Search Results (100)

Climate change is reshaping plant reproductive processes, particularly at the vulnerable seed germination stage. This study examines the germination responses of four Actinidia species (A. rufa, A. latifolia, A. deliciosa, and A. setosa) under controlled experimental conditions, integrating empirical germination data with classifier modeling to predict species-specific responses under future climate scenarios. Unlike traditional species distribution models (SDMs), our classifier approach incorporates physiological dormancy mechanisms and key environmental cues such as chilling requirements, temperature fluctuations, and drought stress. Results reveal significant interspecific differences: A. rufa exhibited strong ecological plasticity, maintaining stable germination under warming and drought, while A. deliciosa displayed extreme sensitivity to warming, with germination dropping below 25% due to its strict chilling requirement. A. latifolia showed latitude-dependent vulnerability, with southern populations experiencing reduced germination under warming conditions, and A. setosa demonstrated complex dormancy patterns with higher germination at high elevations. The predictive accuracy of our models was validated against long-term field data, underscoring their robustness in forecasting climate-induced germination shifts. These findings highlight the need for targeted breeding programs to develop A. deliciosa cultivars with reduced chilling requirements and suggest A. rufa as a strong candidate for ecological restoration under future warming scenarios. By refining climate impact assessments through physiological modeling, this study provides valuable insights for kiwifruit conservation, agricultural adaptation, and broader plant-climate interactions under global warming. Full article

Kiwifruit (Actinidia deliciosa) is a globally important crop presenting challenges for ensuring cross-pollination. This study aimed to (1) record the entomological fauna visiting flowers; (2) evaluate the visitation frequency of pollinators; and (3) test the use of lavender extract to enhance cross-pollination by honeybees and assess the impacts on fruit quality. Nine species of floral visitors were recorded as pollinators, although the most frequent were the exotic honeybee (Apis mellifera) and the native bees Bombus pauloensis and Xylocopa augusti. Honeybees increased their visitation to flowers when the attractant was used, improving pollination service and fruit quality compared to the control-bagged treatment, resulting in fruits that were 20 g heavier (115.4 g vs. 95.6 g, 95% CI). Similarly, the number of seeds per fruit and the fruit shape index (FSI) increased in treatments exposed to bee visitation when compared to the bagged control. However, differences in bee visitation among treatments suggested a non-linear relationship between bee activity and fruit quality. Nevertheless, achieving high-quality fruit standards across treatments could be explained by the extended floral lifespan, which allowed for a high number of visits and ensured pollination. Finally, we did not observe any bias in honeybee visitation by applying sugar syrup combined with the attractant. Hence, to increase honeybees’ visits to flowers, we recommend applying the scent directly in a water solution. Full article

Karrikins, a class of butenolide compounds derived from plant-derived smoke, positively regulate plant development and stress tolerance. However, their effects on postharvest fruit have scarcely been reported. In this study, karrikin solution was prepared by absorbing maize straw smoke into water, and kiwifruits (Actinidia deliciosa) were immersed in different concentrations of this solution to determine the optimal concentration based on respiratory rate, relative conductivity, firmness, soluble solids content, and appearance of the kiwifruits. Subsequently, the regulation of reactive oxygen species (ROS) and soluble sugars metabolism by karrikins were studied. The results showed that the optimal dose of karrikins for kiwifruit was 1.20 μmol L⁻¹. Karrikins enhanced the activities of superoxide dismutase, catalase, enzymes in the ascorbate–glutathione pathway, and soluble sugars metabolism, increased the concentrations of reducing ascorbate, glutathione, sucrose, and fructose-6-phosphate, suppressed ROS concentrations, and maintained the quality of kiwifruit during storage. These results suggest that karrikins could be a potential tool to modulate fruit ripening, with their effects depending on the dosage used. Full article

Drought stress significantly affects the yield and quality of agricultural crops. Plants have developed various adaptations to cope with drought stress. These adaptations involve the regulation of physiological and biochemical mechanisms regulated by many genes. Therefore, identification of cultivars with strong responses to drought stress will provide important contributions to breeding programs. In this study, Hayward and Matua kiwifruit cultivars were used and the plants were subjected to drought in vitro in nutrient media containing PEG 6000 (Polyethyleneglycol) at concentrations of 0, 1, 2, and 3%. The morphological parameters of the plants were examined during the culture period and WRKY TF was utilized to determine the molecular regulations induced by drought stress in plants. For this purpose, the expression levels of WRKY3, WRKY9, WRKY21, WRKY28, WRKY41, WRKY47, WRKY65 and WRKY71 genes were analyzed in leaf and root tissues of the cultivars. The findings showed that the plants in the 2% and 3% PEG media were significantly affected by drought stress, with a notably low root formation performance. The gene expression analysis revealed that the expression levels of genes in the leaf and root tissues of plants under drought conditions were higher compared to the control group. The data obtained from the analyses indicated that the Hayward and Matua cultivars exhibited strong responses to drought both morphologically and genetically. Full article

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

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

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

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

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

Background/Objectives: Growing interest in natural, health-promoting ingredients for functional foods, nutraceuticals, and cosmetics has increased the demand for bioactive compounds from kiwi (Actinidia deliciosa). This study aimed to assess the antioxidant, anti-inflammatory, and antithrombotic properties of amphiphilic bioactives extracted from kiwi fruit and its by-products, including peel, seeds, and pulp. Methods: Bioactive compounds were extracted and analyzed using liquid chromatography–mass spectrometry (LC–MS) and attenuated total reflectance–Fourier transform infrared (ATR–FTIR) spectroscopy. Antioxidant activity was evaluated using DPPH and ABTS radical scavenging assays. Anti-inflammatory and antithrombotic effects were assessed through inhibition of platelet aggregation induced by platelet-activating factor (PAF) and adenosine diphosphate (ADP) in human platelets. Results: All extracts showed significant antioxidant activity. FTIR and LC–MS analyses confirmed the presence of phenolics, flavonoids, carotenoids, and polar lipids. Kiwi peel extract exhibited the strongest inhibition of PAF- and ADP-induced platelet aggregation, attributed to its higher content of phenolics and unsaturated polar lipids. LC–MS data indicated a favorable fatty acid profile with high omega-9 levels and a low omega-6/omega-3 ratio. Polar lipid structural analysis revealed a predominance of phospholipids with unsaturated fatty acids at the sn-2 position. Conclusions: Kiwi by-products are valuable sources of health-promoting bioactives with antioxidant and anti-inflammatory potential. These findings support their incorporation into nutraceutical, nutricosmetic, and cosmeceutical products and lay the groundwork for further studies on safety, efficacy, and practical application. Full article

The chloroplast genome, as an important evolutionary marker, can provide a new breakthrough direction for the population evolution of plant species. Actinidia deliciosa represents one of the most economically significant and widely cultivated fruit species in the genus Actinidia. In this study, we sequenced and analyzed the complete chloroplast genomes of seven cultivars of Actinidia. deliciosa to detect the structural variation and population evolutionary characteristics. The total genome size ranged from 156,404 bp (A. deliciosa cv. Hayward) to 156,495 bp (A. deliciosa cv. Yate). A total of 321 simple sequence repeats (SSRs) and 1335 repetitive sequences were identified. Large-scale repeat sequences may facilitate indels and substitutions, molecular variations in A. deliciosa varieties' chloroplast genomes. Additionally, four polymorphic chloroplast DNA loci (atpF-atpH, atpH-atpI, atpB, and accD) were detected, which could potentially provide useful molecular genetic markers for further population genetics studies within A. deliciosa varieties. Site-specific selection analysis revealed that six genes (atpA, rps3, rps7, rpl22, rbcL, and ycf2) underwent protein sequence evolution. These genes may have played key roles in the adaptation of A. deliciosa to various environments. The population evolutionary analysis suggested that A. deliciosa cultivars were clustered into an individual evolutionary branch with moderate-to-high support values. These results provided a foundational genomic resource that will be a major contribution to future studies of population genetics, adaptive evolution, and genetic improvement in Actinidia. Full article

Biochar, a by-product of agri-food waste, has shown benefits in plant growth and soil health. However, its use in vitro remains underexplored. This study investigates the impact of biochar supplementation in the culture medium, alone or in combination, with 6-benzylaminopurine (BAP), on kiwifruit (Actinidia chinensis var. deliciosa), cv. Tomuri proliferation. Kiwifruit explants were cultured on media enriched with 0, 4, or 6 g/L biochar, without or with BAP (0.2 mg/L), over two subcultures (SUB1 and SUB2). Parameters such as shoot and root number and length, fresh and dry weight, as well as plantlets’ total phenolic content and antioxidant activity, were measured and analyzed. Biochar enhanced plantlets proliferation, particularly with BAP. In SUB1, at 4 g/L, biochar promoted shoot production (2.00 vs. 1.63) and their length (1.50 cm vs. 0.98), independently of the presence of BAP. The presence of biochar in the BAP-free media, favored rhizogenesis; particularly in SUB2, where on average, 5.58 roots per plantlets were recorded. Biochar increased the plantlets’ total phenolic content and antioxidant activity, especially in BAP-free media. The addition of biochar as an additive to the culture medium during the kiwifruit in vitro proliferation phase could be a breakthrough outcome for the nursery sector. Full article

Calcium (Ca) is one of the most important nutrients involved in fruit quality and storability; therefore, its application in fruit trees is often used in pre- and post-harvest. The aims of this study were to manipulate soil Ca, K, and N availability, photosynthetic active radiation, and fruit transpiration rate to understand their implication on fruit Ca accumulation on green-flesh kiwifruit grown in calcareous soil. Our results show that Ca partitioning into the fruit is not affected by the applications of Ca, K, and N, as well as the increase of photosynthetic active radiation. However, the presence of reflective films reduced fruit firmness and increased soluble solid content at harvest and during cold storage, thus enhancing fruit quality. Fruit calcium accumulation is decreased by the reduction of fruit transpiration rate; however, it has the possibility to recover, even close to fruit harvest, when the fruit transpiration is restored. The presence of bags reduced fruit weight from 84 to 63 g even though bags were removed. Our data provide evidence of the inefficiency of calcium fertilization in kiwifruit in calcareous soils and demonstrate the extension of calcium transportation into the fruit, which seems to occur during the entire growing season. Full article