Actinidia Chinensis Research Articles

Breeding of new kiwifruit (Actinidia chinensis) cultivars with yellow (golden) fleshed and superior characteristics

The most widely cultivated species globally is Actinidia deliciosa cv. ‘Hayward’. However, in recent years, consumers have shown greater demand for new varieties with novel flesh colour, flavour and appearance in international markets. To meet these expectations, one breeding study was started in 2016 at the University of Guilan in Iran to develop new kiwifruit cultivars with superior characteristics. In this breeding program, 201 female and 534 male hybrid genotypes were obtained from combinations of six different parents using the controlled cross-breeding technique. The evaluations were carried out over three consecutive stages. In the first stage, 201 female hybrid genotypes and control (‘Golden’) were evaluated based on 25 phenological and pomological traits. In the second stage, hybrids passed the desired threshold values in 7 key attributes were selected. Sensory testing in the next stage evaluated these selected hybrid genotypes more. As a result of the first stage, 30 hybrid genotypes with fruit weight (90 ≥ g) were selected. Then, in the second stage, 21 hybrids that showed acceptable dry matter, hue angle, flesh firmness, soluble solid content, acidity, and ascorbic acid were selected. Finally, 13 hybrid genotypes received high scores in sensory testing, and just two hybrid genotypes represented a 100% of novelty with positive texture. These genotypes were selected as potential cultivar candidates. In future studies, fruit yield, disease/pest resistance, and post-harvest performance trials of the 13 selected candidates will be evaluated at different sites. Thus, the ones that give the best results will be introduced to kiwifruit growers.

Identification and Characterization of Innate Immunity in Actinidia melanandra in Response to Pseudomonas syringae pv. actinidiae.

Pseudomonas syringae pv. actinidiae biovar 3 (Psa3) has decimated kiwifruit orchards growing susceptible kiwifruit Actinidia chinensis varieties. Effector loss has occurred recently in Psa3 isolates from resistant kiwifruit germplasm, resulting in strains capable of partially overcoming resistance present in kiwiberry vines (Actinidia arguta, Actinidia polygama, and Actinidia melanandra). Diploid male A. melanandra recognises several effectors, sharing recognition of at least one avirulence effector (HopAW1a) with previously studied tetraploid kiwiberry vines. Sequencing and assembly of the A. melanandra genome enabled the characterisation of the transcriptomic response of this non-host to wild-type and genetic mutants of Psa3. A. melanandra appears to mount a classic effector-triggered immunity (ETI) response to wildtype Psa3 V-13, as expected. Surprisingly, the type III secretion (T3SS) system-lacking Psa3 V-13 ∆hrcC strain did not appear to trigger pattern-triggered immunity (PTI) despite lacking the ability to deliver immunity-suppressing effectors. Contrasting the A. melanandra responses to an effectorless Psa3 V-13 ∆33E strain and to Psa3 V-13 ∆hrcC suggested that PTI triggered by Psa3 V-13 was based on the recognition of the T3SS itself. The characterisation of both ETI and PTI branches of innate immunity responses within A. melanandra further enables breeding for durable resistance in future kiwifruit cultivars.

Genome-wide investigation and analysis of U-box E3 ubiquitin-protein ligase gene family in kiwifruit (Actinidia chinensis) in response to the yeast antagonist, Wickerhamomyces anomalus

ABSTRACT Although the ubiquitin ligase U-box protein family is a vital component of plant development and stress response, the exact role of kiwifruit U-box genes family is not known. The study identified 73 putative U-box genes from the kiwifruit genome. Chromosomal localisation, phylogenetic analysis, physicochemical properties, gene structure, motifs, and promoters of these genes were analysed. Distribution of Actinidia chinensis PUB (AcPUB) genes exhibited varying densities across 27 chromosomes. The study found that U-box clusters were classified into groups I–VII in phylogenetic analyses of a variety of plants, including kiwifruit, Arabidopsis thaliana, and rice, with most of the genes in kiwifruit being related to rice. The conserved motif analyses revealed that all the AcPUB genes have typical U-box structural domains. Analysis of the cis-acting elements suggested that AcPUBs expression may be responsive to several hormones and stresses. RNA-Seq analysis showed that six kiwifruit U-box genes were differentially expressed after induction by Wickerhamomyces anomalus, suggesting a potential involvement of these U-box genes in the kiwifruit's response to W. anomalus, which might include mechanisms related to resistance. Overall, our findings provide valuable insights into the function and structure of U-box genes that will help develop new genomic technologies and study plant resistance.

Actinidia chinensis polysaccharide interferes with the epithelial-mesenchymal transition of gastric cancer by regulating the nuclear transcription factor-κB pathway to inhibit invasion and metastasis.

To investigate the mechanisms of the effect of Actinidia chinensis polysaccharide (ACPS) on the invasion and metastasis of gastric cancer cells. BGC-823-Luc gastric cancer cells stably transfected with a luciferase gene were used to establish an insitutransplanted tumor mouse model. A live mouse imaging system was used to observe tumor growth, and hematoxylin and eosin staining was applied to analyze tissue histopathology. Transwell and scratch wound assays were performed to examine the invasive and migratory ability of BGC-823 cells. Immunofluorescence, confocal microscopy, immunohistochemistry, and Western blot assays were used to analyze the expressions of the nuclear transcription factor-κB (NF-κB) signaling pathway and epithelial-mesenchymal transition (EMT)-related proteins. ACPS significantly inhibited the growth of subcutaneously transplanted BGC-823-Luc gastric cancer tumors in nude mice and reduced inflammatory cell infiltration in tumor tissues. ACPS inhibited Epidermal Growth Factor-induced invasion, migration, and morphological changes in the cytoskeleton of BGC-823 cells. ACPS inhibited gastric cancer EMT and decreased the expression of matrix metallopeptidase 9, N-cadherin and p-NF-κB p65 in transplanted tumor tissues. ACPS inhibited the expression of matrix metalloproteinases and vascular adhesion factors in BGC-823 cells, promoted p65-NF-κB nuclear translocation, and regulated proteins associated with the NF-κB p65 pathway. ACPS inhibited gastric cancer invasion and metastasis both in vivo and in vitro, which evidenced the inhibition of gastric cancer EMT viaregulating the NF-κB inflammatory pathway.

Effect of the Localized Insecticides Spray Technique to Control Halyomorpha halys in Actinidia chinensis Orchards.

Kiwifruit (Actinidia chinensis) cultivation is expanding worldwide, with China, New Zealand, and Italy being the major producing countries. Halyomorpha halys, the brown marmorated stink bug, is raising serious concerns to kiwifruit cultivation both in China and Italy. This study aimed at improving the chemical control efficacy against this pest by comparing two insecticide spray techniques (a conventional ray atomizer and a trumpet-modified atomizer adapted for localized spray application) in kiwifruit. In fact, kiwifruit is often grown with a 'pergola' training system, which may reduce the effectiveness of insecticide penetration into the canopy. Experiments were performed in naturally infested orchards of both Actinidia chinensis var. chinensis 'Jintao' and A. chinensis var. deliciosa 'Hayward'. Furthermore, mesh cages containing H. halys adults were deployed within orchards to assess the insects' mortality at 1, 3, 7, and 10 days after an insecticide application with two spray techniques during two consecutive seasons. In the cultivar 'Jintao', the two systems performed similarly, while in the cultivar 'Hayward', an overall significantly higher insect mortality was recorded with the trumpet atomizer (94-100%) compared to the conventional atomizer (59-78%). Crop damage was also evaluated on both cultivars, simulating the grower insecticide applications with the two spray techniques. At harvest, no difference emerged between the spray techniques, which provided a significantly better protection compared to the untreated control (12-17% compared to 33-47% of injured fruits). Further investigations in this direction are needed also considering the restriction of insecticidal active substances ongoing in the European Union and the need to maximize the efficacy of the available tools.

Evolving Archetypes: Learning from Pathogen Emergence on a Nonmodel Host.

Research initiatives undertaken in response to disease outbreaks accelerate our understanding of microbial evolution, mechanisms of virulence and resistance, and plant-pathogen coevolutionary interactions. The emergence and global spread of Pseudomonas syringae pv. actinidiae (Psa) on kiwifruit (Actinidia chinensis) showed that there are parallel paths to host adaptation and antimicrobial resistance evolution, accelerated by the movement of mobile elements. Significant progress has been made in identifying type 3 effectors required for virulence and recognition in A. chinensis and Actinidia arguta, broadening our understanding of how host-mediated selection shapes virulence. The rapid development of Actinidia genomics after the Psa3 pandemic began has also generated new insight into molecular mechanisms of immunity and resistance gene evolution in this recently domesticated, nonmodel host. These findings include the presence of close homologs of known resistance genes RPM1 and RPS2 as well as the novel expansion of CCG10-NLRs (nucleotide-binding leucine-rich repeats) in Actinidia spp. The advances and approaches developed during the pandemic response can be applied to new pathosystems and new outbreak events.

Chromosome doubling increases PECTIN METHYLESTERASE 2 expression, biomass, and osmotic stress tolerance in kiwifruit

Abstract Chromosome doubling-induced polyploidization is a popular tool for crop breeding. Polyploidy crops commonly have multiple advantages, including increased biomass and stress tolerance. However, little is known about the genes responsible for these advantages. We found kiwifruit (Actinidia chinensis cv. Hongyang) PECTIN METHYLESTERASE 2 (AcPME2)is substantially upregulated in artificially created tetraploid plants that show increased biomass and enhanced tolerance to osmotic stress. Overexpression (OE) of AcPME2 led to increased biomass and enhanced stress tolerance in Arabidopsis (Arabidopsis thaliana), tomato (Solanum lycopersicum), and kiwifruit. Upon short-term osmotic stress treatment, AcPME2-OE plants showed higher levels of demethylesterified pectins and more Ca2+ accumulation in the cell wall than Col-0 plants, which led to increased cell wall stiffness. The stress-induced plasmolysis assays indicated that AcPME2 dynamically mediated the cell wall stiffness in response to osmotic stress, which is dependent on Ca2+ accumulation. Transcriptomic analysis discovered that dozens of stress-responsive genes were significantly upregulated in the AcPME2-OE plants under osmotic stress. Besides, AcPME2-mediated cell wall reinforcement prevented cell wall collapse and deformation under osmotic stress. Our results revealed a single gene contributes to two advantages of polyploidization (increased biomass and osmotic stress tolerance) and that AcPME2 dynamically regulates cell wall stiffness in response to osmotic stress.

Actinidia chinensis Planch Ameliorates Photoaging in UVB-Irradiated NIH-3T3 Cells and SKH-1 Hairless Mice by Controlling the Reactive Oxygen Species/AKT Pathway.

In this study, we evaluated the antiphotoaging properties of Actinidia chinensis Planch (ACP) and the molecular mechanisms underlying its ability to prevent UVB-mediated photoaging. Administration of the ethanolic extract of ACP (EEACP) to the dorsal area of hairless mice effectively ameliorated UVB-mediated wrinkle formation, epidermal thickening, and loss of lipid droplets in the epidermis. Additionally, the UVB-induced loss of collagen content in the epidermis was significantly attenuated in mouse skin treated with EEACP. The expression of procollagen type 1 and metalloproteinase-1a, which are related to collagen content in the epidermis, was restored by EEACP treatment in UVB-irradiated mice and NIH-3T3 mouse skin fibroblast cells. Interestingly, EEACP effectively ameliorated UVB-induced reactive oxygen species overproduction. Furthermore, the activation/phosphorylation of AKT, rather than mitogen-activated protein kinases, has been identified as a major target of EEACP in preventing UVB-mediated photoaging. Additionally, N-(1 deoxy-1-fructosyl) valine and phenethylamine glucuronide were identified as analytical indicators of EEACP using high-performance liquid chromatography/mass spectrometry. These results suggest that EEACP can be developed as a functional natural agent capable of preventing photoaging by attenuating UVB-induced activation of the reactive oxygen species/AKT pathway.

Genome-wide identification of kiwifruit K+ channel Shaker family members and their response to low-K+ stress

Background‘Hongyang’ kiwifruit (Actinidia chinensis cv ‘Hongyang’) is a high-quality variety of A. chinensis with the advantages of high yield, early ripening, and high stress tolerance. Studies have confirmed that the Shaker K+ genes family is involved in plant uptake and distribution of potassium (K+).ResultsTwenty-eight Shaker genes were identified and analyzed from the ‘Hongyang’ kiwifruit (A. chinensis cv ‘Hongyang’) genome. Subcellular localization results showed that more than one-third of the AcShaker genes were on the cell membrane. Phylogenetic analysis indicated that the AcShaker genes were divided into six subfamilies (I-VI). Conservative model, gene structure, and structural domain analyses showed that AcShaker genes of the same subfamily have similar sequence features and structure. The promoter cis-elements of the AcShaker genes were classified into hormone-associated cis-elements and environmentally stress-associated cis-elements. The results of chromosomal localization and duplicated gene analysis demonstrated that AcShaker genes were distributed on 18 chromosomes, and segmental duplication was the prime mode of gene duplication in the AcShaker family. GO enrichment analysis manifested that the ion-conducting pathway of the AcShaker family plays a crucial role in regulating plant growth and development and adversity stress. Compared with the transcriptome data of the control group, all AcShaker genes were expressed under low-K+stress, and the expression differences of three genes (AcShaker15, AcShaker17, and AcShaker22) were highly significant. The qRT-PCR results showed a high correlation with the transcriptome data, which indicated that these three differentially expressed genes could regulate low-K+ stress and reduce K+ damage in kiwifruit plants, thus improving the resistance to low-K+ stress. Comparison between the salt stress and control transcriptomic data revealed that the expression of AcShaker11 and AcShaker18 genes was significantly different and lower under salt stress, indicating that both genes could be involved in salt stress resistance in kiwifruit.ConclusionThe results showed that 28 AcShaker genes were identified and all expressed under low K+ stress, among which AcShaker22 was differentially and significantly upregulated. The AcShaker22 gene can be used as a candidate gene to cultivate new varieties of kiwifruit resistant to low K+ and provide a reference for exploring more properties and functions of the AcShaker genes.

Genome-Wide Identification of the DOF Gene Family in Kiwifruit (Actinidia chinensis) and Functional Validation of AcDOF22 in Response to Drought Stress.

DNA-binding one zinc finger (DOF) transcription factors are crucial plant-specific regulators involved in growth, development, signal transduction, and abiotic stress response generation. However, the genome-wide identification and characterization of AcDOF genes and their regulatory elements in kiwifruit (Actinidia chinensis) has not been thoroughly investigated. In this study, we screened the kiwifruit genome database and identified 42 AcDOF genes (AcDOF1 to AcDOF42). Phylogenetic analysis facilitated the categorization of these genes into five subfamilies (DOF-a, DOF-b, DOF-c, DOF-d, and DOF-e). We further analyzed the motifs, conserved domains, gene structures, and collinearity of the AcDOFgene family. Gene ontology (GO) enrichment analysis indicated significant enrichment in the "flower development" term and the "response to abiotic stress" category. Promoter prediction analysis revealed numerous cis-regulatory elements related to responses to light, hormones, and low-temperature and drought stress in AcDOF promoters. RNA-seq expression profiles demonstrated the tissue-specific expression of AcDOF genes. Quantitative real-time PCR results showed that six selected genes (AcDOF04, AcDOF09, AcDOF11, AcDOF13, AcDOF21, and AcDOF22) were differentially induced by abscisic acid (ABA), methyl jasmonate (MeJA), and cold, salt, and drought stresses, with AcDOF22 specifically expressed at high levels in drought-tolerant cultivars. Further experiments indicated that transient AcDOF22 overexpression in kiwifruit leaf disks reduced water loss and chlorophyll degradation. Additionally, AcDOF22 was localized to the nucleus and exhibited transcriptional activation, enhancing drought resistance by activating the downstream drought marker gene AcDREB2A. These findings lay the foundation for elucidating the molecular mechanisms of drought resistance in kiwifruit and offer new insights into drought-resistant breeding.

Integrated transcriptome and targeted metabolome analyses provide insights into flavonoid biosynthesis in kiwifruit (Actinidia chinensis)

So far, a variety of metabolite components of kiwifruit have been elucidated. However, the identification and analysis of flavonoids in different tissues of kiwifruit are rarely carried out. In this study, we performed transcriptome and metabolome analyses of roots (Gkf_R), stems (Gkf_T), leaves (Gkf_L), and fruits (Gkf_F) to provide insights into the differential accumulation and regulation mechanisms of flavonoids in kiwifruit. Results showed that a total of 301 flavonoids were identified, in four tissues with different accumulation trends, and a large proportion of flavonoids had high accumulation in Gkf_L and Gkf_R. A total of 84 genes have been identified involved in the flavonoid biosynthesis pathway, and the expression levels of five LAR, two DFR, and one HCT were significantly correlated with the accumulation of 16 flavonoids and co-localized in the flavonoid biosynthesis pathway. In addition, a total of 2362 transcription factor genes were identified, mainly MYBs, bHLHs, ERFs, bZIPs and WRKYs, among which the expression level of bHLH74, RAP2.3L/4L/10L, MYB1R1, and WRKY33 were significantly correlated with 25, 56, 43, and 24 kinds of flavonoids. Our research will enrich the metabolomic data and provide useful information for the directed genetic improvement and application in the pharmaceutical industry of kiwifruit.

Saccharin induces resistance against Pseudomonas syringae pv. actinidiae (Psa biovar 3) in glasshouse kiwifruit and orchard vines

AbstractThe artificial sweetener saccharin has been reported to enhance resistance against pathogen attack in various plant species. In this study, foliar application of saccharin resulted in increased resistance to leaf infection by Pseudomonas syringae pv. actinidiae biovar 3 (Psa) in two Actinidia chinensis cultivars, Hayward and Zesy002. In glasshouse plants, the application of saccharin at 0.25, 0.5, 1.0 and 2.0 g/L, 1 week before inoculation with Psa, induced a dose‐dependent reduction in leaf necrosis in both cultivars. Saccharin at 2.0 g/L reduced leaf necrosis in Hayward by 77% and in Zesy002 by over 90%. However, saccharin (2.0 g/L) did not inhibit growth of Psa in liquid media, thus suggesting induced resistance (IR) as the primary mode of action against leaf infection. The development of IR in both cultivars was concomitant with the accumulation of salicylic acid (SA) and salicylate glycoside (SAG), and the upregulation of SA‐pathway genes (PR1 and PR2) in treated leaves. In orchard‐grown Hayward vines, saccharin (1.0 g/L) induced the upregulation of SA‐pathway genes and reduced Psa leaf necrosis and flower bud rot by 50% and 25%, respectively, compared with controls. However, saccharin residues were detected in fruit collected from vines that were sprayed with saccharin (1.0 g/L) before flowering. Residue level correlated with application frequency and timing and was highest (0.051 mg/kg) in vines that received three preflowering sprays. This exceeds the default maximum residue limit (MRL; 0.01 mg/kg) for some export markets and could limit the use of saccharin for disease management.

Fruit Variation in Yellow-Fleshed Actinidia (Actinidia chinensis Planch) Plants Grown in Southern Italy as a Function of Shoot Type

One of the goals of modern orcharding is to produce a high volume of fruits with uniform size, organoleptic parameters, and health characteristics. The aim of this work was to study various shoot types and their prevailing positions along the cane and to identify how shoot type can influence the quality of fruit from the Actinidia tree. The experiment was conducted over a two-year period in a commercial orchard of Actinidia chinensis, cv. Gold 3. The shoots along the cane were classified as follows: spur shoots (SPs), terminated shoots (TEs), non-terminated shoots (NTs), and cut non-terminated shoots (CNTs). The data were statistically processed using ANOVA and Principal Component Analysis (ACP). Four different categories of fruit were obtained from the four shoot types, and their various attributes were compared. The prevailing category (comprising 55% of the studied fruits) was TEs, which are characterised by a higher soluble solid content, sweetness, and excellent health characteristics, as well as the reduced hardness of their pulp, which would support the hypothesis that harvesting could be brought forward. The second most common category (comprising 19% of total fruit) with the lowest soluble solid content, but a high antioxidant capacity, was that which was detached from the CNTs, while 13% of the fruit was produced from NTs, which had the lowest health value but good sweetness perception. Finally, the category with the lowest fruit percentage over the total fruit harvested (10%) was SPs, which are characterised by their smaller size. It has yet to be determined what the performance of each category will be post-harvest; whether it is possible to assign the quality categories while harvesting the fruit or to differentiate the harvest time accordingly remains subject to debate.

First Report of Fusarium fujikuroi Causing Postharvest Rot of Kiwifruit (Actinidia chinensis) in Jiangxi Province, China.

Kiwifruits (Actinidia chinensis) are among the most widely planted fruit in Jiangxi Province, China. Infected kiwifruits of the cultivars 'Hongyang' and 'Jinyan' were obtained from a commercial orchard in Fengxin county, Jiangxi Province (28°67' N; 115°42' E) from September to November 2022. The 1200 kiwifruits were collected from cold storage (cold stored for 3 months at 2°C), and moved to room temperatures (15 to 20°C), approximately 20% had symptoms of postharvest soft rot 7 days later. The infected fruits had brown or dark gray spots on the peel. Most were round or oval, with a diameter of approximately 1~3 cm. The pulp was milky white, and there was a waterlogged ring at the junction of decay. The pathogen was isolated by removing several small pieces (3×3 mm) of infected tissue from the diseased kiwifruits, which were sterilized with 75% ethanol for 30 s, dipped in 1% NaClO for 1 min, and rinsed three times with sterile distilled water. These pieces were transferred onto potato dextrose agar (PDA) and incubated for 5 days at 28°C, 75% relative humidity (RH), separated, and repurified. Eight unidentified isolates with similar morphology were obtained on PDA (D3-1 to D3-8). These isolates had abundant aerial fluffy mycelia. The colonies were white during the early stage of culture and turned light purple in the later stage. The mycelia grew 5.8 mm day-1 (n=5) on average and produced abundant conidia 10 days later. The microconidia were solitary, transparent, ovoid, with 0 to 1 septa, and 3.6 to 11.2 × 1.6 to 3.5 µm (average 6.5 × 2.9 µm, n = 50). The macroconidia were sickle-shaped, slender and slightly curved, with 3 to 5 septa, and 22.3 to 53.9 × 2.6 to 5.4 µm (average 39.5 × 4.3 µm, n = 50). Chlamydospores were absent. The morphological characteristics enabled the identification of the pathogen as Fusarium spp. (Leslie and Summerell, 2006). Isolate D3-2 was further confirmed, and the primers ITS1/ITS4 (White et al. 1990), 5F2/7CR and EF1/EF2 (O'Donnell et al. 2022) were used to amplify the internal transcribed spacer (ITS) region, RNA polymerase II largest subunit (RPB2) gene and translation elongation factor-1 alpha regions (TEF-1α). The ITS (accession no. PP077075), RPB2 (PP566653) and TEF-1α (PP566654) sequences shared 99.62 to 100% identities with ITS (ON564593.1), RPB2 (ON734380.1) and TEF-1α (ON697186.1) of F. fujikuroi from NCBI, respectively. Thus, the pathogen was identified as F. fujikuroi based on morphological and molecular characteristics. Each of the three isolates was inoculated on surface-disinfected (75% ethanol, 5 min) disease-free kiwifruits of cv. 'Jinyan' and 'Hongyang'. The six kiwifruits were pierced by a sterile inoculation needle and inoculated with 20 μl spore suspension (1×106 spores/ml), and six kiwifruits were treated with spore suspension without any wounds, four control fruits were inoculated with sterile distilled water. All the fruits were sealed in a storage box, kept at an RH of 90%-95%, and incubated at a constant temperature of 28°C for 5 days. After 3 days, the fruit rotted at the inoculation site, and after 5 days, the lesions gradually increased, and the symptoms were the same as those of the original sample. The control fruits remained disease-free. The pathogenicity tests were repeated three times. Koch's postulates were completed by reisolating the fungus from infected kiwifruits, which was identified as F. fujikuroi by sequencing. Although F. solani (Yang et al. 2018) and F. acuminatum (Wang et al. 2015) have been previously reported to rot kiwifruits in China, this is the first report of F. fujikuroi causing postharvest rot on kiwifruits in China. This discovery can alert agronomists to prevent and control this pathogen.

Honeybee (Apis mellifera L.) pollination enhances the yield and flavor quality of kiwifruit.

Pollination is essential for achieving high yields and enhancing the quality of kiwifruit cultivation, both of which significantly influence growers' interests and consumers' preferences. However, compared to studies on yield, there are fewer studies exploring the impact of pollination methods on the flavor of kiwifruit Actinidia chinensis Planchon. This study examined the effects of bee (Apis mellifera L.) pollination and artificial pollination on the yield and flavor of kiwifruit in the main producing areas of China. Compared with those pollinated artificially, bee-pollinated kiwifruit exhibited a greater fruit set rate, heavier fruit weight, and greater number of seeds. Notably, the number of seeds was positively correlated with fruit weight in bee-pollinated kiwifruit, whereas no such correlation was detected in artificially pollinated fruit. Bee pollination not only enhanced the yield but also improved the flavor of kiwifruit. Specifically, bee-pollinated kiwifruit contained higher levels of sucrose and lower concentrations of glucose and fructose, while the acid content was less affected by pollination methods. Furthermore, significant differences were observed in the volatile organic compound (VOC) levels in kiwifruit subjected to different pollination treatments, with bee-pollinated fruit exhibiting a superior flavor. Our findings provide new insights into the beneficial role of bee pollination in enhancing kiwifruit yield and quality, underscoring the crucial importance of bees in kiwifruit pollination.

An Improved and Simplified Agrobacterium-Mediated Genetic Transformation Protocol for Solanum nigrum with a Shorter Growth Time.

Solanum nigrum (Solanaceae family) is widely consumed as a fruit or local leafy vegetable after boiling; it also serves as a medicinal plant. Although Agrobacterium-mediated genetic transformation has been established in S. nigrum, the transformation period is long. Specifically, induction of roots takes approximately five weeks for tetraploid and hexaploid S. nigrum, and 7 weeks for diploid Solanum americanum. In this study, we developed an improved rooting-induced method that requires only about 1 week and avoids the use of tissue culture. After generating the transgenic shoots, they were directly transplanted into the soil to facilitate root formation. Remarkably, 100% of the transgenic shoots developed roots within 6 days. Our improved method is time-saving (saving more than 1 month) and simpler to operate. The improved rooting-induced step can be applied to induce roots in various plants using tissue culture, exemplified by the carnation (Dianthus caryophyllus L.). Furthermore, we applied the improved method to generate S. americanum plants expressing AcMYB110 from kiwifruit (Actinidia chinensis spp.). This method will contribute to speeding up gene functional analysis and trait improvement in S. nigrum and might have potential in fast plant molecular breeding processes in crops and rapid rooting induction in tissue culture.

First Report of Fruit Scab Caused by Alternaria alternata on Actinidia chinensis in Korea.

Kiwi (Actinidia chinesis) is an economically important fruit in Korea, with 1,300 ha cultivated and a production of approximately 25,000 tons per year (Kim and Koh, 2018; Kim and Choi, 2023). In late June 2020, fruit scab symptoms were observed on A. chinensis var. rufopulpa in an orchard in Suncheon, Korea. The incidence of scab symptoms among 20-year-old trees was over 75%, primarily superficial, but rendered the fruit less marketable. In the initial stages of the disease, small, light-brown, circular, and oval spots were formed. As the superficial spots expanded, they became cracked scabs measuring 1 to 7 cm with light edges at the later stages. To isolate the causal pathogen, two lesions were cut from two sections of symptomatic tissue, from each of seven fruits from seven trees. Lesions were surface-sterilized with 70% ethanol for 1 min and washed three times with sterilized distilled water (SDW). The sterilized pieces were placed on potato dextrose agar (PDA) and incubated in the dark at 25°C for one week. After subculturing on PDA, single-spore isolation produced 14 isolates: SYP-410 to 423). All 14 colonies appeared greyish-green and cottony on PDA after 7 d. Conidia were pale brown, ellipsoid to obclavate, with ornamented walls, 1 to 6 transverse and 0 to 3 vertical septa, and length × width of 21.5 to 53.4 × 7.3 to 19.2 μm (avg. 33.0 × 12.0 μm, n = 100). Their morphological characteristics were consistent with Alternaria spp. (van der Waals et al. 2011; Woudenberg et al. 2015). We randomly selected three isolates from the morphologically similar cultures and named them SYP-412 to 414 for further investigation. The ITS (GenBank accession nos.: OR901850 to 52), gapdh (OR924309 to 11), tef1 (OR924312 to 14), rpb2 (OR924315 to 17), Alt a1 (OR924318 to 20), endoPG (OR924321 to 23), and OPA10-2 (OR924324 to 26) sequences from SYP-412 to 414 had a 100% (515 bp/515 bp), 100% (578/578), 100% (240/240), 100% (724/724), 95.55% (451/472), 99.33% (445/448), and 100% (634/634) identity with that of type strain A. alternata CBS 918.96 (AF347032, AY278809, KC584693, KC584435, AY563302, KP124026, and KP124633), respectively. Results from the maximum likelihood phylogenetic analysis, based on the seven concatenated gene sequences, placed the representative isolates in a clade with A. alternata. Pathogenicity of SYP-412 was tested using 12 surface-sterilized two-month-old kiwifruits on a 20-year-old trees. Six kiwifruits were spray-inoculated with 5 mL of a conidial suspension (1 × 106 conidia/ml) generated after culturing in PDA medium for 7 d, with or without wounding. Another six control fruits were inoculated with SDW with and without wounding. The inoculated kiwifruits were enclosed in plastic bags to maintain high humidity for one day. Scab symptoms were observed in both wounded and unwounded fruits six weeks after inoculation, but not in the control. The pathogenicity test was performed on a total of three separate trees twice. To satisfy Koch's postulates, A. alternata was re-isolated from all the symptomatic tissues and confirmed by analyzing the ITS and rpb2 genes. Although scab disease caused by A. tenuissima (now A. alternata) has been previously reported in kiwifruit of A. chinensis var. rufopulpa in China (Woudenberg et al. 2015; Ma et al., 2019), this is the first report of its occurrence on kiwifruit in Korea and will help in future detection and control.

Evolution of Quality Parameters and Bioactivity of Actinidia chinensis cv. Sungold (Kiwifruit) Slices Subjected to Different Drying Conditions Storage for 4 Months.

The present study aimed to investigate the impact on nutritional and functional properties of dried kiwifruit (Actinidia chinensis cv. Sungold) slices during conservation for 120 days in sealed containers in the dark at 25 °C. For this purpose, kiwifruits slices were dried at two different temperatures, 40 and 55 °C, for 30 and 25 h, respectively. Fresh and dried kiwi slices were analyzed for their pH, activity water, total solid soluble (TSS), color, titratable acidity, total phenols (TPC) and flavonoids content (TFC), organic acids, and radical scavenging activities. Analysis carried out on the dehydrated samples showed a good aptitude of kiwi material towards the drying process. Particularly, it has been observed that the drying treatment at low temperature helped to preserve the nutraceutical properties of the fruits. In fact, samples treated at 40 °C (KLT) showed at day 0 (T0) the highest TPC and TFC with values of 979.42 Gallic Acid Equivalents (GAE)/100 g of dried weight (dw) and 281.84 mg catechin equivalents (CTE)/100 g dw even if compared with fresh kiwi slices sample (FKF). Moreover, KLT also exhibited the highest values of antioxidant activity (1657 mmol Trolox/100 g dw). After 120 days storage, all dried samples showed a high ascorbic acid content (429-339 mg/100 g dw fruits) and only a slight variation of physicochemical parameters. Textural Parameters (hardness, springiness, cohesiveness, gumminess, and chewiness), apart from resilience results, showed significant differences between kiwifruit dried at 55 °C and at 50 °C (KLT and KHT, respectively). Color and aroma intensity were the main sensory descriptors with higher scores.

Ethanolic extract of Actinidia chinensis var. delicious fruit ameliorates scopolamine-induced cognitive impairment in rats

AimThe present study was to assess the anti-amnesic effect of Actinidia chinensis var deliciosa in a rat model of scopolamine-induced amnesia. Method36 rats were divided into 6 groups and assigned name to each group i.e. Group 1 rats (normal control) received 1 ml/kg normal saline for 14 days intraperitoneally (i.p.). Group 2 rats received scopolamine (3 mg/kg, i.p.) 30 min prior to the trial on the 14th day. Group 3 rats received 3 mg/kg/day of donepezil as pre-treatment for 14 days and scopolamine (3 mg/kg, i.p.) 30 min before the trial on the 14th day. Group 4, 5, and 6 rats received Actinidia chinensis var deliciosa (200, 400, and 600 mg/kg/day) for 14 days and scopolamine (3 mg/kg, i.p) 30 min before the trial on the 14th day respectively. On day 15, 6 rats from each group were sacrificed and the brain tissue of these rats was isolated for the estimation of biochemical parameters, and histopathological examination. ResultScopolamine-treated rats demonstrated increased escape latency and lipid peroxidation levels in the hippocampus compared to the control group (p < 0.001). However, pre-treatment with Actinidia chinensis var deliciosa extract (ACEE) at various doses and the standard drug donepezil significantly improved these parameters. Histopathological examination revealed that ACEE and donepezil protected against pyramidal cell degeneration, neuronophagia, and vascular inflammation in scopolamine-treated rats. Discussion: Actinidia chinensis var deliciosa showed promising anti-amnesic activity against scopolamine-induced amnesia in rats. This could be attributed to its brain acetylcholinesterase level and alteration in neurotransmitter level.

NbPTR1 confers resistance against Pseudomonas syringae pv. actinidiae in kiwifruit.

Pseudomonas syringae pv. actinidiae biovar 3 (Psa3) causes a devastating canker disease in yellow-fleshed kiwifruit (Actinidia chinensis). The effector HopZ5, which is present in all isolates of Psa3 causing global outbreaks of pandemic kiwifruit canker disease, triggers immunity in Nicotiana benthamiana and is not recognised in susceptible A. chinensis cultivars. In a search for N. benthamiana nonhost resistance genes against HopZ5, we found that the nucleotide-binding leucine-rich repeat receptor NbPTR1 recognised HopZ5. RPM1-interacting protein 4orthologues from N. benthamiana and A. chinensis formed a complex with NbPTR1 and HopZ5 activity was able to disrupt this interaction. No functional orthologues of NbPTR1 were found in A. chinensis. NbPTR1 transformed into Psa3-susceptible A. chinensis var. chinensis 'Hort16A' plants introduced HopZ5-specific resistance against Psa3. Altogether, this study suggested that expressing NbPTR1 in Psa3-susceptible kiwifruit is a viable approach to acquiring resistance to Psa3 and it provides valuable information for engineering resistance in otherwise susceptible kiwifruit genotypes.