Search Results (348)

Kiwifruit (Actinidia spp.) is a globally important economic fruit with high nutritional value. Fruit peelability, defined as the mechanical ease of separating the peel from the fruit flesh, is a critical quality trait influencing consumer experience and market competitiveness and has emerged as a critical breeding target in fruit crop improvement programs. The present review systematically synthesized existing studies on kiwifruit peelability, and focused on its evolutionary trajectory, genotypic divergence, quantitative evaluation, possible underlying mechanisms, and artificial manipulation strategies. Kiwifruit peelability research has advanced from early exploratory studies in New Zealand (2010s) to systematic investigations in China (2020s), with milestones including the development of evaluation metrics and the identification of genetic resources. Genotypic variation exists among kiwifruit genera. Several Actinidia eriantha accessions and the novel Actinidia longicarpa cultivar ‘Guifei’ exhibit superior peelability, whereas most commercial Actinidia chinensis and Actinidia deliciosa cultivars exhibit poor peelability. Quantitative evaluation highlights the need for standardized metrics, with “skin-flesh adhesion force” and “peel toughness” proposed as robust, instrument-quantifiable indicators to minimize operational variability. Mechanistically, peelability is speculated to be governed by cell wall polysaccharide metabolism and phytohormone signaling networks. Pectin degradation and differential distribution during fruit development form critical “peeling zones”, whereas ethylene, abscisic acid, and indoleacetic acid may regulate cell wall remodeling and softening, collectively influencing skin-flesh adhesion. Owing to the scarcity of easy-to-peel kiwifruit cultivars, artificial manipulation methods, including manual peeling benchmarking, lye treatment, and thermal peeling, can be employed to further optimize kiwifruit peelability. Currently, shortcomings include incomplete genotype-phenotype characterization, limited availability of easy-peeling germplasms, and a fragmented understanding of the underlying mechanisms. Future research should focus on methodological innovation, germplasm development, and the elucidation of relevant mechanisms. Full article

Actinidia arguta is a dioecious plant, and the selection of superior male germplasm is crucial for ensuring effective pollination of female cultivars, maximizing their economic traits, and achieving high-quality yields. This study evaluated 30 male germplasms for pollen quantity, germination capacity, storage characteristics, and ultrastructural features. Results revealed significant variation in pollen germination rates (1.56–96.57%) among germplasms, with ‘Lvwang’, ‘TL20083’, and ‘TG06023’ performing best (all >90% germination). The storage characteristics study demonstrated that −80 °C is the optimal temperature for long-term pollen storage in A. arguta. Significant variations were observed in storage tolerance among different germplasms. Among them, Lvwang exhibited the best performance, maintaining a germination rate of 97.40% after 12 months of storage at −80 °C with no significant difference from the initial value, followed by TT07063. Pollen morphology was closely correlated with fertility. High-fertility pollen grains typically exhibited standard prolate or ultra-prolate shapes, featuring a tri-lobed polar view and an elliptical equatorial view, with neat germination furrows and clean surfaces. In contrast, low-fertility pollen grains frequently appeared shrunken and deformed, with widened germination furrows and visible exudates. Based on these findings, the following recommendations are proposed: ① Prioritize the use of germplasms with pollen germination rates >80% as pollinizers; ② Establish a rapid screening system based on pollen morphological characteristics. This study provides important scientific basis for both male germplasm selection and efficient cultivation practices in A. arguta (kiwiberry). Full article

Postharvest storage of kiwifruit requires the implementation of precise environmental conditions to maintain fruit quality and reduce decay. In this research, conducted over two years, we examined whether the storage conditions, characterized by low temperature (1 ± 1 °C) and ultra-high relative humidity (higher than 99%, close to saturation), generated by the Xedavap^® machine from Xeda International, were effective in maintaining the fruit quality and reducing postharvest rots compared to standard storage conditions, characterized by involved low temperature (1 ± 1 °C) and high relative humidity (98%). Kiwifruits preserved under the experimental conditions exhibited a significantly lower rot incidence after 60 days of storage, with the treated fruits showing 4.48% rot compared to 23.03% under the standard conditions in the first year, using inoculated fruits, and 6.30% versus 9.20% in the second year using naturally infected fruits, respectively. After shelf life (second year only), rot incidence remained significantly lower in the treated fruits (12.80%) compared to the control (42.30%). Additionally, quality analyses showed better parameters when using the Xedavap^® system over standard methods. The ripening process was effectively slowed down, as indicated by changes in the total soluble solids, firmness, and titratable acidity compared to the control. These results highlight the potential of ultra-high relative humidity conditions to reduce postharvest rot, extend the shelf life, and enhance the marketability of kiwifruit, presenting a promising and innovative solution for the horticultural industry. Full article

Genetic transformation is an essential tool for investigating gene function and editing genomes. Kiwifruit, recognized as a significant global fresh fruit crop, holds considerable economic and nutritional importance. However, current genetic transformation techniques for kiwifruit are impeded by low efficiency, lengthy culture durations (a minimum of six months), and substantial labor requirements. In this research, we established an efficient system for shoot regeneration and the stable genetic transformation of the ‘Hayward’ cultivar, utilizing leaf explants in conjunction with two strains of Agrobacterium that harbor the expression vector pBI121-35S::GFP, which contains the green fluorescent protein (GFP) gene as a visible marker within the T-DNA region. Our results show that 93.3% of leaf explants responded positively to the regeneration medium, producing multiple independent adventitious shoots around the explants within a six-week period. Furthermore, over 71% of kanamycin-resistant plantlets exhibited robust GFP expression, and the entire transformation process was completed within four months of culture. Southern blot analysis confirmed the stable integration of GFP into the genome, while RT-PCR and fluorescence microscopy validated the sustained expression of GFP in mature plants. This efficient protocol for regeneration and transformation provides a solid foundation for micropropagation and the enhancement of desirable traits in kiwifruit through overexpression and gene silencing techniques. Full article

The market for specialised kiwifruit varieties, such as those with red pulp, remains a niche sector with considerable growth potential in several European countries, including Spain, Italy, Germany, and France. This study applies to the Rasch model to gain a comprehensive understanding of consumer behaviour, specifically pertaining to preferences, attitudes, and propensity towards purchasing both conventional and novel kiwifruit variants. A questionnaire was developed and administered to gather specific information on consumer behaviour. The collected data were analysed using a Rating Scale Rasch Model to construct a valid measure of attitude toward kiwifruit, which was subsequently used in regression models to explain purchase propensity. The findings indicate that marketing strategies should focus on enhancing attitudes towards kiwifruit by leveraging specific product attributes and addressing demographic nuances to effectively promote the consumption of yellow, red, and organic varieties. Full article

Gold kiwifruits from two different farms, harvested at different times, were analysed using both non-destructive and destructive methods. A computer vision system (CVS) and a portable spectroradiometer were used to perform non-destructive measurements of firmness, titratable acidity, pH, soluble solids content, dry matter, and soluble sugars (glucose and fructose), with the goal of building predictive models for the maturity index. Hyperspectral data from the visible–near-infrared (VIS–NIR) and short-wave infrared (SWIR) ranges, collected via the spectroradiometer, along with colour features extracted by the CVS, were used as predictors. Three different regression methods—Partial Least Squares (PLS), Support Vector Regression (SVR), and Gaussian process regression (GPR)—were tested to assess their predictive accuracy. The results revealed a significant increase in sugar content across the different harvesting times in the season. Regardless of the regression method used, the CVS was not able to distinguish among the different harvests, since no significant skin colour changes were measured. Instead, hyperspectral measurements from the near-infrared (NIR) region and the initial part of the SWIR region proved useful in predicting soluble solids content, glucose, and fructose. The models built using these spectral regions achieved R² average values between 0.55 and 0.60. Among the different regression models, the GPR-based model showed the best performance in predicting kiwifruit soluble solids content, glucose, and fructose. In conclusion, for the first time, the effectiveness of a fully portable spectroradiometer measuring surface reflectance until the full SWIR range for the rapid, contactless, and non-destructive estimation of the maturity index of kiwifruits was reported. The versatility of the portable spectroradiometer may allow for field applications that accurately identify the most suitable moment to carry out the harvesting. Full article

The molecular identification of valuable genotypes is an important problem of germplasm management. In this study, we evaluated the potential of 11 universal primer pairs for the DNA barcoding of locally derived cultivars of subtropical crops (actinidia, feijoa, citrus, and tea). A total of 47 accessions (elite cultivars, forms, and breeding lines) of these four genera were included in the study. The efficiency of the following universal primers was assessed using Sanger sequencing: ITS-p5/ITS-u4, ITS-p5/ITS-u2, ITS-p3/ITS-u4, 23S,4.5S&5S, 16S, petB/petD, rpl23/rpl2.l, rpl2 intron, rpoC1 intron, trnK intron, and trnE-UUC/trnT-GUU. Among these primers, trnE-UUC/trnT-GUU showed greater intraspecific polymorphisms, while rpl2 intron and 16S displayed the lowest polymorphism levels in all crops. In addition, the 23S,4.5S & 5S, and rpoC1 intron were efficient for intraspecific analysis of tea and actinidia species. Using five efficient chloroplast primers, a total of 22/6 SNPs/InDels were observed in tea accessions, 45/17 SNPs/InDels in actinidia, 23/3 SNPs/InDels in mandarins, and 5/4 SNPs/InDels in feijoa. These results will be useful for the further development of DNA barcodes of related accessions. Full article

Kiwifruit is a high-value subtropical crop with significant nutritional and economic importance, but its cultivation faces growing challenges due to climate change, particularly in Caucasus. This study aims to study the impact of abiotic stressors such as temperature extremes, drought, and frost on the yield of the ‘Hayward’ cultivar over a 20-year period (from 2003 to 2022). Using a combination of agroclimatic data analysis, measurements of soluble solid content, and soil moisture assessments, this research identified key factors which limit kiwifruit cultivation productivity. The results revealed a high yield variability—68%, with the mean value declining by 16.6% every five years due to increasing aridity and heat stress. Extreme temperature rises of up to 30 °C caused yield losses of 79–89%, and the presence of frost led to declines of 71–94%. In addition, it is objectively proven that the vulnerability of kiwifruit is subject to climate-driven water imbalances. This highlights the need for adaptive strategy formation in the area of optimized irrigation for the sustainable cultivation of fruit in the subtropics. One of the study’s limitations was that it was organized around a single variety of kiwifruit (‘Hayward’). In view of the fact that there are significant differences in growth characteristics among kiwifruit varieties, future research should focus on overcoming this shortcoming. Full article

This study investigated the influence of cane diameter on vegetative, productive, and physiological behaviors in Actinidia chinensis, cv. Gold 3. Conducted over two years (2021–2022), the experiment compared canes with larger (HD) and smaller (LD) proximal diameters. This research focused on parameters such as shoot morphology, leaf gas exchange, fruit quality, and hydraulic resistance. The results revealed that HD canes promoted more vigorous growth, with a higher proportion of long and medium shoots, whereas LD canes resulted in shorter shoots. Additionally, the HD canes demonstrated a higher leaf area and more extensive leaf coverage, contributing to enhanced photosynthetic activity, as evidenced by enhanced gas exchange, stomatal conductance, and transpiration rates. This higher photosynthetic efficiency in HD canes resulted in more rapid fruit growth, with a larger fruit size and weight, particularly in fruits from non-terminate shoots. By contrast, fruits on LD canes exhibited slower growth, particularly in terms of fresh weight and dry matter accumulation. Despite these differences, maturation indices, including soluble solids and acidity levels, were not significantly affected by cane type. The findings suggest that selecting HD canes during winter pruning could lead to earlier harvests, with improved fruit quality and productivity, making this practice beneficial for optimizing vineyard management in Actinidia chinensis. Full article

Drought stress is one of the primary environmental factors affecting plant survival rates and productivity, and it is a key bottleneck restricting the development of the world kiwifruit industry. Therefore, studying the drought resistance-related genes and drought resistance mechanisms of kiwifruit is essential. The bHLH (basic helix-loop-helix) TF family plays a crucial role in the resistance of kiwifruit to abiotic stresses such as drought stress. In this study, we analyzed the response of the AcbHLH gene in kiwifruit under drought stress based on the kiwifruit genome database, transcriptome data, and metabolome data. One hundred eighty-seven AcbHLH genes were identified via bioinformatics and divided into eighteen subfamilies via phylogenetic analysis. The cis-acting elements of the AcbHLH gene are mainly hormone-related cis-acting elements. Under drought stress, 64 AcbHLH genes were significantly different, 5 AcbHLH genes whose expression significantly differed were randomly selected for qRT-PCR verification, and the correlation between the qRT-PCR results and the transcriptome data was high. The determination of plant hormone contents revealed that the contents of plant hormones, such as JA, changed markedly before and after drought stress. Through the combined analysis of transcriptome and metabolome data, it was speculated that AcbHLH84 and AcbHLH97 have functions similar to those of the MYC2 transcription factor and are the main downstream effectors in the JA signaling pathway; these functions could be activated and participate in the JA signaling pathway and that the activation of the JA signaling pathway would inhibit the production of reactive oxygen species. In turn, the drought resistance of kiwifruit is improved. The AcbHLH84 and AcbHLH97 genes could be candidate genes for breeding new transgenic drought-resistant kiwifruit varieties. Full article

Kiwifruit has attracted much attention in fruit and vegetable processing due to its high nutritional and economic value. However, there is a lack of systematic research on the effects of long-term frozen storage on the pulp quality of kiwifruit. Using kiwifruit pulp stored at −20 °C for 0, 3, 6, 9, and 12 months as the research materials, the dynamic changes in the phenotype, color, antioxidant activity, and flavor compounds were comprehensively evaluated. The results showed that frozen storage caused a significant decline in the quality of the fruit pulp. Specifically, the contents of chlorophyll and carotenoids decreased and the color deteriorated (color difference increased); the turbidity and centrifugal sedimentation rates increased, and pH and viscosity changed in different stages. Additionally, antioxidant compounds, such as vitamin C and total phenols, were significantly reduced with the extension of storage duration, and the 2,2-diphenyl-1-picrylhydrazyl (DPPH)/2,2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) free radical scavenging ability was decreased. The content of volatile aroma compounds diminished, leading to a notable shift in the flavor profile. Correlation analysis revealed that changes in volatile substances were significantly correlated with physical, chemical, and antioxidant indicators (p < 0.05). These correlations can serve as a key basis for assessing quality deterioration. This study systematically elucidated, for the first time, the mechanism of quality deterioration in kiwifruit pulp during frozen storage, thereby providing theoretical support for enterprises to optimize pulp grading strategies and the timing of by-product development. Hence, it is recommended that the duration of freezing should be limited to less than 9 months for kiwifruit pulp. Moreover, it is essential to consider varietal differences and new pretreatment technologies to further enhance the industrial utilization and economic value of frozen pulp. Full article

Background: The Actinidia deliciosa cultivar ‘Guichang’ is a remarkable kiwifruit variety. The phenotypic traits of this variety are influenced by the climatic conditions in Guizhou. The flowering time, which is shaped by multiple environmental factors, has a substantial impact on both the fruit yield and quality. Objectives and Methods: This study was designed to explore the molecular mechanisms underlying the transition from bud to flowering in ‘Guichang’ through transcriptomic and proteomic analyses. Results: The transcriptomic results revealed that 6201 genes were up-regulated, while 5849 genes were down-regulated during this transition. Key genes related to hormone signaling, such as AdPIF4, AdBSK, AdBRI1, and AdCYCD3, were recognized as crucial regulators. The proteomic analysis detected a total of 10,488 proteins. Among them, AdBSK1 was regulated, while AdPIF4, AdBRI1, and AdCYCD3 showed stable expressions. A moderate positive correlation (with a Pearson correlation coefficient of 0.445) was found between the expression levels of transcriptomics and proteomics. When AdBSK1 was over-expressed in Arabidopsis, it promoted earlier flowering. This was achieved by down-regulating FLC and up-regulating FT and SOC1. Conclusions: This study clarifies the molecular mechanisms involved in the bud-to-flowering transition in ‘Guichang’. It emphasizes the intricate interactions among hormonal pathways, key genes, and proteins, which are consistent with the broader understanding of plant flowering regulation in recent research. These findings are significant for deepening our understanding of, and potentially controlling, the flowering mechanisms. Full article

To develop new kiwifruit cultivars (Actinidia chinensis var. chinensis) with desirable traits, we conducted wild resource surveys in the Wudang Mountains region of China. Seven promising accessions were identified through preliminary screening, exhibiting fruit weights ranging from 50.46 g to 75.06 g and a soluble solids content (SSC) between 14.33% and 16.32%. The accession ‘WD-03-1’ stood out by meeting the dual selection criteria of fruit weight exceeding 70 g and a SSC above 15%. After a decade-long evaluation, this elite genotype was officially certified as a superior cultivar by the Hubei Provincial Variety Committee for Forestry in 2016, receiving the registered name ‘Wudang 1’. Distinguished as a rare green-fleshed variety in the A. chinensis var. chinensis, ‘Wudang 1’ produces uniform elliptical fruits (shape index of 1.34) with an average weight of 83.22 g. Its flesh combines sweet and tart flavors with exceptional nutritional parameters: 16.33% SSC, 15.28% dry matter, 12.10% soluble sugars, 1.24% titratable acidity, 132.10 mg/100 g vitamin C, and 7.77 mg/g amino acids. Comparative analysis with established cultivars ‘Jinnong’ and ‘Cuiyu’ revealed that ‘Wudang 1’ matures earlier and demonstrates superior performance in three key quality metrics (SSC, dry matter, and vitamin C). Further analysis of aromatic profiles during the prime consumption stage identified 41 volatile compounds, predominantly comprising aldehydes, esters, alcohols, and ketones, which collectively contribute to its distinctive fragrance. Full article

Kiwifruit allergy was first described over 40 years ago and is becoming increasingly common worldwide. This is most likely related to the fact that kiwifruit production and consumption increased by almost two orders of magnitude during the last 50 years. Currently, there are thirteen officially registered allergens belonging to the species Actinidia deliciosa (green kiwifruit), and three officially registered allergens belonging to the species Actinidia chinensis (golden kiwifruit). The molecular properties of the kiwifruit allergens are summarized, and their features are discussed, considering the protein families to which they belong. At present, kiwifruit allergens are found to belong to 13 protein families. Allergic reactions caused by these molecules can be local, for example, related to the oral cavity, but in some cases systemic responses, such as anaphylaxis, are also observed. Generally, kiwifruit allergy should not be considered as a homogenous disorder, as it was noted that there are distinct groups of patients with different sensitization profiles. Therefore, the diagnostic process may be challenging, as in many cases other food allergies must be considered. Frequently cross-reactivity between kiwifruit allergens and their homologs originating from other organisms has a significant impact on the wellbeing of the affected individuals. Full article

Drought can limit plant growth. The ABRE binding factor (ABF) gene family is extensively involved in multifarious bioregulatory processes in plants. However, kiwifruit has not yet been systematically analyzed. This study analyzed the response of kiwifruit AcABF genes to drought stress. Eleven AcABF genes were distributed on nine chromosomes and clustered into three subfamilies with Arabidopsis AtABF genes, AcABF2, AcABF3, AcABF8, AcABF9, and AcABF10, which have drought resistance functions, and AtABF1, AtABF2, AtABF3, and AtABF4 were clustered in Group I. The structural domains of the nine ABF genes in Group I were highly conserved, and the protein structures were highly similar. In the analysis of the five AcABF genes in Group I, all of their cis-acting elements were related to ABA, the content of ABA-like hormones was significantly increased after drought stress, and most of the GO (Gene Ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) enrichment results were related to hormonal processes. A total of six AcABF genes were upregulated under drought stress. qRT-PCR was performed to validate the AcABF genes of Group I. The correlation coefficients of the results with the transcriptome data were all above 0.70, and the expression level of ABA increased under drought treatment. These results indicated that the five AcABF genes were positively correlated with ABA under drought stress and that, by synthesizing ABA and facilitating the expression of ABF gene family members, the tolerance of kiwifruit increased. These results provide a solid foundation for further research on improving drought tolerance in kiwifruit. Full article