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Suberin consisting of the polyaliphatic and polyphenolic domain confers the hydrophobic barrier of wound fruit and vegetables, providing essential protection from excessive water loss, ion outflow and pathogen invasion. The ω-hydroxyacid/fatty alcohol hydroxycinnamoyl transferase (FHT) is required for cross-linking of the polyaliphatic and polyphenolic domain in suberin biosynthesis. The transcription factor AchMYC2 acts as a positive activator in suberin biosynthesis but it is not known how it interacts with AchFHT in kiwifruit. In this study, overexpression of AchFHT in kiwifruit increased accumulation of suberin monomers, such as ferulate and ω-hydroxyacids. Yeast one-hybrid (Y1H) and dual-luciferase reporter (DLR) assays showed that AchMYC2 activated AchFHT transcript via interacting with the gene promoter. Overexpression of AchMYC2 in kiwifruit resulted in the upregulation of AchFHT , the accumulation of FHT protein and suberin monomers. Further, using yeast two-hybrid (Y2H) assay screened a jasmonate ZIM-domain protein (AchJAZ1, a key repressor of JA signaling pathway) which interacted with AchMYC2. Methyl jasmonate (MeJA) treatment increased expression levels of AchMYC2 and AchFHT , and the content of FHT protein, accompanying by the rapid wound healing process, as indicated by rapid suberin deposition, the reduced weight loss and relative electrolyte leakage. These results indicate that AchMYC2 activates AchFHT transcript to involve in MeJA-mediated suberin biosynthesis in wound healing of kiwifruit. • Methyl jasmonate (MeJA) accelerated suberin deposition in wound healing of kiwifruit. • MeJA stimulated expression levels of AchFHT and AchMYC2 and increased FHT content. • AchMYC2 activated AchFHT transcript by interacting with the gene promoter. [ABSTRACT FROM AUTHOR]

• Abscisic acid (ABA) application accelerated wound healing of Chinese yam tubers. • ABA raised the contents of suberin polyphenolics (SPP), lignin and total phenols. • ABA raised gene expressions, contents and activities of enzymes in SPP formation. Water loss, nutrient elution and pathogen attacks caused by mechanical wounding are the primary sources of postharvest loss of fruit and vegetables. Continuously increasing information has unraveled that abscisic acid (ABA) can accelerate wound healing of fruit and vegetables via stimulating suberin polyphenolics (SPP) biosynthesis, whereas the effect of ABA in wound healing of Chinese yam tubers remains unclear. The treatment of ABA and fluridone (FLD, an inhibitor of ABA biosynthesis) on postharvest wound healing of yam tubers was investigated in this study. The results showed that ABA treatment facilitated wound healing process of yam tubers, representing by the reduced weight loss and relative electrolyte leakage (REL). ABA enhanced the expression levels of phenylalanine ammonialyase (PAL), cinnamic acid 4-hydroxylase (C4H) and 4-coumarate-CoA ligase (4CL), as well as the corresponding enzyme contents and activities. Correspondingly, the contents of major monomers such as ferulic acid, caffeic acid and p -coumaric acid also increased. Simultaneously, ABA could improve the expression of peroxidase (POD), the enzyme content and activity, as well as hydrogen peroxide (H 2 O 2) production, which might contribute to the polymerization of SPP and lignin. Inversely, inhibition of ABA production by FLD application displayed an opposite effect to ABA treatment. These results demonstrate that application of ABA stimulated wound healing of Chinese yam tubers via improving the gene expressions of relevant enzymes, their contents and activities, so that maintain high quality of postharvest yam tubers. [ABSTRACT FROM AUTHOR]

Suberin polyaliphatics (SPA) is an important component of suberin, which plays a pivotal role in controlling water loss and solute fluxes during wound healing of fruit and vegetables. The objective of this study was to investigate the effect of exogenous methyl jasmonate (MeJA) on wound-induced SPA deposition in Chinese yam tubers. The results exhibited that MeJA treatment accelerated the deposition of SPA and the wound healing process. The gene expressions of β-ketoacyl-CoA synthases (DoKCS2 , DoKCS6), CYP86 subfamily of cytochrome P450 monooxygenases (DoCYP86A1 , DoCYP86B1) and Glycerol-3-phosphate acyltransferases (DoGPAT5 , DoGPAT7) and their corresponding protein content (i.e. KCS, CYP, GPAT) associated with SPA monomer biosynthesis were notably increased by MeJA application. Meanwhile, MeJA also enhanced gene expressions of ATP-binding cassette transporter subfamily G proteins (DoABCG2 , DoABCG6) and GDSL-type esterase/lipases (DoGELP38 , DoGELP51 , DoGELP96) and increased ABCG content, which might participate in the trafficking and polymerization of SPA monomer. Noteworthily, application of diethyldithiocarbamic acid (DICA), an inhibitor of jasmonic acid (JA) synthesis, showed an opposite effect to MeJA treatment. These results suggest that MeJA could promote SPA deposition by positively regulating relevant gene expression and corresponding protein content, thereby accelerating wound healing of Chinese yam tubers. • Methyl jasmonate (MeJA) could accelerate wound healing of yam tubers. • MeJA reduced weight loss and relative electrolyte leakage of wound yam tubers. • MeJA improved SPA deposition by increasing gene expressions and enzyme contents. [ABSTRACT FROM AUTHOR]

Suberin is a cell-wall biopolymer with aliphatic and aromatic domains that is synthesized in the wound tissues of plants in order to restrict water loss and pathogen infection. ω-hydroxyacid/fatty alcohol hydroxycinnamoyl transferase (FHT) is required for cross-linking of the aliphatic and aromatic domains. ABA is known to play a positive role in suberin biosynthesis but it is not known how it interacts with FHT. In this study, the kiwifruit (Actinidia chinensis) AchnFHT gene was isolated and was found to be localized in the cytosol. Transient overexpression of AchnFHT in leaves of Nicotiana benthamiana induced massive production of ferulate, ω-hydroxyacids, and primary alcohols, consistent with the in vitro ability of AchnFHT to catalyse acyl-transfer from feruloyl-CoA to ω-hydroxypalmitic acid and 1-tetradecanol. A regulatory function of four TFs (AchnABF2, AchnMYB4, AchnMYB41, and AchnMYB107) on AchnFHT was identified. These TFs localized in the nucleus and directly interacted with the AchnFHT promoter in yeast one-hybrid assays. Dual-luciferase analysis indicated that AchnABF2, AchnMYB41, and AchnMYB107 activated the AchnFHT promoter while AchnMYB4 repressed it. These findings were supported by the results of transient overexpression in N. benthamiana , in which AchnABF2 , AchnMYB41 , and AchnMYB107 induced expression of suberin biosynthesis genes (including FHT) and accumulation of suberin monomers, whilst AchnMYB4 had the opposite effect. Exogenous ABA induced the expression of AchnABF2 , AchnMYB41 , AchnMYB107 , and AchnFHT and induced suberin monomer formation, but it inhibited AchnMYB4 expression. In addition, fluridone (an inhibitor of ABA biosynthesis) was found to counter the inductive effects of ABA. Activation of suberin monomer biosynthesis by AchnFHT was therefore controlled in a coordinated way by both repression of AchnMYB4 and promotion of AchnABF2, AchnMYB41, and AchnMYB107. [ABSTRACT FROM AUTHOR]

Abstract: BACKGROUND: Rapid wound healing would be critical for successful long‐term storage of fruits and vegetables. However, there was no direct evidence for the requirement and efficiency of oxygen in the fruit wound‐healing process. This study was conducted to investigate the role of oxygen in wound‐induced suberization by analyzing melanin, suberin polyphenolics (SPPs) and related enzymes in half‐cut kiwifruits exposed to 100%, 50%, 21% and 0% oxygen. RESULTS: By 3 days after wounding, the wound surface of kiwifruit in high (50 and 100%) oxygen appeared as a continuous layer of melanin and SPPs underneath, which effectively prevent excessive water vapor loss from the fruit halves. In contrast, melanin and SPPs deposition in the wound surface in 0% oxygen was significantly reduced, with high water vapor loss. Rapid decrease of soluble phenolic acids (caffeic, p‐coumaric, ferulic acids) was coupled with the increase of bound ferulic acid (coniferyl diacetate) especially in high oxygen by 9 days after wounding. Meanwhile, high oxygen enhanced peroxidase, catalase, phenylalanine ammonia‐lyase, and polyphenol oxidase activities. CONCLUSION: Oxygen is required for wound‐induced melanin and SPPs formation, and high oxygen is effective in promoting wound suberization in postharvest kiwifruit. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

• Methyl jasmonate (MeJA) reduced weight loss of wound yam tubers. • MeJA promoted the biosynthesis and polymerization of suberin polyphenolic monomers. • MeJA activated phenylpropanoid metabolism, peroxidase activity and H 2 O 2 production. Suberin is a cell wall-associated heteropolymer composed of suberin polyaliphatics (SPA) and suberin polyphenolics (SPP), which confers a hydrophobic barrier to plants against dehydration and pathogen invasion. Jasmonic acid (JA) plays a positive role in wound-induced SPP deposition in kiwifruit and potato tubers, but the mechanism underlying the regulation of JA on wound healing of Chinese yam tubers remains unknown. In this study, the biochemical and physiological responses to methyl jasmonate (MeJA) and diethyldithiocarbamic acid (DIECA, an inhibitor of JA biosynthesis) treatments in wound yam tubers were investigated. The results showed that exogenous MeJA promoted the production of endogenous JA with increased gene expressions of lipoxygenase (LOX) and 12-oxo-phytodienoic acid reductase (OPR) in wound tubers. The activities and gene expressions of phenylalanine ammonialyase (PAL), cinnamic acid 4-hydroxylase (C4H) and 4-coumarate-CoA ligase (4CL) in wound tubers were pronouncedly enhanced by MeJA, along with increase of SPP monomers, especially, hydroxycinnamic acids (HAs). Meanwhile, MeJA increased the activities and gene expressions of peroxidase (POD), NADPH oxidase (NOX), polyamine oxidase (PAO), and the generation of hydrogen peroxide (H 2 O 2), which were likely to be involved in the polymerization of SPP monomers resulting in SPP deposition. Conversely, inhibition of JA biosynthesis by DIECA reversed the positive impact of MeJA on wound healing process. The results indicate that rapid wound healing in Chinese yam tubers could be induced by MeJA via stimulating phenylpropanoid metabolism, POD activity and H 2 O 2 generation involved in SPP deposition. [ABSTRACT FROM AUTHOR]

• AchLOX3 and AchOPR3 were involved in JA biosynthesis of kiwifruit. • ABA-induced AchABF1-1 was a nucleus-localized transcription factor. • AchABF1-1 activated AchLOX3 and AchOPR3 expression by binding to their promoters. • ABA promoted SPP formation by the induction of JA biosynthesis. 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. [ABSTRACT FROM AUTHOR]

Quick suberin-based healing after wounding played a protective role for plant to prevent further damage. In this study, the stimulative effect of exogenous abscisic acid (ABA) on wound suberization in postharvest kiwifruit was evaluated through suberin staining with toluidine blue O as well as the determination of suberin phenolics and aliphatics in wound tissue. Furthermore, to reveal the regulatory involvement of ABA in wound suberization, comparative quantitative proteomics and transcriptomics analyses based on iTRAQ and qRT-PCR technique were performed. In proteomics levels, a total of 95 protein species consistently showed differential abundance between ABA and control, including 29 down-regulated and 66 up-regulated protein species. The Kyoto Encyclopedia of Genes and Genomes (KEGG) with protein-protein interaction analyses revealed that ABA mainly affected the antioxidant system, phenylpropanoid metabolism and lipid metabolism associated with wound suberization. Based on the data of proteomics analysis, the differential expressions of genes encoding 11 selected protein species were confirmed by qRT-PCR analyses. GSH-Px, MDHAR, SOD, APX, POD, PAL, CCR, PPO, CYP86B1, DGGT and KCS11 were likely to be the key enzymes that involved the response of ABA to stimulate wound suberization by mediating the antioxidant system, phenylpropanoid metabolism and lipid metabolism. Biological significance Kiwifruit is susceptible to physical injury causing postharvest deterioration during harvest, transportation and storage. Therefore, quick healing is important for maintaining the postharvest quality of injured fruit. This work elucidated the potential role of ABA and the proteomic mechanism of its regulation in wound suberization of postharvest kiwifruit. [ABSTRACT FROM AUTHOR]

Suberin polyphenolic (SPP), a kind of agronomically significant biopolymer, is composed primarily of phenolic acids generally synthesized by phenylpropanoid metabolism. In this study, the transcriptional activation of suberin polyphenolic biosynthesis by jasmonic acid (JA) inducible-transcription factor AchMYC2 was confirmed in wound tissues of kiwifruit (Actinidia chinensis). Three general phenylpropanoid metabolism-related genes, AchPAL , AchC4H and Ach4CL respectively encoding phenylalanine ammonia-lyase (PAL), cinnamic acid-4-hydroxylase (C4H) and 4-coumaric-CoA ligase were determined in the kiwifruit core tissues overexpressing these genes. Besides, the positive regulation of AchMYC2 on AchPAL , AchC4H and Ach4CL was observed. JA-induced AchMYC2 locating in the nucleus activated the transcriptional expression of AchPAL , AchC4H and Ach4CL through binding to their promoters. The results were further evidenced in the kiwifruit core tissues overexpressing of AchMYC2, in which AchMYC2 enhanced the expression levels of AchPAL , AchC4H and Ach4CL and increased the accumulation of phenolic acids including cinnamic acid, p -coumaric acid, caffeic acid, ferulic acid and sinapic acid. Meanwhile, the contents of five phenolic acids in the kiwifruit wound tissues were increased by methyl jasmonate (MeJA), but reduced by diethyldithiocarbamic acid (DIECA, an inhibitor of JA biosynthesis). Together results indicated that AchMYC2 activated AchPAL , AchC4H and Ach4CL transcription to promote JA-mediated suberin polyphenolic accumulation in the wound healing of kiwifruit. • AchPAL, AchC4H, and Ach4CL involved in suberin polyphenolic precursors synthesis. • MeJA-induced AchMYC2 was a nucleus-localized transcription factor. • AcnMYC2 activates AchPAL, AchC4H, and Ach4CL expression by binding to their promoters. • AchMYC2 promotes JA-mediated suberin polyphenolic accumulation of wounded kiwifruit. [ABSTRACT FROM AUTHOR]