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The fruit of most wild Actinidia eriantha are late maturing, which greatly restrict their commercial development. Fortunately, our team found an early maturing genotype, 'Ganlv 2', with excellent fruit quality traits at an altitude of 750 m in Nancheng County, Jiangxi Province, China. In order to clarify whether the early maturity trait is stable and provide evidence for new cultivar protection, we performed DUS (Distinctness, Uniformity and Stability) tests during 2017-2019 and used SSR technology to construct a molecular fingerprint. The results showed that 'Ganlv 2' is a novel diploid genotype, and matures about 20 d earlier than other A. eriantha cultivars. The average fruit weight of 'Ganlv 2' was 45 g, and the maximum was 58 g at harvest. The fruit shape was oval and the peelable skin were covered with dense white hair. The three-year average value was 15.2% for its fruit soluble solids concentration, 17.4% for dry matter, 9.3% for total sugar content, 1.0% for total acid content, and 466.24 mg/100 g FW for vitamin C. In conclusion, the early maturity trait of 'Ganlv 2' appears to be stable, and it provides a novel genotype for studying the mechanism of early fruit maturity in kiwifruit. [ABSTRACT FROM AUTHOR]

The STAY-GREEN (SGR) proteins play an important role in chlorophyll (Chl) degradation and are closely related to plant photosynthesis. However, the availability of inadequate studies on SGR motivated us to conduct a comprehensive study on the identification and functional dissection of SGR superfamily members in kiwifruit. Here, we identified five SGR genes for each of the kiwifruit species [Actinidia chinensis (Ac) and Actinidia eriantha (Ae)]. The phylogenetic analysis showed that the kiwifruit SGR superfamily members were divided into two subfamilies the SGR subfamily and the SGRL subfamily. The results of transcriptome data and RT-qPCR showed that the expression of the kiwifruit SGRs was closely related to light and plant developmental stages (regulated by plant growth regulators), which were further supported by the presence of light and the plant hormone-responsive cis-regulatory element in the promoter region. The subcellular localization analysis of the AcSGR2 protein confirmed its localization in the chloroplast. The Fv/Fm, SPAD value, and Chl contents were decreased in overexpressed AcSGR2, but varied in different cultivars of A. chinensis. The sequence analysis showed significant differences within AcSGR2 proteins. Our findings provide valuable insights into the characteristics and evolutionary patterns of SGR genes in kiwifruit, and shall assist kiwifruit breeders to enhance cultivar development. [ABSTRACT FROM AUTHOR]

In order to find an efficient, economical and feasible method for soft ripening storage of kiwifruit, two softening methods (on-vine, cold) were utilized for the 'Ganlv-2' kiwifruit (Actinidia. eriantha) cultivar. A comprehensive evaluation was conducted on the quality changes in 'Ganlv-2' under different methods after fruit ripening by principal component analysis and mathematical modeling. Compared to kiwifruit under cold softening, kiwifruit treated with on-vine soft ripening had slightly greater sugar-acid ratios and flesh firmness and higher contents of dry matter, soluble solids, and soluble sugar. The titratable acid content was slightly lower in the on-vine group than in the cold group. The sensory evaluation results manifested little difference in fruit flavor between the two groups. However, at the end of the trial, the overripe taste of the on-vine group was lighter and the taste was sweeter than those of the cold group. More aromatic substances were emitted from the kiwifruit in the on-vine group. According to the mathematic model, there was no significant difference in fruit quality and flavor between the on-vine and traditional cold groups. The fruit in the on-vine group had a stronger flavor and lighter overripe flavor when they reached the edible state. This paper provided a novel storage method of A. eriantha, it can reduce the cost of traditional cold storage and reduce the pressure on centralized harvesting, and the feasibility of this method was verified from the fruit quality. [ABSTRACT FROM AUTHOR]

In order to better understand the changes in fruit quality and soluble sugar components in wild Actinidia eriantha at the soft ripening stage, this study explored the fruit quality indexes, soluble sugar components, sucrose metabolism-related enzyme activities and the expression of sucrose metabolism-related enzyme genes in wild A. eriantha germplasm resources. The results showed that the fruit quality of wild A. eriantha at the soft ripening stage was quite different, and the coefficient of variation of fructose content was the largest, followed by sucrose and glucose. Principal component analysis and systematic clustering analysis showed that the comprehensive performance of fruit quality indexes of M28 and M10 was the most prominent. The accumulation and composition of soluble sugar components in different wild A. eriantha varieties (lines) were not consistent. The activities of sucrose metabolism enzymes among wild A. eriantha varieties (lines) were different to some extent. The sucrose metabolism-related enzyme genes among wild A. eriantha germplasm resources had different expression patterns. The results will contribute to understanding the fruit quality changes and the mechanism of sugar metabolism in wild A. eriantha at the soft ripening stage, and lay a foundation for the protection and utilization of wild A. eriantha germplasm resources. [ABSTRACT FROM AUTHOR]

Actinidia eriantha Benth. (Called Maohuamihoutao in China) is a plant that has been utilized as a heat-clearing drug in She ethnic minority group for a long time in China. Specifically, it has been involved in the treatment of stomach cancer, colon cancer, cirrhosis with ascites, chronic hepatitis, leukemia, rectal prolapse, hernia and uterine prolapse. Pharmacological research provides partial evidence for the traditional use of A. eriantha and might have demonstrated the folk utilization of A. eriantha to combat many cancers. Crude extracts and relatively pure components of A. eriantha possess a variety of pharmacological activities, including anti-cancer, immunoregulatory, anti-angiogenic, neuroprotective, anti-inflammatory, and antioxidant activities. In addition, over 104 chemical substances have been determined from A. eriantha, involving terpenoids, alcohols, phenolics, aldehydes, organic acids, flavonoids glycosides, ketones, and glucoside. The existing literature reveals that a large proportion of the therapeutic effects of A. eriantha were rendered by the polysaccharides. However, the mechanisms of action and the structure-function correlations of these compounds, as well as the synergistic and antagonistic effects between them, need to be investigated further. Therefore, we propose that future studies on A. eriantha should focus on comprehensively assessing its medicinal quality, exploring its multi-target nature using network pharmacology approaches, and evaluating its long-term toxicity and efficacy in vivo. [ABSTRACT FROM AUTHOR]

Light-harvesting chlorophyll a/b-binding (LHC) protein is a superfamily that plays a vital role in photosynthesis. However, the reported knowledge of LHCs in kiwifruit is inadequate and poorly understood. In this study, we identified 42 and 45 LHC genes in Actinidia chinensis (Ac) and A. eriantha (Ae) genomes. Phylogenetic analysis showed that the kiwifruit LHCs of both species were grouped into four subfamilies (Lhc, Lil, PsbS, and FCII). Expression profiles and qRT-PCR results revealed expression levels of LHC genes closely related to the light, temperature fluctuations, color changes during fruit ripening, and kiwifruit responses to Pseudomonas syringae pv. actinidiae (Psa). Subcellular localization analysis showed that AcLhcb1.5/3.1/3.2 were localized in the chloroplast while transient overexpression of AcLhcb3.1/3.2 in tobacco leaves confirmed a significantly increased content of chlorophyll a. Our findings provide evidence of the characters and evolution patterns of kiwifruit LHCs genes in kiwifruit and verify the AcLhcb3.1/3.2 genes controlling the chlorophyll a content. [ABSTRACT FROM AUTHOR]

'Ganlv 1' is a new cultivar of Actinidia eriantha selected from the wild natural population, which has the advantages of moderate taste, high yield, easy peeling and high ascorbic acid (AsA) content. In this study, 'Ganlv 1' was used to explore the changes in fruit quality, soluble sugar components, sucrose metabolism-related enzymes activities and sucrose metabolism-related enzyme genes' expression during the fruit's development. The results showed that, except for AsA, the changes in the fruit quality index and fruit growth and development during the development of 'Ganlv 1' basically exhibited the same trend. The fruit shape index was different in the different development stages of the fruit, and tended to be stable with fruit growth and development. The dynamic changes of the dry matter content indicated that the best time for fruit harvest was about 160 days after full bloom. The main sugar components in the fruit were fructose, glucose and sucrose, and sucrose and glucose were the main sugars in the soft-ripening stage. The trend of sucrose accumulation, the activities of the sucrose metabolism-related enzymes and the expression of the sucrose metabolism-related genes indicated that 130–145 days after full bloom (DAFB) might be the critical period of sucrose metabolism. The results are of great significance for clarifying the developmental characteristics and dynamic changes in the sugar components in A. eriantha fruits, and lay a foundation for further studying of the mechanism of sugar metabolism in A. eriantha. [ABSTRACT FROM AUTHOR]

Background: Refugia is considered to be critical for maintaining biodiversity; while discerning the type and pattern of refugia is pivotal for our understanding of evolutionary processes in the context of conservation. Interglacial and glacial refugia have been studied throughout subtropical China. However, studies on refugia along the oceanic–continental gradient have largely been ignored. We used a liana Actinidia eriantha, which occurs across the eastern moist evergreen broad-leaved forests of subtropical China, as a case study to test hypotheses of refugia along the oceanic–continental gradient and 'oceanic' adaptation. Results: The phylogeographic pattern of A. eriantha was explored using a combination of three cpDNA markers and 38 nuclear microsatellite loci, Species distribution modelling and dispersal corridors analysis. Our data showed intermediate levels of genetic diversity [haplotype diversity (hT) = 0.498; unbiased expected heterozygosity (UHE) = 0.510] both at the species and population level. Microsatellite loci revealed five clusters largely corresponding to geographic regions. Coalescent time of cpDNA lineages was dated to the middle Pliocene (ca. 4.03 Ma). Both geographic distance and climate difference have important roles for intraspecific divergence of the species. The Zhejiang-Fujian Hilly Region was demonstrated to be a refugium along the oceanic–continental gradient of the species and fit the 'refugia in refugia' pattern. Species distribution modelling analysis indicated that Precipitation of Coldest Quarter (importance of 44%), Temperature Seasonality (29%) and Mean Temperature of Wettest Quarter (25%) contributed the most to model development. By checking the isolines in the three climate layers, we found that A. eriantha prefer higher precipitation during the coldest quarter, lower seasonal temperature difference and lower mean temperature during the wettest quarter, which correspond to 'oceanic' adaptation. Actinidia eriantha expanded to its western distribution range along the dispersal corridor repeatedly during the glacial periods. Conclusions: Overall, our results provide integrated evidence demonstrating that the Zhejiang-Fujian Hilly Region is a refugium along the oceanic–continental gradient of Actinidia eriantha in subtropical China and that speciation is attributed to 'oceanic' adaptation. This study gives a deeper understanding of the refugia in subtropical China and will contribute to the conservation and utilization of kiwifruit wild resources in the context of climate change. [ABSTRACT FROM AUTHOR]

Kiwifruit (Actinidia eriantha) is a peculiar berry resource in China, and the maturation period is generally late. Fortunately, we found an early mature A. eriantha germplasm. In order to explore the formation mechanism of its early mature trait, we determined the main carbohydrate and endogenous hormone content of the fruit, and used off-target metabolomics and transcriptomics to identify key regulatory metabolites and genes. We found that early mature germplasm had faster starch conversion rate and higher sucrose, glucose, and fructose content when harvested, while with lower auxin (IAA), abscisic acid (ABA), and zeatin (ZR) content. Through the non-targeted metabolome, 19 and 20 metabolites closely related to fruit maturity and early maturity were identified, respectively. At the same time, weighted correlation network analysis (WGCNA) showed that these metabolites were regulated by 73 and 99 genes, respectively, especially genes related to sugar metabolism were mostly. Based on above, the formation of early mature trait of A. eriantha was mainly due to the sucrose decomposition rate was reduced and the soluble solid content (SSC) accumulated at low levels of endogenous hormones, so as to reach the harvest standard earlier than the late mature germplasm. Finally, ten single nucleotide polymorphism (SNP) loci were developed which can be used for the identification of early mature trait of A. eriantha. [ABSTRACT FROM AUTHOR]

Kiwifruit (Actinidia eriantha) is a dioecious vine, and the pollen of its male cultivars has a direct effect on the quality of its fruits. In this study, to facilitate molecular breeding and gene identification, we performed genome-wide association studies (GWAS) on 11 traits of flower and leaf. A total of 946,337 highly consistent SNP markers were obtained in the whole genome. Phylogenetic tree analysis and population structure analysis showed that the 143 germplasms can be divided into two groups. The linkage disequilibrium analysis showed that A. eriantha have a relatively fast attenuation rate, and that the average attenuation distance of LD was 0.1–0.3 Kb. The MLM (QK) model was determined as best for correlation analysis, and eight and three SNPs associated with flower- and leaf-related traits were identified, respectively, at 0.01 significance level. However, SNP markers associated with stamen number per flower, pollen viability, total chlorophyll content, and total flavonoid content were not identified at the 0.01 significant level, although it is worth noting that one, one, five, and two SNPs were identified to be associated with these traits at the 0.05 significant level. This study provides insights into the complex flower- and leaf-related biology, and identifies genes controlling important traits in A. eriantha through GWAS, which extends the genetic resources and basis for facilitating molecular breeding in kiwifruits. [ABSTRACT FROM AUTHOR]

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Background: NAC transcription factors (TFs) are plant-specific proteins encoded by a large gene family. They play important roles in diverse biological processes, such as plant growth and development, leaf senescence, and responses to biotic or abiotic stresses. Functions of a number of NAC TFs have been identified mainly in model plants. However, very few studies on NAC TFs have been conducted in the fruit tree of kiwifruit. Results: Genome-wide NAC genes were identified and their phylogeny, genomic structure, chromosomal location, synteny relationships, protein properties and conserved motifs were analyzed. In addition, the fruit developmental process was evaluated in a new kiwifruit cultivar of Actinidia eriantha 'Ganlu 1'. And expressions for all those NAC genes were analyzed by quantitative real-time PCR method in fruits of 'Ganlu 1' during its developmental process. Our research identified 142 NAC TFs which could be phylogenetically divided into 23 protein subfamilies. The genomic structures of those NAC genes indicated that their exons were between one and ten. Analysis of chromosomal locations suggested that 116 out of 142 NACs distributed on all the 29 kiwifruit chromosomes. In addition, genome-wide gene expression analysis showed that expressions of 125 out of 142 NAC genes could be detected in fruit samples. Conclusion: Our comprehensive study provides novel information on NAC genes and expression patterns in kiwifruit fruit. This research would be helpful for future functional identification of NAC genes involved in kiwifruit fruit development. [ABSTRACT FROM AUTHOR]

Actinidia eriantha Benth. is a diploid perennial woody vine native to China and is recognized as a valuable species for commercial kiwifruit improvement with high levels of ascorbic acid as well as having been used in traditional Chinese medicine. Due to the lack of genomic resources for the species, microsatellite markers for population genetics studies are scarce. In this study, RNASeq was conducted on fruit tissue of A. eriantha, yielding 5,678,129 reads with a total output of 3.41 Gb. De novo assembly yielded 69,783 non-redundant unigenes (41.3 Mb), of which 21,730 were annotated using protein databases. A total of 8,658 EST-SSR loci were identified in 7,495 unigene sequences, for which primer pairs were successfully designed for 3,842 loci (44.4%). Among these, 183 primer pairs were assayed for PCR amplification, yielding 69 with detectable polymorphism in A. eriantha. Additionally, 61 of the 69 polymorphic loci could be successfully amplified in at least one other Actinidia species. Of these, 14 polymorphic loci (mean NA = 6.07 ± 2.30) were randomly selected for assessing levels of genetic diversity and population structure within A. eriantha. Finally, a neighbor-joining tree and Bayesian clustering analysis showed distinct clustering into two groups (K = 2), agreeing with the geographical distributions of these populations. Overall, our results will facilitate further studies of genetic diversity within A. eriantha and will aid in discriminating outlier loci involved in local adaptation. [ABSTRACT FROM AUTHOR]

Kiwifruit has a high commercial value and is especially rich in vitamin C. Successful fruit set in kiwifruit depends on several reproductive processes including pollen germination and pollen tube growth. In this study, we investigated impacts of heat stress temperatures (27, 30, 33 and 36 °C) on pollen germination and pollen tube growth of 25 wild genotypes ofActinidia eriantha. Before heat stress application, pollens were stored at −20 °C for 6 months. The results showed great variation among genotypes in each treatment. Eight genotypes showed no significant change in the reduction of germination percentage. Some genotypes gave unsteady response in tube growth. MH22, MH30 and MH58 were evaluated as more tolerant genotypes. In contrast, MH48 and MH67 were the two most sensitive genotypes. The research of heat stress impact on pollen germination and pollen tube growth will be helpful for breeding new varieties and the identified tolerant genotypes can be used in future breeding programmes. [ABSTRACT FROM PUBLISHER]

In this research, eight kiwi fruit genotypes (six hardy kiwis ( Actinidia arguta and their hybrids), one of Actinidia deliciosa 'Hayward,' and one of Actinidia eriantha 'Bidan' were examined and compared by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), Fourier transform infrared (FT-IR) spectra, and nuclear magnetic resonance (NMR) spectroscopy. Proteins were extracted from lyophilized fruits, flesh with seeds, grinded seeds, and singular seeds and then separated by SDS-PAGE. Matrix similarity and dendrogram was generated using Nei coefficient and Unweighted Pair Group Method with Arithmetic mean (UPGMA) algorithm. Based on protein patterns, Actinidia species were clearly distinguishable, whereas differences between hardy kiwi fruit cultivars were minor or nondetectable. The electrophoretical separations were able to distinguish a half of hardy kiwi fruit cultivars, so cluster analysis revealed a limited number of cultivar groups. Intervarietal polymorphism was low and this affected the results of similarity analysis. One distinct cluster, composed of two pairs of cultivars and identical by protein patterns, was obtained. Cultivars 'Ananasnaya' and 'Weiki,' according to the morphological description, were similar. Oppositely, 'M' cultivar significantly differed from other hardy kiwi cultivars by densitometrical bands intensity. All examined singular seeds of 'Ananasnaya' cultivar possessed identical protein patterns. The protein patterns of 'Bingo' and 'Ananasnaya' hardy kiwi fruits harvested in 2011 and 2013 were identical. Three weeks storage after harvest did not affect the protein composition of these cultivars. FT-IR and NMR spectrum of hardy kiwi fruits were presented and compared with 'Hayward' and 'Bidan' and showed slight differences in comparison with the protein profiles. SDS-PAGE is more applicable than FT-IR and NMR for comparison of different kiwi fruit cultivars. The used analytical methods can be applied to any food analysis in order to distinguish the main compounds and to present fingerprints of different cultivars. [ABSTRACT FROM AUTHOR]

We report the release of a new, largefruited kiwifruit cultivar, 'White', selected from Actinidia eriantha. Fruit of 'White' had a mean fruit weight of 94 g, and a maximum fruit weight of 132 g at harvest in Zhejiang, China. The mean fruit weight is c. 2-4 times that of wild A. eriantha fruit found in Zhejiang and nearly 4 times that of 'Bidan', the only other registered A. eriantha cultivar. The fruit are oblong and the peelable skin is covered with dense white hair. The flesh of ripe fruit is green and has good eating quality but little juice. The soluble solids concentration was 14.7%, total sugar 9%, total acid 1.24%, and vitamin C 628.37 mg/100 g fresh weight. Its harvest season is during the last 10 days of October in the south of Zhejiang province, which is c. 2 weeks later than A. deliciosa 'Bruno' in the same area. It is sometimes referred to as the "banana kiwifruit" because the skin is easy to peel. This new cultivar has been registered in China (PVR No. CNA20050673.0). [ABSTRACT FROM AUTHOR]

The complete chloroplast (cp) genome sequence of Actinidia eriantha was sequenced and assembled using Illumina paired-end data. The cp genome from A. eriantha is 156,964 bp in length, composed of a pair of 23,892 bp inverted repeat regions (IR) separated by a large single copy region (LSC) of 88,639 bp and a small single copy region (SSC) of 20,541 bp. The cp genome contained 113 unique genes, including 79 protein-coding genes, 30 tRNA genes, and four ribosomal RNA genes. The phylogenetic position of A. eriantha based the cp genome data was sister to the group A. rufa, A. deliciosa, and A. chinensis. [ABSTRACT FROM AUTHOR]

Studies on organic acid metabolism have been mainly concentrated on the fruit, whereas, few have focused on the mechanism of high organic acids content in the fruit of Actinidia eriantha. Fruits of 'Ganmi 6' harvested at eleven developmental periods were used as materials. The components and content of organic acids were determined by high-performance liquid chromatography (HPLC) system, the activities of the related enzyme were detected, and gene expression levels were measured by quantitative real-time PCR (qRT-PCR). Components of ascorbic acid (AsA) and eight kinds of organic acids were detected. These results showed that quinic acid and citric acid were the main organic acids in the fruit of 'Ganmi 6'. Correlation analysis showed that NADP-Quinate dehydrogenase (NADP-QDH), NADP-Shikimate dehydrogenase (NADP-SDH), and Cyt-Aconitase (Cyt-Aco) may be involved in regulating organic acids biosynthesis. Meanwhile, the SDH gene may play an important role in regulating the accumulation of citric acid. In this study, the activities of NADP-SDH, Mit-Aconitase (Mit-Aco), and NAD-Isocitrate dehydrogenase (NAD-IDH) were regulated by their corresponding genes at the transcriptional level. The activity of Citrate synthase (CS) may be affected by post-translational modification. Our results provided new insight into the characteristics of organic acid metabolism in the fruit of A. eriantha. [ABSTRACT FROM AUTHOR]

Studies on anthocyanin biosynthesis have been mainly concentrated on the fruit, whereas few have focused the mechanism of flower coloration in kiwifruit. Here, we report that the structural gene, AeCHS, is involved in anthocyanin accumulation and indispensable for normal petal coloration in Actinidia eriantha. Petals from three different species including Actinidia eriantha (red petals), Actinidia hemsleyana (light pink petals) and Actinidia arguta (white petals) were selected for anthocyanin determination and gene expression analysis. The anthocyanin components in A. eriantha were significantly higher than in A. hemsleyana or A. arguta. Consistently, gene expression profiles suggested that AeCHS expression in A. eriantha was higher than in A. hemsleyana or A. arguta. Cluster analysis showed that AeCHS was clustered into a single group and distinctly separated from other genes, indicating the expression pattern of AeCHS gene was different from any other. Additionally, correlation analysis revealed AeCHS expression significantly correlated with anthocyanin content. The complete coding sequence of AeCHS was cloned from petals of A. eriantha 'Zaoxu', showing the length of AeCHS was 1170 bp encoding a protein of 389 amino acids. AeCHS was located in the cytoplasm, indicating it is indeed a structural gene involved in anthocyanin biosynthesis. AeCHS silencing performed by infiltration grafting-mediated virus-induced gene silencing (VIGS) reduced petal anthocyanin content and bleached red petals in A. eriantha. Our results confirm a crucial role of AeCHS in anthocyanin biosynthesis and accumulation in A. eriantha petals; furthermore, they offer important basic information and constitute a reference point for further research. [ABSTRACT FROM AUTHOR]

Background Kiwifruit (Actinidia spp.) is a dioecious plant with fruits containing abundant vitamin C and minerals. A handful of kiwifruit species have been domesticated, among which Actinidiaeriantha is increasingly favored in breeding owing to its superior commercial traits. Recently, elite cultivars from A. eriantha have been successfully selected and further studies on their biology and breeding potential require genomic information, which is currently unavailable. Findings We assembled a chromosome-scale genome sequence of A. eriantha cultivar White using single-molecular sequencing and chromatin interaction map–based scaffolding. The assembly has a total size of 690.6 megabases and an N50 of 21.7 megabases. Approximately 99% of the assembly were in 29 pseudomolecules corresponding to the 29 kiwifruit chromosomes. Forty-three percent of the A. eriantha genome are repetitive sequences, and the non-repetitive part encodes 42,988 protein-coding genes, of which 39,075 have homologues from other plant species or protein domains. The divergence time between A. eriantha and its close relative Actinidia chinensis is estimated to be 3.3 million years, and after diversification, 1,727 and 1,506 gene families are expanded and contracted in A. eriantha, respectively. Conclusions We provide a high-quality reference genome for kiwifruit A. eriantha. This chromosome-scale genome assembly is substantially better than 2 published kiwifruit assemblies from A. chinensis in terms of genome contiguity and completeness. The availability of the A. eriantha genome provides a valuable resource for facilitating kiwifruit breeding and studies of kiwifruit biology. [ABSTRACT FROM AUTHOR]