title: AhDGR2, an amaranth abiotic stress-induced DUF642 protein gene, modifies cell wall structure and composition and causes salt and ABA hyper-sensibility in transgenic Arabidopsis.
abstract: An amaranth DGR gene, induced under abiotic stress, modifies cell wall structure and causes hypersensitivity to ABA and salt when overexpressed in Arabidopsis. DUF642 is a highly conserved plant-specific family of unknown cell wall-associated proteins. The AhDGR2 gene, coding for a DUF642 protein, was significantly induced in grain amaranth (Amaranthus hypochondriacus) plants subjected to water-deficit and salinity stress, thereby suggesting its participation in abiotic stress tolerance in this plant. A role in development was also inferred from the higher AhDGR2 expression rates detected in young tissues. Subsequent overexpression of AhDGR2 in transgenic Arabidopsis plants (OE-AhDGR2) supported its possible role in development processes. Thus, OE-AhDGR2 plants generated significantly longer roots when grown in normal MS medium. However, they showed a hypersensitivity to increasing concentrations of abscisic acid or NaCl in the medium, as manifested by shorter root length, smaller and slightly chlorotic rosettes, as well as highly reduced germination rates. Contrary to expectations, OE-AhDGR2 plants were intolerant to abiotic stress. Moreover, cell walls in transgenic plants were thinner, in leaves, and more disorganized, in roots, and had significantly modified pectin levels. Lower pectin methylesterase activity detected in leaves of OE-AhDGR2 plants, but not in roots, was contrary to previous reports associating DUF642 proteins and decreased pectin esterification levels in cell walls. Nonetheless, microarray data identified candidate genes whose expression levels explained the phenotypes observed in leaves of OE-AhDGR2 plants, including several involved in cell wall integrity and extension, growth and development, and resistance to abiotic stress. These results support the role of DUF642 proteins in cell wall-related processes and offer novel insights into their possible role(s) in plants.
authors.affiliation: Laboratorio de Biología Molecular, Instituto Tecnológico de Tlajomulco, Jalisco, km 10 Carretera a San Miguel Cuyutlán, CP 45640, Tlajomulco de Zúñiga, Jalisco, Mexico.
authors.forename: Paola A
authors.initials: PA
authors.lastname: Palmeros-Suárez
authors.affiliation: Biotechnology and Biochemistry Department, Centro de Investigación y de Estudios Avanzados del I. P. N., Unidad Irapuato, Km 9.6 del Libramiento Norte Carretera Irapuato-León, CP 36821, Irapuato, GTO., Mexico.
authors.forename: Julio A
authors.initials: JA
authors.lastname: Massange-Sánchez
authors.affiliation: Biotechnology and Biochemistry Department, Centro de Investigación y de Estudios Avanzados del I. P. N., Unidad Irapuato, Km 9.6 del Libramiento Norte Carretera Irapuato-León, CP 36821, Irapuato, GTO., Mexico.
authors.forename: Lino
authors.initials: L
authors.lastname: Sánchez-Segura
authors.affiliation: Biotechnology and Biochemistry Department, Centro de Investigación y de Estudios Avanzados del I. P. N., Unidad Irapuato, Km 9.6 del Libramiento Norte Carretera Irapuato-León, CP 36821, Irapuato, GTO., Mexico.
authors.forename: Norma A
authors.initials: NA
authors.lastname: Martínez-Gallardo
authors.affiliation: Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias, Km 13.5 Carrretera Los Reyes-Texcoco, CP 56250, Coatlinchán Texcoco, Estado de México, Mexico.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Espitia Rangel
authors.affiliation: Laboratorio de Biología Molecular, Instituto Tecnológico de Tlajomulco, Jalisco, km 10 Carretera a San Miguel Cuyutlán, CP 45640, Tlajomulco de Zúñiga, Jalisco, Mexico.
authors.forename: Juan F
authors.initials: JF
authors.lastname: Gómez-Leyva
authors.affiliation: Biotechnology and Biochemistry Department, Centro de Investigación y de Estudios Avanzados del I. P. N., Unidad Irapuato, Km 9.6 del Libramiento Norte Carretera Irapuato-León, CP 36821, Irapuato, GTO., Mexico. jdelano@ira.cinvestav.mx.
authors.forename: John P
authors.initials: JP
authors.lastname: Délano-Frier
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology*; D027703:Amaranthaceae / Q000235:genetics*; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D002473:Cell Wall / Q000378:metabolism*; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D020411:Oligonucleotide Array Sequence Analysis; D010802:Phylogeny; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D030821:Plants, Genetically Modified; D012639:Seeds / Q000187:drug effects / Q000254:growth & development; D017422:Sequence Analysis, DNA; D012965:Sodium Chloride / Q000494:pharmacology*; D013312:Stress, Physiological / Q000187:drug effects / Q000235:genetics*; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics
chemical_list: D010940:Plant Proteins; D012965:Sodium Chloride; D000040:Abscisic Acid
keywords: Abiotic stress; Abscisic acid; Cell wall; DUF642; DUF642 L-GalL-responsive gene; Grain amaranth; Pectin; Pectin methylesterase