Overexpression of the 3’ half of the PHYB partially suppresses dwarfism in the brassinosteroid-insensitive bri1-5 mutant

• Published in: Journal of plant biology = Singmul Hakhoe chi Vol. 59; no. 1; pp. 83 - 91
• Main Authors: Jeong, Yu Jeong, Park, Slki, Suh, Su Jeoung, Kwon, Soon Il, Cha, Richard, Kim, Yoong Eun, Choe, Sunghwa
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.02.2016; Springer Nature B.V; 한국식물학회
• Subjects: Arabidopsis; Biomedical and Life Sciences; Brassinosteroids; cDNA libraries; chimerism; Chloroplasts; complementary DNA; Deoxyribonucleic acid; DNA; dwarfing; Dwarfism; gene overexpression; genes; Genomes; genomics; Genotype & phenotype; Identification methods; Life Sciences; loss-of-function mutation; Mutagenesis; Mutants; Original Article; petioles; phenotype; Phenotypes; Plant Breeding/Biotechnology; plant development; Plant Ecology; Plant Genetics and Genomics; Plant growth; Plant Sciences; Plant Systematics/Taxonomy/Biogeography; promoter regions; ribosomal RNA; rRNA; screening; signal transduction; steroid receptors; 생물학; Overexpression mutagenesis; Brassinosteroid; Gateway-cDNA library
• ISSN: 1226-9239; 1867-0725
• DOI: 10.1007/s12374-016-0513-6

Brassinosteroids (BRs) control virtually every aspect of plant growth and development. BRs act alone or in combination with other signals. To identify the signaling components that interact with BRs, we screened for mutants that suppress the dwarf phenotypes of brassinosteroid insensitive 1-5 ( bri1-5 ) using an overexpression mutagenesis method. We established a mutant population by introducing a cDNA library in which cDNA was overexpressed under a constitutive promoter into Arabidopsis bri1-5 plants, which lacked a functional brassinosteroid (BR) receptor. One of the mutants, dubbed ‘ bri1-5 with long petioles’ ( blp ), was selected based on its suppression phenotype. blp contained a chimeric DNA consisting of the 3’ half of PHYB , a 2-bp insertion, and a part of the chloroplast ribosomal RNA gene. Re-introduction of the chimeric DNA into bri1-5 recapitulated the blp phenotype. Prompted by the phenotypic similarity between blp and phyB , we examined both the transcript and protein levels of PHYB in the mutants. The levels were lower in blp 35Spro:PHYB than in 35Spro:PHYB plants, suggesting that introduction of the chimeric gene interfered with the stability of PHYB transcripts. Genome-wide screening for a specific target phenotype resulted in the finding that overexpression of the 3’ half of PHYB in the sense direction can cause a loss-of-function phenotype, and that PHYB plays an important role in BR signaling. Our results validate overexpression mutagenesis as a method to identify the function of Arabidopsis genes.