Mature Green Stage Research Articles

Transcriptomics Analysis of Tomato Ripening Regulated by Carbon Dioxide

Tomatoes are a perishable and seasonal fruit with a high economic impact. Carbon dioxide (CO2), among several other reagents, is used to extend the shelf-life and preserve the quality of tomatoes during refrigeration or packaging. To obtain insight into CO2 stress during tomato ripening, tomatoes at the late green mature stage were conditioned with one of two CO2 delivery methods: 5% CO2 for 14 days (T1) or 100% CO2 for 3 h (T2). Conventional physical and chemical characterization found that CO2 induced by either T1 or T2 delayed tomato ripening in terms of color change, firmness, and carbohydrate dissolution. However, T1 had longer-lasting effects. Furthermore, ethylene production was suppressed by CO2 in T1, and promoted in T2. These physical observations were further evaluated via RNA-Seq analysis at the whole-genome level, including genes involved in ethylene synthesis, signal transduction, and carotenoid biosynthesis. Transcriptomics analysis revealed that the introduction of CO2 via the T1 method downregulated genes related to fruit ripening; in contrast, T2 upregulated the gene encoding for ACS6, the enzyme responsible for S1 ethylene synthesis, even though there was a large amount of ethylene present, indicating that T1 and T2 regulate tomato ripening via different mechanisms. Quantitative real-time PCR assays (qRT-PCR) were used for validation, which substantiated the RNA-Seq data. The results of the present research provide insight into gene regulation by CO2 during tomato ripening at the whole-genome level.

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.

Infestation of Pink-Flesh Guava by Frugivorous Fruit Flies (Diptera: Tephritidae and Lonchaeidae) in an Orchard of Mixed Mandarin and Guava Trees at Morelos, Mexico

Guavas (Psidium guajava L.) are a main host of several Lonchaeidae and Tephritidae fruit flies. In Mexico, guavas are infested mostly by Anastrepha striata Schiner, A. fraterculus (Wiedemann), and occasionally by A. obliqua Macquart. We sampled 240 pink-flesh guavas from an orchard of mixed mandarin (Citrus reticulata Blanco) and guava trees at San Rafael de Zaragoza, Morelos. Fruit was collected biweekly during two fruiting periods [August-September 2021 (wet season) and January-February 2022 (dry season)]. Infestation rate, Host Suitability Index (HSI), and co-infestations by frugivorous fruit flies were assessed. We found 728 pupae (76% Anastrepha spp.), and an unusually large number of Neosilba spp. (24%). More infestation was detected during the dry season (432 pupae in the dry season versus 296 pupae in the wet season) probably caused by scarce availability of fruit. We reported for the first time, infestation of pink-flesh guavas by A. ludens from field-collected guavas picked from trees in mature-green stage. Using the HS Index, pink-flesh guavas were an inadequate host for A. ludens but were a good host for A. striata. We reported Neosilba spp. as a primary invader of guavas and discussed findings in the context of quarantine risk assessment.

Improved Forage Quality in Alfalfa (Medicago sativa L.) via Selection for Increased Stem Fiber Digestibility

The low digestibility of fiber in alfalfa (Medicago sativa L.) limits dry matter intake and energy availability in ruminant animal production systems. Previously, alfalfa plants were identified for low or high rapid (16 h) and low or high potential (96 h) in vitro neutral detergent fiber digestibility (IVNDFD) of plant stems. Here, two cycles of bidirectional selection for 16 h and 96 h IVNDFD were carried out. The resulting populations were evaluated for total herbage, percentage of stems to total biomass, IVNDFD, neutral detergent fiber (NDF), and acid detergent lignin as a proportion of NDF (ADL/NDF) at three maturity stages. Within these populations, 96 h IVNDFD was highly heritable (h2 = 0.71), while 16 h IVNDFD had lower heritability (h2 = 0.46). Selection for high IVNDFD reduced NDF and ADL/NDF in plant stems at the late flowering and green pod maturity stages and reduced seasonal variability in stem digestibility but did not alter the percentage of stems. Stability analyses across 12 harvest environments found that selection for high IVNDFD had little effect on environmental stability of the trait compared to the unselected population. Thus, selection for stem IVNDFD was a highly effective strategy for developing alfalfa populations with improved nutritional quality without changing the percentage of stems to total biomass.

The transcription factor CaBBX20 regulates capsanthin accumulation in pepper (Capsicum annuum L.)

Carotenoids are important pigments whose accumulation is regulated by transcription factors such as those from the MADS-box and MYB families. BBXs are a kind of zinc finger transcription factors with one or two B-box domains, which were identified involved in photomorphogenesis. However, little is known about the function of CaBBX in the pigmentation of pepper fruit (Capsicum annuum). Here, we selected two red-fruited pepper cultivars to investigate carotenoid contents at three developmental stages (Mg: mature green stage, Tf: turning stage, and Rf: ripen stage) during fruit ripening (30, 45 and 60 days after flowering). Our results showed that carotenoid accumulation in pepper fruits begins at turning stage (Tf) and peaks in ripen stage (Rf), which was reflected in the fruit color change (from green to brown, and then to red). The expression of CaBBX20 was upregulated with the pigmentation during fruit ripening. Silencing CaBBX20 led to reduced carotenoid accumulation, as well as downregulated expression of CaCCS, suggesting a positive role of CaBBX20 in carotenoid metabolism of pepper fruit. Our study thus provides basic insight into carotenoid biosynthesis during pepper fruit pigmentation.

Gene actions of resistance to anthracnose (Colletotrichum acutatum) of six F1 hybrid chili cultivars at the mature green fruit stage

Gene actions of resistance to anthracnose (<i>Colletotrichum acutatum</i>) of six F₁ hybrid chili cultivars at the mature green fruit stage

Indole-3-acetic acid, a hormone potentially involved in chilling-induced seed browning of pepper (Capsicum annuum L.) fruit during cold storage

Pepper (Capsicum annuum L.) fruit is affected by chilling temperatures below 7–10 °C; thus, there are limitations to maintaining postharvest freshness during its cold storage and distribution. Here, the six endogenous hormones, abscisic acid, gibberellic acid, indole-3-acetic acid (IAA), jasmonic acid, jasmonoyl-isoleucine, and salicylic acid, were quantitatively analyzed, and the genes and amino acids associated with them were investigated under the hypothesis that hormones are primarily involved in chilling injury (CI) of pepper fruit. Pepper fruit of two different genotypes, ‘Takanotsume’ (‘TK’) and ‘Gyeonggiyangpyeong’ (‘GG’), were harvested at the mature-green stage and stored at 2 °C for 21 d. Seed browning was the most visible symptom of CI during storage. Seed browning was rarely observed for ‘TK’; however, it was observed for ‘GG’ with a higher production of reactive oxygen species. Thus, ‘TK’ was less sensitive to chilling than ‘GG’, as demonstrated by the completely different CI levels. IAA levels substantially increased in ‘GG’ on 3 d of cold storage; however, it did not change in ‘TK’ during the entire storage period. Since the pattern between the expression level of CaAMI1 and the IAA content was similar, the IAM pathway was probably involved in the IAA production in ‘GG’. The content of individual amino acids substantially changed in ‘GG’ compared to ‘TK’ but the initial proline content was highest in ‘TK’. ‘GG’ showed a more complex correlation between the analyzed factors compared to ‘TK’. The CI level of ‘TK’ positively correlated with gamma-aminobutyric acid (GABA) and auxin response factor 19 (CaARF19). The CI level of ‘GG’ had a positive, and negative correlation with GABA and alanine, and CaARF6, respectively. These results might help elucidate the mechanism of chilling-induced seed browning in pepper fruit and develop pepper cultivars that are resistant to CI during cold storage and distribution.

Regulating Enzymatic Antioxidants, Biochemical and Physiological Properties of Tomato under Cold Stress: A Crucial Role of Ethylene

The production of tomato under low-temperature stress in the open fields is a challenge faced by many farmers. The current study compares the use of different ethylene treatments to accelerate the fruit ripening of tomato during two successive seasons under cold stress. The treatments included foliar application of ethrel (2500, 5000, and 7500 ppm) in the open field at the mature green stage, dipping collected fruits in ethrel solution (1000, 1500, and 2000 ppm) right after harvest, and application of gaseous ethylene (100, 200, and 300 ppm) to the harvested fruits. The effects were compared to untreated fruits (control). Characteristics, such as physical properties (ripening, weight loss, firmness, decay, and fruit color), chemical properties (ascorbic acid, acidity, total soluble sugars, and pigments), and enzymatic activities (polygalacturonase and pectin methylesterase), were sampled throughout the storage period. In general, the ethylene gas application was the most effective method in accelerating the fruit ripening process compared to the other methods applied. The highest vitamin C total soluble solid contents and redness parameters were found after applying the highest dose of ethylene gas (300 ppm). This indicates that the ripening of tomato fruits, which are cultivated under cold stress conditions as found during the early summer season in a Mediterranean climate, might be harvested at a mature green stage and exposed to ethylene application.

Physiological and metabolomic analysis reveals maturity stage-dependent nitrogen regulation of vitamin C content in pepper fruit.

Pepper is one of the most vitamin C enriched vegetables worldwide. Although applying nitrogen (N) fertilizer is an important practice for high fruit yield in pepper production, it is still unclear how N application regulates pepper fruit vitamin C anabolism at different maturity stage. To further the understanding, we combined physiological and metabolomic analysis to investigate the fruit vitamin C content (including ascorbic acid (AsA) and dehydroascorbic acid (DHA)), related enzyme activity and non-targeted metabolites of field-grown chili pepper produced under different N levels at mature green and red stages. The results showed that increasing N application reduced AsA content in pepper fruit at both maturity stages, but highly elevated DHA content only at mature green stage. Regardless of N application level, AsA content displayed an increasing trend while DHA content was reduced as pepper fruit maturity advanced, resulting in a higher content of total vitamin C at the mature green stage. The L-galactose pathway, D-galacturonate pathway, and myo-inositol pathway were identified for AsA biosynthesis. The involved precursor metabolites were mainly negatively regulated by increasing N application, and their accumulation increased when pepper fruit developed from green to red stage. Meanwhile, the activities of key enzymes and metabolites in relation to degradation and recycling processes of AsA and DHA were increased or did not change with increasing N application, and they were differently influenced as fruit maturing. As a result, the recommended N application level (250kg N ha-1) could maintain relatively high total vitamin C content in pepper fruits without yield loss at both maturity stages. These findings highlight the importance of optimizing N application level to maximize vitamin C content in pepper fruits, and provide a better understanding of the maturity stage-dependent N regulation on vitamin C anabolism.

Influence of Preharvest Bagging on Maturity Indices and Postharvest Quality of Cherry Tomato (Solanum lycopersicum var. cerasiforme)

The production of cherry tomato (Solanum lycopersicum var. cerasiforme) is negatively affected by harsh environmental conditions such as extremely high and low temperatures, wind and hail damage, and pest and disease infestation. These factors delay maturity and cause uneven ripening, fruit abrasion, and blemishes, which consequently result in poor fruit quality and reduced shelf life. Preharvest bagging is an environmentally friendly alternative technique for enhancement of fruit quality and hence alleviates the stated problems. The study evaluated the physico-chemical quality of ‘Tinker’ and ‘Roma VF’ cherry tomato as influenced by preharvest bagging (transparent and blue plastics) during 8 days of shelf life at ambient conditions. Five clusters of fruit per plant per cultivar with a diameter of 1.5 to 2.0 cm were bagged after 16 days of fruit set and harvested at the green maturity stage, 12 days after preharvest bagging for the assessment of postharvest quality. Preharvest bagging effectively accelerated fruit maturity and ripening as indicated by enhanced fruit size, uniform color development, high pH, dry matter (DM) content, soluble solid content (SSC), and low titratable acidity (TA) during shelf life. Bagged fruit had higher loss of firmness and weight mainly due to ripening and showed very slight incidence of diseases during shelf life of 8 days. Unbagged cherry tomato had delayed maturity and ripening; small-sized fruit; uneven color development; low pH, SSC, and DM; and high TA. Although unbagged cherry tomato had lower firmness and weight loss due to delayed ripening, fruit showed moderate to severe incidence of tomato bacterial canker disease (Clavibacter michiganensis subsp. michiganensis) during shelf life. These results indicated that preharvest bagging accelerated fruit maturity and ripening, improved physico-chemical quality, and reduced disease infestation on cherry tomato during shelf life.

The Changes of Antioxidant Contents and Antioxidant Activities of the Tomato Cultivar Fentailang during the Maturity Stages.

The aim of this study was to analyze the contents of ascorbic acid, phenolics, flavonoids, carotenoids, lycopene, β-carotene and their antioxidant activities in the different maturity stages of tomatoes. The results showed that tomatoes in pink and red stages exhibited higher contents of ascorbic acid concomitant with the correspondent higher hydrophilic antioxidant activities. The contents of phenolics, carotenoids and lycopene were increasing till the red maturity stage. Significant correlation between the DPPH radical scavenging activity and carotenoids, however lycopene was effective in its lowest concentration. The β-carotene was intensively synthesized between the green and breaker maturity stages, and higher correlated with the FRAP capacity. These findings indicated that tomatoes can be considered as natural sources of bioactive compounds regardless of the maturity stages, while tomatoes in pink and red maturity stages has higher nutritional value and antioxidant activity.

Variations in mango fruit quality in response to management factors on a pre- and post-harvest continuum

Summary Fruit quality is a key factor – beginning with the producer, continuing through the supply chain, and ending with the consumer. It is described by multiple indicators and varies during the growth and ripening of the fruit. This study focused on two main aspects of Cogshall mango (Mangifera indica L.) quality: (i) the physical properties of the fruit with fresh mass (FM), pulp dry matter content (DMC), and pulp coloration; and (ii) the chemical properties with pulp sugar content and pulp acidity. These indicators were monitored on on-tree fruit, from about 60 days after bloom until full maturity. The same indicators were also monitored on fruit stored in cold storage rooms during ripening. The effects of leaf-to-fruit ratio (manageable by pruning or fruit thinning), maturity stage of fruit at harvest (manageable by harvest date), and storage temperature on the kinetics of quality traits of on-tree and stored fruit were assessed. In addition, a change-point analysis was applied to the sweetness index kinetics (used as a proxy of fruit ripening) to study fruit ripening induction. The leaf-to-fruit ratio mainly influenced fruit growth in terms of FM and pulp DMC, whereas it had less impact on the evolution of fruit chemical properties. The maturity stage of the fruit at harvest was a key factor in determining the potential quality at the ripe stage. Ripening occurs naturally at the mature green stage for on-tree fruit, but ripening at an earlier stage can be induced by harvesting the fruit. During the ripening phase, a low leaf-to-fruit ratio and a cold storage temperature tended to slow down the daily rate of sweetness increase. The use of cold temperatures during storage slowed down starch degradation and sucrose accumulation, while almost stopping the variation in fruit coloration and acidity.

Enhancement of the fruit quality and postharvest life expectancy of mango fruit (Mangifera indica L.) applying ecofriendly bio-coatings

The higher losses of fruits and vegetables during post-harvest handling are a serious matter for any country whose economy is based on agriculture. The products of this plant are a significant source of horticultural produce storage used for the control of different post-harvest losses, which include diseases as well as microorganisms. Bio-coatings may be used as a better alternative to the synthetic chemicals. The impact of edible coating on the quality and storage life of mango (cv. ‘Anwar Rataul’) fruit was investigated by harvesting the fruits at a firm green stage of physiological maturity and coating them with corn oil, peanut oil, sunflower oil, soya bean oil, and animal fat. The uncoated and coated fruits were stored at 25 °C and the relative humidity (RH) was 75%. The fruits were analyzed for physicochemical quality attributes during storage at 0 (harvest time), 5, 10, 15, 20, and 25 days. The data showed that most of the parameters were affected significantly by the materials of coating and storage intervals (P ≤ 0.05). The fruits coated with animal fat had significantly superior fruit color, taste, aroma, firmness, total sugar content, and acidity of fruit juice, total soluble solids, and ascorbic acid content, as well as delayed ripening. Animal fat-coated fruits retained titratable acidity, ascorbic acid content (mg.100g-1) and fruit firmness (kg.cm-2) with minimal disease incidence, and weight loss (%), whereas uncoated fruits did not retain all quality attributes and deteriorated after 20 days of storage. In conclusion, mango fruits could be coated with animal fat and stored for up to 25 days without deterioration in quality.

Storage Time as an Index for Varietal Prediction of Mango Ripening: A Systemic Approach Validated on Five Senegalese Varieties.

Mangifera indica species presents a wide varietal diversity in terms of fruit size and morphology and also of physicochemical and organoleptic properties of the pulp. In Senegal, in addition to the well-known export varieties, such as 'Kent', local varieties have been little studied particularly during ripening. This study aims to propose prediction models integrating variables deduced from varietal characteristics. Five mango varieties ('Diourou', 'Papaye', 'Sierraleone', 'Boukodiekhal' and 'Sewe') endemic to Senegal were characterized at harvest and followed during ripening storage. Caliber parameters were determined at green-mature stage as well as storage (25 °C) weight losses. Considering the 'ripening storage time' (RST) variable as ripeness level index, intra-varietal prediction models were built by multi-linear regression (R2 = 0.98) using pulp pH, soluble solid content (SSC) and Hue angle. In addition to these physicochemical parameters, variety-specific size, shape and weight loss parameters, were additional variables in multi-linear models (R2 = 0.97) for multi-varietal prediction of RST. Results showed that storage time, which was the most influential factor on the pH, SSC and Hue, can be used as a response for varietal prediction of mango ripening. As a decision support tool, theses statistical models, validated on two seasons, will contribute to reduce post-harvest losses and enhance mango value chain through a better ripening process monitoring.

Application of 5-aminolevulinic acid promotes ripening and accumulation of primary and secondary metabolites in postharvest tomato fruit.

5-Aminolevulinic acid (ALA) plays a vital role in promoting plant growth, enhancing stress resistance, and improving fruit yield and quality. In the present study, tomato fruits were harvested at mature green stage and sprayed with 200 mg L-1 ALA on fruit surface. During ripening, the estimation of primary and secondary metabolites, carotenoids, and chlorophyll contents, and the expression levels of key genes involved in their metabolism were carried out. The results showed that ALA significantly promoted carotenoids accumulation by upregulating the gene expression levels of geranylgeranyl diphosphate synthase (GGPPS, encoding geranylgeranyl diphosphate synthase), phytoene synthase 1 (PSY1, encoding phytoene synthase), phytoene desaturase (PDS, encoding phytoene desaturase), and lycopeneβ-cyclase (LCYB, encoding lycopene β-cyclase), whereas chlorophyll content decreased by downregulating the expression levels of Mg-chelatase (CHLH, encoding Mg-chelatase) and protochlorophyllide oxidoreductase (POR, encoding protochlorophyllide oxidoreductase). Besides, the contents of soluble solids, vitamin C, soluble protein, free amino acids, total soluble sugar, organic acid, total phenol, and flavonoid were increased in ALA-treated tomato fruit, but the fruit firmness was decreased. These results indicated that the exogenous ALA could not only promote postharvest tomato fruit ripening but also improve the internal nutritional and flavor quality of tomato fruit.

Tomato Cultivar Nyagous Fruit Surface Metabolite Changes during Ripening Affect Salmonella Newport

Tomatoes are a valuable crop consumed year-round. Ripe fruit is picked for local sale, whereas tomatoes intended for transit may be harvested at late mature green or breaker stages when fruit firmness preserves quality. In this study, we evaluated Solanum lycopersicum cv. BHN602 association with three Salmonella serotypes and S. lycopersicum cv. Nyagous with Salmonella Newport using fruit at two ripeness stages. Counts of Salmonella Javiana and Typhimurium were higher from red ripe fruit surfaces of BHN602, and counts of Salmonella Newport were higher from ripe Nyagous fruit than from mature green fruit (P < 0.05). Aqueous fruit washes containing fruit surface compounds collected from ripe Nyagous fruit supported more Salmonella Newport growth than green fruit washes (P < 0.05). Growth curve analysis showed that between 2 and 6 h, Salmonella Newport grew at a rate of 0.25 log CFU/h in red fruit wash compared with 0.17 log CFU/h in green fruit wash (P < 0.05). The parallel trend in Salmonella interaction between fruit and wash suggested that surface metabolite differences between unripe and ripe fruit affect Salmonella dynamics. Untargeted phytochemical profiling of tomato fruit surface washes with gas chromatography time-of-flight mass spectrometry showed that ripe fruit had threefold-lower amino acid and fourfold-higher sugar (fructose, glucose, and xylose) levels than green fruit. Green fruit had higher levels of lauric, palmitic, margaric, and arachidic acids, whereas red fruit had more capric acid. The phenolics ferulic, chlorogenic, and vanillic acid, as well as tyrosol, also decreased with ripening. Although limitations of this study preclude conclusions on how specific compounds affect Salmonella, our study highlights the complexity of the plant niche for foodborne pathogens and the importance of understanding the metabolite landscape Salmonella encounters on fresh produce. Fruit surface phytochemical profiling generated testable hypotheses for future studies exploring the differential Salmonella interactions with tomato varieties and fruit at various ripeness stages.

Transition to ripening in tomato requires hormone-controlled genetic reprogramming initiated in gel tissue.

Ripening is the last stage of the developmental program in fleshy fruits. During this phase, fruits become edible and acquire their unique sensory qualities and post-harvest potential. Although our knowledge of the mechanisms that regulate fruit ripening has improved considerably over the past decades, the processes that trigger the transition to ripening remain poorly deciphered. While transcriptomic profiling of tomato (Solanum lycopersicum L.) fruit ripening to date has mainly focused on the changes occurring in pericarp tissues between the Mature Green and Breaker stages, our study addresses the changes between the Early Mature Green and Late Mature Green stages in the gel and pericarp separately. The data showed that the shift from an inability to initiate ripening to the capacity to undergo full ripening requires extensive transcriptomic reprogramming that takes place first in the locular tissues before extending to the pericarp. Genome-wide transcriptomic profiling revealed the wide diversity of transcription factor (TF) families engaged in the global reprogramming of gene expression and identified those specifically regulated at the Mature Green stage in the gel but not in the pericarp, thereby providing potential targets toward deciphering the initial factors and events that trigger the transition to ripening. The study also uncovered an extensive reformed homeostasis for most plant hormones, highlighting the multihormonal control of ripening initiation. Our data unveil the antagonistic roles of ethylene and auxin during the onset of ripening and show that auxin treatment delays fruit ripening via impairing the expression of genes required for System-2 autocatalytic ethylene production that is essential for climacteric ripening. This study unveils the detailed features of the transcriptomic reprogramming associated with the transition to ripening of tomato fruit and shows that the first changes occur in the locular gel before extending to pericarp and that a reformed auxin homeostasis is essential for the ripening to proceed.

Integrated omics analysis identified genes and their splice variants involved in fruit development and metabolites production in Capsicum species.

To date, several transcriptomic studies during fruit development have been reported; however, no comprehensive integrated study on expression diversity, alternative splicing, and metabolomic profiling was reported in Capsicum. This study analyzed RNA-seq data and untargeted metabolomic profiling from early green (EG), mature green (MG), and breaker (Br) fruit stages from two Capsicum species, i.e., C. annuum (Cann) and C. frutescens (Cfrut) from Northeast India. A total of 117,416 and 96,802 alternatively spliced events (AltSpli-events) were identified from Cann and Cfrut, respectively. Among AltSpli-events, intron retention (IR; 32.2% Cann and 25.75% Cfrut) followed by alternative acceptor (AA; 15.4% Cann and 18.9% Cfrut) were the most abundant in Capsicum. Around 7600 genes expressed in at least one fruit stage of Cann and Cfrut were AltSpli. The study identified spliced variants of genes including transcription factors (TFs) potentially involved in fruit development/ripening (Aux/IAA 16-like, ETR, SGR1, ARF, CaGLK2, ETR, CaAGL1, MADS-RIN, FUL1, SEPALLATA1), carotenoid (PDS, CA1, CCD4, NCED3, xanthoxin dehydrogenase, CaERF82, CabHLH100, CaMYB3R-1, SGR1, CaWRKY28, CaWRKY48, CaWRKY54), and capsaicinoids or flavonoid biosynthesis (CaMYB48, CaWRKY51), which were significantly differentially spliced (DS) between consecutive Capsicum fruit stages. Also, this study observed that differentially expressed isoforms (DEiso) from 38 genes with differentially spliced events (DSE) were significantly enriched in various metabolic pathways such as starch and sucrose metabolism, amino acid metabolism, cysteine cutin suberin and wax biosynthesis, and carotenoid biosynthesis. Furthermore, the metabolomic profiling revealed that metabolites from aforementioned pathways such as carbohydrates (mainly sugars such as D-fructose, D-galactose, maltose, and sucrose), organic acids (carboxylic acids), and peptide groups significantly altered during fruit development. Taken together, our findings could help in alternative splicing-based targeted studies of candidate genes involved in fruit development and ripening in Capsicum crop.

Silencing of the Target of Rapamycin Complex Genes Stimulates Tomato Fruit Ripening.

The target of rapamycin complex (TORC) plays a key role in plant cell growth and survival by regulating the gene expression and metabolism according to environmental information. TORC activates transcription, mRNA translation, and anabolic processes under favorable conditions, thereby promoting plant growth and development. Tomato fruit ripening is a complex developmental process promoted by ethylene and specific transcription factors. TORC is known to modulate leaf senescence in tomato. In this study, we investigated the function of TORC in tomato fruit ripening using virus-induced gene silencing (VIGS) of the TORC genes, TOR, lethal with SEC13 protein 8 (LST8), and regulatory-associated protein of TOR (RAPTOR). Quantitative reverse transcription-polymerase chain reaction showed that the expression levels of tomato TORC genes were the highest in the orange stage during fruit development in Micro-Tom tomato. VIGS of these TORC genes using stage 2 tomato accelerated fruit ripening with premature orange/red coloring and decreased fruit growth, when control tobacco rattle virus 2 (TRV2)-myc fruits reached the mature green stage. TORC-deficient fruits showed early accumulation of carotenoid lycopene and reduced cellulose deposition in pericarp cell walls. The early ripening fruits had higher levels of transcripts related to fruit ripening transcription factors, ethylene biosynthesis, carotenoid synthesis, and cell wall modification. Finally, the early ripening phenotype in Micro-Tom tomato was reproduced in the commercial cultivar Moneymaker tomato by VIGS of the TORC genes. Collectively, these results demonstrate that TORC plays an important role in tomato fruit ripening by modulating the transcription of various ripening-related genes.

Determination of the relationship between respiration rate and ethylene production by fruit sizes of different tomato types.

Tomatoes of different types and cultivars are grown in different parts of the world. Accordingly, the phenological, pomological and biochemical characteristics of these types and cultivars may differ from each other, and therefore their ripening behaviours may also differ. The present study aimed to determine the respiration rate and ethylene production of twelve commonly grown cultivars in Turkey at harvest and during the ripening stage. The fruits were harvested at the mature green stage and categorized according to their size as small, medium and large-fruited cultivars. At harvest time, the highest respiration rate was determined from 'Moda' (small-fruited) cultivar and the lowest was from 'Elips' (medium-fruited). The highest ethylene production was determined from 'Sarikiz' (small-fruited) and the lowest was from 'Alberty' (large-fruited). All tomato cultivars examined in the study showed climacteric respiration behavior during the ripening, and it was determined that small-fruited types had a higher respiration rate and ethylene production compared to medium and large-fruited ones. 'Sarikiz' (small-fruited) had the highest climacteric peak and 'Gulpembe' (large-fruited) had the lowest. Moreover, it was determined that the respiration rate of small-fruited cultivars were 5.01-fold higher compared to other cultivars and this type of cultivars produced 4.19-fold higher ethylene compared to big-fruited cultivars at harvest. Medium-fruited tomatoes had 1.90-fold higher respiration rate and 1.64-fold ethylene production compared to big-fruited tomatoes. It was determined that fruit size and respiration rate were related independently of the cultivars, although there was no relationship between fruit size and ethylene production. © 2022 Society of Chemical Industry.