title: Isolation and characterization of rice (Oryza sativa L.) E3-ubiquitin ligase OsHOS1 gene in the modulation of cold stress response.
abstract: Plants can cope with adverse environmental conditions through the activation of stress response signalling pathways, in which the proteasome seems to play an important role. However, the mechanisms underlying the proteasome-mediated stress response in rice are still not fully understood. To address this issue, we have identified a rice E3-ubiquitin ligase, OsHOS1, and characterized its role in the modulation of the cold stress response. Using a RNA interference (RNAi) transgenic approach we found that, under cold conditions, the RNAi::OsHOS1 plants showed a higher expression level of OsDREB1A. This was correlated with an increased amount of OsICE1, a master transcription factor of the cold stress signalling. However, the up-regulation of OsDREB1A was transient and the transgenic plants did not show increased cold tolerance. Nevertheless, we could confirm the interaction of OsHOS1 with OsICE1 by Yeast-Two hybrid and bi-molecular fluorescence complementation in Arabidopsis protoplasts. Moreover, we could also determine through an in vitro degradation assay that the higher amount of OsICE1 in the transgenic plants was correlated with a lower amount of OsHOS1. Hence, we could confirm the involvement of the proteasome in this response mechanism. Taken together our results confirm the importance of OsHOS1, and thus of the proteasome, in the modulation of the cold stress signalling in rice.
authors.affiliation: Genomics of Plant Stress laboratory, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal.
authors.forename: Tiago
authors.initials: T
authors.lastname: Lourenço
authors.forename: Helena
authors.initials: H
authors.lastname: Sapeta
authors.forename: Duarte D
authors.initials: DD
authors.lastname: Figueiredo
authors.forename: Mafalda
authors.initials: M
authors.lastname: Rodrigues
authors.forename: André
authors.initials: A
authors.lastname: Cordeiro
authors.forename: Isabel A
authors.initials: IA
authors.lastname: Abreu
authors.forename: Nelson J M
authors.initials: NJ
authors.lastname: Saibo
authors.forename: M Margarida
authors.initials: MM
authors.lastname: Oliveira
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D058639:Cold-Shock Response; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics*; D018506:Gene Expression Regulation, Plant / Q000235:genetics; D020868:Gene Silencing; D008969:Molecular Sequence Data; D012275:Oryza / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D059748:Proteolysis; D034622:RNA Interference; D011993:Recombinant Fusion Proteins; D016415:Sequence Alignment; D015398:Signal Transduction; D015533:Transcriptional Activation; D020798:Two-Hybrid System Techniques; D044767:Ubiquitin-Protein Ligases / Q000235:genetics* / Q000378:metabolism; D054875:Ubiquitination; D015854:Up-Regulation
chemical_list: D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; D044767:Ubiquitin-Protein Ligases; D046988:Proteasome Endopeptidase Complex