ripening converts α-tomatine to the non-bitter and less toxic Esculeoside A. This important metabolic shift prevents bitterness and toxicity in ripe tomato fruit. While the enzymes catalyzing glycosylation and hydroxylation reactions in the Esculeoside A pathway have been resolved, the proposed acetylating step remains, to date, elusive. Here, we discovered that GAME36 (GLYCOALKALOID METABOLISM36), a BAHD-type acyltransferase catalyzes SGA-acetylation in cultivated and wild tomatoes. This finding completes the elucidation of the core Esculeoside A biosynthetic pathway in ripe tomato, allowing reconstitution of Esculeoside A production in heterologous microbial and plant hosts. The involvement of GAME36 in bitter SGA detoxification pathway points to a key role in the evolution of sweet-tasting tomato as well as in the domestication and breeding of modern cultivated tomato fruit.

Quantitative proteomic analysis of tomato fruit ripening behavior in response to exogenous abscisic acid.

To determine how abscisic acid (ABA) affects tomato fruit ripening at the protein level, mature green cherry tomato fruit were treated with ABA, nordihydroguaiaretic acid (NDGA), or sterile water (control, CK). The proteomes of treated fruit were analyzed and quantified using tandem mass tags (TMTs) at 7 d after treatment, and the gene transcription abundances of differently expressed proteins (DEPs) were validated with qRT-PCR. The postharvest tomato fruit underwent faster color transformation and ripening than the CK when treated with ABA. In total, 6310 proteins were identified among the CK and treatment groups, of which 5359 were quantified. Using a change threshold of 1.2 or 0.83 times, 1081 DEPs were identified. Among them, 127 were upregulated and 127 were downregulated in the ABA vs CK comparison group. According to KEGG and protein-protein interaction network analyses, the ABA-regulated DEPs were primarily concentrated in the photosynthesis system and sugar metabolism pathways, and 102 DEPs associated with phytohormones biosynthesis and signal transduction, pigment synthesis and metabolism, cell wall metabolism, photosynthesis, redox reactions, allergens, and defense responses were identified in the ABA vs CK and NDGA vs CK comparison groups. ABA affects tomato fruit ripening at the protein level to some extent. The results of this study provided comprehensive insights and datas for further research on the regulatory mechanism of ABA in tomato fruit ripening. This article is protected by copyright. All rights reserved.

The effect of layers of high tunnel covering and soil mulching on tomato fruit quality.

High tunnels (HT) and plastic mulch can increase yield, extend growing seasons, protect plants from harsh weather conditions, and produce more marketable and attractive tomatoes. However, plastic covering reduces solar radiation, which may affect the quality of tomatoes. This study investigated the effects of single-layer versus double-layer HT and plastic mulch versus bare soil on the quality of fully ripe tomato fruits. The study was conducted over 2 years (2021 and 2022). The fruit color (L*, a*, and b*), vitamin C, pH, total titratable acid (TTA), total soluble solids (TSS), and lycopene content of the two tomato cultivars (Brandywine and Rebelski) were quantified. The results showed that quality parameters varied with the plastic layers of HT, plastic mulch, and planting year. The double-layer HT only showed a slight but significant influence on the color of tomatoes of both cultivars in the same year (P < 0.05). Brandywine tomatoes grown in the double-layer HT had significantly lower pH and lycopene content than those grown in single-layer HT, regardless of mulching. The effect of plastic layers on TTA, TSS, and lycopene depended on whether the soil was mulched. Tomatoes grown on bare soil had higher TTA and TSS values than those grown on mulched soil in double-layer HT. Tomatoes grown in single-layer HTs had significantly higher vitamin C content than those in the double-layer HT for both cultivars regardless of mulching. This study demonstrates that double-layer HT is unnecessary for the improvement of the overall quality of tomatoes. © 2023 Society of Chemical Industry.

Studies on postharvest loss assessment of Tomato fruits using Aloe Vera gel as mitigating agent

This work evaluates effect of aloe gel coatings on post-harvest quality management of red ripe tomato fruits. Red ripe tomato fruits were purchased from Mandate market, Ilorin, Kwara State. It was sorted and washed with potable water. The sample was divided into four (4) lots for dip treatment in already prepared different aloe vera solutions and labelled: A0 (control), A1 (1.5% aloe vera), A2 (50% aloe vera) and A3 (100% aloe Vera). The pre-treated lots were stored on a laboratory shelf at ambient for 15 days. Physicochemical and nutritional properties were evaluated using standard procedures. Moisture (97.58%) and ash contents (0.68%) of lot A3 (100% aloe gel) were significantly higher (p&lt;0.05) than the other lots. Results showed that lot A1 had the lowest weight loss of 13.1%, while A3 recorded the highest (37.2%). Lot A1 had significantly (p&lt;0.05) higher sensory attributes than the other lots. At day 15, TTA was between 0.13 and 0.35 %, with lot A1 recording significantly (p&lt;0.05) higher value of 0.35 %. TSS content of the tomato fruits decreased with increase in storage with exception to lot A2 which had the highest value (5.30 oBrix). There was a decrease in pH value of both the untreated and treated lots. The results also showed that the vitamin C content of the stored tomato fruits increased significantly (p&lt;0.05) in all the lots as storage days progressed. The result from the study showed that Lot A1 retarded water loss and delayed fruit softening thereby making them acceptable to consumer.

Gamma irradiation delays tomato (Solanum lycopersicum) ripening by inducing transcriptional changes.

Tomato (Solanum lycopersicum) has a relatively short shelf life as a result of rapid ripening, limiting its transportability and marketability. Recently, gamma irradiation has emerged as a viable method for delaying tomato fruit ripening. Although few studies have shown that gamma irradiation delays the ripening of tomatoes, the underlying mechanism remains unknown. Therefore, the present study aimed to examine the effects of gamma irradiation on tomato fruit ripening and the underlying mechanisms using transcriptomics. Following gamma irradiation, the total microbial count, weight loss, and decay rate of tomatoes significantly reduced during storage. Furthermore, the redness (a*), color change (∆E), and lycopene content of gamma-irradiated tomatoes decreased in a dose-dependent manner during storage. Moreover, gamma irradiation significantly upregulated the expression levels of genes associated with DNA, chloroplast, and oxidative damage repairs, whereas those of ethylene and auxin signaling-, ripening-, and cell wall metabolism-related, as well as carotenoid genes, were downregulated. Gamma irradiation effectively delayed ripening by downregulating the expression of ripening-related genes and inhibiting microbial growth, which prevented decay and prolonged the shelf life of tomatoes. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

A Lycopene ε-Cyclase TILLING Allele Enhances Lycopene and Carotenoid Content in Fruit and Improves Drought Stress Tolerance in Tomato Plants.

In the scenario of climate change, the availability of genetic resources for tomato cultivation that combine improved nutritional properties and more tolerance to water deficiency is highly desirable. Within this context, the molecular screenings of the Red Setter cultivar-based TILLING platform led to the isolation of a novel lycopene ε-cyclase gene (SlLCY-E) variant (G/3378/T) that produces modifications in the carotenoid content of tomato leaves and fruits. In leaf tissue, the novel G/3378/T SlLCY-E allele enhances β,β-xanthophyll content at the expense of lutein, which decreases, while in ripe tomato fruit the TILLING mutation induces a significant increase in lycopene and total carotenoid content. Under drought stress conditions, the G/3378/T SlLCY-E plants produce more abscisic acid (ABA) and still conserve their leaf carotenoid profile (reduction of lutein and increase in β,β-xanthophyll content). Furthermore, under said conditions, the mutant plants grow much better and are more tolerant to drought stress, as revealed by digital-based image analysis and in vivo monitoring of the OECT (Organic Electrochemical Transistor) sensor. Altogether, our data indicate that the novel TILLING SlLCY-E allelic variant is a valuable genetic resource that can be used for developing new tomato varieties, improved in drought stress tolerance and enriched in fruit lycopene and carotenoid content.

ChIP-Seq Analysis of SlAREB1 Downstream Regulatory Network during Tomato Ripening.

SlAREB1, a member of the abscisic acid (ABA) response element-binding factors (AREB/ABFs) family, was reported to play a crucial role in the expression of ABA-regulated downstream genes and affect the ripening of tomato fruit. However, the downstream genes of SlAREB1 are still unclear. Chromatin immunoprecipitation (ChIP) is a powerful tool and a standard method for studying the interactions between DNA and proteins at the genome-wide level. In the present study, SlAREB1 was proved to continually increase until the mature green stage and then decrease during the ripening period, and a total of 972 gene peaks were identified downstream of SlAREB1 by ChIP-seq analysis, mainly located in the intergenic and promoter regions. Further gene ontology (GO) annotation analysis revealed that the target sequence of SlAREB1 was the most involved in biological function. Kyoto Encylopaedia of Genes and Genomes (KEGG) pathway analysis showed that the identified genes were mainly involved in the oxidative phosphorylation and photosynthesis pathways, and some of them were associated with tomato phytohormone synthesis, the cell wall, pigment, and the antioxidant characteristic of the fruit as well. Based on these results, an initial model of SlAREB1 regulation on tomato fruit ripening was constructed, which provided a theoretical basis for further exploring the effects of the regulation mechanism of SlAREB1 and ABA on tomato fruit ripening.

Early-maturing varieties of open-ground tomato of domestic breeding in the conditions of the Tersko-Sulak subprovincion of Dagestan

Relevance. Dagestan is a zone of prosperous agriculture, distinguished by the abundance of heat, sun and irrigation in the plain zone. Tomatoes occupy a special place among vegetable crops in the world, including in the Republic of Dagestan. Determinant varieties are now the most common in the production of tomatoes, especially in the open ground. The main areas of specialized cultivation of tomatoes in the open ground are concentrated in the Kizlyar and Derbent districts of plain Dagestan. In these areas, there are high average daily temperatures for the formation and ripening of tomato fruits in excess, which is favorably reflected in the overall productivity of the bushes. Whereas in the foothills of Dagestan, insufficient heat resources do not allow growing tomato varieties with a long growing season. In the foothill part of the republic there is a large labor-resource potential, vegetable growing, as a labor-intensive type of agribusiness, acts as a sphere of employment for a significant part of the rural population. The demand for tomato varieties with a short growing season in this part of the republic is great.Methods. The research was carried out on the basis of the Tersko Sulak subprovincion of the FGBNU of the FANC RD of the Kizlyar district. The soil of the experimental site is alluvial-meadow, medium-saline, medium loamy in mechanical composition. Agrotechnics is generally accepted in the Republic of Dagestan for tomato culture.Results. The method for the study was the new semi-stamp cultivars of FGBNU FNCO (VNIISSOK) selection: Fakel (counter), Blagodatny, Viking, Voskhod VNIISSOKa, Magnat, Severyanka, Sodruzhestvo, Perst, Patrice. According to the maturation dates, the samples were divided into three groups: very early – Severyanka, Blagodatny, Magnat, Voskhod VNIISSOK (97-100 days); early – Patrice, Viking, Perst (102-105 days); middle-early – Sodruzhestvo, Fakel (111-114 days). According to the type of bush, we have identified 5 ordinary and semi-lamb samples with a height of no more than 78 cm. Two samples had a height of 50-53 cm (Patrice, Perst) and an average fetal weight of 72 and 60 g. Three samples had a height of 70, 71, 72 cm (Voskhod VNIISSOKa, Blagodatny, Sodruzhestvo) and an average fetal weight of 107, 110, 130 g. According to the output of gross output, the best indicators were of the following varieties: Blagodatny – 86.3; Voskhod VNIISSOKa – 82.7; Sodruzhestvo – 77.6 t/ha; Patrice – 68.2 t/ha. The following grades had a high yield of marketable products: Voskhod VNIISSOKa, Patrice – 92%; Blagodatny – 91%; Perst – 90%. The varieties also have a relatively high dry matter index of 5.3-6.4%.

Molecular Responses of Red Ripe Tomato Fruit to Copper Deficiency Stress.

Fruit nutritional value, plant growth, and yield can be compromised by deficient copper (Cu) bioavailability, which often appears in arable lands. This condition causes low Cu content and modifications in the ripening-associated processes in tomato fruit. This research studies the transcriptomic changes that occur in red ripe tomato fruit grown under suboptimal Cu conditions to shed light on the molecular mechanisms underlying this stress. Comparative RNA-sequencing and functional analyses revealed that Cu deficiency during cultivation activates signals for metal ion transport, cellular redox homeostasis, pyridoxal phosphate binding, and amino acid metabolism while repressing the response to phosphate starvation in harvested fruit. Transcriptomic analyses highlighted a number of novel Cu stress-responsive genes of unknown function and indicated that Cu homeostasis regulation in tomato fruit may involve additional components than those described in model plants. It also studied the regulation of high-affinity Cu transporters and a number of well-known Cu stress-responsive genes during tomato fruit ripening depending on Cu availability, which allowed potential candidates to be targeted for biotechnological improvements in reproductive tissues. We provide the first study characterizing the molecular responses of fruit to Cu deficiency stress for any fruit crop.

The brassinosteroid signaling component SlBZR1 promotes tomato fruit ripening and carotenoid accumulation.

The plant hormone ethylene is essential for climacteric fruit ripening, although it is unclear how other phytohormones and their interactions with ethylene might affect fruit ripening. Here, we explored how brassinosteroids (BRs) regulate fruit ripening in tomato (Solanum lycopersicum) and how they interact with ethylene. Exogenous BR treatment and increased endogenous BR contents in tomato plants overexpressing the BR biosynthetic gene SlCYP90B3 promoted ethylene production and fruit ripening. Genetic analysis indicated that the BR signaling regulators Brassinazole-resistant1 (SlBZR1) and BRI1-EMS-suppressor1 (SlBES1) act redundantly in fruit softening. Knocking out SlBZR1 inhibited ripening through transcriptome reprogramming at the onset of ripening. Combined transcriptome deep sequencing and chromatin immunoprecipitation followed by sequencing identified 73 SlBZR1-repressed targets and 203 SlBZR1-induced targets involving major ripening-related genes, suggesting that SlBZR1 positively regulates tomato fruit ripening. SlBZR1 directly targeted several ethylene and carotenoid biosynthetic genes to contribute to the ethylene burst and carotenoid accumulation to ensure normal ripening and quality formation. Furthermore, knock-out of Brassinosteroid-insensitive2 (SlBIN2), a negative regulator of BR signaling upstream of SlBZR1, promoted fruit ripening and carotenoid accumulation. Taken together, our results highlight the role of SlBZR1 as a master regulator of tomato fruit ripening with potential for tomato quality improvement and carotenoid biofortification.

Comparative Characteristics of Genes 9-Cis-Epoxycarotinoid-Dioxygenase SINCED1 and SINCED2 during the Development and Ripening of Tomato Fruit

Comparative Characteristics of Genes 9-Cis-Epoxycarotinoid-Dioxygenase SINCED1 and SINCED2 during the Development and Ripening of Tomato Fruit

Potential of Neem Leaves on Preservation of Selected Elemental Compositions in Two Tomato Cultivars from Sokoto, Nigeria

The aim of this study is to determine the effect of neem leaves in preserving the mineral elements content of two tomato types from Sokoto state, Nigeria. Healthy, ripe and firm tomato fruits brought from Sokoto City, were selected, cleaned for this study. 5%, 10% and 25% by were prepared by dissolving respective 5g, 10g and 25g neem extracts in 9.5, 9.0 and 7.5 liters of distilled water respectively to preserve tomatoes. The experiment was laid in a completely randomized design. And elements, Na, K, Ca, Mg, and P were determined in the tomatoes after the experiment using atomic absorption spectroscopy. The levels of Na, K, Ca, and P in Daneka after preservation ranges are: 1.1-1.3(ppm), 2.1-2.3 (ppm), 1.0-1.3 (ppm), 0.30-0.34 (ppm), and 0.3200-0.3330 (ppm) respectively. The levels of Na, K, Ca, and P in UTC after preservation ranges are: 1.6-1.10 (ppm), 1.6-1.10 (ppm), 0.10-1.16 (ppm), 0.30-0.35 (ppm), and 0.9997-1.0998 (ppm) respectively; revealing an increasing trend of elemental contents of all the tomato cultivars with an increasing neem concentration. Thus, the neem leaves indicate the capacity to preserve a typical quality parameter of tomatoes, that is concentration of Na, K, Ca, and P elements at p &lt; 0.05 significant level.

Abundance of Phytoparasitic Root Nematodes Associated with Tomato (Solanum lycopersicum Mill.) in Kalaburagi, Karnataka, India

Tomato (Solanum lycopersicum Mill.) is the most commonly grown prime vegetable crop in India and all around the world. Tomato is cultivated majorly in many states of the nation including Karnataka and plays an important role in the Indian economy. The ripe tomato fruits act as the best source of vitamin A, Vitamin D and also have various antioxidant properties. Tomato crop progressively gets infested by various diseases at different stages from vegetation up to fruiting. The diseases such as bacterial leaf spot, bacterial wilt, leaf curl, fruit canker and Septoria leaf spot are caused by different Bacteria, Viruses and Fungi. Nematodes also result in root-knot, stunting and fusarium wilt diseases which may reduce the crop yield and fruit quality. The present survey was carried out from June 2021 to November 2021 in selected tomato plots of Kalaburagi district to identify different species of root nematodes affecting tomato crop in the selected study area. According to the survey results a total of six species of root nematodes were isolated and identified namely Meloidogyne spp., Globodera Spp., Paratrichodors minor, Helicotylenchus dihystera, Pratylenchus spp. and Rotylenchus buxophilus from selected study plots of Nirgudi, Bhosga, Bhosga Tanda, Gobbur, Sannur, Nadikur and Khanadal. The results suggest that Meloidogyne sps and Paratrichodors minor were most commonly recorded. The highest abundance of these nematodes recrded in Nirgudi region and in Nandikur region population of these root nematodes is least abundant.

Plastidial engineering with coupled farnesyl diphosphate pool reconstitution and enhancement for sesquiterpene biosynthesis in tomato fruit

Sesquiterpenes represent a large class of terpene compounds found in plants with broad applications such as pharmaceuticals and biofuels. The plastidial MEP pathway in ripening tomato fruit is naturally optimized to provide the 5-carbon isoprene building blocks of all terpenes for production of the tetraterpene pigment lycopene and other carotenoids, making it an excellent plant system to be engineered for production of high-value terpenoids. We reconstituted and enhanced the pool of sesquiterpene precursor farnesyl diphosphate (FPP) in plastids of tomato fruit by overexpressing the fusion gene DXS-FPPS encoding a fusion protein of 1-deoxy-D-xylulose 5-phosphate synthase (DXS) linked with farnesyl diphosphate synthase (originally called farnesyl pyrophosphate synthase, and abbreviated as FPPS) under the control of fruit-ripening specific polygalacturonase (PG) promoter concomitant with substantial reduction in lycopene content and large production of FPP-derived squalene. The supply of precursors achieved by the fusion gene expression can be harnessed by an engineered sesquiterpene synthase that is retargeted to plastid to engineer high-yield sesquiterpene production in tomato fruit, offering an effective production system for high-value sesquiterpene ingredients.

Effect of Methyl Jasmonate on the Biosynthesis of Volatile Compounds Associated with the Ripening of Grape Tomato Fruits

The present work aims to evaluate the roles of methyl jasmonate (MeJA) in the formation of volatile organic compounds (VOC) from grape tomatoes during ripening. Fruits were treated with MeJA, ethylene, 1-MCP (1-methylcyclopropene), and MeJA+1-MCP, with analyses of the VOC and levels of the gene transcripts for the enzymes lipoxygenase (LOX), alcohol dehydrogenase (ADH), and hydroperoxide lyase (HPL). An intimate relationship between MeJA and ethylene in aroma formation was detected, mainly among the VOC from the carotenoid pathway. Expression of the fatty acid transcripts, LOXC, ADH, and HPL pathway genes, was reduced by 1-MCP, even when associated with MeJA. In ripe tomato, MeJA increased most of the volatile C6 compounds, except 1-hexanol. The MeJA+1-MCP treatment followed most of the increases in volatile C6 compounds that were increased by MeJA alone, which evidenced some ethylene-independent mechanism in the production of the volatile C6 compounds. In ripe tomato, MeJA and MeJA+1-MCP increased the levels of 6-methyl-5-hepten-2-one, which is derived from lycopene, evidencing an ethylene-independent biosynthetic process.

Comparative Characteristics of Genes 9-Cis-Epoxycarotinoid-Dioxygenase SlNCED1 and SlNCED2 during the Development

Tomato Solanum lycopersicum L. is an important agricultural crop and, at the same time, a model for studying the ontogeny of the succulent fruit. The decisive role in the ripening of the fruit is played by abscisic acid, which is formed as a result of the oxidative cleavage of epoxycarotenoids 9-cis-epoxycarotenoid dioxygenases NCED. Gene-expression profiles of SlNCED1 and SlNCED2 and the content of carotenoids in fruits at different stages of development were determined in three varieties of tomato with different color of ripe fruit. It was shown that transcripts of both genes are present in all organs. Transcript level of SlNCED1 was approximately four to six times higher than the level of SlNCED2 transcripts; peak activity of SlNCED1 occurs in the late stages of ripening, while that of SlNCED2 is at the initial stage. Ripe fruits are characterized by the highest amount of carotenoids; lycopene was found only in the fruits of late stages in red-fruited varieties, the highest content of -carotene was found in ripe fruits of the yellow-fruited variety. The precursor of abscisic acid, violaxanthin, is present only in the immature fruit; the other precursor, neoxanthin, decreases with ripening and is absent at the ripeness stage. In red-fruited varieties, a correlation was found between the level of SlNCED1 and SlNCED2 transcripts with the content of -carotene. Findings suggest the coparticipation of SlNCED1 and SlNCED2 in the biosynthesis of abscisic acid during the development and ripening of tomato fruit. In this case, the key role belongs to the gene SlNCED1, the peak of activity of which falls on the stage of changing the color of the fruit. Lower levels of SINCED2 transcripts and its peak activity in the early stages of fruit development suggests a division of NCED functions between the two enzymes.

Functional characterization of transcriptional activator gene SIARRI in tomato reveals its role in fruit growth and ripening.

Auxins regulate several characteristics of plant development and growth. Here, we characterized a new transcriptional activator SIARRI which binds specific DNA sequences and was revealed in Arabidopsis (ARR1). SIARRI acts as a two-component response regulator and its Arabidopsis homologous gene is AT3G16857. It belongs to the subfamily of type-B response regulators in the cytokinin signaling pathway. The study aimed to characterize the transgenic Micro-Tom plants by the overexpression of Solanum lycopersicum two-component response regulator ARR1. Overexpression of SIARRI results in a pleiotropic phenotype during fruit development and ripening. This study indicates that SIARRI is a primary regulator of leaf morphology and fruit development. Moreover, overexpressed plants showed variations in growth related to auxin as well as shorter hypocotyl elongation, enlarged leaf vascularization, and decreased apical dominance. The qRT-PCR investigation revealed that expression was downregulated at the breaker stage and high at Br+6 at various stages of fruit growth and ripening. In contrast to the fruit color, lycopene and β-carotene concentrations in red-yellow overexpression line fruits were reduced significantly, and also slightly reduced in some red fruits. The quantity of β-carotene in the transgenic fruits was lower than that of lycopene. This study showed that this gene might be a new transcriptional activator in fruit development and ripening. Furthermore, this study will provide new insights into tomato fruit ripening.

Suppression of the target of rapamycin kinase accelerates tomato fruit ripening through reprogramming the transcription profile and promoting ethylene biosynthesis.

Tomato fruit ripening is a unique process of nutritional and energy metabolism. Target of rapamycin (TOR), a conserved serine/threonine protein kinase in eukaryotes, controls cell growth and metabolism by integrating nutrient, energy, and hormone signals. However, it remains unclear whether TOR participates in the modulation of tomato fruit ripening. Here, we showed that the manipulation of SlTOR by chemical or genetic methods greatly alters the process of tomato fruit maturation. Expression pattern analysis revealed that the transcripts of SlTOR declined as fruit ripening progressed. Moreover, suppression of SlTOR by TOR inhibitor AZD8055 or knock down of its transcripts by inducible RNA interference, accelerated fruit ripening, and led to overall effects on fruit maturity, including changes in colour and metabolism, fruit softening, and expression of ripening-related genes. Genome-wide transcription analysis indicated that silencing SlTOR reprogrammed the transcript profile associated with ripening, including cell wall and phytohormone pathways, elevated the expression of ethylene biosynthetic genes, and further promoted ethylene production. In contrast, the ethylene action inhibitor 1-MCP efficiently blocked fruit maturation, even following SlTOR inhibition. These results suggest that accelerated fruit ripening caused by SlTOR inhibition depends on ethylene, and that SlTOR may function as a regulator in ethylene metabolism.