title: Initial characterization of shade avoidance response suggests functional diversity between Populus phytochrome B genes.
abstract: Shade avoidance signaling involves perception of incident red/far-red (R/FR) light by phytochromes (PHYs) and modulation of downstream transcriptional networks. Although these responses are well studied in Arabidopsis, little is known about the role of PHYs and the transcriptional responses to shade in the woody perennial Populus. Tissue expression and subcellular localization of Populus PHYs was studied by quantitative real-time PCR (qRT-PCR) and protoplast transient assay. Transgenic lines with altered PHYB1 and/or PHYB2 expression were used in phenotypic assays and transcript profiling with qRT-PCR. RNA-Seq was used to identify transcriptional responses to enriched FR light. All three PHYs were differentially expressed among tissue types and PHYBs were targeted to the nucleus under white light. Populus PHYB1 rescued Arabidopsis phyB mutant phenotypes. Phenotypes of Populus transgenic lines and the expression of candidate shade response genes suggested that PHYB1 and PHYB2 have distinct yet overlapping functions. RNA-Seq analysis indicated that genes associated with cell wall modification and brassinosteroid signaling were induced under enriched FR light in Populus. This study is an initial attempt at deciphering the role of Populus PHYs by evaluating transcriptional reprogramming to enriched FR and demonstrates functional diversity and overlap of the Populus PHYB1 and PHYB2 in regulating shade responses.
authors.affiliation: BioSciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
authors.forename: Abhijit A
authors.initials: AA
authors.lastname: Karve
authors.affiliation: BioSciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
authors.forename: Sara S
authors.initials: SS
authors.lastname: Jawdy
authors.affiliation: BioSciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
authors.forename: Lee E
authors.initials: LE
authors.lastname: Gunter
authors.affiliation: BioSciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.|Department of Plant Sciences, University of Tennessee, Knoxville, TN, USA.
authors.forename: Sara M
authors.initials: SM
authors.lastname: Allen
authors.affiliation: BioSciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
authors.forename: Xiaohan
authors.initials: X
authors.lastname: Yang
authors.affiliation: BioSciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
authors.forename: Gerald A
authors.initials: GA
authors.lastname: Tuskan
authors.affiliation: Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
authors.forename: Stan D
authors.initials: SD
authors.lastname: Wullschleger
authors.affiliation: BioSciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
authors.forename: David J
authors.initials: DJ
authors.lastname: Weston
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D060406:Brassinosteroids / Q000378:metabolism; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D002473:Cell Wall / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005816:Genetic Complementation Test; D008027:Light; D010641:Phenotype; D051939:Phytochrome B / Q000235:genetics* / Q000378:metabolism; D018521:Plant Physiological Phenomena; D030821:Plants, Genetically Modified / Q000235:genetics / Q000502:physiology / Q000528:radiation effects; D010957:Plasmids / Q000235:genetics / Q000378:metabolism; D032107:Populus / Q000235:genetics* / Q000502:physiology / Q000528:radiation effects; D011523:Protoplasts / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods; D017423:Sequence Analysis, RNA; D015398:Signal Transduction; D014158:Transcription, Genetic
chemical_list: D029681:Arabidopsis Proteins; D060406:Brassinosteroids; C497952:PHYB protein, Arabidopsis; D018749:RNA, Plant; D051939:Phytochrome B