title: Populus endo-beta-mannanase PtrMAN6 plays a role in coordinating cell wall remodeling with suppression of secondary wall thickening through generation of oligosaccharide signals.
abstract: Endo-1,4-β-mannanase is known to able to hydrolyze mannan-type polysaccharides in cell wall remodeling, but its function in regulating wall thickening has been little studied. Here we show that a Populus endo-1,4-β-mannanase gene, named PtrMAN6, suppresses cell wall thickening during xylem differentiation. PtrMAN6 is expressed specifically in xylem tissue and its encoded protein localizes to developing vessel cells. Overexpression of PtrMAN6 enhanced wall loosening as well as suppressed secondary wall thickening, whilst knockdown of its expression promoted secondary wall thickening. Transcriptional analysis revealed that PtrMAN6 overexpression downregulated the transcriptional program of secondary cell wall thickening, whilst PtrMAN6 knockdown upregulated transcriptional activities toward secondary wall formation. Activity of PtrMAN6 hydrolysis resulted in the generation of oligosaccharide compounds from cell wall polysaccharides. Application of the oligosaccharides resulted in cellular and transcriptional changes that were similar to those found in PtrMAN6 overexpressed transgenic plants. Overall, our results demonstrated that PtrMAN6 plays a role in hydrolysis of mannan-type wall polysaccharides to produce oligosaccharides that may serve as signaling molecules to suppress cell wall thickening during wood xylem cell differentiation.
authors: National Key Laboratory of Plant Molecular Genetics/Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
authors: Yunjun
authors: Y
authors: Zhao
authors: Dongliang
authors: D
authors: Song
authors: Jiayan
authors: J
authors: Sun
authors: Laigeng
authors: L
authors: Li
mesh_terms: D002454:Cell Differentiation; D002462:Cell Membrane / Q000378:metabolism; D002473:Cell Wall / Q000201:enzymology*; D017343:Genes, Plant; D006031:Glycosylation; D006868:Hydrolysis; D009844:Oligosaccharides / Q000096:biosynthesis*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D032107:Populus / Q000201:enzymology*; D055503:Protein Multimerization; D021381:Protein Transport; D014158:Transcription, Genetic; D052584:Xylem / Q000378:metabolism; D044902:beta-Mannosidase / Q000235:genetics / Q000378:metabolism*
chemical_list: D009844:Oligosaccharides; D044902:beta-Mannosidase