Early Fruit Research Articles

Fruiting and Productivity of the Argan (Argania spinosa) Tree and Evaluation of the Nutritional Value of Its Early and Late Fruits from Western Algeria

ABSTRACT The Argan tree (Argania spinosa (L.) (Skeels)) is a woody species endemic to Algeria (Tindouf region mostly) and Morocco. It is a plant species of oleo-agro-sylvo-pastoral and ecological importance as it contributes to the fight against desertification and climate change. Moreover, the seed is used for extracting oil, which has high dietic and cosmetic qualities. In this work, the fruit harvest period and Argania spinosa productivity are related to the phenological process of flowering and fruiting. Our results show that the experimental argan trees of Mostaganem bloom late to be pollinated in the spring and remain dormant throughout the summer, in contrast to the endemic Tindouf trees that bloom early in September, bear fruit and ripen in the same season. This explains why that the fruits of the Tindouf region are the richest compared to the fruits of the other two regions. Our study shows that the pulp always contains more than almonds, as the oil was extracted and analyzed, the pulp is the fraction richest in phenols, while almond is the poorest fraction (3.43 ± 0.72 mg/g, 1.34 ± 0.03 mg/g), the same thing goes for the total flavonoid content (9 ± 0.5 mg/g, 2.83 ± 0.14 mg/g). The greatest activity was recorded in the fruits of Tindouf. As for the components of the fruit, the highest activity was recorded in the pulps then the almonds and the lowest in the oil (502 ± 11.42 g, 216 ± 8.43 g, 174 ± 3.61 g), respectively. Concerning primary metabolites, the fruit is rich (the almond is rich in proteins, the pulp is rich in sugar and the oil is rich in lipids).

Identification of tomato AHL gene families and functional analysis their roles in fruit development and abiotic stress response

The AT-HOOK MOTIF CONTAINING NUCLEAR LOCALIZED (AHL) transcription factors play important roles in regulating plant development and stress response. However, the AHL family genes have not been identified in tomato (Solanum lycopersicum) and their biological functions have not been elucidated. In this work, the gene families encoding AHLs were identified in tomato genome, and their physical and chemical characteristics, subcellular localization, gene expression profiles during fruit development and upon abiotic stimulus were investigated. Overall, a total of 18 AHL members were identified in tomato genome, phylogenetic analysis classified these SlAHL members into two clades, clade A (SlAHL1-8) and clade B (SlAHL9-18). Six clade A SlAHLs were detected to be subcellular localized in the nucleus. The transcripts of the representative clade A SlAHLs predominantly accumulated 10 days post anthesis (dpa) in tomato fruits, revealing an involvement of these SlAHLs in early fruit development. Furthermore, compared with clade B members, the transcripts of the clade A SlAHLs were more responsive to heat, drought, cold and salt stresses, suggesting that these SlAHLs may play major roles in response to abiotic stresses. Moreover, overexpression of SlAHL1 and SlAHL7 in Arabidopsis increased the sensitivity to ABA during seed germination and seedling stages. Overexpression of SlAHL1 inhibited seed germination while increased primary root elongation upon salt and drought stresses. Together, our work suggested that the clade A SlAHL genes may play an important role in response to abiotic stresses, which paving the way for future functional analysis of AHL genes in tomato and other Solanaceae species.

Multi-omics quantitative data of tomato fruit unveils regulation modes of least variable metabolites

BackgroundThe composition of ripe fruits depends on various metabolites which content evolves greatly throughout fruit development and may be influenced by the environment. The corresponding metabolism regulations have been widely described in tomato during fruit growth and ripening. However, the regulation of other metabolites that do not show large changes in content have scarcely been studied.ResultsWe analysed the metabolites of tomato fruits collected on different trusses during fruit development, using complementary analytical strategies. We identified the 22 least variable metabolites, based on their coefficients of variation. We first verified that they had a limited functional link with the least variable proteins and transcripts. We then posited that metabolite contents could be stabilized through complex regulations and combined their data with the quantitative proteome or transcriptome data, using sparse partial-least-square analyses. This showed shared regulations between several metabolites, which interestingly remained linked to early fruit development. We also examined regulations in specific metabolites using correlations with individual proteins and transcripts, which revealed that a stable metabolite does not always correlate with proteins and transcripts of its known related pathways.ConclusionsThe regulation of the least variable metabolites was then interpreted regarding their roles as hubs in metabolic pathways or as signalling molecules.

Transcriptome Analysis Unveiled the Intricate Interplay between Sugar Metabolism and Lipid Biosynthesis in Symplocos paniculate Fruit.

Symplocos paniculate is an oil plant exhibiting tissue-specific variations in oil content and fatty acid composition across the whole fruit (mainly pulp and seed). And its oil synthesis is intricately linked to the accumulation and transformation of sugars. Nevertheless, there remains a dearth of understanding regarding how sugar metabolism impacts oil synthesis in S. paniculate fruit. To unravel the intricate mechanism underlying the impact of sugar metabolism on lipid biosynthesis in S. paniculata fruit, a comparative analysis was conducted on the transcriptome and metabolite content of pulp and seed throughout fruit development. The findings revealed that the impact of sugar metabolism on oil synthesis varied across different stages of fruit development. Notably, during the early fruit developmental stage (from 90 to 120 DAF), pivotal genes involved in sugar metabolism, such as PGK3, PKP1, PDH-E1, MDH, and malQ, along with key genes associated with oil synthesis like KAR, HAD, and PAP were predominantly expressed in the pulp. Consequently, this preferential expression led to earlier accumulation of oil in the pulp tissue compared to the seed. Whereas, during the fruit maturity stage (from 120 DAF to 140 DAF), these genes exhibited a high level of expression in seed, thereby facilitating the rapid and substantial accumulation of seed oil compared to pulp. The sugar metabolism activity in various parts of S. paniculata fruit plays a pivotal role in oil synthesis and is contingent upon the developmental stage. These findings can offer alternative genes for further gene enhancement through molecular biotechnology, thereby augmenting fruit oil yield and altering fatty acid composition.

Selenium application during fruit development can effectively inhibit browning of fresh-cut apples by enhancing antioxidant capacity and suppressing polyphenol oxidase activity

Browning is a crucial factor affecting the quality of fresh-cut apples. A safe, simple, and effective method to inhibit browning is urgently needed in fresh-cut apple production. We carried out this study to explore the effect mechanism of exogenous selenium (Se) fertilizer on fresh-cut apple browning. During the development of apples, 0.75 kg/plant Se fertilizer was exerted on the ‘Fuji’ apple tree at the critical stage of the young fruit stage (late May), early fruit expansion stage (late June), and fruit expansion stage (late July), an equal amount of Se-free organic fertilizer was used as control. Polyphenol oxidase (PPO), peroxidase (POD), and phenylalanine ammonia-lyase (PAL) activities, phenolic and malondialdehyde (MDA) content, antioxidant enzymes activity, and DPPH free radical scavenging rate of the apple at different development stages were investigated. The highest Se accumulation efficiency was observed in apple fruit one month after applying Se fertilizer, which was 41.1%. Se-rich apples exhibited a more remarkable ability to resist browning than control after fresh-cut. The anti-browning effect of the fertilization group (M7) was the best, the PPO activity decreased to 0.5 × 103 U kg−1, and the browning index was 28.6. The total Se content (TSC) of 331.4 μg kg−1 DW and organic Se content (OSC) of 292.0 μg kg−1 DW were the highest in the apple samples, reached the classification standard of Se content in Se-rich food. The correlation analysis found that fresh-cut apple browning was closely related to antioxidant capacity and PPO activity. The stronger the antioxidant capacity of fresh-cut apples treated with Se fertilizer, the lower their browning degree. Therefore, exogenous Se can alleviate fresh-cut apples browning by improving antioxidant capacity and reducing PPO activity. Se-rich apples could increase the Se content of the human essential trace element and inhibit the browning of fresh-cut apples, which would become a new, safe and effective way to solve the fresh-cut apples browning.

Factors affecting development of disorders expressed after storage of ‘Gala’ apple fruit

This study investigated factors influencing susceptibility and development of physiological disorders and decay expressed after long-term storage in ‘Gala’ apple fruit (Malus domestica Borkh.). Five experiments were performed over ten production years with fruit from two environmentally different orchard locations in a humid subtropical climate at 990 m (warmer) and 1415 m above sea level. Fruit were harvested at two maturity stages (early and advanced), treated or not treated with 1-methylcyclopropene (1-MCP) and stored at 0.5 °C or 2 °C in a controlled atmosphere (CA, 1.5 kPa O2 and 2.5 kPa CO2), for 240 d plus 7 d shelf life. In one experiment, fruit were stored in CA with CO2 concentrations of 1.5 or 3 kPa. The relationship between fruit mineral composition and physiological disorders was assessed in one production year. Flesh browning (FB) was the predominant disorder, followed by decay, cracking, and lenticel breakdown-wet (LB-wet). The average severity index of lenticel breakdown-dry (LB-dry), leather blotch and bitter pit were low and variable across production years. The FB index was lowest in fruit produced at the colder orchard location, early harvest, treatment with 1-MCP, and storage at 2 °C. These factors also influenced fruit softening after storage. The major source of variance of the FB index in order of decreasing contribution were harvest maturity, production year, orchard location, 1-MCP and storage temperature. Production year variability of FB index correlated positively with early summer rain and negatively with early spring temperature. A weak positive correlation was also found between FB index and fruit K+Mg/Ca ratio. Higher CA CO2 concentration increased FB in fruit stored at 0.5 °C but not at 2 °C. The same factors affected decay, cracking and LB-wet disorder similarly as for FB, except that decay and cracking were not consistently affected by storage temperature, and decay and LB-wet were not impacted by 1-MCP. Storage temperature had the most influence on the variance of LB-wet. LB-dry was highest in late harvest fruit and, in the production year with the highest index, in fruit stored at 0.5 °C. Leather blotch was highest in early harvest fruit and in fruit stored at 0.5 °C. 1-MCP treatment did not affect disorders other than FB and cracking. These results suggest that interactions among harvest and postharvest factors influence the development of ‘Gala’ FB and other disorders and indicate a possible relationship of chilling in FB development. The information may be useful for implementing practical strategies to reduce the development of these postharvest disorders in ‘Gala’ apple fruit.

Metabolic fingerprint of ‘WA 38’ green spot symptoms reveals increased production of epicuticular metabolites by parenchyma

Green spot is a pre-harvest physiological disorder of ‘WA 38’ apple fruit that can culminate in corking immediately underneath the peel surface. Unlike bitter pit and many other corking disorders, superficial symptoms emerge in the middle of the growing season as areas of peel discoloration, with the most severe symptoms appearing as parenchyma necrosis or corking that worsens until harvest. Our previous work demonstrated the mitigative effect of early season fruit bagging on green spot appearance, but the mechanism of its onset and the biochemical signatures associated with it remained unknown. We used metabolic profiling to, first, identify metabolites associated with green spot symptoms in the peel and cortex of ‘WA 38’ apples and, then, track changes before and after disorder onset until harvest from apples that were bagged, under a shade net, or uncovered (control). We linked metabolites from multiple metabolic pathways, including carotenoids, phenolics, triglycerides, and triterpenes, with peel and cortex green spot symptoms. Many pigment and triterpene compounds associated with cortex symptoms are typically far less abundant in cortex tissue than in peel. Light-altering treatments also impacted levels of several of these compounds during the growing season; however, the inability to predict which pre-symptomatic tissue would later develop symptoms compromised the establishment of disorder genesis and latent development using this technique. Despite these challenges, we linked novel metabolites and pathways with the disorder, including those that may indicate strengthening and isolation of symptomatic tissue, possibly to provide protections similar to the fruit surface.

Impact of heat stress, water stress, and their combined effects on the metabolism and transcriptome of grape berries

Recurring heat and drought episodes present challenges to the sustainability of grape production worldwide. We investigated the impacts of heat and drought stress on transcriptomic and metabolic responses of berries from two wine grape varieties. Cabernet Sauvignon and Riesling grapevines were subjected to one of four treatments during early fruit ripening: (1) drought stress only, (2) heat stress only, (3) simultaneous drought and heat stress, (4) no drought or heat stress (control). Berry metabolites, especially organic acids, were analyzed, and time-course transcriptome analysis was performed on samples before, during, and after the stress episode. Both alone and in conjunction with water stress, heat stress had a much more significant impact on berry organic acid content, pH, and titratable acidity than water stress. This observation contrasts with previous reports for leaves, which responded more strongly to water stress, indicating that grape berries display a distinct, organ-specific response to environmental stresses. Consistent with the metabolic changes, the global transcriptomic analysis revealed that heat stress had a more significant impact on gene expression in grape berries than water stress in both varieties. The differentially expressed genes were those associated with the tricarboxylic acid cycle and glyoxylate cycle, mitochondrial electron transport and alternative respiration, glycolysis and gluconeogenesis, carbohydrate allocation, ascorbate metabolism, and abiotic stress signaling pathways. Knowledge regarding how environmental stresses, alone and in combination, impact the berry metabolism of different grape varieties will form the basis for developing recommendations for climate change mitigation strategies and genetic improvement.

Correlation between soil environment and yield and quality of Sharen (Amomi Fructus) under different planting patterns

ObjectiveTo study the effects of soil environment on the growth, yield, and quality of Sharen (Amomi Fructus) under different planting patterns. MethodsSoil physical and chemical indices and enzyme activities in four periods including early flowering (March), full flowering (June), fruit ripening (September), and late fruit picking (December), were measured under three planting patterns including natural forest, greenhouse, and rubber forest in Xishuangbanna, China. The changes in soil indices during the growth periods of Sharen (Amomi Fructus) under different planting patterns were analyzed, and the differences in plant growth, yield, and quality under different planting patterns were explored. Pearson correlation analysis was used to analyze the relationship between soil indices and Sharen (Amomi Fructus) growth, yield, and quality. Principal component analysis was used to investigate the effects of soil environment under different planting patterns on Sharen (Amomi Fructus) growth, yield, and quality. ResultsThe soil moisture, available potassium content, and urease activity of the three planting patterns of Sharen (Amomi Fructus) increased initially and decreased afterwards throughout the year; pH and organic matter content showed little change in the whole year. Exchangeable manganese content and acid phosphatase activity gradually increased throughout the year. Hydrolyzed nitrogen content, exchangeable calcium content, available zinc content, protease activity, and sucrase activity decreased initially and increased afterwards throughout the year. Exchangeable magnesium content, available iron content, and catalase activity decreased annually. Total nitrogen content, total phosphorus content, and available phosphorus content fluctuated throughout the year. The total potassium content under natural forest and greenhouse planting decreased throughout the year, while the total potassium content under rubber forest showed an upward trend all year round. The organic matter content, total nitrogen content, total potassium content, available potassium content, available zinc content, urease activity, acid phosphatase activity, and catalase activity under greenhouse were significantly lower than those under natural and rubber forests (P < 0.05). Correlation analysis showed that plant growth, yield, and quality of Sharen (Amomi Fructus) were significantly correlated with soil organic matter, total nitrogen, hydrolyzed nitrogen, total phosphorus, available phosphorus, total potassium, available potassium, exchangeable manganese, exchangeable magnesium, exchangeable calcium, available zinc, urease, acid phosphatase, and invertase (P < 0.05). The results of the principal component analysis indicated that the soil environment of Sharen (Amomi Fructus) under natural forest was the best, followed by rubber forest and greenhouse. The order of its advantages and disadvantages is consistent with the growth index of Sharen (Amomi Fructus), but contrary to the yield of Sharen (Amomi Fructus), indicating that the soil environment directly affects the growth index and nutritional components of plants. ConclusionDifferent planting patterns of Sharen (Amomi Fructus) have different soil nutrient content, and the change rules in the growths period are not similar, with some differences. Soil indices have impacts on plant growth, yield, and quality of Sharen (Amomi Fructus). Soil ecological environment is positively correlated with the growth characteristics of Sharen (Amomi Fructus) plants, but has no direct correlation with yield and quality.

Performance comparison of different convolutional neural networks for vegetable and fruit recognition

Image classification, a significant research problem in the computer vision community, aims to assign different types of images to a certain category in a fixed category set according to different information features reflected in images. With the continuous improvement of living standards, people's daily demand for accurate identification of food categories (such as vegetable, fruit, etc.) is growing. Early vegetable and fruit recognition mostly relied on manual features and machine learning algorithms, with low recognition accuracy and weak generalization ability. Thanks to the rapid evolution of the convolutional neural network, vegetable and fruit recognition based on depth learning has made breakthroughs in accuracy and speed. In this paper, three representative convolutional neural networks are introduced around vegetable and fruit recognition, and their performance differences are quantitatively compared on different data sets to explore the boundaries of their applications. In addition, we summarized the research problems in vegetable and fruit recognition and discussed its future development direction.

CHARACTERISTICS OF THE PHYSICAL PROPERTIES OF SEEDS AND REPRODUCTIVE ASPECTS OF Paullinia stellata Radlk

Paullinia stellata is found in anthropogenic places and lowland forests, yet little information about their reproductive characteristics is known. This study aimed to determine the physical properties of seeds and the characteristics of their reproductive aspects. Racemes, fruits, and seeds were measured and weighed. The physical properties of the seeds were determined using three-dimensional data. A descriptive statistic was applied for racemes and fruits, and a statistic of small samples was conducted for the physical properties. The results showed low magnitude variations for variables analyzed in both parameters. The physical properties of the seeds are relatively moderate variations from low oscillations. Fruit maturity is detected by the opening of the endocarp exposing the seed, but it presents early and late fruit with asynchronous maturation. This study was conducted only on a single plant and observed asynchronous fruits within the same raceme.

Loss of S-Nitrosoglutathione reductase disturbs phytohormone homeostasis and regulates shoot side branching and fruit growth in tomato.

S-nitrosoglutathione (GSNO) plays a central role in nitric oxide (NO) homeostasis, and GSNO reductase (GSNOR) regulates the cellular levels of GSNO across kingdoms. Here, we investigated the role of endogenous NO in shaping shoot architecture and controlling fruit set and growth in tomato (Solanum lycopersicum). SlGSNOR silencing promoted shoot side branching and led to reduced fruit size, negatively impacting fruit yield. Greatly intensified in slgsnor knockout plants, these phenotypical changes were virtually unaffected by SlGSNOR overexpression. SlGSNOR silencing or knockout intensified protein tyrosine nitration and S-nitrosation and led to aberrant auxin production and signaling in leaf primordia and fruit-setting ovaries, besides restricting the shoot basipetal polar auxin transport stream. SlGSNOR deficiency triggered extensive transcriptional reprogramming at early fruit development, reducing pericarp cell proliferation due to restrictions on auxin, gibberellin and cytokinin production and signaling. Abnormal chloroplast development and carbon metabolism were also detected in early-developing NO-overaccumulating fruits, possibly limiting energy supply and building blocks for fruit growth. These findings provide new insights into the mechanisms by which endogenous NO fine-tunes the delicate hormonal network controlling shoot architecture, fruit set and post-anthesis fruit development, emphasizing the relevance of NO-auxin interaction for plant development and productivity.

Fruit Juice Consumption, Body Mass Index, and Adolescent Diet Quality in a Biracial Cohort

Fruit juice consumption during childhood remains controversial. Here, we evaluated the association between preadolescent 100% fruit juice intake and later adolescent diet quality and body mass index (BMI). We used prospective data over 10 years from the National Growth and Health Study for 1921 black and white girls, ages 9–10 years at baseline, for analyses of diet quality, and 2165 girls for BMI analyses. Statistical analyses included repeated measures analysis of variance and logistic regression models. Girls who drank ≥1.0 cup/day of fruit juice in preadolescence consumed 0.44 cup/day more total fruit in later adolescence than non-juice-drinking girls (p &lt; 0.0001). White and black girls who drank ≥1.25 cups/day in preadolescence were 2.62 (95% CI: 1.35–5.08) and 2.54 (1.27–5.07) times more likely, respectively, to meet the Dietary Guidelines for whole fruit by later adolescence than those with the lowest juice intakes. Further, fruit juice consumption was positively associated with diet quality scores. Overall, girls consuming ≥1.25 cups/day of juice had a BMI in late adolescence that was 1.7 kg/m2 lower than that of non-juice-drinking girls. In conclusion, early adolescent fruit juice intake was positively associated with subsequent whole fruit consumption, better diet quality, and lower BMI in later adolescence.

Transcriptomics and metabolomics provide insight into the anti-browning mechanism of selenium in freshly cut apples.

Enzymatic browning has a considerable negative impact on the acceptability and marketability of freshly cut apples. However, the molecular mechanism by which selenium (Se) positively affects freshly cut apples in this regard is not yet clear. In this study, 0.75 kg/plant of Se-enriched organic fertilizer was applied to "Fuji" apple trees during the young fruit stage (M5, May 25), the early fruit enlargement stage (M6, June 25), and the fruit enlargement stage (M7, July 25), respectively. The same amount of Se-free organic fertilizer was applied as a control. Herein, the regulatory mechanism by which exogenous Se exerts its anti-browning effect in freshly cut apples was investigated. The results showed that the M7 treatment applied in Se-reinforced apples could remarkably inhibit their browning at 1h after being freshly cut. Additionally, the expression of polyphenol oxidase (PPO) and peroxidase (POD) genes treated with exogenous Se was significantly reduced compared to controls. Moreover, the lipoxygenase (LOX) and phospholipase D (PLD) genes, which are involved in membrane lipid oxidation, were expressed at higher levels in the control. The gene expression levels of the antioxidant enzymes catalase (CAT), superoxide dismutase (SOD), glutathione S-transferase (GST), and ascorbate peroxidase (APX) were upregulated in the different exogenous Se treatment groups. Similarly, the main metabolites measured during the browning process were phenols and lipids; thus, it could be speculated that the mechanism by which exogenous Se produces its anti-browning effect may be by reducing phenolase activity, improving the antioxidant capacity of the fruits, and alleviating membrane lipid peroxidation. In summary, this study provides evidence regarding and insight into the response mechanism employed by exogenous Se to inhibit browning in freshly cut apples.

Boron stimulates fruit formation and reprograms developmental metabolism in sweet cherry.

Boron modulates a wide range of plant developmental processes; however, the regulation of early fruit development by boron remains poorly defined. We report here the physiological, anatomical, metabolic, and transcriptomic impact of pre-flowering boron supply on the sweet cherry fruit set and development (S1-S5 stages). Our findings revealed that endogenous boron content increased in early growth stages (S1 and S2 stages) following pre-flowering boron exogenous application. Boron treatment resulted in increased fruit set (S1 and S2 stages) and mesocarp cell enlargement (S2 stage). Various sugars (e.g., fructose, glucose), alcohols (e.g., myo-inositol, maltitol), organic acids (e.g., malic acid, citric acid), amino acids (e.g., valine, serine) accumulated in response to boron application during the various developmental stages (S1-S5 stages). Transcriptomic analysis at early growth (S1 and S2 stages) identified boron-responsive genes that are mainly related to secondary metabolism, amino acid metabolism, calcium-binding, ribosome biogenesis, sugar homeostasis and especially to photosynthesis. We found various boron-induced/repressed genes, including those specifically involved in growth. Several heat shock proteins displayed distinct patterns during the initial growth in boron-exposed fruit. Gene analysis also discovered several putative candidate genes like PavPIP5K9, PavWAT1, PavMIOX, PavCAD1, PavPAL1 and PavSNRK2.7, which could facilitate the investigation of the molecular rationale underlying boron function in early fruit growth. Substantial changes in the expression of numerous transcription factors, including PavbHLH25, PavATHB.12L and PavZAT10.1,.2 were noticed in fruits exposed to boron. The current study provides a baseline of information for understanding the metabolic processes regulated by boron during sweet cherry fruit early growth and fruit development in general.

Synthesis of active cytokinins mediated by LONELY GUY is associated with cell production during early fruit growth in peach [Prunus persica (L.) Batsch

Early fruit growth in peach is characterized by cell production. Cytokinins have established roles in regulating cell division and may regulate cell production during early fruit growth. However, the role of active cytokinins and regulation of their metabolism are not well characterized in the peach fruit. In this study, fruit growth parameters, concentrations of active cytokinin bases and a cytokinin riboside, and expression of three key cytokinin metabolism-related gene families were determined during early fruit growth. Early fruit growth was associated with intensive cell production until around 40 days after full bloom. During the early stages of this period, trans-zeatin (tZ), isopentenyladenine (iP), dihydrozeatin (DHZ) and tZ-riboside (tZR), displayed higher abundance which declined rapidly by 3.5- to 16-fold during the later stages. Changes in concentration of active cytokinin bases were consistent with roles for them in regulating cell production. Expression analyses of members of cytokinin biosynthesis-related gene families, ISOPENTENYL TRANSFERASE (IPT) and LONELY GUY (LOG), further indicated that mechanisms of synthesis of cytokinin metabolites and their activation are functional within the fruit pericarp. Changes in expression of multiple members of the LOG family paralleled changes in active cytokinin concentrations. Specifically, transcript abundance of LOG3 and LOG8 were correlated with concentrations of tZ, and iP and DHZ, respectively, suggesting that the direct activation pathway is an important route for active cytokinin base synthesis during early fruit development. Transcript abundance of two CYTOKININ OXIDASE (CKX) genes, CKX1 and CKX2, was consistent with roles in cytokinin catabolism during later stages of early fruit growth. Together, these data support a role for active cytokinins synthesized in the fruit pericarp in regulating early fruit growth in peach.

UV-C Promotes the Accumulation of Flavane-3-ols in Juvenile Fruit of Grape through Positive Regulating VvMYBPA1.

Flavane-3-ol monomers are the precursors of proanthocyanidins (PAs), which play a crucial role in grape resistance. Previous studies showed that UV-C positively regulated leucoanthocyanidin reductase (LAR) enzyme activity to promote the accumulation of total flavane-3-ols in juvenile grape fruit, but its molecular mechanism was still unclear. In this paper, we found that the contents of flavane-3-ol monomers increased dramatically at the early development stage grape fruit after UV-C treatment, and the expression of its related transcription factor VvMYBPA1 was also enhanced significantly. The contents of (-)-epicatechin and (+)-catechin, the expression level of VvLAR1 and VvANR, and the activities of LAR and anthocyanidin reductase (ANR) were improved significantly in the VvMYBPA1 overexpressed grape leaves compared to the empty vector. Both VvMYBPA1 and VvMYC2 could interact with VvWDR1 using bimolecular fluorescence complementation (BiFC) and yeast two hybrid (Y2H). Finally, VvMYBPA1 was proven to bind with the promoters of VvLAR1 and VvANR by yeast one hybrid (Y1H). To sum up, we found that the expression of VvMYBPA1 increased in the young stage of grape fruit after UV-C treatment. VvMYBPA1 formed a trimer complex with VvMYC2 and VvWDR1 to regulate the expression of VvLAR1 and VvANR, thus positively promoting the activities of LAR and ANR enzyme, and eventually improved the accumulation of flavane-3-ols in grape fruit.

Gene-specific silencing of SlPL16, a pectate lyase coding gene, extends the shelf life of tomato fruit

Pectate lyase plays an important role in fruit development and ripening. Although earlier studies showed SlPL, a pectate lyase encoding gene, functions dominantly in tomato fruit softening, the functions of many other pectate lyase encoding genes involved in tomato fruit development and softening remain unknown. Here, gene-specific silencing of SlPL16 (Solyc06g083580) by RNA interference (RNAi) resulted in reduced pectate lyase enzyme activity, pericarp thickness, and soluble sugar content, and increased both the firmness and shelf life of tomato fruit. Through microscopic observation, it was found that the SlPL16-RNAi pericarp had reduced cell size, in comparison to the wild-type (WT). Moreover, gene silencing of SlPL16 resulted in the down-regulation of genes involved in cell wall degradation and pectin synthesis at various fruit developmental stages. Together, these results indicate that SlPL16 provides an important supplement of pectate lyase activity in tomato fruit softening, along with a fundamental role in cell expansion during early fruit development. Additionally, this study provides a potential gene locus in genetic engineering to improve fruit storage tolerance.

Dwarfism in Fruit Plants: A Review

In this modern era, farmers are adopting high density planting (HDP) for most of the fruit crops. Dwarfing is based on the principle of making the optimal use of vertical and horizontal space per unit time and harnessing the highest potential returns per unit of inputs and natural resources. Dwarfing in fruit crops can be accomplished through a variety of methods, including the use of dwarfing rootstock, the selection of spur type scion cultivars, use of interstock, pruning, root pruning, various training systems, girdling, scoring, bark invasion and the application of growth retardants. One strategy for promoting early fruiting, less vigour and increasing production is to utilize dwarf root stocks. The mechanism underlying dwarfing involves anatomical, physiological and biochemical changes. It has been proposed that dwarfing rootstock or interstock control tree size by regulating the auxin that passes through the rootstock or interstock’s bark. Paclobutrazol retards growth, shoot elongation and reduced internodal length by inhibiting gibberellins synthesis. Dwarfness can be imparted by the using incompatible rootstock. Dwarfing can be induced by inducing viral infection, although, it is not commercially adopted. Recombinant DNA technology has recently expanded the gene pool that can be managed to cause dwarfism and maximize benefits in horticulture crops.

ASYMMETRIC LEAVES 2 and ASYMMETRIC LEAVES 2-LIKE are partially redundant genes and essential for fruit development in tomato.

Fruit size and shape are controlled by genes expressed during the early developmental stages of fruit. Although the function of ASYMMETRIC LEAVES 2 (AS2) in promoting leaf adaxial cell fates has been well characterized in Arabidopsis thaliana, the molecular mechanisms conferring freshy fruit development as a spatial-temporal expression gene in tomato pericarp remain unclear. In the present study, we verified the transcription of SlAS2 and SlAS2L, two homologs of AS2, in the pericarp during early fruit development. Disruption of SlAS2 or SlAS2L caused a significant decrease in pericarp thickness as a result of a reduction in the number of pericarp cell layers and cell area, leading to smaller tomato fruit size, which revealed their critical roles in tomato fruit development. In addition, leaves and stamens exhibited severe morphological defects in slas2 and slas2l single mutants, as well as in the double mutants. These results demonstrated the redundant and pleiotropic functions of SlAS2 and SlAS2L in tomato fruit development. Yeast two-hybrid and split-luciferase complementation assays showed that both SlAS2 and SlAS2L physically interact with SlAS1. Molecular analyses further indicated that SlAS2 and SlAS2L regulate various downstream genes in leaf and fruit development, and that some genes participating in the regulation of cell division and cell differentiation in the tomato pericarp are affected by these genes. Our findings demonstrate that SlAS2 and SlAS2L are vital transcription factors required for tomato fruit development.