title: Two Hydroxyproline Galactosyltransferases, GALT5 and GALT2, Function in Arabinogalactan-Protein Glycosylation, Growth and Development in Arabidopsis.
abstract: Hydroxyproline-O-galactosyltransferase (GALT) initiates O-glycosylation of arabinogalactan-proteins (AGPs). We previously characterized GALT2 (At4g21060), and now report on functional characterization of GALT5 (At1g74800). GALT5 was identified using heterologous expression in Pichia and an in vitro GALT assay. Product characterization showed GALT5 specifically adds galactose to hydroxyproline in AGP protein backbones. Functions of GALT2 and GALT5 were elucidated by phenotypic analysis of single and double mutant plants. Allelic galt5 and galt2 mutants, and particularly galt2 galt5 double mutants, demonstrated lower GALT activities and reductions in β-Yariv-precipitated AGPs compared to wild type. Mutant plants showed pleiotropic growth and development phenotypes (defects in root hair growth, root elongation, pollen tube growth, flowering time, leaf development, silique length, and inflorescence growth), which were most severe in the double mutants. Conditional mutant phenotypes were also observed, including salt-hypersensitive root growth and root tip swelling as well as reduced inhibition of pollen tube growth and root growth in response to β-Yariv reagent. These mutants also phenocopy mutants for an AGP, SOS5, and two cell wall receptor-like kinases, FEI1 and FEI2, which exist in a genetic signaling pathway. In summary, GALT5 and GALT2 function as redundant GALTs that control AGP O-glycosylation, which is essential for normal growth and development.
authors.affiliation: Molecular and Cellular Biology Program, Department of Environmental and Plant Biology, Ohio University, Athens, Ohio, United States of America.
authors.forename: Debarati
authors.initials: D
authors.lastname: Basu
authors.affiliation: Molecular and Cellular Biology Program, Department of Environmental and Plant Biology, Ohio University, Athens, Ohio, United States of America.
authors.forename: Wuda
authors.initials: W
authors.lastname: Wang
authors.affiliation: Molecular and Cellular Biology Program, Department of Environmental and Plant Biology, Ohio University, Athens, Ohio, United States of America.
authors.forename: Siyi
authors.initials: S
authors.lastname: Ma
authors.affiliation: Molecular and Cellular Biology Program, Department of Environmental and Plant Biology, Ohio University, Athens, Ohio, United States of America.
authors.forename: Taylor
authors.initials: T
authors.lastname: DeBrosse
authors.affiliation: Molecular and Cellular Biology Program, Department of Environmental and Plant Biology, Ohio University, Athens, Ohio, United States of America.
authors.forename: Emily
authors.initials: E
authors.lastname: Poirier
authors.affiliation: Molecular and Cellular Biology Program, Department of Environmental and Plant Biology, Ohio University, Athens, Ohio, United States of America.
authors.forename: Kirk
authors.initials: K
authors.lastname: Emch
authors.affiliation: Molecular and Cellular Biology Program, Department of Environmental and Plant Biology, Ohio University, Athens, Ohio, United States of America.
authors.forename: Eric
authors.initials: E
authors.lastname: Soukup
authors.affiliation: Molecular and Cellular Biology Program, Department of Environmental and Plant Biology, Ohio University, Athens, Ohio, United States of America.
authors.forename: Lu
authors.initials: L
authors.lastname: Tian
authors.affiliation: Molecular and Cellular Biology Program, Department of Environmental and Plant Biology, Ohio University, Athens, Ohio, United States of America.
authors.forename: Allan M
authors.initials: AM
authors.lastname: Showalter
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D035264:Flowers / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D005685:Galactans / Q000378:metabolism*; D005690:Galactose / Q000378:metabolism; D005700:Galactosyltransferases / Q000235:genetics* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D006031:Glycosylation; D006909:Hydroxyproline / Q000378:metabolism; D009088:Mucoproteins / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D010641:Phenotype; D010843:Pichia / Q000235:genetics / Q000378:metabolism; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D030821:Plants, Genetically Modified
chemical_list: D029681:Arabidopsis Proteins; D005685:Galactans; D009088:Mucoproteins; D010940:Plant Proteins; C006619:arabinogalactan proteins; D000244:Adenosine Diphosphate; D005700:Galactosyltransferases; D006909:Hydroxyproline; C005653:arabinogalactan; D005690:Galactose