title: Plant proximity perception dynamically modulates hormone levels and sensitivity in Arabidopsis.
abstract: The shade avoidance syndrome (SAS) refers to a set of plant responses initiated after perception by the phytochromes of light enriched in far-red colour reflected from or filtered by neighbouring plants. These varied responses are aimed at anticipating eventual shading from potential competitor vegetation. In Arabidopsis thaliana, the most obvious SAS response at the seedling stage is the increase in hypocotyl elongation. Here, we describe how plant proximity perception rapidly and temporally alters the levels of not only auxins but also active brassinosteroids and gibberellins. At the same time, shade alters the seedling sensitivity to hormones. Plant proximity perception also involves dramatic changes in gene expression that rapidly result in a new balance between positive and negative factors in a network of interacting basic helix-loop-helix proteins, such as HFR1, PAR1, and BIM and BEE factors. Here, it was shown that several of these factors act as auxin- and BR-responsiveness modulators, which ultimately control the intensity or degree of hypocotyl elongation. It was deduced that, as a consequence of the plant proximity-dependent new, dynamic, and local balance between hormone synthesis and sensitivity (mechanistically resulting from a restructured network of SAS regulators), SAS responses are unleashed and hypocotyls elongate.
authors.affiliation: Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Bellaterra, 08193-Barcelona, Spain.
authors.forename: Jordi
authors.initials: J
authors.lastname: Bou-Torrent
authors.affiliation: Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Bellaterra, 08193-Barcelona, Spain.
authors.forename: Anahit
authors.initials: A
authors.lastname: Galstyan
authors.affiliation: Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Bellaterra, 08193-Barcelona, Spain.
authors.forename: Marçal
authors.initials: M
authors.lastname: Gallemí
authors.affiliation: Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Bellaterra, 08193-Barcelona, Spain.
authors.forename: Nicolás
authors.initials: N
authors.lastname: Cifuentes-Esquivel
authors.affiliation: Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Bellaterra, 08193-Barcelona, Spain.
authors.forename: Maria José
authors.initials: MJ
authors.lastname: Molina-Contreras
authors.affiliation: Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Bellaterra, 08193-Barcelona, Spain.
authors.forename: Mercè
authors.initials: M
authors.lastname: Salla-Martret
authors.affiliation: RIKEN Plant Science Center, Yokohama, Kanagawa 230-0045, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Jikumaru
authors.affiliation: RIKEN Plant Science Center, Yokohama, Kanagawa 230-0045, Japan.
authors.forename: Shinjiro
authors.initials: S
authors.lastname: Yamaguchi
authors.affiliation: RIKEN Plant Science Center, Yokohama, Kanagawa 230-0045, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kamiya
authors.affiliation: Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Bellaterra, 08193-Barcelona, Spain Institució Catalana de Recerca i Estudis Avançats, 08010-Barcelona, Spain jaume.martinez@cragenomica.es.
authors.forename: Jaime F
authors.initials: JF
authors.lastname: Martínez-García
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects / Q000528:radiation effects; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000502:physiology* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D060406:Brassinosteroids / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000528:radiation effects; D017343:Genes, Plant; D018546:Hypocotyl / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D007210:Indoleacetic Acids / Q000494:pharmacology; D008027:Light; D009154:Mutation / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis; D010937:Plant Growth Regulators / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D029681:Arabidopsis Proteins; D060406:Brassinosteroids; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators
keywords: Arabidopsis; auxins; brassinosteroids; gibberellins; hypocotyl elongation; plant proximity; shade avoidance syndrome.