title: Phylogenetically distant barley legumains have a role in both seed and vegetative tissues.
abstract: Legumains or vacuolar processing enzymes are cysteine peptidases (C13 family, clan CD) with increasingly recognized physiological significance in plants. They have previously been classified as seed and vegetative legumains. In this work, the entire barley legumain family is described. The eight members of this family belong to the two phylogenetic clades in which the angiosperm legumains are distributed. An in-depth molecular and functional characterization of a barley legumain from each group, HvLeg-2 and HvLeg-4, was performed. Both legumains contained a signal peptide and were located in the endoplasmic reticulum, were expressed in seeds and vegetative tissues, and when expressed as recombinant proteins showed legumain and caspase proteolytic activities. However, the role of each protein seemed to be different in their target tissues. HvLeg-2 responded in leaves to biotic and abiotic stimuli, such as salicylic acid, jasmonic acid, nitric oxide, abscisic acid, and aphid infestation, and was induced by gibberellic acid in seeds, where the protein is able to degrade storage globulins. HvLeg-4 responded in leaves to wounding, nitric oxide, and abscisic acid treatments, and had an unknown role in the germinating seed. From these results, a multifunctional role was assumed for these two phylogenetically distant legumains, achieving different physiological functions in both seed and vegetative tissues.
authors.affiliation: Centro de Biotecnología y Genómica de Plantas (UPM-INIA), Campus Montegancedo, Universidad Politécnica de Madrid, Autovía M40 (Km 38), 28223-Pozuelo de Alarcón, Madrid, Spain.
authors.forename: Israel
authors.initials: I
authors.lastname: Julián
authors.forename: Jacinto
authors.initials: J
authors.lastname: Gandullo
authors.forename: Ludier K
authors.initials: LK
authors.lastname: Santos-Silva
authors.forename: Isabel
authors.initials: I
authors.lastname: Diaz
authors.forename: Manuel
authors.initials: M
authors.lastname: Martinez
mesh_terms: D003546:Cysteine Endopeptidases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000201:enzymology / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D001467:Hordeum / Q000145:classification / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D008969:Molecular Sequence Data; D005810:Multigene Family; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D021382:Protein Sorting Signals; D021381:Protein Transport; D012639:Seeds / Q000145:classification / Q000201:enzymology / Q000235:genetics / Q000254:growth & development*; D000099240:Asparaginyl Endopeptidase
chemical_list: D003546:Cysteine Endopeptidases; D010940:Plant Proteins; D021382:Protein Sorting Signals; D000099240:Asparaginyl Endopeptidase
keywords: barley; legumains; multifunctional role; seed expression; vacuolar processing enzymes; vegetative expression.