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Authors: L. Wang, E. Brouard, D. Prodhomme, G. Hilbert, C. Renaud, J.-P. Petit, E. Edwards, A. Betts, S. Delrot, N. Ollat, S. Guillaumie, Z.W. Dai and E. Gomès.
Acta Horticulturae (2024)
Abstract: "High temperatures (HT) usually increase berry sugar concentrations, while reducing organic acids and anthocyanin levels, thereby modifying wine quality and character. Viticultural practices such as leaf-to-fruit ratio (L/F) manipulation, combined with application of abscisic acid (ABA) can potentially be used to mitigate HT effects and adjust berry composition. In the present work, after confirming the effects of LF and ABA applications on berry composition over a six-year period, we studied the mechanisms underlying these effects on berry composition and ABA metabolism in 'Cabernet Sauvignon' fruiting-cuttings (i.e., Mullins' vines). Reducing L/F significantly reduced berry sugar and anthocyanin contents, and slightly increased total organic acid content. ABA application increased anthocyanin concentration, and partially restored the coupling between sugar and anthocyanin accumulation under low L/Fs, without affecting the sugar/organic acid ratio. Several transcripts of the anthocyanin biosynthesis pathway (CHS2, CHS3, CHI, F3H, DFR, LODX, UFGT, MybA1 and MybA2) were less abundant under low L/F ratio, whereas some transcripts (CHI, F3H, F35H, LODX, UFGT, MybA1 and MybA2) were upregulated after ABA treatment. ABA treatment had little effect on the transcript abundance of genes related to sugar accumulation, except SWEET10 in 12L plants. Carbon source limitation to clusters also had little effect on ABA biosynthetic genes, but decreased berry ABA concentration. In conclusion, our results show that ABA and sugar signaling synergistically interact to regulate the expression of anthocyanin biosynthetic genes and increase anthocyanin accumulation. Thus, combining L/F ratio manipulation with ABA applications may offer a fine-tuned way to reduce sugar concentration, while maintaining anthocyanin concentrations in grape berry, potentially offering a way to partially alleviate the warming effects of climate change."
Authors: Diego Alejandro Gutiérrez-Villamil, Stanislav Magnitskiy and Helber Enrique Balaguera-López.
Postharvest Biology and Technology (2024)
Highlights • BR have a potential signaling function in the regulation of fruit development. • BR are a postharvest technology to regulate the ripening of fruits and vegetables. • BR mitigate chilling injury by increasing antioxidant systems. • BR induce expression genes of defense and immunity against postharvest pathogens.
Abstract: "Fresh horticultural products satisfy the nutritional, and industrial needs of consumers worldwide. However, the lack of understanding of the fruit development process, the accelerated senescence process and the lack of post-harvest technology in some regions, present a threat to the food and economic security of the food agribusiness. Brassinosteroids (BR) are plant hormones involved in the regulation of various physiological processes and have recently proven to be a viable post-harvest technology alternative to regulate the ripening and senescence of fruits and vegetables. In this review, the current state of BR research on fruit growth and development, physicochemical changes during ripening, and biotic-abiotic stress during the post-harvest life of horticultural products is presented. Furthermore, the review encompasses the effect of the application of exogenous BR and its relationship with molecular signaling on the processes mentioned above, including aspects such as methods, moments and BR analogues at the time of application, and the molecular mechanisms involved. This review proposes a basis for research of the physiological aspects of BR regulation in fruits and vegetables during their development and post-harvest period, and also points to a direction for in-depth investigation of the molecular mechanisms."
Authors: Mengmeng Zhang, Yiteng Liu, Zhuo Chen, Zhaokun Zhi, A-ning Wang, Huafeng Yue, Fangdong Li, Shulin Zhang and Gao-Pu Zhu.
Preprints (2024)
Abstract: "Fruit cracking or splitting, a severe physiological disease that highly affects appearance and quality, compromise the commodity value of fruit and also causes huge economical losses to the producers of several fleshy fruit crops. The growth-promoting phytohormone gibberellic acid (GA) and growth-inhibiting phytohormone abscisic acid (ABA) antagonistically regulate numerous developmental processes throughout the plant life cycle. Homeostasis of endogenous GA and ABA play a significant role in the normal growth of fruits, and its imbalance may lead to the occurrence of cracking or splitting during the process of fruit growth, development, ripening and postharvest storage. The pathways of GA and ABA metabolism and signaling have been studied widely, and the major components were well characterized, which including the genes encoding major biosynthesis and catabolism enzymes and the key signaling components. Nevertheless, our knowledge of the mechanisms of GA and ABA governing fruit cracking is not comprehensive enough. In this review, we not only focus on the scenarios of effects of endogenous GA and ABA contents in the fruit and exogenous plant growth regulators GA and ABA treatments, but also endeavor to provide some genetic cues on the function of GA and ABA responsible for fruit cracking modulation. Information from this review aims to strengthen the understanding of potential molecular bases underlying GA and ABA in fruit cracking control and provide guidance in breeding of fruit cultivars with cracking-resistant ideotypes, and also make great theoretical significance in guiding the establishment of integrated prevention and control measures to fruit cracking or splitting."
Authors: Lichao Hu, Xiaomin Wang, Hongxia Liu, Yaqiong Wu, Wenlong Wu, Lianfei Lyu and Weilin Li.
Scientia Horticulturae (2023)
Highlights • 100 mg/L GA3 induces better results in seedless blueberries. • Exogenous GA3 treatment promoted the elongation of blueberry fruit flesh cells. • Exogenous GA3 treatment caused endosperm dysplasia in blueberry fruit. • Screening was conducted for 16 genes that may regulate seed abortion in blueberries.
Abstract: "Blueberry fruit, is flavorful and nutrient, rich and has very broad market prospects. Seedless blueberries are preferred by consumers when eaten fresh, preserved or processed. Here, 50, 100, and 150 mg/L gibberellic acid (GA3) were used to treat the flowers of 'Sharpblue' blueberry after 5 and 10 days of full opening, resulting in varying seed abortion rates. The 50 mg/L GA3 treatment yielded the lowest seedlessness rate, fruit shape index, and fruit weight. Treatment with 150 mg/L GA3 inhibited fruit expansion and prolonged ripening after treatment, although the seedlessness rate was 98.78%. In contrast, 100 mg/L GA3 induced 100% seedlessness and did not significantly affect the fruit phenotype, solid-to-acid ratio, or firmness compared to those of control seeded fruit. The brassinosteroid (BR), cytokinin (CTK), zeatin (ZT), and ethylene (ETH) levels increased when the seeds stopped developing at the S2 stage under 100 mg/L GA3, while the abscisic acid (ABA) and indole-3-acetic acid (IAA) levels were lower than those in the control group. Transcriptome analysis revealed 87 differentially expressed genes (DEGs) related to phytohormones and 49 DEGs related to seed development. The expression of 21 genes potentially regulating seed development was initially validated by RT-qPCR, and the RT-qPCR results for 16 DEGs were consistent with their RNA-seq results. Additionally, comprehensive transcriptome and metabolome analyses revealed that the differentially expressed metabolite (DEM) (±)-abscisic acid had the strongest positive correlation with the DEG AMAT and the DEM gibberellic acid with DEG JAZ1. Collectively, the developmental process of blueberry fruit and seeds may be regulated by the synergistic effects of multiple hormones, and differential expression of 16 genes associated with seed development may influence seed abortion in blueberry fruit. This study investigated the effects of different concentrations of GA3 treatments on blueberry fruit seedlessness, fruit quality, and hormone and gene expression, providing valuable reference data for exploring the internal inhibition mechanism of blueberry seed development and inducing seedless blueberry fruit formation."
Authors: S. Srividhya, M. Jayakanthan and P. Jeyakumar
Plant Physiology Reports (2023)
Abstract: "1-Methylcyclopropene (1-MCP), an ethylene receptor inhibitor, has been widely applied in delaying the ripening of fruits including several tropical and temperate fruit crops. A molecular docking approach has been attempted in this study to understand the effect of 1-MCP and ethylene in regulating the fruit ripening process in addition to postharvest wet lab experiments. The molecular docking approach executed in this study is a first of kind approach to study the interaction of 1-MCP and ethylene molecule to the ethylene binding receptor protein and study the effectiveness of 1-MCP in inhibiting ethylene responses. Also, using bioinformatics tools, an attempt was made to predict the complete protein structure of ethylene receptors ETR1 and ERS1, which is not available so far. The in-silico approach and postharvest studies reveal that 1-MCP has higher affinity to bind ethylene receptors (less binding energy) than ethylene, confirming its efficacy on inhibiting ethylene signaling, thus can also be regarded as ethylene perception inhibitor. Hence, 1-MCP has a greater scope in delaying the ripening process as observed in the present investigation. The study also shows a plausible mechanism at the molecular level for delaying ripening process in papaya fruit which paves way to identify alternative GRAS compounds to extend shelf life of perishables.
Authors: Seong-Jin Choi, Gwang-Hwan Ahn, Kyung Hae Lee and Wan Jin Jahng.
ACS Omega (2023)
Abstract; "Ethylene is a gaseous hydrocarbon molecule known as a plant hormone that promotes fruit ripening and senescence. Efficiently controlling ethylene is a central key to maintaining the quality of agricultural products. The current study uncovered a synthetic method for 1-(2,2-dimethylpropyl)-cyclopropene (1-DCP) as a cyclopropene derivative to inhibit ethylene action in fruit ripening and senescence. We synthesized 1-DCP using α-diisobutylene through a two-step process, including allylic chlorination by hypochlorite and HCl, followed by α-elimination of the allylic chloride using a strong base, lithium diethylamide. GC–MS and NMR analyses demonstrated that 1-DCP was synthesized efficiently with 35% yield and 95% purity. When treated as an aqueous emulsion on plants, including persimmon and banana fruits, 1 mM 1-DCP showed effective inhibition of ethylene action by delaying the flesh softening and peel degreening, which are representative phenomena of fruit ripening and senescence induced by ethylene. Our data demonstrated that 1-DCP could be synthesized and used as a sprayable ethylene antagonist for pre- or post-harvest growth regulation in plants and fruits.
Authors: E.J. Ordoñez Trejo, S. Brizzolara, V. Cardillo, B. Ruperti, C. Bonghi and P. Tonutti.
Scientia Horticulturae (2023)
Highlights • PGRs are used in the field to control vegetative and reproductive activities in fruit crops. • Effects of PGRs applied pre-harvest can be present also during storage. • The main postharvest effects of field-applied PGRs are on the progress of ripening. • Postharvest physiological disorders can be reduced by specific PGRs.
Abstract: "In horticulture, Plant Growth Regulators (PGRs) are applied during cultivation in the field to control and regulate different processes with positive effects on stress responses and general performance, including yield, composition, and quality of the harvested produce. Both vegetative and reproductive activities may be affected by PGRs and, considering specifically fruit crops, the effects of these field treatments can also be observed in terms of storage behavior and postharvest physiology. The postharvest effects of inhibitors, antagonists, promoters or releasers of gibberellins, cytokinins, auxins and ethylene depend on the concentration, chemical formulation and plant developmental stage at the time of treatments. Ethylene-related PGRs in particular, applied to control ripening and optimize harvesting, have marked residual effects observed during the storage life. In addition to these hormonal categories, other substances such as salicylic acid, brassinosteroids and jasmonates, recognized as having physiological effects in developing plants and inducing compositional changes in fruits at harvest, are effective in altering specific postharvest ripening processes, such as firmness loss and ethylene physiology. The stimulation of antioxidant enzymes activity and the maintenance of cell membrane integrity during storage, resulting in a reduction of chilling injury incidence, appear to be among the main effects of the field application of these PGRs. This review emphasizes the implications of PGR applications during cultivation on fruit postharvest."
Authors: Jingyu Zhang, Yuhao Cao, Jia Tang, Xujie He, Ming Li, Chen Li, Xiaolin Ren and Yuduan Ding.
Horticulturae (2023)
Abstract: "Gibberellins (GAs) are plant hormones indispensable in regulating the growth and development of fruits. Recent studies have shown that GAs play important roles in delaying horticultural crop ripening and senescence, enhancing the internal and external quality of horticultural crops and resistance to stress and disease. We reviewed the role of GAs in the postharvest physiology of fruits in recent years. GAs are closely related to their ability to retard fruit senescence. GAs could effectively improve fruit storage quality and significantly increase flesh hardness, reduce respiration intensity, inhibit the release of endogenous ethylene, and effectively inhibit fruit softening and ripening. It can also improve the intrinsic and extrinsic quality of fruit storage by improving fruit shape, regulating color, delaying the reduction of soluble solids, promoting sugar accumulation, and delaying vitamin loss. GAs also play a role in postharvest biotic and abiotic stress resistance. The GA treatment effectively reduces the cold damage index, reduces the production and accumulation of superoxide anion(O2−), improves the antioxidant capacity of fruits, and maintains the integrity of cell membranes during low-temperature storage. Moreover, GAs could effectively control some postharvest fruit diseases. In conclusion, GAs play an important role in the physiological regulation of postharvest fruits and have important application prospects in postharvest fruits."
Authors: Qian Li, Guang Wang, Siting Lai and Shijiang Zhu.
LWT - Food Science and Technology (2023)
Highlights • Pineapples display internal browning and reduced spermidine (Spd) after storage. • ABA alleviates internal browning and GA3 aggravates internal browning. • ABA enhances Spd synthesis, while GA3 does not obviously affect it. • Exogenous application of Spd reduces pineapple internal browning. • The findings suggest Spd plays an important role in regulating internal browning.
Abstract: "Spermidine is one of the secondary metabolites (SM) related to plant tissue browning caused by chilling, but whether it plays a role in pineapple internal browning (IB) occurred at ambient temperature remains unknown. In this study, pineapples affected by severe IB after 9-d storage showed dramatic changes in SMs, with 94.94% of 79 being upregulated. Among the 4 downregulated were spermidine. Exogenous abscisic acid (ABA) suppressed and gibberellin (GA3) aggravated IB and they differentially regulated SMs and spermidine. Compared with the control, ABA downregulated 65 of 70 SMs and upregulated spermidine, while GA3 upregulated 7 of 24 SMs and did not obviously affect spermidine. Exogenous spermidine alleviated IB, confirming the role of spermidine in regulating IB. ABA upregulated spermidine biosynthesis genes AcARG1 and AcSPDS, while GA3 upregulated AcPAO2. ABA downregulated and GA3 upregulated SAM, ACS and ACO. ABA reduced 1-aminocyclopropane 1-Carboxylate (ACC) and GA3 did not. ABA upregulated NCED, ABA2 and AAO3 and increased endogenous ABA, while GA3 showed opposite effects. Collectively, the findings indicate spermidine play an important role in regulating IB of pineapple. Moreover, this work may provide novel insight into the mechanism underlying interactions of spermidine with ABA and GA in regulating quality of harvested fruit."
Autor: Antonio Ferrante
In Book: "The Plant Hormone Ethylene" (2023). Edited by Nafees A. Khan, Antonio Ferrante and Sergi Munné-Bosch.
Abstract: "Ethylene is a plant hormone involved in several physiological and biochemical processes that regulate plant growth and product quality. Ethylene is an important regulator of plant growth and development, and its action can have positive or negative effects on crop production and produce quality. In horticultural crops, the positive effect of ethylene can be limited to the ripening induction of some climacteric fruits or the improvement of produce aroma. Most of studies and applications are, instead, oriented toward the reduction of ethylene production and protection from its action. In climacteric fruits, ethylene is the key factor for extending the storage and shelf life. In leafy vegetables, ethylene in mature leaves can induce physiological disorders that can compromise visual and nutritional quality. Sensitive ornamental plants can be dramatically compromised by the quality and the commercialization. Understanding the efficacy of ethylene inhibitors can provide important information for preserving quality. The use of inhibitors of ethylene action had a large practical application and an overview of the studies performed, and further investigations are discussed."
Authors: Haiying Yang, Jianzhao Li, Xiaohe Li, Rui Wu, Xueli Zhang, Xinguang Fan, Guotian Li, Hansheng Gong, Xueren Yin and Aidi Zhang.
Postharvest Biology and Technology (2023)
Highlights: • GA3 treatment delayed postharvest kiwifruit ripening and softening. • GA3 inhibited starch/cell wall degradation, and ethylene/ester production. • 3116 DEGs responded to GA3 treatment were identified from RNA-seq. • 16 major DEGs might be involved in controlling kiwifruit ripening.
Abstract: "Gibberellins (GAs) control numerous processes in plants, including fruit ripening. However, the role of GAs in kiwifruit ripening is not well characterized. Here, we noticed that GA3 treatment in postharvest kiwifruit delayed the ripening process and many physiological traits were detected such as firmness, starch/total soluble solid content, cell-wall components (pectin, cellulose and hemicellulose), ethylene and ester production, and ascorbic acid (vitamin C) concentration. Transcriptome analysis supplied a molecular basis for investigating the inhibiting mechanism of GA3 and metabolic variations during kiwifruit ripening. A total of 3116 differently expressed genes (DEGs) were identified, including 51 genes involved in plant hormone signal transduction pathways and 36 structural genes related to these physiological traits. 16 major DEGs were analyzed by real-time PCR during the whole storage period. The expression of most of them was significantly suppressed by GA3 treatment, such as two ethylene biosynthesis genes (ACOs ), two β-amylase (BAMs), five cell-wall modification genes, one GA2ox, and one GA receptor GID1, whereas the expression of Actinidia29942 (JAZ) was enhanced by GA3 treatment. Correlation analysis between multiple physiological indicators and candidate genes showed that GA3 could regulate kiwifruit postharvest ripening effectively and comprehensively. Together, these GA-responsive genes may play important roles in controlling kiwifruit ripening, and GA treatment could be a promising approach for the preservation of postharvest kiwifruit."
Authors: Nathalie Kuhn, Macarena Arellano, Claudio Ponce, Christian Hodar, Francisco Correa, Salvatore Multari, Stefan Martens, Esther Carrera, Jose Manuel Donoso and Lee A. Meisel.
bioRxiv (2022)
Abstract: "Abscisic acid (ABA) plays a key role in the ripening process of non-climacteric fruits, triggering pigment production, fruit softening, and sugar accumulation. Transcriptomic studies show that ABA modifies the expression of several ripening-related genes, but to date, the epigenetic approach has not been utilized to characterize the role of ABA during this process. Therefore, this work aimed to perform transcriptomic and DNA methylation analyses of fruit samples treated with ABA during the fruit ripening process in the non-climacteric sweet cherry model. RNA-seq analyses revealed an overrepresentation of transcripts annotated in functional categories related to ABA response, secondary metabolism, and sugar synthesis. In contrast, Whole Genome Bisulfite Sequencing (WGBS) revealed DNA hypomethylation in the 5′UTR region of genes related to carotene catabolism. Genes encoding xyloglucan enzymes were regulated transcriptionally and epigenetically during ripening. ABA treatment enhanced color development and ripening. GO analysis of DEGs in the RNA-seq of the ABA treatment revealed expression variations in genes encoding members of the Aux/IAA and ARF families. In the WGBS, genes encoding enzymes of the cytokinin biosynthesis had differential DNA methylation after the ABA treatment. Our work shows the genetic factors modulated by ABA at the genetic and epigenetic levels during non-climacteric ripening."
Authors: Jianyang Liu, Md Tabibul Islam and Sherif M. Sherif.
Horticulturae (2022)
Abstract: "Preharvest fruit drop is a significant physiological problem that affects numerous commercially significant apple varieties, including ‘Gala.’ AVG and 1-MCP are two plant growth regulators commonly used to reduce fruit drop by reducing ethylene synthesis and perception, respectively. To optimize yield and market acceptance, a complete investigation of AVG and 1-MCP impacts on fruit drop and fruit quality of ‘Gala’ apples is required. In this study, four trials were conducted over the course of three years to determine the effects of AVG and 1-MCP on fruit drop and quality at harvest and after cold storage. Our results indicated that applications of AVG at the full-rate (130 mgL−1) three weeks before harvest (WBAH) were more effective at minimizing fruit drop than applications at the half-rate (65 mgL−1) and did not differ significantly from the double rate (260 mgL−1). Additionally, a single application of AVG was as effective in preventing fruit drop as two applications of 1-MCP. We also demonstrated that AVG decreased fruit skin pigmentation when used alone or in conjunction with GA4+7 or 1-MCP, while 1-MCP applications had no negative effect on fruit color. Finally, our data showed that when compared to 1-MCP and GA4+7, AVG alone was more effective in preventing stem-end splitting in Gala apples."
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Authors: Xianghan Cheng, Feifei Liu, Xiaolei Liu and Xuan Yang.
Journal of the Science of Food and Agriculture (2024)
Abstract: "Background - The influences of abscisic acid (ABA) applications on precursors and gene expression in 3-alkyl-2-methoxypyrazines (MPs) biosynthetic pathway, MPs concentration and sensory evaluation of its derived peculiar odors in Cabernet Sauvignon grapes and wines were investigated. At the vineyard, ABA solution with 25, 100 and 400 mg L−1 (AT1, AT2 and AT3, respectively) and an aqueous solution (control) were sprayed three times from veraison to pre-harvest. Results - Higher concentration ABA applications (AT2 and AT3) in grapes could significantly reduce MPs concentration and its derived peculiar odors in grapes and wines compared to a lower concentration ABA application (AT1) and control, with AT2 application having the strongest effect. The changes in MPs were mainly a result of the downregulated expression of VvOMTs genes at higher concentration ABA applications, independent of the levels of their potential precursors. Conclusion - The present study reveals that ABA application had the potential to decrease production of MPs in Cabernet Sauvignon grapes and wines, and this result provides reference values for the removal of unpleasant vegetable odors from Cabernet Sauvignon wines in production.
Authors: Paula Muñoz, Verónica Tijero, Celia Vincent and Sergi Munné-Bosch.
Biochemical Journal (2024)
Abstract: "Tocopherols are lipophilic antioxidants known as vitamin E and synthesized from the condensation of two metabolic pathways leading to the formation of homogentisate and phytyl diphosphate. While homogentisate derives from tyrosine metabolism, phytyl diphosphate may be formed from geranylgeranyl diphosphate or phytol recycling from chlorophyll degradation. Here we hypothesized that abscisic acid (ABA) could induce tocopherol biosynthesis in sweet cherries by modifying the expression of genes involved in vits biosynthesis, including those from the phytol recycling pathway. Hence, expression of key tocopherol biosynthesis genes was determined together with vitamin E and chlorophyll contents during natural development of sweet cherries on-tree. Moreover, the effects of exogenously applied ABA on the expression of key tocopherol biosynthesis genes were also investigated during on-tree fruit development, and tocopherols and chlorophylls contents analyzed. Results showed that expression of tocopherol biosynthesis genes, including VTE5, VTE6, HPPD and HPT showed contrasting patterns of variation, but in all cases, increased by 2- and 3-fold over time during fruit de-greening. This was not the case for GGDR and VTE4, the first showing constitutive expression during development and the second with marked downregulation at ripening onset. Furthermore, exogenous ABA stimulated production of both α- and γ-tocopherols by 60% and 30%, respectively, promoted chlorophyll degradation and significantly enhanced VTE5 and VTE6 expression, and also that of HPPD and VTE4, altogether increasing total tocopherol accumulation. In conclusion, ABA increases promote the transcription of phytol recycling enzymes, which may contribute to vitamin E biosynthesis during fruit development in stone fruits like sweet cherries."
Authors: S. Thunyamada, K. Ohkawa, H. Ohara, T. Saito, Y. Todoroki and S. Kondo.
European Journal of Horticultural Science (2023)
Abstract: "The effects of the inhibition of ABA 8′-hydroxylase activity by abscinazole-E3M (Abz) on endogenous ABA, sugar metabolism, and aroma volatiles were examined in grapes. Abz increased the endogenous ABA concentration through downregulation of ABA 8′-hydroxylase gene (VvCYP707A1). Abz also enhanced the expression of sucrose transporter genes (VvSUC11 and VvSUC12), which led to sucrose accumulation. Glucose and fructose concentrations increased in the Abz-treated berries with the increased expression of hexose transporter gene (VvHT2). Abz increased the concentration of C6 aldehyde via hydroperoxide lyase gene (VvHPL1) upregulation. In contrast, Abz suppressed the expression of the pathogenesis-related (PR) gene (VvPR1) but positively induced the expression of chitinase genes (VvChi26 and VvChi31). Our results suggested that the inhibition of ABA 8′-hydroxylase by Abz application increased the endogenous ABA concentration and enhanced the expression of sugar transporter-related genes, resulting in sugar accumulation in grape berries. In addition, Abz enhanced C6 aldehyde biosynthesis and PR gene expressions related to stress tolerance."
Significance of this study: What is already known on this subject? Abscisic acid (ABA) application at pre-veraison promoted anthocyanin formation in grapes, but exogenous ABA application did not affect sugar concentrations. ABA application can increase volatile compounds in the skin of grapes. ABA application induces drought tolerance in grapevines, but the effects are temporary. What are the new findings? The application of abscinazole (Abz) increased endogenous ABA accumulation and induced ABA signaling in grape flesh. Abz treatment enhanced sugar transporter genes such as SUC and HT, and increased sugar concentrations in grape flesh. Abz application influenced C6 aldehyde biosynthesis and the expression of PR genes. What is the expected impact on horticulture? To understand the mechanism of sugar increase by Abz application. To advance the development of techniques to improve fruit quality including sugar accumulation and volatile compounds.
Authors: Ziyan Liu, Tanglu Hu, Chunxin Yu, Weiming Tan, Yuanyue Shen and Liusheng Duan.
Journal of Plant Growth Regulation (2024)
Abstract: "Apple is a kind of fruit that can be stored for a relatively long time, but softening, browning, and decay will occur during the long-term storage. Therefore, the research on apple preservation is meaningful. The application of ethylene inhibitors is an effective way to prolong fruit shelf life. Aminoethoxyvinylglycine (AVG) and its functional analogues are ethylene synthesis inhibitors that can significantly prolong the shelf life of tomato fruit. In this work, 11 AVG analogues (2a–2k) were explored on apple fruit preservation and analyzed by the molecular docking based on the structure of apple 1-aminocyclopropane-1-carboxylic acid synthase (ACS) protein (Protein Data Bank ID: 1YNU). The compounds 2c, 2i, 2j, and 2k show higher binding affinity than AVG. More importantly, analogues 2c and 2j significantly delay the fruit softening, the decrease of soluble solid content and weight loss and 2j is the most effective analogue in prolonging apple shelf life, indicating that the function of these analogues in apple preservation is basically associated with their predicted binding affinity to apple ACS. This study explores the application potential of AVG analogue resources and provides some new analogues for apple preservation. This research also demonstrates that molecular docking analysis based on target protein has important guiding significance for drug design."
Authors: Gang Ma, Lancui Zhang, Kan Murakami, Masaki Yahata and Masaya Kato.
The Horticulture Journal (2023)
Abstract: ‘Miyagawa-wase’ (Citrus unshiu Marcow.), an early-season citrus variety, is rich in multiple nutrients and widely consumed in Japan. In ‘Miyagawa-wase’, when the pulp reaches maturity and is ready to eat, the peel is still a greenish color because of the relatively high temperature in the harvest season. In this study, to improve the coloration of ‘Miyagawa-wase’ peel, we treated the fruit with 1-naphthaleneacetic acid (NAA) after harvest. The results showed that postharvest treatment with NAA was effective to induce chlorophyll degradation and carotenoid accumulation in ‘Miyagawa-wase’ peel during storage. In the NAA treatment, the reduction in the chlorophyll contents after harvest was in parallel with decreases in the expression of chlorophyll biosynthetic genes (CitGGDR, CitCHLH, CitCHL27, CitPORA, and CitCAO) and an increase in chlorophyll degradation gene CitPPH. The contents of the major carotenoids, β-cryptoxanthin and 9-cis-violaxanthin, were increased by the NAA treatment through upregulation of the expression of carotenoid biosynthetic genes (CitPSY, CitPDS, CitZDS, CitLCYb2, and CitHYb) after harvest. In addition, it was found that the positive effect on degreening in the NAA treatment was inhibited by the ethylene antagonist 1-MCP. In the combination treatment using NAA and 1-MCP, the total chlorophyll content was much higher, while the contents of β-cryptoxanthin and 9-cis-violaxanthin were lower compared with NAA treatment alone, indicating that the acceleration of degreening by NAA may be caused by ethylene. The results presented in this study suggest that postharvest NAA treatment is an effective method for improving the peel coloration in early-season citrus varieties."
Authors: Shubham Temgire, Anis Ahmad Mirza, Abdul Waheed Wani, Kondle Ravi, Pratik Tanpure and Suprikesh Kadlag.
Annals of Phytomedicine (2023)
Abstract: "In warm climates, 'Crimson Seedless' may fail to develop an appropriate red colour, despite being a high-quality, red table grape (Vitis vinifera L.). Green berries also persist in most bunches even when the rest of the bunch has turned red. The plant hormone abscisic acid (ABA) is involved in the accumulation of anthocyanins in grape berry skin during maturation. Temperature increases are negatively affecting anthocyanin biosynthesis and other fruit quality characteristics in warmer regions of the world, making high-quality table grapes challenging to cultivate. Crop productivity and sustainability can be improved with nanotechnology. Table grapes are marketed based on their red colour, which is one of the most significant criteria for fruit quality. Several chemicals and practices were evaluated in this review to determine their effect on the bunch colour and metabolic profile of the grapevine variety, Crimson Seedless."
Authors: Wei Wu, Ning-jing Sun, Yang Xu, Yu-tong Chen, Xiao-fen Liu, Li-yu Shi, Wei Chen, Qing-gang Zhu, Bang-chu Gong, Xue-ren Yin and Zhen-feng Yang.
Plant Physiology (2023)
Abstract: "As the harvest season of most fruit is concentrated, fruit maturation manipulation is essential for the fresh fruit industry to prolong sales time. Gibberellin (GA), an important phytohormone necessary for plant growth and development, has also shown a substantial regulatory effect on fruit maturation; however, its regulatory mechanisms remain inconclusive. In this research, preharvest GA3 treatment effectively delayed fruit maturation in several persimmon (Diospyros kaki) cultivars. Among the proteins encoded by differentially expressed genes, two transcriptional activators (NAC TRANSCRIPTION FACTOR DkNAC24 and ETHYLENE RESPONSIVE FACTOR DkERF38) and a repressor (MYB-LIKE TRANSCRIPTION FACTOR DkMYB22) were direct regulators of GERANYLGERANYL DIPHOSPHATE SYNTHASE DkGGPS1, LYSINE HISTIDINE TRANSPORTER DkLHT1, and FRUCTOSE-BISPHOSPHATE ALDOLASE DkFBA1 respectively, resulting in the inhibition of carotenoid synthesis, outward transport of an ethylene precursor, and consumption of fructose and glucose. Thus, the present study not only provides a practical method to prolong the persimmon fruit maturation period in various cultivars, but also provides insights into the regulatory mechanisms of GA on multiple aspects of fruit quality formation at the transcriptional regulation level."
Authors: Christine H. Nguyen, Dawei Yan and Eiji Nambara.
Genes (2023)
Abstract: "Abscisic acid (ABA) is a plant hormone that regulates numerous plant processes, including plant growth, development, and stress physiology. ABA plays an important role in enhancing plant stress tolerance. This involves the ABA-mediated control of gene expression to increase antioxidant activities for scavenging reactive oxygen species (ROS). ABA is a fragile molecule that is rapidly isomerized by ultraviolet (UV) light and catabolized in plants. This makes it challenging to apply as a plant growth substance. ABA analogs are synthetic derivatives of ABA that alter ABA’s functions to modulate plant growth and stress physiology. Modifying functional group(s) in ABA analogs alters the potency, selectivity to receptors, and mode of action (i.e., either agonists or antagonists). Despite current advances in developing ABA analogs with high affinity to ABA receptors, it remains under investigation for its persistence in plants. The persistence of ABA analogs depends on their tolerance to catabolic and xenobiotic enzymes and light. Accumulated studies have demonstrated that the persistence of ABA analogs impacts the potency of its effect in plants. Thus, evaluating the persistence of these chemicals is a possible scheme for a better prediction of their functionality and potency in plants. Moreover, optimizing chemical administration protocols and biochemical characterization is also critical in validating the function of chemicals. Lastly, the development of chemical and genetic controls is required to acquire the stress tolerance of plants for multiple different uses."
Authors: Xiaofang Li, Pingping Fang, Mingxuan Li and Pei Xu.
In Vitro Cellular & Developmental Biology - Plant (2023)
Abstract: "Structural analogs of enzyme substrates involved in plant hormone biosynthesis can either inhibit or enhance hormone-related responses depending on their specific chemical characteristics. Ethylene is an important gaseous phytohormone regulating a myriad of physiological and developmental processes. The substrate of the ethylene biosynthesis key enzyme ACC oxidase (ACO), 1-aminocyclopropane-1-carboxylate acid (ACC), is the direct precursor of ethylene. Previous studies have identified a series of ACC analogs as ethylene antagonists competitively binding with ACO. Here, this study identified methyl 1-aminocyclopropanecarboxylate (methyl-ACC), a structural analog of ACC, as an agonist of ethylene response in plants. Methyl-ACC triggered enhanced ethylene-related responses in plants similar to the effects of ACC, such as restrained root elongation, increased root hair number, promoted dark-induced leaf senescence, and accelerated ripening of postharvest tomato fruit. A higher amount of ethylene release was detected from the tomato leaves treated with methyl-ACC than from the mock control. These bioactivities of methyl-ACC render it a potential plant growth regulator (PGR) for the agricultural and postharvest industries. RT-qPCR revealed a generally upregulated expression of the ethylene biosynthesis genes in detached tomato leaves under methyl-ACC treatment. In vivo and in vitro enzymatic activity analyses showed that methyl-ACC had no obvious effect on the total ACO activity in detached tomato leaves nor on the activity of recombinant SlACO1, the predominantly expressed ACO family member in this tissue. This study offers a promising new PGR and adds to the current knowledge on the structure–function-regulation relationship of compounds associated with ethylene biosynthesis. The mechanism by which methyl-ACC exerts its function is discussed."
Authors: Patricio Olmedo, Gerardo Núñez-Lillo, Juan Vidal, Carol Leiva, Bárbara Rojas, Karen Sagredo, César Arriagada, Bruno G. Defilippi, Alonso G. Pérez-Donoso, Claudio Meneses, Sebastien Carpentier, Romina Pedreschi and Reinaldo Campos-Vargas.
Food Chemistry (2023)
Highlights • Application of forchlorfenuron N–(2–chloro–4–pyridinyl)–N’–phenylurea (CPPU) was associated with increased berry size and firmness. • Forchlorfenuron N–(2–chloro–4–pyridinyl)–N’–phenylurea (CPPU) was associated with increased glycolysis and TCA cycle-related proteins. • Forchlorfenuron N–(2–chloro–4–pyridinyl)–N’–phenylurea (CPPU) was associated with modified accumulation of sugars and organic acids.
Abstract: "Consumers around the world prefer high quality table grapes. To achieve higher quality traits at ripening, grapevine producers apply different plant growth regulators. The synthetic cytokinin forchlorfenuron N–(2–chloro–4–pyridinyl)–N’–phenylurea (CPPU) is widely used, its effect on grape quality is poorly understood. We hypothesized that the use of CPPU in pre-flowering can lead to changes in the metabolism that affects grape quality at harvest. Therefore, we investigated the role of CPPU applications on the quality of grapes by integrating proteomics and metabolomics. CPPU-treated grapevines showed a significant increase in berry size and firmness. Proteomic analyses indicated that CPPU-treated berries accumulated enzymes associated with carbohydrate metabolism, glycolysis, and tricarboxylic acid (TCA) cycle at harvest. Metabolomic analyses showed shifts in the abundance of compounds associated with carbohydrate metabolism and TCA cycle in CPPU-treated grapes. These findings suggest that CPPU applications modulate central carbon metabolism, improving grape berry quality."
Authors: Jiajia Li, Hafiz Umer Javed, Zishu Wu, Lei Wang, Jiayu Han, Ying Zhang, Chao Ma, Songtao Jiu, Caixi Zhang and Shiping Wang.
Frontiers in Plant Science (2022)
Abstract: "Grape berries contain a variety of metabolites, such as anthocyanins, sugars, fatty acids, and antioxidants. Endogenous phytohormones strongly influence these metabolites, which regulate berry quality improvement. In this study, we evaluated the effects of 2,4-epibrassinolide (EBR, brassinolide (BR)-like growth regulator), jasmonic acid (JA), and their signaling inhibitors brassinazole (Brz), and sodium diethyldithiocarbamate (DIECA) on berry quality and antioxidant ability. Overall, the pre-harvest application of 0.5 mg L-1 EBR and 100 μmol L-1 JA significantly influences the quality of the grape berry. Results showed that EBR was superior to other treatments at enhancing the content of different metabolites, including anthocyanins, fructose, glucose, and a variety of fatty acids, in grapes. EBR and JA also enhanced the synthesis of gibberellin3 (GA3), cytokinin (CTK), salicylic acid (SA), JA, methyl jasmonate (MeJA), BR, and abscisic acid (ABA), while inhibiting the synthesis of auxin (IAA). Most genes related to BR/JA and anthocyanins/sugars/fatty acids biosynthesis were up-regulated. The effects of Brz and DIECA on the grape berry quality were totally reversed throughout the study, as shown by EBR and JA. According to correlation analysis, EBR and JA have a beneficial positive interaction that promotes the formation of strong coherences in grape berries between ABA/IAA/ZT-fruit expansion, BR/JA/MeJA/GA3/ZR-biochemical characteristics development, JA/MeJA/ABA/GA3/SA/ZR-antioxidant capacity enhancement, and JA/MeJA/IAA/GA3/ZT/ZR-fatty acids accumulation. In this regard, we concluded that preharvest exogenous 0.5 mg L-1 EBR and 100 μmol L-1 JA is a successful way to improve grape berry quality."
Authors: Abdul H. Kazimi, Oscar W. Mitalo, Azimullah Azimi, Kanae Masuda, Chikara Yano, Takashi Akagi, Koichiro Ushijima and Yasutaka Kubo.
The Horticulture Journal (2023)
Abstract: "A major challenge in terms of commercializing 1-methylclopropene (1-MCP) to extend the storage life and control physiological disorders in European pears is that it irreversibly inhibits fruit ripening in some cultivars, particularly flesh softening that is necessary for optimal consumption quality. In this study, we examined the effect of 1-MCP pretreatments on fruit ripening and associated transcriptomic changes in ‘La France’ (Pyrus communis L.) pears during storage at 20°C and 5°C. Compared to non-treated controls, 1-MCP pretreatment suppressed fruit respiration and ethylene production rates, and markedly delayed flesh softening. Normal ripening (ethylene production and flesh softening to eating quality firmness) was observed in 1-MCP treated fruit after 42 d at 20°C, and 112 d at 5°C. Subsequent RNA-Seq analysis revealed that 6,427 genes, including those associated with ethylene biosynthesis (ACS1, ACS1b, ACO1, and ACO2), cell wall degrading enzymes (PG3, β-GAL, EG, and EXP1), and transcription factors (AGL18 and NAC29) were up- or down-regulated in non-treated fruit both at 20°C and 5°C. The expression patterns of these genes were disrupted by 1-MCP pretreatment, but up- or down-regulation was also observed when ethylene was detected in 1-MCP-treated fruit. Together, these findings demonstrate the potential for practical use of 1-MCP to extend storage life in ‘La France’ pears given that (i) a single application markedly extended storage life to 56 d at 20°C and 112 d at 5°C, and (ii) treated fruit could regain their softening capacity, thus eliminating previous irreversible ripening blockage concerns."
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