Chinensis Cv Research Articles

The involvement of the phenylpropanoid and jasmonate pathways in methyl jasmonate-induced soft rot resistance in kiwifruit (Actinidia chinensis).

Botryosphaeria dothidea is a major postharvest causal agent of soft rot in kiwifruit. Methyl jasmonate (MeJA) is an important plant hormone that participates as a plant defense against pathogens from a signal molecule. However, the impact and regulatory mechanism of MeJA on the attenuation of kiwifruit fungal decay remains unknown. This work investigated the effects of exogenous MeJA on the enzyme activity, metabolite content and gene expression of the phenylpropanoid and jasmonate pathways in kiwifruit. The results revealed that MeJA inhibited the expansion of B. dothidea lesion diameter in kiwifruit (Actinidia chinensis cv. 'Hongyang'), enhanced the activity of enzymes (phenylalanine ammonia lyase, cinnamate 4-hydroxylase, 4-coumarate: coenzyme A ligase, cinnamyl alcohol dehydrogenase, peroxidase and polyphenol oxidase), and upregulated the expression of related genes (AcPAL, AcC4H, Ac4CL, and AcCAD). The accumulation of metabolites (total phenolics, flavonoids, chlorogenic acid, caffeic acid and lignin) with inhibitory effects on pathogens was promoted. Moreover, MeJA enhanced the expression of AcLOX, AcAOS, AcAOC, AcOPR3, AcJAR1, AcCOI1 and AcMYC2 and reduced the expression of AcJAZ. These results suggest that MeJA could display a better performance in enhancing the resistance of disease in kiwifruit by regulating the phenylpropanoid pathway and jasmonate pathway.

Telomere-to-telomere and gap-free reference genome assembly of the kiwifruit Actinidia chinensis.

Kiwifruit is an economically and nutritionally important fruit crop with extremely high contents of vitamin C. However, the previously released versions of kiwifruit genomes all have a mass of unanchored or missing regions. Here, we report a highly continuous and completely gap-free reference genome of Actinidia chinensis cv. 'Hongyang', named Hongyang v4.0, which is the first to achieve two de novo haploid-resolved haplotypes, HY4P and HY4A. HY4P and HY4A have a total length of 606.1 and 599.6Mb, respectively, with almost the entire telomeres and centromeres assembled in each haplotype. In comparison with Hongyang v3.0, the integrity and contiguity of Hongyang v4.0 is markedly improved by filling all unclosed gaps and correcting some misoriented regions, resulting in ~38.6-39.5Mb extra sequences, which might affect 4263 and 4244 protein-coding genes in HY4P and HY4A, respectively. Furthermore, our gap-free genome assembly provides the first clue for inspecting the structure and function of centromeres. Globally, centromeric regions are characterized by higher-order repeats that mainly consist of a 153-bp conserved centromere-specific monomer (Ach-CEN153) with different copy numbers among chromosomes. Functional enrichment analysis of the genes located within centromeric regions demonstrates that chromosome centromeres may not only play physical roles for linking a pair of sister chromatids, but also have genetic features for participation in the regulation of cell division. The availability of the telomere-to-telomere and gap-free Hongyang v4.0 reference genome lays a solid foundation not only for illustrating genome structure and functional genomics studies but also for facilitating kiwifruit breeding and improvement.

A comparison of physicochemical and ripening characteristics of golden-fleshed ‘Haegeum' and green-fleshed ‘Hayward' kiwifruit during storage at 0 °C and ripening at 25 °C

Postharvest storage plays a key role in determining the marketability of kiwifruits. ‘Haegeum’ (Actinidia chinensis var. chinensis cv. ‘Haegeum’), a golden-fleshed kiwifruit, although gained popularity, knowledge of its postharvest qualities is limited. Here, we performed a comparative analysis of the physicochemical characteristics of golden-fleshed ‘Haegeum’ and green-fleshed ‘Hayward’ (A. chinensis var. deliciosa cv. ‘Hayward’) kiwifruit. The fruit were stored for 1, 2, or 3 months at 0 °C after harvest and subsequently transferred to a room at 25 °C for a week to induce ripening. ‘Haegeum’ had lower firmness (∼9 N lower) than ‘Hayward’ during cold storage, which was reversed during ripening, and both cultivars revealed the same firmness after a week of storage at 25 °C. ‘Haegeum’ had higher (>50 %) ascorbic acid content than ‘Hayward,’ which did not reveal significant change during the experimental period. During ripening, a spontaneous increase in respiration rate and ethylene production was observed. ‘Hayward’ had both earlier initiation and higher levels of ethylene production than ‘Haegeum’ after 2 months of storage at 0 °C followed by a week at 25 °C, which c°uld have increased the polygalacturonase expression leading to a faster softening of the fruit. Principal component analysis and heat-map of volatile compounds (VOCs) revealed distinctive changes in individual VOC profiles in both cultivars, suggesting that the VOCs in kiwifruit vary with cultivars. Based on the changes in the expression of genes related to ripening, we proposed a scheme to delineate the ripening process in kiwifruit. In conclusion, the study revealed that both cultivars have different ripening characteristics and can fetch wider marketability owing to better consumer preference. The findings also provided insights into the underlying mechanism of the ripening process in kiwifruit, which will eventually help understand and manage their postharvest qualities.

γ-Aminobutyric acid treatment induced chilling tolerance in postharvest kiwifruit (Actinidia chinensis cv. Hongyang) via regulating ascorbic acid metabolism

The effect of γ-Aminobutyric acid (GABA) treatment on ascorbic acid (AsA) metabolism and chilling injury in postharvest kiwifruit was studied. The results revealed that kiwifruit treated with GABA displayed higher chilling tolerance and better quality maintenance as compared to the controls. Higher AsA was observed in GABA-treated fruit which was beneficial to cell membrane protection and damage alleviation against chilling mediated oxidative stress. Gene expression analysis found the increased expression of AsA anabolic and regenerative genes and down-regulation of its catabolic genes together could contribute to the elevation of AsA levels in kiwifruit after GABA treatment. In addition, the transcripts of several candidate transcription factors such as bHLHs and HZ1 involved in AsA biosynthesis were also enhanced by GABA treatment. Collectively, our results indicated that GABA induced chilling tolerance in postharvest kiwifruit due to the higher AsA content by positively regulating ascorbate metabolic genes and candidate transcription factors.

Integrating untargeted metabolites and targeted analysis for discrimination of kiwifruits from different cultivars

To investigate the differences among kiwifruits from six different cultivars (Actinidia chinensis, Actinidia delicosa and Actinidia arguta), UPLC-QTOF-MS and UPLC-ESI-MS/MS coupled to multivariate statistical analysis were applied to untargeted metabolites and targeted analysis of kiwifruit samples for the first time. In untargeted analysis, the metabolome of kiwifruits was exhibited by principal component analysis (PCA), a total of 44 up-regulated feature compounds were screened based on the orthogonal partial least squares-discriminant analysis (OPLS-DA) and identified as glycosyl compounds, hydrocinnamic acids and various flavonoids. Furthermore, the contents of 27 targeted procyanidins, flavonoids and hydrocinnamic acids were analyzed by a UPLC-ESI-MS/MS method. It was indicated that phenol glycosides were much higher in A. arguta, responsible for the aroma of kiwifruits, various quercetin glycosides were higher in A. arguta, and much higher flavan-3-ols and hydrocinnamic acids were rich in A. Chinensis cv. Hongyang (red) kiwifruits. In addition, the results of chemometric analysis showed the untargeted metabolites and targeted compounds were responsible for the classification on the kiwifruits, which can benefit the scientific understanding of chemical diversity for kiwifruits, and improve the investigation of new wild kiwifruit cultivars, especially red kiwifruit and A. arguta.

Residue Analysis and the Effect of Preharvest Forchlorfenuron (CPPU) Application on On-Tree Quality Maintenance of Ripe Fruit in "Feizixiao" Litchi (Litchi chinensis Sonn.).

Litchi is a highly perishable fruit. Ripe litchi fruit loses quality quickly as they hang on tree, giving a very short hanging life and thus harvest period. This study attempted to explore the roles of cytokinin in regulating fruit ripening and senescence of litchi and examine the possibility of applying cytokinin in “on-tree storage” of the fruit. Exogenous cytokinin, forchlorfenuron (CPPU), was applied at 20 mg L−1 7 weeks after full bloom on litchi (Litchi chinensis cv. Feizixiao) fruit clusters. Color parameters, chlorophylls, anthocyanins, fruit and fruit part weights, total soluble solutes (TSSs), soluble sugars, organic acids, non-anthocyanin flavonoids, ethanol, and also CPPU residue in fruit were traced. CPPU residue was higher but decreased faster in the pericarp than in the aril, where it maintained < 10 μg kg−1. CPPU had no significant effect on fruit weight but tended to increase pericarp weight. The treatment suppressed chlorophyll loss and anthocyanin accumulation in the pericarp, increased non-anthocyanin flavonoids in the aril, but had no significant effects on non-anthocyanin flavonoids in the pericarp and total sugar and organic acids in the aril. As the commercially ripe fruit hanged on tree, TSSs, total sugar, and sucrose decreased with ethanol and acetic acid accumulation in the aril. CPPU significantly suppressed the loss of sucrose and total sugar and the accumulation of ethanol and acetic acid in the aril and inhibited malondialdehyde accumulation in the pericarp of the overripe fruit. Soluble invertase, alcohol dehydrogenase, and pyruvate decarboxylase (PDC) activity and gene expression in the aril were downregulated by CPPU. The results suggest that cytokinin partially suppresses the ripening process in litchi and is effective to slow quality loss in the overripe fruit on tree.

Comprehensive analysis of plastid gene expression during fruit development and ripening of kiwifruit.

Global survey of plastid gene expression during fruit ripening in kiwifruit provides cis-elements for the futureengineering ofthe plastid genome of kiwifruit. A limitation in the application of plastid biotechnology for molecular farming is the low-level expression of transgenes in non-green plastids compared with photosynthetically active chloroplasts. Unlike other fruits, not all chloroplasts are transformed into chromoplasts during ripening of red-fleshed kiwifruit (Actinidia chinensis cv. Hongyang) fruits, which may make kiwifruit an ideal horticultural plant for recombinant protein production by plastid engineering. To identify cis-elements potentially triggering high-level transgene expression in edible tissues of the 'Hongyang' kiwifruit, here we report a comprehensive analysis of kiwifruit plastid gene transcription in green leaves and fruits at three different developmental stages. While transcripts of a few photosynthesis-related genes and most genetic system genes were substantially upregulated in green fruits compared with leaves, nearly all plastid genes were significantly downregulated at the RNA level during fruit development. Expression of a few genes remained unchanged, including psbA, the gene encoding the D1 polypeptide of photosystem II. However, PsbA protein accumulation decreased continuously during chloroplast-to-chromoplast differentiation. Analysis of post-transcriptional steps in mRNA maturation, including intron splicing and RNA editing, revealed that splicing and editing may contribute to regulation ofplastid gene expression. Altogether, 40 RNA editing sites were verified, and 5 of them were newly discovered. Taken together, this study has generated a valuable resource for the analysis of plastid gene expression and provides cis-elements for future efforts to engineer the plastid genome of kiwifruit.

ABA-responsive transcription factor ABF1-1 promotes JA biosynthesis to accelerate suberin polyphenolic formation in wounded kiwifruit (Actinidia chinensis)

Mechanical damage is a central limiting factor in the maintenance of the postharvest fruit quality during harvest, transportation, and processing. In this study, wounded kiwifruit (Actinidia chinensis cv. Xuxiang) were respectively treated with abscisic acid (ABA), fluridone (FLD, an inhibitor of ABA biosynthesis), methyl jasmonate (MeJA), diethyldithiocarbamic acid (DIECA, an inhibitor of JA biosynthesis), and ABA+DIECA to investigate the potential interaction between ABA and JA in the process of wound healing. The results showed that blocking JA biosynthesis significantly reduced the positive effect of ABA on the accumulation of suberin polyphenolic (SPP). Besides, transiently overexpressed the AchLOX3 and AchOPR3 in tobacco (Nicotiana benthamiana) leaves confirmed that these two genes respectively encoded lipoxygenase and 12-oxo-phytodienoic acid reductase involved in JA biosynthesis. Notably, the positive regulation of transcription factor (TF) AchABF1-1 on AchLOX3 and AchOPR3 was identified. ABA-induced AchABF-1 located in the nucleus and activated the transcriptional expression of AchLOX3 and AchOPR3 through binding to their promoters. These results were further confirmed in the tobacco leaves overexpressing AchABF1-1 in which AchABF1-1 promoted NbLOX and NbOPR expression with the increases of JA content. In addition, exogenous ABA increased endogenous JA content, and enhanced LOX and OPR activities as well as their related gene expression, while FLD reduced these indices. These results suggested that the promotion effect of JA on the SPP accumulation was enhanced through the promotion of JA biosynthesis by ABA-responsive transcription factor AchABF1-1 during the wound healing process of kiwifruit.

Fermentation of kiwifruit juice from two cultivars by probiotic bacteria: Bioactive phenolics, antioxidant activities and flavor volatiles

Three commercial lactic acid bacteria (LAB), namely Lactobacillus acidophilus 85 (La85), Lactobacillus helveticus 76 (Lh76) and Lactobacillus plantarum 90 (Lp90), were employed to investigate the effects on the phenolic compounds, antioxidant capacities and flavor volatiles of kiwifruit juices prepared from two cultivars (Actinidia deliciosa cv. Xuxiang and Actinidia chinensis cv. Hongyang). Results showed that both kiwifruit juices were favorable matrices for LAB growth and the colony counts remained above 9.0 log CFU/mL after fermentation. Total phenolics and flavonoids in Xuxiang and Hongyang juices were increased dramatically by Lh76. Correspondingly, antioxidant capacities based on DPPH, ABTS and FRAP methods were improved significantly and positively correlated with protocatechuic acid and catechin contents (p < 0.05), two newly formed phytochemicals in fermented kiwifruit juices. Furthermore, results of hierarchical cluster analysis revealed that flavor profiles were improved significantly by LAB, and there were noticeable differences between fermented Xuxiang and Hongyang juices.

Agrobacterium rhizogenes-mediated hairy root transformation as an efficient system for gene function analysis in Litchi chinensis

BackgroundLitchi chinensis Sonn. is an economically important fruit tree in tropical and subtropical regions. However, litchi functional genomics is severely hindered due to its recalcitrance to regeneration and stable transformation. Agrobacterium rhizogenes-mediated hairy root transgenic system provide an alternative to study functional genomics in woody plants. However, the hairy root transgenic system has not been established in litchi.ResultsIn this study, we report a rapid and highly efficient A. rhizogenes-mediated co-transformation system in L. chinensis using Green Fluorescent Protein (GFP) gene as a marker. Both leaf discs and stem segments of L. chinensis cv. ‘Fenhongguiwei’ seedlings were able to induce transgenic hairy roots. The optimal procedure involved the use of stem segments as explants, infection by A. rhizogenes strain MSU440 at optical density (OD600) of 0.7 for 10 min and co-cultivation for 3 days, with a co-transformation efficiency of 9.33%. Furthermore, the hairy root transgenic system was successfully used to validate the function of the key anthocyanin regulatory gene LcMYB1 in litchi. Over-expression of LcMYB1 produced red hairy roots, which accumulated higher contents of anthocyanins, proanthocyanins, and flavonols. Additionally, the genes involving in the flavonoid pathway were strongly activated in the red hairy roots.ConclusionWe first established a rapid and efficient transformation system for the study of gene function in hairy roots of litchi using A. rhizogenes strain MSU440 by optimizing parameters. This hairy root transgenic system was effective for gene function analysis in litchi using the key anthocyanin regulator gene LcMYB1 as an example.

Integrative analyses of metabolome and genome-wide transcriptome reveal the regulatory network governing flavor formation in kiwifruit (Actinidia chinensis).

Soluble sugars, organic acids and volatiles are important components that determine unique fruit flavor and consumer preferences. However, the metabolic dynamics and underlying regulatory networks that modulate overall flavor formation during fruit development and ripening remain largely unknown for most fruit species. In this study, by integrating flavor-associated metabolism and transcriptome data from 12 fruit developmental and ripening stages of Actinidia chinensis cv Hongyang, we generated a global map of changes in the flavor-related metabolites throughout development and ripening of kiwifruit. Using this dataset, we constructed complex regulatory networks allowing to identify key structural genes and transcription factors that regulate the metabolism of soluble sugars, organic acids and important volatiles in kiwifruit. Moreover, our study revealed the regulatory mechanism involving key transcription factors regulating flavor metabolism. The modulation of flavor metabolism by the identified key transcription factors was confirmed in different kiwifruit species providing the proof of concept that our dataset provides a suitable tool for clarification of the regulatory factors controlling flavor biosynthetic pathways that have not been previously illuminated. Overall, in addition to providing new insight into the metabolic regulation of flavor during fruit development and ripening, the outcome of our study establishes a foundation for flavor improvement in kiwifruit.

The complete chloroplast genome of ‘Yulinglong’ (Narcissus tazetta var. chinensis) with double-petaled in southeast of China

In this study, the complete chloroplast (cp) genome of Narcissus tazetta var. chinensis cv ‘Yulinglong’ was sequenced and assembled by next-generation sequencing. The complete cp genome is 159,376 in length and contained 137 genes, consisting of 91 protein-coding genes, eight ribosomal RNA genes, and 38 transfer RNA genes. Phylogenetic analyses based on chloroplast genomes highly supported that ‘Yulinglong’ was evolutionarily close to Narcissus tazetta subsp.chinensis, which may provide more desirable information for the phylogenetic relationship between Narcissus tazetta var. chinensis and its relative species.

Prolonged sublethal effects of essential oils from non-wood parts of nine conifers on key insect pests and vectors

Conifers are of high economic importance due to their exploitation for timber, gardening and landscaping, construction and paper, varnishes, adhesives and waterproof coatings, perfumes and pharmaceuticals, bioplastics and biodiesel. They are endowed in all parts with secretory channels producing a semi-solid resin and a liquid fraction composed of a mixture of monoterpenes and sesquiterpenes, which are obtainable as a steam distillable essential oil. In most of industrial processes involving conifers, a huge biomass, made up mostly of green twigs, is produced, causing a waste disposal concern. The reuse of this material to produce essential oils may be important in a circular economy scenario. On this basis, in the present study we selected nine conifer species grown in central Italy (Abruzzo), namely Cupressus arizonica, x Cupressocyparis leylandii, Cupressus lusitanica, Juniperus chinensis cv. ‘stricta’, Juniperus communis, Juniperus × pfitzeriana, Picea abies, Pinus halepensis, and Pinus sylvestris, and evaluated the insecticidal potential of their essential oils from the non-wood renewable parts (twigs). For comparative purposes, in the case of J. communis two essential oils obtained from both male and female individuals were considered. The essential oils were obtained by hydrodistillation (yield in the range 0.3–2.0 %), and analyzed for chemical composition by gas chromatography-flame ionization detection (GC-FID) and gas chromatography-mass spectrometry (GC–MS), and for the enantiomeric distribution of the main optically active isomers by chiral chromatography. The essential oils were assessed for their insecticidal activity against three important insect species, i.e. the larvae of a moth pest, Spodoptera littoralis, the larvae of the mosquito vector Culex quinquefasciatus, and the adults of the housefly, Musca domestica. Pyrethrum extract was the positive control. The essential oils with the highest potential as insecticide were those obtained from twigs of x C. leylandii, P. abies and P. sylvestris. These oils were made up mainly of monoterpenes, with δ-3-carene (20.5 %), α-pinene (16.7 %), limonene (15.4 %) and sabinene (10.4 %); camphene (14.5 %) and limonene (13.4 %), bornyl acetate (15.6 %) and borneol (11.2 %); α-pinene (25.7 %), limonene (15.6 %) and δ-cadinene (11.4 %), as the main constituents, respectively. α-Pinene occurred in these oils mostly with the (+) enantiomeric form; limonene was present mainly as (-)-enantiomer in C. leylandii whereas in P. abies and P. sylvestris the (+)-enantiomer prevailed. Furthermore, being exposed to LD20-30/LC30 of these three essential oils significantly reduced the longevity, development and vitality of the target insects. Overall, our findings showed that the x C. leylandii, P. abies and P. sylvestris essential oil bioactivity fairly overpassed that of the large majority of essential oils considered in earlier studies, allowing us to successfully candidate these botanical byproducts for further insecticide formulations.

Genome-wide analysis of the bZIP gene family and the role of AchnABF1 from postharvest kiwifruit (Actinidia chinensis cv. Hongyang) in osmotic and freezing stress adaptations

Chilling injury (CI) is a barrier to the refrigeration of kiwifruit, resulting in decreased fruit quality and increased nutrient loss during storage. Understanding the molecular basis underlying the cold response and its regulation in refrigerated kiwifruit is therefore highly important. Basic (region) leucine zipper (bZIP) transcription factors (TFs) have been widely studied for their roles in abiotic stress resistance in various species. In this study, we identified 81 bZIP family proteins in kiwifruit and classified them into 11 groups. Further transcriptome analysis revealed that the expression of members of the AREB/ABF family was strongly induced by low temperature and abscisic acid (ABA). Ectopic expression of AchnABF1 enhanced plant cold tolerance by upregulating the expression of several key genes associated with ABA-dependent and ABA-independent pathways in Arabidopsis thaliana. Reactive oxygen species (ROS) metabolism was suggested to be involved in the AchnABF1-mediated osmotic stress response. For instance, enhanced ROS-scavenging ability was observed in transgenic plants with enhanced activity of catalase (CAT) and peroxidase (POD), which resulted in decreased in situ O2.− and H2O2 accumulation, ion leakage, and malondialdehyde (MDA) content under various abiotic stresses. In addition, AchnABF1 also participated in the osmotic stress response during both the germination and postgermination stages. We concluded that AchnABF1 may play an important role in kiwifruit during refrigeration.

Citral Delays Postharvest Senescence of Kiwifruit by Enhancing Antioxidant Capacity under Cold Storage

Citral is an aliphatic aldehyde extracted from citrus essential oil. The aim of the study was to examine how citral treatment affects the weight loss, firmness, respiration, and ripening index, as well as the antioxidant capacity of kiwifruit (Actinidia chinensis cv. ‘Jinkui’). The citral treatment was seen to reduce the weight loss, softening, and fruit respiration compared to control fruits. Citral treatment also had an inhibitory effect on ripening index, O2•− production rate, and malondialdehyde (MDA) accumulation. The degradations of ascorbic acid (AsA) content, total flavonoids content (TFC), and total phenolics content (TPC) were also suppressed by citral. In contrast, citral treatment induces the activation of antioxidant enzyme system such as superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT). Collectively, the results indicated that citral treatment delays postharvest senescence and prolongs storage life by enhancing antioxidant capacity in harvested kiwifruits. These findings suggest that citral has the potential to be used as a promising natural preservative for the extension of postharvest quality in harvested kiwifruit.

Anti-aging potential, anti-tyrosinase and antibacterial activities of extracts and compounds isolated from Rosa chinensis cv. ‘JinBian’

Rosa chinensis cv. ‘JinBian’, a cultivar of Rosa chinensis Jacq., is one of major raw material of rose tea and possesses sufficient plant resources in China. However, the studies on the chemical constituents and cosmetic activities of R. chinensis cv. ‘JinBian’ are almost blank. The main purpose of this study was to evaluate the anti-aging, skin-whitening, and antibacterial potentials of extracts and chemical constituents of the flower by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, elastase inhibition, anti-tyrosinase, and antibacterial assays. Bioassay results suggested both 95 % and 65 % ethanol extracts possessed significant antioxidant, elastase inhibition, and anti-tyrosinase activities. The combined active extract was studied with bioassay-guided fractionation to give a new compound, kaempferol 3-O-α-l-rhamnopyranosyl (1→6)-(2”,3”-O-digalloyl)-β-d-glucopyranoside (1) and fourteen known compounds (2–15). All compounds were firstly isolated from this species and subjected to the above mentioned bioassays. Ten compounds exhibited antioxidant activities with DPPH radical scavenging rate from 63.40 %–94.04 % under the concentration of 100 μg/mL. The antioxidant activities of 1, 2-phenylethyl 1-O-β-d-(6'-O-galloyl)-glucopyranoside (12), vomifoliol (14), and 4, 4'-dimethoxy-3'-hydroxy-7, 9': 7', 9-diepoxylignan-3-O-β-d-glucopyranoside (15) were firstly found with DPPH radical scavenging rate of 83.24 %, 91.10 %, 63.40 %, and 77.75 %, respectively. The moderate elastase inhibitory activities of 12, ethyl gallate (13), and 15 were firstly found with the inhibitory rate of 43.69 %, 43.25 %, and 35.34 % at the concentration of 100 μg/mL. Multiflorin B (3), 12, and 13 showed strong tyrosinase inhibitory activities with the inhibition rate at 43.83 %–55.80 %, comparing with the positive control, α-arbutin (22.15 %). In addition, 1 showed significant antibacterial activity against Staphylococcus aureus with the MIC50 of 8.51 ± 0.26 μg/mL. Compounds 2–4 and 12–14 showed moderate antibacterial activities against S. aureus. Compounds 6 and 13 also exhibited moderate inhibitory effects against Klebsiella pneumoniae. Above results manifested that R. chinensis cv. ‘JinBian’ possessed potential application values in the development of natural anti-aging, skin-whitening and antibacterial products.

Phenolic acid and flavonoid production in agar, agitated and bioreactor-grown microshoot cultures of Schisandra chinensis cv. Sadova No. 1 – a valuable medicinal plant

In vitro cultures and raw materials (fruits and leaves) of the valuable medicinal plant species – Schisandra chinensis cultivar Sadova No. 1 (SchS) – were evaluated for the production of two groups of phenolic compounds, phenolic acids and flavonoids, and their antioxidant potential. A series of experiments was conducted, aimed at optimizing culture conditions for maximum growth and phenolic production in SchS microshoots. Different concentrations of plant growth regulators (6-benzyladenine – BA and 1-naphthaleneacetic acid – NAA, from 0 to 3 mg/l) in Murashige-Skoog (MS) medium were tested in several cultivation systems (agar, agitated, bioreactor) over various growth periods (10, 20, 30, 40, 50 and 60 days). Furthermore, an elicitation experiment was conducted in which the bioreactor-grown microshoots were exposed to yeast extract. HPLC-DAD analyses confirmed the presence of eight phenolic acids – chlorogenic, cryptochlorogenic, gallic, neochlorogenic, protocatechuic, salicylic, syringic and vanillic, and two flavonoids: kaempferol and quercitrin, in the in vitro biomasses. The highest total phenolic acid (357.93 mg/100 g DW) and flavonoid (105.07 mg/100 g DW) contents were obtained in agar culture extracts cultivated for 30 days on MS medium containing 2 mg/l BA and 0.5 mg/l NAA and for 50 days on MS medium containing 0.1 mg/l BA and 2 mg/l NAA, respectively. These amounts were 1.59- and 5.95-fold lower than in parent plant leaf extracts (569.66 mg/100 g DW), and 4.30- and 1.25-fold higher than in fruit extracts (83.17 mg/100 g DW), respectively. Microshoots grown in a Plantform bioreactor also proved to be a good source of phenolic compounds, however, the elicitor treatment had no noticeable effect on their accumulation. Antioxidant capacity assessed by the Folin-Ciocalteu, FRAP, DPPH and CUPRAC assays revealed significantly higher potential in extracts from in vitro biomass and leaves of the parent plant, as compared to the parent plant fruit extracts.

Metabolomic and transcriptomic profiling of three types of litchi pericarps reveals that changes in the hormone balance constitute the molecular basis of the fruit cracking susceptibility of Litchi chinensis cv. Baitangying

Many Litchi chinensis cv. Baitangying orchards are suffering from a serious fruit cracking problem, but few studies have improved our understanding of the mechanism or the molecular basis of cracking susceptibility in 'Baitangying'. We conducted metabolome and transcriptome analyses of three types of litchi pericarps. To prevent passive progression after fruit cracking from affecting the results, we mainly focused on 11 metabolites and 101 genes that showed the same regulatory status and overlap in pairwise comparisons of cracking 'Baitangying' versus noncracking 'Baitangying' and noncracking 'Baitangying' versus noncracking 'Feizixiao'. Compared with the cracking-resistant cultivar 'Feizixiao', the 'Baitangying' pericarp has higher abscisic acid contents, and the presence of relevant metabolites and genes suggests increased biosynthesis of ethylene and jasmonic acid and decreased auxin and brassinosteroid biosynthesis. The fruit cracking-susceptible trait in 'Baitangying' might be associated with differences in the balance of these five types of hormones between the pericarp of this cultivar and that of 'Feizixiao'. Additionally, combined analyses showed a correspondence between the metabolite profiles and transcript patterns. qRT-PCR validation indicated the reliability of our high-throughput results. The acquired information might help in further studying the mechanisms that mediate fruit cracking susceptibility in 'Baitangying' and other litchi cultivars.

Physicochemical characteristics and antioxidant activities of non-starch polysaccharides from different kiwifruits

Non-starch polysaccharides are considered the main bioactive ingredients in kiwifruits. In order to well understand the chemical structures and antioxidant activities of non-starch polysaccharides from different varieties of kiwifruits (KPSs), the physicochemical characteristics and antioxidant activities of KPSs extracted by hot water extraction from Actinidia deliciosa cv. Hayward, A. chinensis cv. Hort16A, A. chinensis cv. Jinshi, A. chinensis cv. Hongshi, A. polygama, A. macrosperma, and A. arguta were investigated and compared. Results showed that extraction yields and contents of total uronic acids in KPSs ranged from 2.60% to 5.52%, and from 35.07% to 42.20%, respectively. Molecular weights and intrinsic viscosities of KPSs ranged from 1.405 × 105 to 1.620 × 106 Da, and from 0.34 dL/g to 1.24 dL/g, respectively. The dominant constituent monosaccharides of KPSs were galacturonic acid, arabinose, and galactose. Furthermore, KPSs from kiwifruits, especially KPSs extracted from A. arguta, exerted remarkable 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid and nitric oxide radical scavenging activities, which might be partially attributed to their high content of unmethylated galacturonic acids. Results are helpful for better understanding of the chemical structures and antioxidant activities of KPSs, and KPSs had potential to be further explored as natural antioxidants for the application in the functional food industry.

Molecular cloning and functional characterization of AcGST1, an anthocyanin-related glutathione S-transferase gene in kiwifruit (Actinidia chinensis).

AcGST1, an anthocyanin-related GST, may functions as a carrier to transport anthocyanins from ER to tonoplast in kiwifruit. It was positively regulated by AcMYBF110 through directly binding to its promoter. Anthocyanins are synthesized in the cytoplasmic surface of the endoplasmic reticulum but accumulate predominantly in the vacuole. Previous studies in model and ornamental plants have suggested that a member of the glutathione S-transferase (GST) gene family is involved in sequestration of anthocyanins into the vacuole. However, little is known about anthocyanin-related GST protein in kiwifruit. Here, four putative AcGSTs were identified from the genome of the red-fleshed Actinidia chinensis cv 'Hongyang'. Expression analyses reveal only the expression of AcGST1 was highly consistent with anthocyanin accumulation. Molecular complementation of Arabidopsis tt19 demonstrates AcGST1 can complement the anthocyanin-less phenotype of tt19. Transient expression in Actinidia arguta fruits further confirms that AcGST1 is functional in anthocyanin accumulation in kiwifruit. In vitro assays show the recombinant AcGST1 increases the water solubility of cyanidin-3-O-galactoside (C3Gal) and cyanidin-3-O-xylo-galactoside (C3XG). We further show that AcGST1 protein is localized not only in the ER but also on the tonoplast, indicating AcGST1 (like AtTT19) may functions as a carrier protein to transport anthocyanins to the tonoplast in kiwifruit. Moreover, the promoter of AcGST1 can be activated by AcMYBF110, based on results from transient dual-luciferase assays and yeast one-hybrid assays. EMSAs show that AcMYBF110 binds directly to CAGTTG and CCGTTG motifs in the AcGST1 promoter. These results indicate that AcMYBF110 plays an important role in transcriptional regulation of AcGST1 and, therefore, in controlling accumulation of anthocyanins in kiwifruit.