DBB1a, involved in gibberellin homeostasis, functions as a negative regulator of blue light-mediated hypocotyl elongation in Arabidopsis.
Double B-box 1a (DBB1a) belongs to the zinc-finger family proteins in Arabidopsis thaliana. Transcriptional analysis uncovered that the DBB1a gene expression was blue light-dependently regulated, and the transcript level of DBB1a in cry1cry2 was decreased but not in phyAphyB compared to wild type under blue light conditions. Transgenic plants containing pDBB1a:GUS (β-glucuronidase) displayed GUS activity in the vascular system of leaves and petioles. Green fluorescent protein (GFP)-fused DDB1a (DBB1a-GFP) protein was found in the nucleus in transient transformation assays with onion epidermal cells as well as in stable transgenic Arabidopsis plants. To investigate the function of DBB1a, we generated DBB1a over-expressing and under-expressing transgenic Arabidopsis plants. Analysis of hypocotyl growth of these lines indicated that DBB1a promoted hypocotyl elongation under blue light condition. The phenotype of transgenic plants with DBB1a over-expression could be impaired by a gibberellin (GA)-biosynthesis inhibitor. Moreover, the expression analysis of GA metabolic and catabolic genes in DBB1a transgenic lines indicated that the DBB1a suppressed GA2-oxidase1 (GA2ox1) and GA2-oxidase8 (GA2ox8) expression, but induced GA3β-hydroxygenase1 (GA3ox1) and GA20-oxidase1 (GA20ox1) expression under blue light. Taken together, we concluded that DBB1a promotes hypocotyl elongation under blue light condition through an increase in bioactive GA levels in Arabidopsis.
Wang
Qiming
Q
College of Biology, State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha, China.
Zeng
Jianxin
J
Deng
Keqin
K
Tu
Xiaoju
X
Zhao
Xiaoying
X
Tang
Dongying
D
Liu
Xuanming
X
D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000254:growth & development* / Q000528:radiation effects*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism / Q000528:radiation effects; D056931:Cryptochromes / Q000378:metabolism; D004268:DNA-Binding Proteins; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D017343:Genes, Plant / Q000235:genetics; D005875:Gibberellins / Q000378:metabolism*; D006706:Homeostasis / Q000528:radiation effects*; D018546:Hypocotyl / Q000254:growth & development* / Q000528:radiation effects; D008027:Light; D009154:Mutation / Q000235:genetics; D018515:Plant Leaves / Q000378:metabolism / Q000528:radiation effects; D018517:Plant Roots / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects; D058526:Plant Vascular Bundle / Q000378:metabolism / Q000528:radiation effects; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics; D021381:Protein Transport / Q000528:radiation effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors; D014158:Transcription, Genetic / Q000528:radiation effects
D029681:Arabidopsis Proteins; C557296:At2g21320 protein, Arabidopsis; C538962:CRY1 protein, Arabidopsis; C103618:CRY2 protein, Arabidopsis; D002352:Carrier Proteins; D056931:Cryptochromes; D004268:DNA-Binding Proteins; D005875:Gibberellins; D012333:RNA, Messenger; D014157:Transcription Factors