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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: 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: Hikaru Ishikawa, Yasuyuki Togano and Tomoki Shibuya.
Horticulture Journal (2023)
Abstract: "The large berry mutant (LBM) of the ‘Delaware’ (V. vinifera × (V. labrusca × V. aestivalis)) is known to produce larger berries than ‘Delaware’ when subjected to traditional double gibberellic acid-3 (GA3) treatment. In this study, we first compared ‘Delaware’ and the LBM in terms of their berry and cluster quality to reevaluate previous findings on LBM. Next, we compared berry size without GA3, histological characteristics of the early developmental berry, and then GA-related gene expression to reveal the characteristics of the LBM. The previous finding that LBM yielded larger berry sizes than ‘Delaware’ with double GA3 treatment was verified, but without GA3 treatment, LBM did not produce larger berries than ‘Delaware’. This highlights the prerequisite of exogenous GA for larger berry size in LBM. Histological analysis revealed an increase in cell numbers of the inner and outer mesocarp walls in the early developmental stage of LBM berries. Gene expression analysis of the flower buds and berries indicated an increased expression of VvGID1A, encoding the GA receptor, in LBM than in ‘Delaware’ 3 h after the first GA3 treatment. Additionally, the expression of VvGID1A and VvGID1B was higher in LBM than that in ‘Delaware’ before and after the second GA3 treatment. The expression of VvGID2A, which interacts with the GA receptor and promotes GA signaling, was also higher in LBM than in ‘Delaware’ before the first GA3 treatment. However, the expression of VvSLR1, VvGAI1, and VvGAI2 that encode DELLA proteins, essential negative regulators for GA reactions, mostly showed no significant changes. These results suggest that LBM berries had higher GA sensitivity than the ‘Delaware’. Based on these results, we believe that the larger berry size in LBM may be due to increased cell numbers resulting from high GA sensitivity."
Authors: Yue Liu, Yang Li, Huixin Guo, Bingsheng Lv, Jing Feng, Huihui Wang, Zhonghua Zhang and Sen Chai.
Horticulture Research (2023)
Abstract: "Spraying N-(2-chloro-4-pyridyl)-N′-phenylurea (CPPU), an exogenous cytokinin (CK) growth regulator, is the conventional method for inducing fruit set during melon (Cucumis melo L.) production; however, the mechanism by which CPPU induces fruit set is unclear. Through histological and morphological observations, the fruit size was comparable between CPPU-induced fruits and normal pollinated fruits because CPPU-induced fruits had higher cell density but smaller cell size compared to normal pollinated fruits. CPPU promotes the accumulation of gibberellin (GA) and auxin and decreases the level of abscisic acid (ABA) during fruit set. Moreover, application of the GA inhibitor paclobutrazol (PAC) partially inhibits CPPU-induced fruit set. Transcriptome analysis revealed that CPPU-induced fruit set specifically induced the GA-related pathway, in which the key synthase encoding gibberellin 20-oxidase 1 (CmGA20ox1) was specifically up-regulated. Further study indicated that the two-component response regulator 2 (CmRR2) of the cytokinin signaling pathway, which is highly expressed at fruit setting, positively regulates the expression of CmGA20ox1. Collectively, our study determined that CPPU-induced melon fruit set is dependent on GA biosynthesis, providing a theoretical basis for the creation of parthenocarpic melon germplasm."
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: Hikari Ishii, Ami Ishikawa, Emi Yumoto, Takeshi Kurokura, Masashi Asahina, Yukihisa Shimada and Ayako Nakamura
Plant Cell Reports (2023)
Key Message: In woodland strawberry, a brassinosteroid biosynthesis inhibitor propiconazole induced typical brassinosteroid-deficient phenotypes and decreased female fertility due to attenuated female gametophyte development.
Abstract: "Brassinosteroids (BRs) play roles in various aspects of plant development. We investigated the physiological roles of BRs in the woodland strawberry, Fragaria vesca. BR-level-dependent phenotypes were observed using a BR biosynthetic inhibitor, propiconazole (PCZ), and the most active natural BR, brassinolide (BL). Endogenous BL and castasterone, the active BRs, were below detectable levels in PCZ-treated woodland strawberry. The plants were typical BR-deficient phenotypes, and all phenotypes were restored by treatment with BL. These observations indicate that PCZ is an effective inhibitor of BR in woodland strawberry. Only one gene for each major step of BR biosynthesis in Arabidopsis is encoded in the woodland strawberry genome. BR biosynthetic genes are highly expressed during the early stage of fruit development. Emasculated flowers treated with BL failed to develop fruit, implying that BR is not involved in parthenocarpic fruit development. Similar to BR-deficient and BR-insensitive Arabidopsis mutants, female fertility was lower in PCZ-treated plants than in mock-treated plants due to failed attraction of the pollen tube to the ovule. In PCZ-treated plants, expression of FveMYB98, the homologous gene for Arabidopsis MYB98 (a marker for synergid cells), was downregulated. Ovules were smaller in PCZ-treated plants than in mock-treated plants, and histological analysis implied that the development of more than half of female gametophytes was arrested at the early stage in PCZ-treated plants. Our findings explain how BRs function during female gametophyte development in woodland strawberry."
Authors: Ghassan Zahid, Sara Iftikharb, Flavien Shimir, Hafiz Muhammad Ahmad and Yıldız Aka Kaçar.
Scientia Horticulturae (2023)
Highlights • Abscisic acid reduces the incidence of cracking in fruits. • Ethylene and salicylic acid are critical under abiotic stresses. • Auxins enhance root elongation and resist salinity stresses in fruits. • Polyamines, brassinosteroids and strigolactones regulate stress tolerance in fruits. • Nitric oxide reduces postharvest fruit yield losses.
Abstract: "Plant growth regulators are organic chemical compounds that alter or regulate various physiological processes appreciably in a plant when used in small concentrations. These plant growth regulators have become an integral component of agro-technical procedures for most plants cultivated and particularly for fruit plants. Fruits are regarded as a highly valuable crop because of their significance in the uplift of the country's economy as well as their crucial role in providing a wide range of health benefits. However, multiple environmental stressors such as drought, salinity, cold, and heat stress, as well as other detrimental factors, have a deleterious effect on the quality of fruit crops around the globe. Among them, salinity stress is a significant constraint to fruit plant growth, yield and biomass production. For instance, exogenous treatments of plant growth regulators like abscisic acid, gibberellins, ethylene, auxin, jasmonic acid, brassinosteroids, salicylic acid, strigolactones, nitric oxide and others that are not recognized as PGRs like polyamines are effective in alleviating the negative impacts of abiotic stress on fruit crops throughout the pre-harvest and post-harvest periods. Furthermore, they not only affect the internal physiology of fruits but are equally significant to fruit set, yield, quality and retention. Therefore, in this review, we have discussed the current breakthroughs in PGR application and their impact on fruit crops, with a focus on their role in alleviating abiotic stresses. Moreover, we also highlighted their complex biosynthesis and signaling pathways during abiotic stress responses. To contextualize, the integration of recent scientific advances will have a substantial impact on fruit yield and quality."
Authors: María Beatriz Pugliese, Yanina Guzmán, Daniela Pacheco, Rubén Bottini, Claudia Travaglia, Jan Hendrik Avenant, Eunice Avenant and Federico Berli.
Revista de la Facultad de Ciencias Agrarias, Universidad Nacional de Cuyo (2022)
Abstract: "Gibberellic acid (GA3) is the most widely used plant growth regulator to thin out bunches and increase berry size in seedless table grapes, but there is evidence of its negative effects, including loss of fertility and malformations of the rachis. This study analyses the effects of applying the auxin indole-3-butyric acid (IBA), as a novel alternative, on fruit yield, bunch structure, anatomy and postharvest quality of cv. Superior Seedless. The application of IBA and GA3 at different phenological stages (15 cm shoot length, full bloom, fruit set and pea-size berry) and doses (2, 20 and 50 ppm) were compared in a two-growing season experiment. Spraying IBA at full bloom or fruit set, improved bunch weight by increasing the size and weight of the berries, correlating with the promotion of rachis vascular tissues. Bunches treated with IBA retained a greater number of berries at harvest without generating compactness, since the elongation of the rachis internodes and lateral shoulders were also promoted. In addition, IBA augmented postharvest quality of bunches by reducing rachis browning and increasing berry firmness. These results suggest that the use of IBA is a beneficial technology to improve bunch structure and quality in seedless grapes."
Author: Satoru Kondo.
Scientia Horticulturae (2022)
Highlights • Jasmonoyl-L-isoleucine (JA-Ile) is a transporting and signaling substance for JA action in plants. • Jasmonates enhance anthocyanin formation through JA-Ile, MYC, JAZ, bHLH, TRB, HIR, NINJA, JAM, MYB, and UF3GT in fruit. • Jasmonates crosstalk with other plant hormones. • Jasmonates mitigate abiotic and biotic stresses through the increase in secondary metabolites in plant.
Abstract: "Plant hormones are associated with many physiological aspects in fruit tree growth and fruit production. Since jasmonates (jasmonic acid (JA) and methyl ester of JA (MeJA)), which are oxylipins from linolenic acid, were found in plants including fruits, many physiological and molecular actions of jasmonates to regulate fruit development and stress tolerance from the environment in fruit production have been studied. Jasmonoyl-L-isoleucine (JA-Ile) is a transporting and signaling substance for JA action in plants. In the JA signaling pathway, MYC transcription factors are key regulators, and the jasmonate-ZIM domain (JAZ) negatively affects MYC transcription factors in JA signaling. Jasmonates can promote anthocyanin production in fruit through the effects of MYB transcription factors. A chemically stable and practical compound in the field, the JA analog n-propyl dihydrojasmonate, has been developed to improve fruit coloration. Jasmonates interact with some other plant hormones. For example, the effects of jasmonates on ethylene metabolism and signaling differ with fruit growth stage. Jasmonate treatment before fruit maturation enhances ethylene production with ethylene biosynthesis and signaling genes. In contrast, jasmonate treatment after fruit maturation decreases ethylene biosynthesis. Jasmonates can mitigate abiotic and biotic stresses from the environment, such as drought, salt, temperature, and disease. When fruit or a fruit tree encounters environmental stress, the stress quickly increases levels of jasmonates, which acts as a kind of elicitor. In fact, treatment of fruit with jasmonates decreased the severity of chilling injury during storage and inhibited fungal infection. This review discusses the usage and action mechanisms of oxylipins including jasmonates on fruit coloration, crosstalk with other plant hormones, and environmental stresses in fruit production.
Authors: Alson Time, Claudio Ponce, Nathalie Kuhn, Macarena Arellano, Boris Sagredo, José Manuel Donoso and Lee A. Meisel.
Preprints (2021)
Abstract: "Abscisic acid (ABA) plays a major role in promoting ripening in sweet cherry, a non-climacteric fruit. Exogenous application of ABA has been performed to study fruit ripening and cracking, but this growth regulator is not used for commercial production. To determine the potential of this growth regulator to improve sweet cherry fruit quality, ABA canopy spraying was assayed in four cultivars. Canopy spraying of S-ABA significantly: 1) enhanced sweet cherry fruit color in ‘Glenred’, ‘Lapins’ and 'Bing' cultivars, but not in ‘Royal Rainier’ (a bi-colored cultivar), and 2) decreased fruit size and firmness in ‘Lapins’, ‘Bing’ and ‘Royal Rainier’. Seasonally reproducible effects were seen in ‘Lapins’ (mid/late-maturing) but not in ‘Glenred’ (early-maturing). Canopy spraying of nordihydroguaiaretic acid (NDGA) decreased color and increased fruit size in ‘Lapins’, but not in ‘Glenred’. Direct application of ABA on fruits attached to the tree, without application to the foliage, increased Lapins' fruit color without reducing size. These results suggest a localized fruit response to exogenous ABA application on fruit color development, but that a decrease in fruit size may be due to the effects of exogenous ABA on the tree canopy foliage."
Authors: Hernán Mauricio Romero, Edison Daza, Iván Ayala-Díaz and Rodrigo Ruiz-Romero.
Agronomy (2021)
Abstract: "Interspecific OxG hybrids of African palm Elaeis guineensis Jacq. and the American palm Elaeis oleifera Cortes produce high-oleic palm oil (HOPO) with low saturated fatty acid content. OxG hybrids are highly productive, grow slowly, and are resistant to bud rot disease. However, OxG hybrid pollen presents low viability and germinability, so assisted pollination is a must. Hybrids can produce parthenocarpic or seedless fruits, with the exogenous application of plant growth regulators. Thus, naphthalene acetic acid (NAA) effects on parthenocarpic fruits induction, bunch formation, and oil quality were evaluated. The OxG hybrid Coari x La Mé was used. NAA doses, frequency, number of applications, and the phenological stages for the treatments were defined. A total dose of 1200 mg L−1 NAA applied three or four times produced bunches with better fruit set, similar average bunch weight, and oil to dry mesocarp than those obtained with assisted pollination. At a semi-commercial scale, 1200 mg L−1 NAA induced bunches that consisted of 93% or more of seedless fruits. Bunch number (2208 ± 84 versus 1690 ± 129) and oil to bunch (32.2 ± 0.7 versus 25.3 ± 0.8) were higher in the NAA induced bunches than in the assisted pollination. However, the average bunch weight was lower (12.2 ± 0.4 versus 14.9 ± 0.6). NAA increased oil to bunch in 36% (8.7 ± 0.1 versus 6.4 ± 0.3). Thus, with this technology, it is plausible to reach more than 10 tons per hectare per year of HOPO. Potentially, without increasing the planted oil palm area, OxG hybrids and NAA applications could alone meet the world’s fats and oil demands."
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Authors: Dongmei Chen, Tianhui Liao, Wenjun Ye, Zhichao Jin and Shichao Ren.
Advanced Agrochem (2024)
Abstract: "Plant growth regulators (PGRs) are chemical substances that imitate the functions of phytohormones to enhance the crop yield and the harvest process. Phenylurea-derived plant growth regulators are known for their excellent efficacy in promoting fruit growth, particularly in kiwifruit, grapes, and melons. Phenylurea derivatives represent one class of the highly efficient and versatile PGRs. Specifically, forchlorfenuron (CPPU, N-(2-chloro-4-pyridinyl)-N’-phenylurea) exhibits similar growth-regulating efficacy to cytokinins and has a significant impact on the plant growth and the crop yield. As a result, there is growing interest in exploring the incorporation of various phenylurea moieties into agrochemicals to enhance their regulatory properties on crops. This review aims to provide a comprehensive overview on representative synthetic approaches for phenylurea derived PGRs. Additionally, we provide our perspective on the future development in this active research field."
Authors: Zhenhua Liu, Yan Wang, Pingyin Guan, Jianfang Hu and Lei Sun.
International Journal of Molecular Sciences (2023)
Abstract: "Exogenous gibberellin treatment can promote early growth of grape fruit, but the underlying regulatory mechanisms are not well understood. Here, we show that VvDELLA2 directly regulates the activity of the VvCEB1 transcription factor, a key regulator in the control of cell expansion in grape fruit. Our results show that VvCEB1 binds directly to the promoters of cell expansion-related genes in grape fruit and acts as a transcriptional activator, while VvDELLA2 blocks VvCEB1 function by binding to its activating structural domain. The exogenous gibberellin treatment relieved this inhibition by promoting the degradation of VvDELLA2 protein, thus, allowing VvCEB1 to transcriptionally activate the expression of cell expansion-related genes. In conclusion, we conclude that exogenous GA3 treatment regulates early fruit expansion by affecting the VvDELLA-VvCEB1 interaction in grape fruit development."
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: 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."
Authors: Shaobo Niu, Yu He, Siwei Yan, Zhengliang Sun, Run Cai and Yan Zhang.
Horticultural Plant Journal (2023)
Abstract: "Gibberellin (GA) is one of the major plant hormones that promote parthenocarpy, a highly valuable agronomic trait. Here, we demonstrated that exogenous GA3 application triggered the formation of parthenocarpic fruits with smaller size but unchanged shape in tomato (Solanum lycopersicum). These fruits exhibited a thicker pericarp, undeveloped ovules, and few jelly tissues, leading to smaller locules with empty cavities. Histological investigation showed that GA treatment produced more cell layers with larger cells in the pericarp, suggesting its promotion in both cell division and expansion. Transcriptomic analyses between GA3- and mock-treated unpollinated ovaries/fruits identified a large number of differentially expressed genes related to hormones, cell division, cell expansion, and transcription factors, implying that they coordinately regulated parthenocarpy conferred by GA. In particular, the downregulation of five reported repressors of tomato parthenocarpy, including two auxin signaling components, AUXIN RESPONSE FACTOR5 (SlARF5) and SlARF7, and three MADS-box genes, TOMATO APETALA3 (TAP3), TOMATO PISTILLATA (TPI), and AGAMOUS-LIKE6 (SlAGL6), after GA treatment might play a key role in this process. Furthermore, we found that the knockdown of a GA signaling factor SlMYB33, which was depressed by GA treatment, induced parthenocarpic fruit set in tomato, an effect that might have been achieved by enhancing GA biosynthesis and decreasing the expression of some repressors of tomato parthenocarpy. Thus, our results provide a basis for understanding the regulatory mechanism of GA in tomato parthenocarpy."
Authors: Satoru Kondo, Hiroyuki Tomiyama, Risa Oda, Takanori Saito, Katsuya Ohkawa, Hitoshi Ohara, S. Aramaki, T. Inoue and Takashi Ohtsuka.
Research Square (2023)
Abstract: "The functions of isoprothiolane (IPT), which is a fungicide against rice blast, in carotenoid accumulation were examined in satsuma mandarin fruit (Citrus unshiu Marc). Whole trees were treated with IPT at 25 days before harvest. Concentrations of gibberellic acid-1 (GA1) and GA4 in the flavedo of IPT-treated trees were significantly decreased at 5 days after treatment (DAT) compared to the untreated control. The expressions of CitGA20ox1 in IPT-treated flavedo were lower than those in the untreated controls at 5 and 25 DAT. The CitGA3ox expressions in IPT-treated flavedo were lower than those in the untreated control at 5 DAT. ABA concentrations in IPT-treated flavedo were significantly higher than those in the untreated control at 25 DAT. The concentrations of b-cryptoxanthin in IPT-treated flavedo were higher than those in the untreated control at 25 DAT. The chlorophyll concentrations of IPT-treated flavedo were lower than those in the untreated control at 5 and 20 DAT. These results suggest that IPT advances b-cryptoxanthin accumulation through the regulation of endogenous GA1 and GA4 based on the inhibition of CitGA20ox1 and CitGA3ox expressions. It is possible that IPT can be utilized to improve coloration in other citrus fruit."
Authors: Xiaojia Zhang, Baolin Zhao, Yibo Sun and Yulong Feng.
Frontiers in Plant Science (2022)
Abstract: "Horticultural plants such as vegetables, fruits, and ornamental plants are crucial to human life and socioeconomic development. Gibberellins (GAs), a class of diterpenoid compounds, control numerous developmental processes of plants. The roles of GAs in regulating growth and development of horticultural plants, and in regulating significant progress have been clarified. These findings have significant implications for promoting the quality and quantity of the products of horticultural plants. Here we review recent progress in determining the roles of GAs (including biosynthesis and signaling) in regulating plant stature, axillary meristem outgrowth, compound leaf development, flowering time, and parthenocarpy. These findings will provide a solid foundation for further improving the quality and quantity of horticultural plants products."
Authors: Lingran Xiao, Tomoki Shibuya, Kazuhisa Kato, Manabu Nishiyama and Yoshinori Kanayama.
Scientia Horticulturae (2022)
Highlights • Plant growth regulators and light quality are discussed in tomatoes. • Light quality affects elongation, fruit color, stress response, etc. • Plant growth regulators are involved in these events. • Photoreceptors and light signal integrators control hormonal actions.
Abstract: "Irradiation with artificial lighting in greenhouses and plant factories is mainly used to promote photosynthesis in tomato cultivation. In addition to photosynthesis, the light effects on morphology, flowering, and metabolism are also crucial as plant responses. Light period and quality have been studied for a long time in relation to the flowering of cut-flowers, strawberries, and many leafy vegetables. Light quality, such as red, far-red, and blue, should be considered with their photoreceptors containing phytochrome, cryptochrome, and flavin-binding kelch repeat, F-box 1. Light quality may also affect plant morphogenesis and the accumulation of valuable metabolites, and plant growth regulators (PGRs) are understandably related to them. However, the effects of PGRs, light quality, and photoreceptors on morphogenesis and metabolite accumulation have been only reported individually and have not been comprehensively discussed. In this review, the information on tomatoes, which are important both industrially and academically, was mainly summarized and discussed. Effects of light quality on plant growth, fruit ripening and metabolite accumulation, and biotic and abiotic stresses, as well as the involvement of gibberellin, auxin, ethylene, abscisic acid, jasmonic acid, and salicylic acid, are discussed here with the roles of the photoreceptors of each light quality and light signal integrators. There is no safety problem for light quality use with appropriate wavelength and intensity, and it is environmentally friendly to use light-emitting diodes as an energy-saving light source. Therefore, once their effect is clear with scientific evidence in relation to PGRs, light quality control technology can be used and contribute to the improvement of production and quality of tomatoes with the usage of PGRs."
Authors: Bárbara Rojas, Felipe Suárez-Vega, Susana Saez-Aguayo, Patricio Olmedo, Baltasar Zepeda, Joaquín Delgado-Rioseco, Bruno G. Defilippi, Romina Pedreschi, Claudio Meneses, Alonso G. Pérez-Donoso and Reinaldo Campos-Vargas.
Plants (2021)
Abstract: "The use of plant growth regulators (PGRs) is widespread in commercial table grape vineyards. The synthetic cytokinin CPPU is a PGR that is extensively used to obtain higher quality grapes. However, the effect of CPPU on berry firmness is not clear. The current study investigated the effects of pre-anthesis applications (BBCH15 and BBCH55 stages) of CPPU on ‘Thompson Seedless’ berry firmness at harvest through a combination of cytological, morphological, and biochemical analyses. Ovaries in CPPU-treated plants presented morphological changes related to cell division and cell wall modification at the anthesis stage (BBCH65). Moreover, immunofluorescence analysis with monoclonal antibodies 2F4 and LM15 against pectin and xyloglucan demonstrated that CPPU treatment resulted in cell wall modifications at anthesis. These early changes have major repercussions regarding the hemicellulose and pectin cell wall composition of mature fruits, and are associated with increased calcium content and a higher berry firmness at harvest."
Authors: Hilary S. Ireland, Sumathi Tomes, Ian C. Hallett, Sakuntala Karunairetnam, Karine M. David, Jia-Long Yao and Robert J. Schaffer.
Fruit Research (2021)
Abstract: "Seedless fruits have high consumer appeal and have made seeded varieties obsolete in some crops. In seedless apple varieties, core tissues which normally contain the seed can be unpalatable, reducing the seedless appeal. Apples are accessory fruit with edible flesh derived from hypanthial tissue – a floral tube fused to a compound ovary. Here we show that through suppression of AGAMOUS-like carpel identity genes and hormone induced fruit set, it is possible to generate coreless and therefore seedless apples. Suppression of AGAMOUS-like genes increased petal whorls and fully eliminated carpel development. Treatments with a combination of gibberellin, cytokinin and auxin, rather than single treatments, were required for fruit initiation in these lines. Transcriptomic analysis of agamous RNAi lines suggested conservation of AGAMOUS-dependent gene networks between apple and Arabidopsis. In the absence of all sexual tissues, the developing fruit continues to grow and follow a ripening process similar to that of a regular apple. The coreless phenotype offers a new concept for pipfruit consumers improving convenience and reducing food waste."
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