Phytochrome interacting factors 4 and 5 control seedling growth in changing light conditions by directly controlling auxin signaling

• Published in: The Plant journal : for cell and molecular biology 2012-09, Vol.71 (5), p.699-711
• Main Authors: Hornitschek, Patricia, Kohnen, Markus V, Lorrain, Séverine, Rougemont, Jacques, Ljung, Karin, López‐Vidriero, Irene, Franco‐Zorrilla, José M, Solano, Roberto, Trevisan, Martine, Pradervand, Sylvain, Xenarios, Ioannis, Fankhauser, Christian
• Format: Article
• Language: English
• Subjects: Arabidopsis; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; auxin; auxins; Basic Helix-Loop-Helix Transcription Factors - genetics; Basic Helix-Loop-Helix Transcription Factors - metabolism; Binding sites; Biological and medical sciences; Biosynthesis; ChIP sequencing; Developmental Biology; Fundamental and applied biological sciences. Psychology; Gene expression; Gene Expression Regulation, Plant; genes; Genes, Plant; Genomics; Hormones; Indoleacetic Acids - metabolism; Light; photoreceptors; phytochrome; phytochrome‐interacting factor; Plant growth; Plant physiology and development; seedling growth; Seedlings - growth & development; Seedlings - metabolism; shade; shade avoidance; transcription factors; Utvecklingsbiologi
• ISSN: 0960-7412; 1365-313X; 1365-313X
• DOI: 10.1111/j.1365-313x.2012.05033.x

Plant growth is strongly influenced by the presence of neighbors that compete for light resources. In response to vegetational shading shade‐intolerant plants such as Arabidopsis display a suite of developmental responses known as the shade‐avoidance syndrome (SAS). The phytochrome B (phyB) photoreceptor is the major light sensor to mediate this adaptive response. Control of the SAS occurs in part with phyB, which controls protein abundance of phytochrome‐interacting factors 4 and 5 (PIF4 and PIF5) directly. The shade‐avoidance response also requires rapid biosynthesis of auxin and its transport to promote elongation growth. The identification of genome‐wide PIF5‐binding sites during shade avoidance revealed that this bHLH transcription factor regulates the expression of a subset of previously identified SAS genes. Moreover our study suggests that PIF4 and PIF5 regulate elongation growth by controlling directly the expression of genes that code for auxin biosynthesis and auxin signaling components.