title: Rice phytochrome-interacting factor protein OsPIF14 represses OsDREB1B gene expression through an extended N-box and interacts preferentially with the active form of phytochrome B.
abstract: DREB1/CBF genes, known as major regulators of plant stress responses, are rapidly and transiently induced by low temperatures. Using a yeast one-hybrid screening, we identified a putative Phytochrome-Interacting bHLH Factor (OsPIF14), as binding to the OsDREB1B promoter. bHLH proteins are able to bind to hexameric E-box (CANNTG) or N-box (CACG(A/C)G) motifs, depending on transcriptional activity. We have shown that OsPIF14 binds to the OsDREB1B promoter through two N-boxes and that the flanking regions of the hexameric core are essential for protein-DNA interaction and stability. We also showed that OsPIF14 down-regulates OsDREB1B gene expression in rice protoplasts, corroborating the OsPIF14 repressor activity observed in the transactivation assays using Arabidopsis protoplasts. In addition, we showed that OsPIF14 is indeed a phytochrome interacting factor, which preferentially binds to the active form (Pfr) of rice phytochrome B. This raises the possibility that OsPIF14 activity might be modulated by light. However, we did not observe any regulation of the OsDREB1B gene expression by light under control conditions. Moreover, OsPIF14 gene expression was shown to be modulated by different treatments, such as drought, salt, cold and ABA. Interestingly, OsPIF14 showed also a specific cold-induced alternative splicing. All together, these results suggest the possibility that OsPIF14 is involved in cross-talk between light and stress signaling through interaction with the OsDREB1B promoter. Although in the absence of stress, OsDREB1B gene expression was not regulated by light, given previous reports, it remains possible that OsPIF14 has a role in light modulation of stress responses.
authors.affiliation: Genomics of Plant Stress Unit, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa and Instituto de Biologia Experimental e Tecnológica, Av. da República, 2780-157 Oeiras, Portugal.
authors.forename: André M
authors.initials: AM
authors.lastname: Cordeiro
authors.affiliation: Genomics of Plant Stress Unit, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa and Instituto de Biologia Experimental e Tecnológica, Av. da República, 2780-157 Oeiras, Portugal.
authors.forename: Duarte D
authors.initials: DD
authors.lastname: Figueiredo
authors.affiliation: University of California, Berkeley, Dept of Plant & Microbial Biology, CA 94720, USA; University of California, Berkeley, USDA, PGEC, CA 94710, USA.
authors.forename: James
authors.initials: J
authors.lastname: Tepperman
authors.affiliation: Genomics of Plant Stress Unit, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa and Instituto de Biologia Experimental e Tecnológica, Av. da República, 2780-157 Oeiras, Portugal.
authors.forename: Ana Rita
authors.initials: AR
authors.lastname: Borba
authors.affiliation: Genomics of Plant Stress Unit, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa and Instituto de Biologia Experimental e Tecnológica, Av. da República, 2780-157 Oeiras, Portugal.
authors.forename: Tiago
authors.initials: T
authors.lastname: Lourenço
authors.affiliation: Genomics of Plant Stress Unit, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa and Instituto de Biologia Experimental e Tecnológica, Av. da República, 2780-157 Oeiras, Portugal.
authors.forename: Isabel A
authors.initials: IA
authors.lastname: Abreu
authors.affiliation: Institute of Biology, Leiden University, Leiden, The Netherlands.
authors.forename: Pieter B F
authors.initials: PB
authors.lastname: Ouwerkerk
authors.affiliation: University of California, Berkeley, Dept of Plant & Microbial Biology, CA 94720, USA; University of California, Berkeley, USDA, PGEC, CA 94710, USA.
authors.forename: Peter H
authors.initials: PH
authors.lastname: Quail
authors.affiliation: Genomics of Plant Stress Unit, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa and Instituto de Biologia Experimental e Tecnológica, Av. da República, 2780-157 Oeiras, Portugal.
authors.forename: M
authors.initials: M
authors.lastname: Margarida Oliveira
authors.affiliation: Genomics of Plant Stress Unit, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa and Instituto de Biologia Experimental e Tecnológica, Av. da República, 2780-157 Oeiras, Portugal. Electronic address: saibo@itqb.unl.pt.
authors.forename: Nelson J M
authors.initials: NJ
authors.lastname: Saibo
mesh_terms: D000595:Amino Acid Sequence / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D003080:Cold Temperature; D004268:DNA-Binding Proteins / Q000235:genetics; D055864:Droughts; D018506:Gene Expression Regulation, Plant; D012275:Oryza / Q000235:genetics* / Q000502:physiology; D051939:Phytochrome B / Q000235:genetics* / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics*; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic; D013312:Stress, Physiological / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; C114578:DREB1A protein, Arabidopsis; D010940:Plant Proteins; D014157:Transcription Factors; D051939:Phytochrome B
keywords: Alternative splicing; Cold stress; Light regulation; OsDREB1B; Protein–DNA interaction; Rice phytochrome-interacting factor 14 (OsPIF14)