Artificial pollination has gained increasing attention in kiwifruit cultivation; however, how different pollination methods influence fruit maturity and ripening remains poorly understood. To address this, the physiological, metabolomic, proteomic and gene expression impact of pollination methods (artificial versus open-field pollination) on the pericarp, placenta and seed tissue of Actinidia chinensis var. deliciosa A. Chev. ‘Hayward’ kiwifruit at maturity harvest and during postharvest ripening following short and long cold storage was investigated. Artificial pollination enhanced fruit set and seed number, resulting in increased fruit size and weight at harvest compared to open-field pollination, supporting its role in improving kiwifruit yield. Metabolomic analysis revealed that carbon is primarily redirected from sugar synthesis toward organic acid production in artificially pollinated fruit. Tissue-specific proteomic analysis indicated that artificial pollination alters plant growth regulator dynamics and induce extensive stress-associated responses. Moreover, artificial pollination accelerated kiwifruit ripening as evidenced by increased ethylene production and faster fruit softening. These changes were accompanied by altered expression of genes and proteins involved in ethylene signaling and cell wall structure, potentially reducing postharvest longevity. Additionally, artificial pollination decreased key esters and increased aldehydes, thus altering aroma volatile profiles. It also reduced the levels of important polyphenols, particularly catechin, epicatechin and procyanidin B2, which aligned with observed changes in gene expression. These findings highlight a critical trade-off: while artificial pollination enhances yield, it also modulates physiological processes that may compromise postharvest fruit quality. Overall, this study provides new insights into how pollination influences kiwifruit maturity and ripening, supporting pollination-based strategies to enhance both fruit yield and quality.

Mineral nutrition management in sweet cherry orchards remains a critical challenge due to the lack of site-specific fertilization guidelines, particularly in Greece, a significant cherry-producing country. This study aimed to develop a predictive framework for total nutrient losses in sweet cherry orchards by proposing simplified estimations using fresh fruit yield as the sole input variable. Field experiments were conducted in two orchards with distinct rootstocks (MxM 14 and CAB-6P), analyzing soil properties, leaf nutrient status, and uptake patterns on different plant components. Results indicated that despite differences in soil texture and pH, nutrient availability was generally sufficient, with only Fe and Zn marginally below optimal levels in leaf tissue. Principal Component Analysis (PCA) revealed distinct nutrient distribution patterns, with N evenly distributed across fruits, peduncles, and prunings, while K was concentrated in fruits and peduncles, and Ca and Mg predominantly in fallen leaves. Notably, K was redistributed from leaves to fruits under high yields, evidenced by negative correlations between leaf biomass and K uptake. Strong relationships (r2 > 0.8) were found between fresh fruit yield and uptake of N, P, K, Mg, B, and Cu, enabling reliable predictions of total nutrient losses. Estimated annual nutrient removals were 85.6 kg ha−1 N, 8.94 kg ha−1 P, 42.7 kg ha−1 K, and 12.0 kg ha−1 Mg, with significant fractions retained in prunings and fallen leaves (e.g., 51.8 kg ha−1 N, 6.2 kg ha−1 P). The developed yield-based models provide a practical tool for optimizing fertilization strategies, while our findings highlight the potential for nutrient recycling through sustainable residue management.

Rosa canina L. is among the woody species which thrive through diverse habitats and is distinguished for its high nutritional value. In recent years R. canina L. has raised awareness due to its high demand in cosmetology and pharmacology. This study focuses on the results of a three-year experimental site including four R. canina L. genotypes treated with two fertilization regimes (conventional, organic) and harvested under four ripening stages. Τhe results indicate the most suitable period for harvesting the rosehip fruit in terms of ascorbic acid, antioxidant capacity and total phenolic compounds. This study recommends the first two ripening stages in order to achieve the highest concentration of ascorbic acid (4.53 mg g-1 F.W.). The last ripening stage came across as being the most appropriate stage for the highest total phenolic content (31.2 mg GAE g-1 FW) and in the meantime, this study highlights that the distinct ripening stages do not fluctuate the levels of total antioxidant capacity. Overall, the current study tries to identify the nutritional potential of domesticated R. canina L. and specify which of the ripening stages and fertilization regimes maximize its post-harvest value.

In the present study, a combination of 17 nuclear and four chloroplast microsatellites were used to identify polymorphisms among 224 Citrus accessions maintained at the ex-situ ELGO-DIMITRA germplasm collection, mainly located in Chania, Greece. The nuclear marker data set revealed 109 unique genetic profiles with a mean gene diversity of 0.63, while the chloroplast DNA data set revealed 28 haplotypes between all accessions. A Bayesian genetic structure analysis was used to assign accessions into groups, and a dendrogram based on chloroplast markers allowed the maternal lineage identification of multiple hybrids. A few indigenous accessions exhibited notable genetic differences compared to the evaluated international counterparts (citron: ‘Cretan Smooth’, mandarin: ‘Common Chios’, lemon: ‘Karystini Xylokastrou’/‘Vakalou’/‘Helen’, lime: ‘Pastolemono Chiou’/‘Glykolemono’, greek bergamots, sweet orange: ‘Botsato Artas’). The rest of them presented highly similar or indistinguishable genetic profiles with known accessions. These results are expected to facilitate further exploration of Citrus genotypes maintained in Greece and assist in efficient conservation and design of breeding programs.

High-depth whole-genome resequencing of 53 diverse fig tree genotypes yielded a rich dataset of genetic variants. We successfully identified 5,501,460 single-nucleotide polymorphisms (SNPs) and 1,228,537 insertions and deletions (InDels), providing a high-density and excellent-quality genetic map of the fig tree. We also performed a detailed population structure analysis, dividing the 53 genotypes into three geographical groups and assessing their genetic diversity and divergence. Analysis of structural variants (SVs) and copy number variations (CNVs) revealed their potential functional impact, particularly in plant-pathogen interaction and secondary metabolism. Metabolomic fingerprinting of fig genotypes uncovered extensive variation in primary metabolites and polyphenolic compounds, highlighting the influence of genotype on fruit quality traits such as nutritional content and bioactive compound composition. The genome-wide association study (GWAS) identified critical SNPs associated with fruit quality and morphological features. The discovery of significant candidate genes, such as AGL62, GDSL, and COBRA-like protein 4 genes, offers promising targets for marker-assisted selection and genome editing approaches to improve fig fruit morphological and quality traits. This extensive genomic analysis of fig trees enhances our understanding of the genetic basis of important agronomic traits and provides a rich resource for future research in this economically and nutritionally significant fruit.

Calcium (Ca2+) is a secondary messenger that plays a pivotal role in kiwifruit ripening; however, the underlying mechanisms are still unclear. Herein, we characterize the physiological and molecular responses of kiwifruit to calcium nutrition and how these changes could influence fruit ripening. Our study addresses the response of kiwifruit to calcium in both the early (8 h after calcium application) and late (during ripening at room temperature following 3 months of cold storage) stages. Exogenously supplied calcium (2% CaCl2) by dipping induced an early endogenous calcium accumulation and stimulated intracellular Ca2+ signals from the inner to outer pericarp and in the vascular tissue. Calcium treatment delays kiwifruit ripening, as evidenced by the reduction of ethylene production and softening that is accompanied by altered levels of genes and proteins involved in ethylene signaling and cell wall structure. An immunomicroscopy approach at the early stage based on epitope distribution using cell wall antibodies such as LM19, JIM13 and LM30 showed that de-esterified homogalacturonans and arabinogalactan proteins were depressed in calcium-exposed fruit. The levels of primary metabolites were decreased, while several secondary metabolites, including epicatechin, catechin and procyanidin B2 were altered by calcium. Treatment with calcium has a profound long-term impact on kiwifruit’s transcriptome and proteome contributing to ripening changes. Particularly, the study uncovered an extensive transcriptomic regulation of ripening signaling, notably through MAPKs and hormone, by calcium. A wide diversity of transcription factors (TFs), particularly the AP2/ERF-ERF group, displayed distinct expression patterns at the early and late stages, providing potential targets for deciphering the initial TFs and late responses that are triggered by calcium. A calcium network of the genes-proteins-metabolites and the connected TFs was also created. Interlinked gene expression and protein accumulation analysis unveil that calcium elicits cysteine modifications, membrane/transporter activity, ascorbate homeostasis and ubiquitination signaling. From the obtained transcriptomic and proteomic data, we constructed a calcium-affected proteogenomic framework, highlighting a possible role for alternative splicing in ripening initiation. These findings provide new knowledge of the physiological processes, biochemical mechanisms, and networks regulated by calcium during kiwifruit ripening.

Rosa canina L. is among the woody species which thrive through diverse habitats and is distinguished for its high nutritional value. In recent years R. canina L. has raised awareness due to its high demand in cosmetology and pharmacology. This study focuses on the results of a three-year experimental site including four R. canina L. genotypes treated with two fertilization regimes (conventional, organic) and harvested under four ripening stages. Tau he results indicate the most suitable period for harvesting the rosehip fruit in terms of ascorbic acid, antioxidant capacity and total phenolic compounds. This study recommends the first two ripening stages in order to achieve the highest concentration of ascorbic acid (4.53 mg g-1 F.W.). The last ripening stage came across as being the most appropriate stage for the highest total phenolic content (31.2 mg GAE g-1 FW) and in the meantime, this study highlights that the distinct ripening stages do not fluctuate the levels of total antioxidant capacity. Overall, the current study tries to identify the nutritional potential of domesticated R. canina L. and specify which of the ripening stages and fertilization regimes maximize its postharvest value.

Despite the widespread use of dry matter content (DMC) as an indicator of kiwifruit quality, the physiological and molecular impact of DMC in fruit ripening remains unknown. Herein, the post-harvest physiological, metabolomic, and transcriptomic influence of DMC status on the pericarp and placenta tissue of 'Hayward' kiwifruit at harvest and at the onset of post-cold ripening was investigated. A segregation strategy based on DMC in commercially harvested kiwifruit was achieved with near-infrared spectroscopy for the estimation of DMC in individual fruits. Additionally, kiwifruits with distinct DMC levels were treated with 1-methylcyclopropene (1MCP) and systematically monitored for ripening changes (20 degrees C) at various intervals after cold storage (0 degrees C). Following 90 and 120 days of cold exposure, high DMC kiwifruit generally exhibited superior physiological characteristics, such as increased pericarp and placenta firmness, and soluble solid and starch contents compared to low DMC kiwifruit, regardless of the 1-MCP application. Evidence is also presented for 1-MCP delaying the ripening of low-DMC fruit to the level of the untreated high-DMC kiwifruit. An accumulation of primary metabolites, particularly sugars and polyphenolic compounds, such as catechin, chlorogenic acid and procyanidin B1/B2 was evidenced in the high DMC group. At harvest, gene expression analysis revealed minor differences between DMC groups, with beta-amylase being the highest up-regulated gene in high DMC kiwifruit. Moreover, the gene expression patterns between DMC groups became more distinct after cold storage. Genes related to starch biosynthesis (i.e., glucose-1-phosphate adenyltransferase), water movement (i.e., aquaporin), polyphenolic biosynthesis (i.e., chalcone synthase) and lipid metabolism (i.e., diacylglycerol acyltransferase) showed strong variations between low and high DMC. Interestingly, the placenta tissue displayed almost 4 times more than DMC-affected differentially expressed genes compared to the pericarp, highlighting the key role of the placenta in kiwifruit ripening, notably following 1-MCP treatment. This study provides insights into the tissuespecific ripening response between kiwifruit with distinct DMC, as well as the gene expression influenced by an interaction of 1-MCP and DMC level, thereby helping develop postharvest programs aimed at improving kiwifruit quality traits.

Mechanical stress of kiwifruit is of major importance since it is directly related to fruit quality and postharvest losses. However, the role of mechanical stress in kiwifruit postharvest metabolism remains poorly explored. The present work characterizes the impact of mechanical stress, applied as compression forces (147.1 N), in 'Hayward' kiwifruit at harvest as well as following short (14 days) or long (3 months) cold (0 celcius) storage. Using several experimental approaches, we documented that the applied compression-imposed stress conditions and induced the fruit ripening process at room temperature (20 celcius). Fluorescent antibody labeling showed that arabinogalactan proteins and xyloglucans were altered due to compression, while gel diffusion assay indicated that pectin methylesterase activity was reduced by the long cold exposure. Intracellular Fluo-3 AM-dependent Ca2+ signals were detected in proximal to the main compressed fruit areas just after mechanical treatment. Several primary metabolites changed (i.e. oxoproline, gamma-aminobutyric acid and malonic acid) in coldstored pericarp and placenta tissues after 8 h of compression treatment. Transcriptomic data also disclosed numerous genes, which are mainly involved in sugar metabolism, TCA cycle, cell wall, ethylene and hormones signaling, that were affected by mechanical stress in pericarp and especially in placenta. The weighted correlation and network analysis based on the integration of metabolome and transcriptome datasets identified candidate modules involved in compression stress. We also detected potential TFs, including bZIP53, WRKY40 and GATA17, that are involved in compression stress while meta-data analysis enabled identification of several TFs that regulated by both compression and wounding in kiwifruit. This work provides a first characterization of the compression-affected changes in fruit tissues that offers insights into molecular basis of mechanical stress in kiwifruit.

Fruit is constantly challenged by wounding events, inducing accelerated ripening and irreversible metabolic changes. However, cognate mechanisms that regulate this process are little known. To expand our knowledge of ripening metabolism induced by wounding, an artificial-wound global transcriptome investigation combined with metabolite profiling study was conducted in postharvest kiwifruit (Actinidia chinensis var. deliciosa (A. Chev.) A. Chev. 'Hayward'). Wounding treatment promoted fruit ripening, as demonstrated by changes in fruit firmness, ethylene production and respiration activity determined periodically during a ripening period of 8 d at room temperature. Calcium imaging using fluorescent probe Fluo-3 AM revealed spatial dynamics of Ca(2+ )signaling in the wounding area following 8d ripening. Several sugars including fructose, glucose, and sucrose as well as organic acids such as citric, succinic and galacturonic acid were increased by wounding. Changes of various amino acids in wounded-treated fruit, especially 5-oxoproline and valine along with alternations of soluble alcohols, like myo-inositol were detected. Gene expression analysis of the wounded fruit showed increased expression of genes that are mainly involved in defense response (e.g., AdTLP.1-3, AdPP2C.1-2, AdMALD1), calcium ion binding (e.g., AdCbEFh, AdCLR, AdANX), TCA cycle (e.g., AdMDH.1, AdMDH.2, AdCS), sugars (e.g., AdSUSA.1, AdSPS4, AdABFr), secondary metabolism (e.g., AdPAL.1-3, AdCCR, AdHCT.1-2), lipid processing (e.g., AdGELP.1-4, AdGELP) and pectin degradation (e.g., AdPE.1-2, AdPAE.1-2, AdPG.1-2) as well as in ethylene (AdERF7, AdERF1B, AdACO.1-4) and auxin (AdICE, AdAEFc, AdASII) synthesis and perception. Moreover, genes related to aquaporins, such as AdAQP2, AdAQP4 and AdAQP7were down-regulated in fruit exposed to wounding. These results demonstrate multiple metabolic points of wounding regulatory control during kiwifruit ripening and provide insights into the molecular basis of wounding-mediated ripening.

The possible role of an early calcium application via sprays (0.25, 0.5 and 1M CaCl2) on dormant buds to improve sweet cherry (cv. Ferrovia) fruit quality at harvest was investigated. Fruit quality characteristics were also investigated in response to the age of spurs, the ripening stage, and their interactions. Results indicate that calcium enters the dormant flower buds and the phloem but not to the dormant vegetative buds. At harvest, the levels of Zn, Mn, and Cu were declined in fruits by increasing CaCl2 doses of sprays. Fruit respiratory activity was higher and on–tree fruit cracking was lower in red-colour (unripe) cherries as well as in fruit that was produced by 2-year-old short spurs or by Ca-treated buds. Differences in the sweet cherry skin metabolic profiles were identified. Fruit produced from Ca-exposed spurs exhibited lower levels of ribose and other cell-wall-related sugars and higher sucrose, maltose, and quininic acid levels. Nutrient shift was increased in red cherries, while anthocyanins were boosted in the black ones. PCA analysis was performed between the high dose of calcium spray and a control for mineral element content and cherry quality traits. This study illustrates that the high dose of calcium application during bud dormancy can effectively improve sweet cherry fruit characteristics, in terms of calcium content, cracking incidence, and fruit set. Overall, the present study contributes to a better understanding of the impact of calcium nutrition in fruit crops, which will provide references for alternative nutrient management and quality control in sweet cherry production.

Sweet cherries, Prunus avium L. ( Rosaceae ), are gaining importance due to their perenniallity and nutritional attributes beneficial for human health. Interestingly, sweet cherry cultivars exhibit a wide range of phenotypic diversity in important agronomic traits, such as flowering time and defense reactions against pathogens. In this study, whole-genome resequencing (WGRS) was employed to characterize genetic variation, population structure and allelic variants in a panel of 20 sweet cherry and one wild cherry genotypes, embodying the majority of cultivated Greek germplasm and a representative of a local wild cherry elite phenotype. The 21 genotypes were sequenced in an average depth of coverage of 33.91×. and effective mapping depth, to the genomic reference sequence of ‘Satonishiki’ cultivar, between 22.21× to 36.62×. Discriminant analysis of principal components (DAPC) with SNPs revealed two clusters of genotypes. There was a rapid linkage disequilibrium decay, as the majority of SNP pairs with r 2 in near complete disequilibrium (>0.8) were found at physical distances less than 10 kb. Functional analysis of the variants showed that the genomic ratio of non-synonymous/synonymous (dN/dS) changes was 1.78. The higher dN frequency in the Greek cohort of sweet cherry could be the result of artificial selection pressure imposed by breeding, in combination with the vegetative propagation of domesticated cultivars through grafting. The majority of SNPs with high impact (e.g., stop codon gaining, frameshift), were identified in genes involved in flowering time, dormancy and defense reactions against pathogens, providing promising resources for future breeding programs. Our study has established the foundation for further large scale characterization of sweet cherry germplasm, enabling breeders to incorporate diverse germplasm and allelic variants to fine tune flowering and maturity time and disease resistance in sweet cherry cultivars.

The impact of ultraviolet-C (UV-C) irradiation on sweet cherry fruit was studied. Following harvest, fruits (cv. Sweetheart) were exposed to different doses of UV-C (0, 1.2, 3.0 or 6.0 kJ m(-2)) and then cold stored (0 degrees C) for 10 days. Treatments with UV-C delayed most ripening features and reduced pitting symptoms, particularly following prolonged UV-C application. Also, application of the highest UV-C dose inhibited pectin degradation and delayed skin resistance to penetration. An activation of antioxidants capacity and bioactive compounds, such as flavonoids and phenolics was observed. Illumination with UV-C diminished respiration and altered metabolite profile in whole fruit and skin samples. Several amino acids (eg., threonine and aspartate), sugars, (eg., glucose and fructose) and alcohols (e.g., inositol and mannitol) were modulated by long-term UV-C treatment in whole cherry fruit. Various metabolites, including malate, galacturonate, oxoproline and glutamine were also modulated by UV-C skin tissue. These data enhance our understanding of UV-C function in fruit biology.