title: Activation-tagged suppressors of a weak brassinosteroid receptor mutant.
abstract: Brassinosteroids (BRs) are important plant hormones that act synergistically with auxin to regulate a variety of plant developmental and physiological processes. In the past decade, genetic and biochemical studies have revealed a linear signaling pathway that relies on protein phosphorylation to transmit the BR signal into the nucleus, altering expression of hundreds of genes to promote plant growth. We conducted an activation-tagging based suppressor screen to look for Arabidopsis genes that, when overexpressed by inserted 35S enhancer elements, could suppress the dwarf phenotype of a weak BR receptor mutant bri1-301. This screen identified a total of six dominant activation-tagged bri1 suppressors (atbs-Ds). Using a plasmid rescue approach, we discovered that the bri1-301 suppression effect in four atbs-D mutants (atbs3-D to atbs6-D) was caused by overexpression of a YUCCA gene thought to be involved in tryptophan-dependent auxin biosynthesis. Interestingly, the three activation-tagged YUCCA genes belong to the YUCCA IIA subfamily that includes two other members out of 11 known Arabidopsis YUCCA genes. In addition, our molecular studies revealed a T-DNA insertion near a basic helix-loop-helix gene in atbs1-D and a T-DNA insertion in a region carrying a BR biosynthetic gene in atbs2-D. Further studies of these atbs-D mutants could lead to better understanding of the BR signaling process and the BR-auxin interaction.
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109-1048, USA.
authors.forename: Bin
authors.initials: B
authors.lastname: Kang
authors.forename: Hao
authors.initials: H
authors.lastname: Wang
authors.forename: Kyoung Hee
authors.initials: KH
authors.lastname: Nam
authors.forename: Jiayang
authors.initials: J
authors.lastname: Li
authors.forename: Jianming
authors.initials: J
authors.lastname: Li
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000502:physiology; D008969:Molecular Sequence Data; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D013260:Steroids, Heterocyclic / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D013260:Steroids, Heterocyclic