title: DkXTH8, a novel xyloglucan endotransglucosylase/hydrolase in persimmon, alters cell wall structure and promotes leaf senescence and fruit postharvest softening.
abstract: Fruit softening is mainly associated with cell wall structural modifications, and members of the xyloglucan endotransglucosylase/hydrolase (XTH) family are key enzymes involved in cleaving and re-joining xyloglucan in the cell wall. In this work, we isolated a new XTH gene, DkXTH8, from persimmon fruit. Transcriptional profiling revealed that DkXTH8 peaked during dramatic fruit softening, and expression of DkXTH8 was stimulated by propylene and abscisic acid but suppressed by gibberellic acid and 1-MCP. Transient expression assays in onion epidermal cells indicated direct localization of DkXTH8 to the cell wall via its signal peptide. When expressed in vitro, the recombinant DkXTH8 protein exhibited strict xyloglucan endotransglycosylase activity, whereas no xyloglucan endohydrolase activity was observed. Furthermore, overexpression of DkXTH8 resulted in increased leaf senescence coupled with higher electrolyte leakage in Arabidopsis and faster fruit ripening and softening rates in tomato. Most importantly, transgenic plants overexpressing DkXTH8 displayed more irregular and twisted cells due to cell wall restructuring, resulting in wider interstitial spaces with less compact cells. We suggest that DkXTH8 expression causes cells to be easily destroyed, increases membrane permeability and cell peroxidation, and accelerates leaf senescence and fruit softening in transgenic plants.
authors.affiliation: College of Horticulture, Northwest A&F University, Yangling, 712100, Shaanxi, China.
authors.forename: Ye
authors.initials: Y
authors.lastname: Han
authors.affiliation: College of Horticulture, Northwest A&F University, Yangling, 712100, Shaanxi, China.
authors.forename: Qiuyan
authors.initials: Q
authors.lastname: Ban
authors.affiliation: College of Horticulture, Northwest A&F University, Yangling, 712100, Shaanxi, China.
authors.forename: Hua
authors.initials: H
authors.lastname: Li
authors.affiliation: College of Horticulture, Northwest A&F University, Yangling, 712100, Shaanxi, China.
authors.forename: Yali
authors.initials: Y
authors.lastname: Hou
authors.affiliation: College of Horticulture, Northwest A&F University, Yangling, 712100, Shaanxi, China.
authors.forename: Mijing
authors.initials: M
authors.lastname: Jin
authors.affiliation: College of Horticulture, Northwest A&F University, Yangling, 712100, Shaanxi, China.
authors.forename: Shoukun
authors.initials: S
authors.lastname: Han
authors.affiliation: College of Horticulture, Northwest A&F University, Yangling, 712100, Shaanxi, China.
authors.forename: Jingping
authors.initials: J
authors.lastname: Rao
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology; D000475:Alkenes / Q000494:pharmacology; D002473:Cell Wall / Q000737:chemistry* / Q000201:enzymology; D003001:Cloning, Molecular; D003521:Cyclopropanes / Q000494:pharmacology; D029788:Diospyros / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D005638:Fruit / Q000502:physiology; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D005875:Gibberellins / Q000494:pharmacology; D016695:Glycosyltransferases / Q000235:genetics* / Q000378:metabolism*; D018515:Plant Leaves / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D000475:Alkenes; D003521:Cyclopropanes; D005875:Gibberellins; D010940:Plant Proteins; D000040:Abscisic Acid; C013658:propylene; C007842:gibberellic acid; D016695:Glycosyltransferases; C473049:xyloglucan - xyloglucosyltransferase; C412563:1-methylcyclopropene