title: Expression of potato RNA-binding proteins StUBA2a/b and StUBA2c induces hypersensitive-like cell death and early leaf senescence in Arabidopsis.
abstract: The Arabidopsis thaliana genome encodes three RNA-binding proteins (RBPs), UBP1-associated protein 2a (UBA2a), UBA2b, and UBA2c, that contain two RNA-recognition motif (RRM) domains. They play important roles in wounding response and leaf senescence, and are homologs of Vicia faba abscisic-acid-activated protein kinase-interacting protein 1 (VfAKIP1). The potato (Solanum tuberosum) genome encodes at least seven AKIP1-like RBPs. Here, two potato RBPs have been characterized, StUBA2a/b and StUBA2c, that are homologous to VfAKIP1 and Arabidopsis UBA2s. Transient expression of StUBA2s induced a hypersensitive-like cell death phenotype in tobacco leaves, and an RRM-domain deletion assay of StUBA2s revealed that the first RRM domain is crucial for the phenotype. Unlike overexpression of Arabidopsis UBA2s, constitutive expression of StUBA2a/b in Arabidopsis did not cause growth arrest and lethality at the young seedling stage, but induced early leaf senescence. This phenotype was associated with increased expression of defence- and senescence-associated genes, including pathogen-related genes (PR) and a senescence-associated gene (SAG13), and it was aggravated upon flowering and ultimately resulted in a shortened life cycle. Leaf senescence of StUBA2a/b Arabidopsis plants was enhanced under darkness and was accompanied by H2O2 accumulation and altered expression of autophagy-associated genes, which likely cause cellular damage and are proximate causes of the early leaf senescence. Expression of salicylic acid signalling and biosynthetic genes was also upregulated in StUBA2a/b plants. Consistent with the localization of UBA2s-GFPs and VfAKIP1-GFP, soluble-modified GFP-StUBA2s localized in the nucleus within nuclear speckles. StUBA2s potentially can be considered for transgenic approaches to induce potato shoot senescence, which is desirable at harvest.
authors.affiliation: Biology Department, Pennsylvania State University, University Park, Pennsylvania 16802 USA Molecular Breeding Division, National Academy of Agricultural Science, RDA, Wanju-gun, Jeollabuk-do 565-851, Republic of Korea.
authors.forename: Jong-Kuk
authors.initials: JK
authors.lastname: Na
authors.affiliation: Division of Life Sciences, College of Life Sciences and Bioengineering, Incheon National University, Incheon 406-772, Republic of Korea.
authors.forename: Jae-Kwang
authors.initials: JK
authors.lastname: Kim
authors.affiliation: Crop Function Division, National Institute of Crop Science, Rural Development Administration, Wanju-gun, Jeollabuk-do 565-851, Republic of Korea Molecular Breeding Division, National Academy of Agricultural Science, RDA, Wanju-gun, Jeollabuk-do 565-851, Republic of Korea sma3@psu.edu.
authors.forename: Dool-Yi
authors.initials: DY
authors.lastname: Kim
authors.affiliation: Biology Department, Pennsylvania State University, University Park, Pennsylvania 16802 USA sma3@psu.edu.
authors.forename: Sarah M
authors.initials: SM
authors.lastname: Assmann
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology* / Q000235:genetics*; D001343:Autophagy / Q000235:genetics; D016923:Cell Death; D003001:Cloning, Molecular; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D018515:Plant Leaves / Q000166:cytology* / Q000235:genetics / Q000254:growth & development*; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011198:Solanum tuberosum / Q000235:genetics / Q000378:metabolism*; D013312:Stress, Physiological / Q000235:genetics; D013347:Subcellular Fractions / Q000378:metabolism; D014026:Nicotiana / Q000235:genetics; D015854:Up-Regulation / Q000235:genetics
chemical_list: D010940:Plant Proteins; D016601:RNA-Binding Proteins; D049452:Green Fluorescent Proteins; D006861:Hydrogen Peroxide
keywords: AKIP proteins; Arabidopsis thaliana; RNA binding proteins; Solanum tuberosum; UBA2 proteins.; senescence