Parthenocarpy and Its Effect on Vegetable Fruits Quality: A Review

Persimmon (Diospyros kaki Thunb.) contains numerous uridine diphosphate glucosyltransferases (UGT), and their roles in fruit development and quality formation have not been well studied because of limited genetic information. This study investigated a persimmon DkUGT3 which is highly expressed in young fruits and leaves during development. DkUGT3 can catalyze ABA glycosylation to form ABA-GE, thereby reducing free ABA. Tomato with overexpressed (OE) DkUGT3 significantly induces pale green color phenotypes in both transgenic young plants and fruits. DkUGT3-OE significantly weakens the tomato ABA signaling which affects the expressions of ABA-inducible transcriptional factors (TFs), such as GLK1 and GLK2 and their downstream target genes involved in chlorophyll synthesis, chloroplast development, sugar metabolism and transport, and photosynthesis, thereby impeding leaf and fruit development and quality. Conversely, DkUGT3-RNAi-treatment recovered the OE tomato fruits from yellowing phenotype to green color. This study found that chlorophyll accumulations and ABA level were increased by DkUGT3-RNAi-treatment in young persimmon leaves. These results demonstrate that DkUGT3 plays crucial roles in ABA-mediated leaf and fruit development. This study provides new evidence for the regulation of ABA in early development.

Consumers today are increasingly aware of the link between food and health, recognizing that certain 16 food components can positively impact physiological processes and help prevent chronic diseases. Apulia, Italy. The research demonstrated a positive correlation between the phenolic content of the 67 grapes and their antioxidant and anticancer activities. Moreover, the grape genotypes exhibited 68 varying levels of antioxidant and anticancer activities, with some genotypes showing higher activities 69 than others. The study suggests that the phenolic compounds found in grapes may be responsible for 70 their beneficial health effects and that the development of new grape varieties with high phenolic 71 content could lead to the production of grapes with increased antioxidant and anticancer activities. 72The findings provide significant insights into the potential health benefits of grapes and underscore 73 the significance of developing new grape varieties with high phenolic content for improving human 74 health outcomes. 75The impact of genotype, together with terroir, seasonality, and farming systems (conventional and 76 organic) was also investigated on functional traits of two tomato cultivars (San Marzano, Round, and 77Roma, Long) by Rocchetti et al. The study demonstrated through a multivariate statistical approach 78 that the phytochemical profile of tomato fruits was hierarchically more affected by the origin and the 79 cultivar than by the farming system, identifying the pedo-climatic conditions and the genotype as the 80 main determinants for the functional quality of tomato. The achieved results showed that the intricate 81 interaction of cultivar and environment, followed by agronomic factors, may play a key role in 82 shaping the potential health-promoting effects and associated benefits of vegetables, such as through 83 the metabolomic profile of tomato fruits and, consequently, their antioxidant and enzyme inhibition 84 capacities. These findings provide significant insights into the relevant contribution of several factors 85 (cultivars, terroir, seasonality) on the functional properties and quality of organic or conventional 86 tomatoes in a broader framework of food safety aspects and sustainability issues. 87 Finally, Yang et al. investigated the regulation of citric acid metabolism during the late 88 developmental stages of strawberry fruit. The study identified that the genes FaGAPC2/FaPKc2.2 89 and FaPEPCK were highly expressed during the late developmental stages of the fruit and were 90 involved in the regulation of citric acid metabolism. These genes were found to be regulated by 91 abscisic acid (ABA) and sugars, which play critical roles in fruit development and ripening. The 92 study suggests that the regulation of citric acid metabolism in the late developmental stages of 93 strawberry fruit is complex and involves several genes and regulatory pathways. These findings have 94 significant implications for the development of new strawberry varieties with improved fruit quality 95 and extended shelf life. The study provides valuable insights into the molecular mechanisms 96 underlying the regulation of citric acid metabolism in strawberry fruit and highlights the potential of 97 genetic engineering approaches to enhance fruit quality and post-harvest storage. 98The Original research studies submitted to this Special Issue underlined the importance of different 99 approaches for the enhancement of nutritional quality in different berry species. The application of 100 molecular, agricultural, and biochemical tools to increase the presence of nutritional molecules in 101 fruits are all valuable and exploitable solutions for the obtainment of new healthier berries, 102 shortening the breeding processes and facilitating the combination of traits of interest in the new 103 progeny.

Abscisic acid (ABA) plays a key role in fruit development and ripening in non-climacteric fruit. A variety of metabolites such as sugars, anthocyanins, fatty acids, and several antioxidants, which are regulated by various phytohormones, are important components of fruit quality in grape. Here, grape cultivar “Ruiduhongyu” was used to investigate the relationship between endogenous phytohormones and metabolites associated to grape berry quality under exogenous ABA treatment. 500 mg/L ABA significantly improved the appearance parameters and the content of many metabolites including sugar, anthocyanin, and other compounds. Exogenous ABA also increased the contents of ABA, auxin (IAA), and cytokinins (CTKs), and transcription level of ABA biosynthesis and signaling related genes in fruit. Furthermore, a series of genes involved in biosynthesis and the metabolite pathway of sugars, anthocyanins, and fatty acids were shown to be significantly up-regulated under 500 mg/L ABA treatment. In addition, Pearson correlation analysis demonstrated that there existed relatively strong cooperativities in the ABA/kinetin (KT)-appearance parameters, ABA/IAA/KT-sugars, ABA/indolepopionic acid (IPA)/zeatin riboside (ZR)-anthocyanins, and gibberellin 3 (GA3)/methyl jasmonate (MeJA)-fatty acids, indicating that 13 kinds of endogenous phytohormones induced by ABA had different contributions to the accumulation of quality-related metabolites, while all of them were involved in regulating the overall improvement of grape fruit quality. These results laid a primary foundation for better understanding that exogenous ABA improves fruit quality by mediating the endogenous phytohormones level in grape.

Strawberry (Fragaria × ananassa) is an ideal plant for fruit development and ripening research due to the rapid substantial changes in fruit color, aroma, taste, and softening. To gain deeper insights into the genes that play a central regulatory role in strawberry fruit development and ripening characteristics, transcriptome profiling was performed for the large green fruit, white fruit, turning fruit, and red fruit stages of strawberry. A total of 6,608 differentially expressed genes (DEGs) with 2,643 up-regulated and 3,965 down-regulated genes were identified in the fruit development and ripening process. The DEGs related to fruit flavonoid biosynthesis, starch and sucrose biosynthesis, the citrate cycle, and cell-wall modification enzymes played important roles in the fruit development and ripening process. Particularly, some candidate genes related to the ubiquitin mediated proteolysis pathway and MADS-box were confirmed to be involved in fruit development and ripening according to their possible regulatory functions. A total of five ubiquitin-conjugating enzymes and 10 MADS-box transcription factors were differentially expressed between the four fruit ripening stages. The expression levels of DEGs relating to color, aroma, taste, and softening of fruit were confirmed by quantitative real-time polymerase chain reaction. Our study provides important insights into the complicated regulatory mechanism underlying the fruit ripening characteristics in Fragaria × ananassa.

Strawberry (Fragaria × ananassa) is an ideal plant for fruit development and ripening research due to the rapid substantial changes in fruit color, aroma, taste and softening. To gain deeper insights into the genes that play a central regulatory role in strawberry fruit development and ripening characteristics, transcriptome profiling was performed for the large green fruit, white fruit, turning fruit, and red fruit stages of strawberry. A total of 6,608 differentially expressed genes (DEGs) with 2,643 up-regulated and 3,965 down-regulated genes were identified in the fruit development and ripening process. The DEGs related to fruit flavonoid biosynthesis, starch and sucrose biosynthesis, the citrate cycle, and cell-wall modification enzymes played important roles in the fruit development and ripening process. Particularly, some candidate genes related to the ubiquitin mediated proteolysis pathway and MADS-box were confirmed to be involved in fruit development and ripening according to their possible regulatory functions. Five ubiquitin-conjugating enzymes and ten MADS-box transcription factors were differentially expressed between the four fruit ripening stages. The expression levels of DEGs relating to color, aroma, taste, and softening of fruit were confirmed by quantitative real-time polymerase chain reaction. Our study provides important insights into the complicated regulatory mechanism underlying the fruit ripening characteristics in Fragaria × ananassa.

BackgroundApple fruit develop over a period of 150 days from anthesis to fully ripe. An array representing approximately 13000 genes (15726 oligonucleotides of 45–55 bases) designed from apple ESTs has been used to study gene expression over eight time points during fruit development. This analysis of gene expression lays the groundwork for a molecular understanding of fruit growth and development in apple.ResultsUsing ANOVA analysis of the microarray data, 1955 genes showed significant changes in expression over this time course. Expression of genes is coordinated with four major patterns of expression observed: high in floral buds; high during cell division; high when starch levels and cell expansion rates peak; and high during ripening. Functional analysis associated cell cycle genes with early fruit development and three core cell cycle genes are significantly up-regulated in the early stages of fruit development. Starch metabolic genes were associated with changes in starch levels during fruit development. Comparison with microarrays of ethylene-treated apple fruit identified a group of ethylene induced genes also induced in normal fruit ripening. Comparison with fruit development microarrays in tomato has been used to identify 16 genes for which expression patterns are similar in apple and tomato and these genes may play fundamental roles in fruit development. The early phase of cell division and tissue specification that occurs in the first 35 days after pollination has been associated with up-regulation of a cluster of genes that includes core cell cycle genes.ConclusionGene expression in apple fruit is coordinated with specific developmental stages. The array results are reproducible and comparisons with experiments in other species has been used to identify genes that may play a fundamental role in fruit development.

Cytokinins (CKs) are thought to play important roles in fruit development, especially cell division. However, the mechanisms and regulation of CK activity have not been well investigated. This study analysed CK concentrations and expression of genes involved in CK metabolism in developing tomato (Solanum lycopersicum) ovaries. The concentrations of CK ribosides and isopentenyladenine and the transcript levels of the CK biosynthetic genes SlIPT3, SlIPT4, SlLOG6, and SlLOG8 were high at anthesis and decreased immediately afterward. In contrast, trans-zeatin concentration and the transcript levels of the CK biosynthetic genes SlIPT1, SlIPT2, SlCYP735A1, SlCYP735A2, and SlLOG2 increased after anthesis. The expression of type-A response regulator genes was high in tomato ovaries from pre-anthesis to early post-anthesis stages. These results suggest that the CK signal transduction pathway is active in the cell division phase of fruit development. This study also investigated the effect of CK application on fruit set and development. Application of a synthetic CK, N-(2-chloro-pyridin-4-yl)-N’-phenylurea (CPPU), to unpollinated tomato ovaries induced parthenocarpic fruit development. The CPPU-induced parthenocarpic fruits were smaller than pollinated fruits, because of reduction of pericarp cell size rather than reduced cell number. Thus, CPPU-induced parthenocarpy was attributable to the promotion of cell division, not cell expansion. Overall, the results provide evidence that CKs are involved in cell division during development of tomato fruit.

Fruits are unique to flowering plants and represent an important component of human and animal diets. Development and maturation of tomato fruit is a well-programmed process, and yet, only a limited number of factors involved in its regulation have been characterized. Micro-RNAs (miRNAs) are small, endogenous RNAs that regulate gene expression in animals and plants. Plant miRNAs have a vital role in the generation of plant forms through post-transcriptional regulation of the accumulation of developmental regulators, especially transcription factors. Recently, we and others have demonstrated that miRNAs and other type of small RNAs are expressed in tomato fruit, and target putative transcription factors during its development and maturation. The original objectives of the approved proposal were: 1. To identify fruit miRNA transcription factor target genes through a bioinformatic approach. 2. To identify fruit miRNA transcription factor target genes up-regulated in tomato Dicer-like 1 silenced fruit. 3. To establish the biological functions of selected transcription factors and examine their utility for improving fleshy fruit quality trait. This project was approved by BARD as a feasibility study to allow initial experiments to peruse objective 2 as described above in order to provide initial evidence that miRNAs do play a role in fruit development. The approach planned to achieve objective 2, namely to identify miRNA transcription factor targets was to clone and silence the expression of a tomato DCL1 homolog in different stages of fruit development and examine alterations to gene expression in such a fruit in order to identify pathways and target genes that are regulated by miRNA via DCL1. In parallel, we characterized two transcription factors that are regulated by miRNAs in the fruit. We report here on the cloning of tomato DCL1 homolog, characterization of its expression in fruit flesh and peel of wild type and ripening mutants and generation of transgenic plants that silence SlDCL1 specifically in the fruit. Our results suggest that the tomato homolog of DCL1, which is the major plant enzyme involved in miRNA biogenesis, is present in fruit flesh and peel and differentially expressed during various stages of fruit development. In addition, its expression is altered in ripening mutants. We also report on the cloning and expression analysis of Sl_SBP and Sl_ARF transcription factors, which serve as targets of miR157 and miR160, respectively. Our data suggest that Sl_SBP levels are highest during fruit ripening supporting a role for this gene in that process. On the other hand Sl_ARF is strongly expressed in green fruit up to breaker indicating a role for that gene at preripening stage which is consistent with preliminary in_situ analyses that suggest expression in ovules of immature green fruit. The results of this feasibility study together with our previous results that miRNAs are expressed in the fruit indeed provide initial evidence that these regulators and their targets play roles in fruit development and ripening. These genes are expected to provide novel means for genetic improvement of tomato fleshy fruit.

cDNA corresponding to two type-I vacuolar H+-inorganic pyrophosphatases (V-PPases) (SlVP1, SlVP2) and one type-II V-PPase (SlVP3) was isolated from tomato fruit to investigate their role in fruit development. Southern analysis revealed that type-I V-PPase genes form a multigene family, whereas there is only one type-II V-PPase gene in the tomato genome. Although SlVP1 and SlVP2 were differentially expressed in leaves and mature fruit, the highest levels of both SlVP1 and SlVP2 mRNA were observed in fruit at 2–4 days after anthesis. The expression pattern of type-II SlVP3 was similar to that of SlVP2, and the highest levels of SlVP3 mRNA were also observed in fruit at 2–4 days after anthesis, thus suggesting that SlVP3 plays a role in early fruit development. Because SlVP1 and SlVP2 mRNA was more abundant than SlVP3 mRNA, expression of type-I V-PPases was analysed further. Type-I V-PPase mRNA was localized in ovules and their vicinities and in vascular tissue at an early stage of fruit development. Tomato RNAi lines in which the expression of type-I V-PPase genes was repressed using the fruit-specific promoter TPRP-F1 exhibited fruit growth retardation at an early stage of development. Although the major function of V-PPases in fruit has been believed to be the accumulation of materials such as sugars and organic acids in the vacuole during cell expansion and ripening, these results show that specific localization of V-PPase mRNA induced by pollination has a novel role in the cell division stage.

The influence of plant growth regulators, including auxins, gibberellins, cytokinins, ethylene, abscisic acid, brassinosteroids, jasmonates, and salicylic acid, on fruit crop development and quality enhancement. Various stages of fruit crop growth, such as flowering, fruit set, ripening, and post-harvest attributes, are examined through comprehensive experimental approaches. Auxins play a crucial role in regulating fruit size, shape, and development by facilitating cell elongation. Gibberellins control fruit elongation, seed germination, and fruit set. Cytokinins influence fruit expansion, sugar metabolism, and overall quality by promoting cell division and differentiation. Ethylene affects fruit ripening processes, including color change, softening, and flavor development. Abscisic acid influences fruit maturation and dormancy. Brassinosteroids regulate fruit development, including size, ripening, and tolerance to abiotic stress. Jasmonates and salicylic acid, involved in defense responses, have an impact on fruit ripening, quality, and disease resistance. The application of these regulators shows promise in improving fruit quality, nutritional composition, and shelf life. This study aims to provide valuable insights into fruit crop physiology and develop strategies to optimize productivity and quality. It emphasizes the importance of proper regulation and responsible use of plant growth regulators to address environmental, health, and ecological concerns associated with excessive or improper application. Excessive use of PGRs can lead to various physiological issues, adversely affecting fruit crop productivity and quality. Therefore, careful control of application procedures, dosages, and timing is necessary to ensure fruit crop health and avoid negative consequences.

Exogenous calcium modulates oxalic acid metabolism via repression of LcAAE3 and mediates calcium accumulation in litchi pericarp and fruit pedicel.

BackgroundExtensive studies have demonstrated that the COBRA gene is critical for biosynthesis of cell wall constituents comprising structural tissues of roots, stalks, leaves and other vegetative organs, however, its role in fruit development and ripening remains largely unknown.ResultsWe identified a tomato gene (SlCOBRA-like) homologous to Arabidopsis COBRA, and determined its role in fleshy fruit biology. The SlCOBRA-like gene is highly expressed in vegetative organs and in early fruit development, but its expression in fruit declines dramatically during ripening stages, implying a primary role in early fruit development. Fruit-specific suppression of SlCOBRA-like resulted in impaired cell wall integrity and up-regulation of genes encoding proteins involved in cell wall degradation during early fruit development. In contrast, fruit-specific overexpression of SlCOBRA-like resulted in increased wall thickness of fruit epidermal cells, more collenchymatous cells beneath the epidermis, elevated levels of cellulose and reduced pectin solubilization in the pericarp cells of red ripe fruits. Moreover, transgenic tomato fruits overexpressing SlCOBRA-like exhibited desirable early development phenotypes including enhanced firmness and a prolonged shelf life.ConclusionsOur results suggest that SlCOBRA-like plays an important role in fruit cell wall architecture and provides a potential genetic tool for extending the shelf life of tomato and potentially additional fruits.

Evaluation of the role of the endo-β-(1,4)-glucanase gene FaEG3 in strawberry fruit softening

The PIN-FORMED (PIN) auxin efflux transport protein family has been well characterized in the model plant Arabidopsis thaliana, where these proteins are crucial for auxin regulation of various aspects of plant development. Recent evidence indicates that PIN proteins may play a role in fruit set and early fruit development in tomato (Solanum lycopersicum), but functional analyses of PIN-silenced plants failed to corroborate this hypothesis. Here it is demonstrated that silencing specifically the tomato SlPIN4 gene, which is predominantly expressed in tomato flower bud and young developing fruit, leads to parthenocarpic fruits due to precocious fruit development before fertilization. This phenotype was associated with only slight modifications of auxin homeostasis at early stages of flower bud development and with minor alterations of ARF and Aux/IAA gene expression. However, microarray transcriptome analysis and large-scale quantitative RT-PCR profiling of transcription factors in developing flower bud and fruit highlighted differentially expressed regulatory genes, which are potential targets for auxin control of fruit set and development in tomato. In conclusion, this work provides clear evidence that the tomato PIN protein SlPIN4 plays a major role in auxin regulation of tomato fruit set, possibly by preventing precocious fruit development in the absence of pollination, and further gives new insights into the target genes involved in fruit set.

Guarding tomato fruit setting in adverse temperatures through the miRNA166-SlHB15A regulatory module