title: XND1, a member of the NAC domain family in Arabidopsis thaliana, negatively regulates lignocellulose synthesis and programmed cell death in xylem.
abstract: Members of the large Arabidopsis NAC domain transcription factor family are regulators of meristem development, organ elongation and separation, and deposition of patterned secondary cell walls. XYLEM NAC DOMAIN 1 (XND1) is highly expressed in xylem. Changes observed for XND1 knockout plants compared with wild-type Arabidopsis thaliana included a reduction in both plant height and tracheary element length and an increase in metaxylem relative to protoxylem in roots of plants treated with the proteasome inhibitor MG132. Overexpression of XND1 resulted in extreme dwarfism associated with the absence of xylem vessels and little or no expression of tracheary element marker genes. In contrast, phloem marker-gene expression was not altered and phloem-type cells still formed. Transmission electron microscopy showed that parenchyma-like cells in the incipient xylem zone in hypocotyls of XND1 overexpressors lacked secondary wall thickenings and retained their cytoplasmic content. Considered together, these findings suggest that XND1 affects tracheary element growth through regulation of secondary wall synthesis and programmed cell death.
authors: Department of Horticulture, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.
authors: Chengsong
authors: C
authors: Zhao
authors: Utku
authors: U
authors: Avci
authors: Emily H
authors: EH
authors: Grant
authors: Candace H
authors: CH
authors: Haigler
authors: Eric P
authors: EP
authors: Beers
mesh_terms: D017209:Apoptosis / Q000235:genetics / Q000502:physiology*; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D002473:Cell Wall / Q000378:metabolism; D002482:Cellulose / Q000096:biosynthesis*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D007976:Leupeptins / Q000494:pharmacology; D008031:Lignin / Q000096:biosynthesis*; D046529:Microscopy, Electron, Transmission; D016254:Mutagenesis, Insertional; D030821:Plants, Genetically Modified; D020133:Reverse Transcriptase Polymerase Chain Reaction; D052584:Xylem / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D029681:Arabidopsis Proteins; D007976:Leupeptins; C036909:lignocellulose; D002482:Cellulose; D008031:Lignin; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde