Restricted responses of AcMYB68 and AcERF74/75 enhanced waterlogging tolerance in kiwifruit.

Most of kiwifruit cultivars (e.g. Actinidia chinensis cv. Donghong, "DH") were sensitive to waterlogging, thus, waterlogging resistant rootstocks (e.g. Actinidia valvata Dunn, "Dunn") were widely used for kiwifruit industry. Those different species provided ideal materials to understand the waterlogging responses in kiwifruit. Compared to the weaken growth and root activities in "DH", "Dunn" maintained the relative high root activities under the prolonged waterlogging. Based on comparative analysis, transcript levels of pyruvate decarboxylase (PDCs) and alcohol dehydrogenase (ADHs) showed significantly difference between these two species. Both PDCs and ADHs had been significantly increased by waterlogging in "DH", while they were only limitedly triggered by 2 days stress and subsided during the prolonged waterlogging in "Dunn". Thus, 19 differentially expressed transcript factors (DETFs) had been isolated using weighted gene co-expression network analysis combined with transcriptomics and transcript levels of PDCs and ADHs in waterlogged "DH". Among these DETFs, dual luciferase and electrophoretic mobility shift assays indicated AcMYB68 could bind to and trigger the activity of AcPDC2 promoter. The stable over-expression of AcMYB68 significantly up-regulated the transcript levels of PDCs but inhibited the plant growth, especially the roots. Moreover, the enzyme activities of PDC in 35S::AcMYB68 were significantly enhanced during the waterlogging response than that in wild type plants. Most interestingly, comparative analysis indicated that the expression patterns of AcMYB68 and the previously characterized AcERF74/75 (the direct regulator on ADHs) either showed no responses (AcMYB68 and AcERF74) or very limited response (AcERF75) in "Dunn". Taken together, the restricted responses of AcMYB68 and AcERF74/75 in "Dunn" endow its waterlogging tolerance.

Full-Length Transcriptome and RNA-Seq Analyses Reveal the Mechanisms Underlying Waterlogging Tolerance in Kiwifruit (Actinidia valvata).

Actinidia valvata possesses waterlogging tolerance; however, the mechanisms underlying this trait are poorly characterized. Here, we performed a transcriptome analysis by combining single-molecule real-time (SMRT) sequencing and Illumina RNA sequencing and investigated the physiological responses of the roots of KR5 (A. valvata, a tolerant genotype) after 0, 12, 24 and 72 h of waterlogging stress. KR5 roots responded to waterlogging stress mainly via carbohydrate and free amino acids metabolism and reactive oxygen species (ROS) scavenging pathways. Trehalose-6-phosphate synthase (TPS) activity, alcohol dehydrogenase (ADH) activity and the total free amino acid content increased significantly under waterlogging stress. The nicotinamide adenine dinucleotide-dependent glutamate synthase/alanine aminotransferase (NADH-GOGAT/AlaAT) cycle was correlated with alanine accumulation. Levels of genes encoding peroxidase (POD) and catalase (CAT) decreased and enzyme activity increased under waterlogging stress. Members of the LATERAL ORGAN BOUNDARIES (LOB), AP2/ERF-ERF, Trihelix and C3H transcription factor families were identified as potential regulators of the transcriptional response. Several hub genes were identified as key factors in the response to waterlogging stress by a weighted gene co-expression network analysis (WGCNA). Our results provide insights into the factors contributing to waterlogging tolerance in kiwifruit, providing a basis for further studies of interspecific differences in an important plant trait and for molecular breeding.

High-Quality Assembly and Comparative Analysis of Actinidia latifolia and A. valvata Mitogenomes.

Kiwifruit (Actinidia) has been recently domesticated as a horticultural crop with remarkably economic and nutritional value. In this study, by combining sequence datasets from Oxford Nanopore long-reads and Illumina short-reads, we de novo assembled two mitogenomes of Actinidia latifolia and A. valvata, respectively. The results indicated that the A. latifolia mitogenome has a single, circular, 825,163 bp molecule while the A. valvata mitogenome possesses two distinct circular molecules, 781,709 and 301,558 bp, respectively. We characterized the genome structure, repeated sequences, DNA transfers, and dN/dS selections. The phylogenetic analyses showed that A. valvata and A. arguta, or A. latifolia and A. eriantha, were clustered together, respectively. This study provides valuable sequence resources for evolutionary study and molecular breeding in kiwifruit.

Physiological Responses of Two Contrasting Kiwifruit (Actinidia spp.) Rootstocks against Waterlogging Stress.

Rootstocks from Actinidia valvata are much more tolerant to waterlogging stress than those from Actinidia deliciosa, which are commonly used in kiwifruit production. To date, the tolerance mechanism of A. valvata rootstocks' adaptation to waterlogging stress has not been well explored. In this study, the responses of KR5 (A. valvata) and 'Hayward' (A. deliciosa) to waterlogging stress were compared. Results showed that KR5 plants performed much better than 'Hayward' during waterlogging by exhibiting higher net photosynthetic rates in leaves, more rapid formation of adventitious roots at the base of stems, and less severe damage to the main root system. In addition to morphological adaptations, metabolic responses of roots including sufficient sucrose reserves, modulated adjustment of fermentative enzymes, avoidance of excess lactic acid and ethanol accumulation, and promoted accumulation of total amino acids all possibly rendered KR5 plants more tolerant to waterlogging stress compared to 'Hayward' plants. Lysine contents of roots under waterlogging stress were increased in 'Hayward' and decreased in KR5 compared with their corresponding controls. Overall, our results revealed the morphological and metabolic adaptations of two kiwifruit rootstocks to waterlogging stress, which may be responsible for their genotypic difference in waterlogging tolerance.

The complete chloroplast genome sequence of actinidia valvata.

In this study, we first presented the complete chloroplast genome of Actinidia valvata by using Illumina Novaseq sequencing. Its complete chloroplast genome is 156,596 bp in length, containing a large single copy region of 88,477 bp and a small single copy region of 20,379 bp separated by a pair of inverted repeat regions of 23,870 bp. The chloroplast genome contains 112 unique genes, including 78 protein-coding genes, 30 tRNA, and four rRNA genes. Phylogenetic analysis based on chloroplast genome sequences of ten plants from the family Actinidiaceae showed that A. valvata is more closely related to A. polygama than other members.

Dynamic changes of flavonoids in Actinidia valvata leaves at different growing stages measured by HPLC-MS/MS.

Flavonoids are a large group of phenolic secondary metabolites havinga wide range of biochemical and pharmacological effects. Quantitative analysis of flavonoid profiles in the genus Actinidia, which has not been intensively conducted, is useful to a better understanding of the pattern and distribution of flavonoids. In the present work, a liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) method was developed to profile the flavonoids, which was then used to determine the dynamic change of 17 biologically active flavonoids in the leaves of Actinidia valvata at the main growing stages, including glucuronides and acylated di- and triglycosides of flavonoids. The contents of flavonoid triglycosides were significantly higher than other flavonoids. The highest concentrations of kaemperol glycosides were observed in June, while other flavonoids showed highest concentrations in October. On the other hand, the contents of four isorhamnetin glycosides were increased sharply in September to October. The flavonoid profiles seem to be related to temperature, UV-B, and water deficit. Further studies are required to examine the functions of flavonoids in the Actinidia valvata and the underlying molecular mechanisms of actions.

Analysis of volatile components from Actinidia valvata by HS-GC-MS based on retention index / 药学实践杂志

Objective To establish a method for determining volatile components from Actinidia valvata Dunn .Methods A static headspace‐gas chromatography‐mass spectrometry (HS‐GC‐MS) method was used to analyze volatile components , and the separated peaks were identified by mass spectal library searching combined with retention index comparison .Results 42 volatile components were separated from Actinidia valvata Dunn and 25 of them were identified ,mainly including alcohols ,es‐ters ,aldehydes ,hydrocarbons and so on .Conclusion Combined with retention index calculation ,this method improved accuracy of qualitation of HS‐GC‐MS and provided scientific proof for the exploitation and utilization of Actinidia valvata Dunn .

Dynamic changes of flavonoids in Actinidia valvata leaves at different growing stages measured by HPLC-MS/MS / 中国天然药物

Flavonoids are a large group of phenolic secondary metabolites havinga wide range of biochemical and pharmacological effects. Quantitative analysis of flavonoid profiles in the genus Actinidia, which has not been intensively conducted, is useful to a better understanding of the pattern and distribution of flavonoids. In the present work, a liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) method was developed to profile the flavonoids, which was then used to determine the dynamic change of 17 biologically active flavonoids in the leaves of Actinidia valvata at the main growing stages, including glucuronides and acylated di- and triglycosides of flavonoids. The contents of flavonoid triglycosides were significantly higher than other flavonoids. The highest concentrations of kaemperol glycosides were observed in June, while other flavonoids showed highest concentrations in October. On the other hand, the contents of four isorhamnetin glycosides were increased sharply in September to October. The flavonoid profiles seem to be related to temperature, UV-B, and water deficit. Further studies are required to examine the functions of flavonoids in the Actinidia valvata and the underlying molecular mechanisms of actions.

Determination of asiatic acid in the root of Actinidia valvata by HPLC / 药学实践杂志

Objective To establish a method for the determination of asiatic acid in the root of Actinidia valvata . Methods HPLC-VWD was used in the analysis .The column was Agilent HC-C18 (4 .6 mm × 250 mm ,5μm);the mobile phase was acetonitrile :(30 mmol/L) acetic acid amine solution (35:65);the flow rate was 1 .0 ml/min;the temperature of column was 25 ℃ ;the detection wavelength was set at 210 nm ;the injection volume was 25 μl;the running time was 35 min .Results <br> Asiatic acid was separated with interference in baseline .The linear range was 25 .30-506 .0 μg/ml with linear correlation of 0 .999 6 for asiatic acid .The result of intra-day and inter-day precisions were both within 5% (n=3) ,and the average recovery was 99.4% with RSD 1 .9% (n=6) .Conclusion The method was simple ,rapid ,accurate and convenient for quality control of asiatic acid in the root of Actinidia valvata .

Anti-tumor constituents from the roots of Actinidia valvata / 第二军医大学学报

Objective: To study the anti-tumor constituents from the roots of Actinidia valvata Dunn. Methods: Column chromatographic techniques were used to isolate and purify the chemical constituents of the plant and their structures were elucidated by spectroscopic analysis, including 1HNMR, 13CNMR and MS. The cytotoxic activities of some individual compounds were examined by MTT assay. Results: Ten triterpenoids: 2α, 3α, 24-trihydroxyurs-12-en-28-oic acid(1), asiatic acid(2), corosolic acid(3), 2α, 3α, 23, 24-tetrahydroxyurs-12-en-28-oic acid(4), 2α, 3α, 13β, 24-tetrahydroxyurs-11-en-28-oic acid-13-lactone(5), 2α, 3α, 24-trihydroxyolean-12-en-28-oic acid(6), 2α, 3α, 19α, 24-tetrahydroxyurs-12-en-28-oic acid(7), 2α, 3α, 24-trihydroxyurs-12, 20(30)-dien-28-oic acid(8), 2α, 3β, 24-trihydroxyurs-12-en-28-oic acid(9), and oleanolic acid (10), and one plant sterol β-citosterol(11) were isolated from the CHCl3 fraction of the roots of Actinidia valvata Dunn. The cytotoxic activities of five compounds (1, 2, 3, 4, and 7) against A549, LOVO and HepG2 cell lines were evaluated. Conclusion: Compounds 3-8 are isolated from this plant for the first time. Compounds 2 and 3 possess cytotoxic activity against LOVO and HepG2 cell lines, and the cytotoxic activity decreases with the increase of polarity of individual compound.

A comparison between the root and stalk of Actinidia valvata / 第二军医大学学报

Objective: To make a comparative study on the root and stalk of Actinidia valvata, so as to lay a ground for expanding medicinal part of Actinidia valvata. Methods: A comparative study was made between the root and stalk of Actinidia valvata on the following aspects: macroscopical properties, physical and chemical properties, contents of active constituents, and pharmacological actions. Results: The root and stalk of Actinidia valvata both showed positive reaction for alkaloids and saponin, and both had 280 nm absorption peak in UV-Vis spectrum. The aqueous extraction yield of the root and stalk were 5.35% and 5.68%, respectively; the contents of dihydrodehydrodiconiferyl alcohol were 0.005 01% and 0.006 41%, respectively. The IC50 of root and stalk extracts against HL60 were 62.39 mg and 75.51 mg, respectively; and against K562 were 70.47 mg and 77.46 mg, respectively. Their extracts had similar scavenging activity for free radicals and reductive effect; neither of them had analgesia actions. Conclusion: The root and stalk of Actinidia valvata have similar physical and chemical properties, contents of active constituents and pharmacological actions, suggesting that it is highly possible to substitute the root of Actinidia valvata with stalk for medicinal usage.