BIL7 enhances plant growth by regulating the transcription factor BIL1/BZR1 during brassinosteroid signaling.

Brassinosteroids (BRs) are plant steroid hormones that regulate plant development and environmental responses. BIL1/BZR1, a master transcription factor that regulates approximately 3000 genes in the BR signaling pathway, is transported to the nucleus from the cytosol in response to BR signaling; however, the molecular mechanism underlying this process is unknown. Here, we identify a novel BR signaling factor, BIL7, that enhances plant growth and positively regulates the nuclear accumulation of BIL1/BZR1 in Arabidopsis thaliana.

BRZ-INSENSITIVE-LONG HYPOCOTYL8 inhibits kinase-mediated phosphorylation to regulate brassinosteroid signaling.

Glycogen synthase kinase 3 (GSK3) is an evolutionarily conserved serine/threonine protein kinase in eukaryotes. In plants, the GSK3-like kinase BRASSINOSTEROID-INSENSITIVE 2 (BIN2) functions as a central signaling node through which hormonal and environmental signals are integrated to regulate plant development and stress adaptation. BIN2 plays a major regulatory role in brassinosteroid (BR) signaling and is critical for phosphorylating/inactivating BRASSINAZOLE-RESISTANT 1 (BZR1), also known as BRZ-INSENSITIVE-LONG HYPOCOTYL 1 (BIL1), a master transcription factor of BR signaling, but the detailed regulatory mechanism of BIN2 action has not been fully revealed.

Light Activates Brassinosteroid Biosynthesis to Promote Hook Opening and Petiole Development in Arabidopsis thaliana.

Although brassinosteroids (BRs) have been proposed to be negative regulators of photomorphogenesis, their physiological role therein has remained elusive. We studied light-induced photomorphogenic development in the presence of the BR biosynthesis inhibitor, brassinazole (Brz). Hook opening was inhibited in the presence of Brz; this inhibition was reversed in the presence of brassinolide (BL).

ERECT LEAF1 suppresses jasmonic acid response in rice by decreasing OsWRKY4 stability.

ERECT LEAF 1 (ELF1), which was identified as a component of brassinosteroid signaling in rice, is involved in brassinosteroid-mediated suppression of jasmonic acid response. Here, by conducting yeast two-hybrid assay and in vitro ubiquitination experiments, we demonstrate that ELF1 interacts with the OsWRKY4 transcription factor, a positive regulator of defense responses to rice sheath blight. ELF1 decreased the stability of OsWRKY4, whereas exogenous jasmonic acid treatment suppressed this effect of ELF1, resulting in OsWRKY4 accumulation in rice plants.

Rice ERECT LEAF 1 acts in an alternative brassinosteroid signaling pathway independent of the receptor kinase OsBRI1.

ERECT LEAF 1 (ELF1) was previously identified as a component of brassinosteroid signaling in rice. A double mutant obtained by crossing elf1-1 (a null mutant of ELF1) with d61-1 (a leaky mutant of OsBRI1) showed a more severe phenotype than did the elf1-1 single mutant, resembling that of a severe brassinosteroid-deficient mutant. Microarray analysis showed that the gene expression profile of elf1-1 was distinct from that of d61-12 (a leaky mutant of OsBRI1 with a phenotype similar to that of elf1-1), and fewer than half of genes differentially expressed between the wild-type and elf1-1 showed similar differences in d61-12 relative to the wild-type.

Evolutionarily conserved BIL4 suppresses the degradation of brassinosteroid receptor BRI1 and regulates cell elongation.

Brassinosteroids (BRs), plant steroid hormones, play important roles in plant cell elongation and differentiation. To investigate the mechanisms of BR signaling, we previously used the BR biosynthesis inhibitor Brz as a chemical biology tool and identified the Brz-insensitive-long hypocotyl4 mutant (bil4). Although the BIL4 gene encodes a seven-transmembrane-domain protein that is evolutionarily conserved in plants and animals, the molecular function of BIL4 in BR signaling has not been elucidated.

Molecular actions of two synthetic brassinosteroids, iso-carbaBL and 6-deoxoBL, which cause altered physiological activities between Arabidopsis and rice.

Brassinosteroid (BR) is an important plant hormone that is perceived by the BRASSINOSTEROID INSENSITIVE 1 (BRI1) receptor. BRI1 is conserved among dicot and monocot species; however, the molecular mechanism underlying BR perception in monocots is not fully understood. We synthesised two BRs, iso-carbabrassinolide (iso-carbaBL) and 6-deoxoBL, which have different BR activities in Arabidopsis thaliana (Arabidopsis) and rice.

nana plant2 Encodes a Maize Ortholog of the Arabidopsis Brassinosteroid Biosynthesis Gene DWARF1, Identifying Developmental Interactions between Brassinosteroids and Gibberellins.

A small number of phytohormones dictate the pattern of plant form affecting fitness via reproductive architecture and the plant's ability to forage for light, water, and nutrients. Individual phytohormone contributions to plant architecture have been studied extensively, often following a single component of plant architecture, such as plant height or branching. Both brassinosteroid (BR) and gibberellin (GA) affect plant height, branching, and sexual organ development in maize (Zea mays).

Aminooxy-naphthylpropionic acid and its derivatives are inhibitors of auxin biosynthesis targeting l-tryptophan aminotransferase: structure-activity relationships.

We previously reported l-α-aminooxy-phenylpropionic acid (AOPP) to be an inhibitor of auxin biosynthesis, but its precise molecular target was not identified. In this study we found that AOPP targets TRYPTOPHAN AMINOTRANSFERASE of ARABIDOPSIS 1 (TAA1). We then synthesized 14 novel compounds derived from AOPP to study the structure-activity relationships of TAA1 inhibitors in vitro.

Loose Plant Architecture1 (LPA1) determines lamina joint bending by suppressing auxin signalling that interacts with C-22-hydroxylated and 6-deoxo brassinosteroids in rice.

Lamina inclination is a key agronomical character that determines plant architecture and is sensitive to auxin and brassinosteroids (BRs). Loose Plant Architecture1 (LPA1) in rice (Oryza sativa) and its Arabidopsis homologues (SGR5/AtIDD15) have been reported to control plant architecture and auxin homeostasis. This study explores the role of LPA1 in determining lamina inclination in rice.

YCZ-18 is a new brassinosteroid biosynthesis inhibitor.

Plant hormone brassinosteroids (BRs) are a group of polyhydroxylated steroids that play critical roles in regulating broad aspects of plant growth and development. The structural diversity of BRs is generated by the action of several groups of P450s. Brassinazole is a specific inhibitor of C-22 hydroxylase (CYP90B1) in BR biosynthesis, and the application use of brassinazole has emerged as an effective way of complementing BR-deficient mutants to elucidate the functions of BRs.

Arabidopsis gulliver1/SUPERROOT2-7 identifies a metabolic basis for auxin and brassinosteroid synergy.

Phytohormone homeostasis is essential for proper growth and development of plants. To understand the growth mechanisms mediated by hormonal levels, we isolated a gulliver1 (gul1) mutant that had tall stature in the presence of both brassinazole and the light. The gul1 phenotype depended on functional BR biosynthesis; the genetic introduction of dwarf4, a BR biosynthetic mutation, masked the long hypocotyl phenotype of gul1.

The role of Arabidopsis ABCG9 and ABCG31 ATP binding cassette transporters in pollen fitness and the deposition of steryl glycosides on the pollen coat.

The pollen coat protects pollen grains from harmful environmental stresses such as drought and cold. Many compounds in the pollen coat are synthesized in the tapetum. However, the pathway by which they are transferred to the pollen surface remains obscure.

Darkness and gulliver2/phyB mutation decrease the abundance of phosphorylated BZR1 to activate brassinosteroid signaling in Arabidopsis.

Light is essential for plant survival; as such, plants flexibly adjust their growth and development to best harvest light energy. Brassinosteroids (BRs), plant growth-promoting steroid hormones, are essential for this plasticity of development. However, the precise mechanisms underlying BR-mediated growth under different light conditions remain largely unknown.

Brassinosteroids regulate plant growth through distinct signaling pathways in Selaginella and Arabidopsis.

Brassinosteroids (BRs) are growth-promoting steroid hormones that regulate diverse physiological processes in plants. Most BR biosynthetic enzymes belong to the cytochrome P450 (CYP) family. The gene encoding the ultimate step of BR biosynthesis in Arabidopsis likely evolved by gene duplication followed by functional specialization in a dicotyledonous plant-specific manner.

An E3 ubiquitin ligase, ERECT LEAF1, functions in brassinosteroid signaling of rice.

A spontaneous rice mutant, erect leaf1 (elf1-1), produced a dwarf phenotype with erect leaves and short grains. Physiological analyses suggested that elf1-1 is brassinosteroid-insensitive, so we hypothesized that ELF1 encodes a positive regulator of brassinosteroid signaling. ELF1, identified by means of positional cloning, encodes a protein with both a U-box domain and ARMADILLO (ARM) repeats.

Plant growth activities of aspyran, asperentin, and its analogues produced by the fungus Aspergillus sp.

Aspyran (1), a novel compound, and the known isocoumarin asperentin (2), also known as cladosporin, together with its analogues 3-6 were isolated from Aspergillus sp. and their structures established by spectroscopic methods including 2D NMR spectroscopy. The effects of 1-6 on plant growth were examined by bioassays using lettuce and rice seedlings.

Genetic variation in plant CYP51s confers resistance against voriconazole, a novel inhibitor of brassinosteroid-dependent sterol biosynthesis.

Brassinosteroids (BRs) are plant steroid hormones with structural similarity to mammalian sex steroids and ecdysteroids from insects. The BRs are synthesized from sterols and are essential regulators of cell division, cell elongation and cell differentiation. In this work we show that voriconazole, an antifungal therapeutic drug used in human and veterinary medicine, severely impairs plant growth by inhibiting sterol-14α-demethylation and thereby interfering with BR production.

Auxins increase expression of the brassinosteroid receptor and brassinosteroid-responsive genes in Arabidopsis.

Auxins and brassinosteroids are essential phytohormones that synergistically regulate physiological and developmental processes in plants. Previously, we demonstrated that auxins stimulate brassinosteroid perception by regulating the level of brassinosteroid receptor in rice. Here we showed that auxin treatment increased expression of the Arabidopsis brassinosteroid receptor gene BRI1.

Arabidopsis brassinosteroid-overproducing gulliver3-D/dwarf4-D mutants exhibit altered responses to jasmonic acid and pathogen.

KEY MESSAGE : Arabidopsis gulliver3 - D/dwarf4 - D displays growth-promoting phenotypes due to activation tagging of a key brassinosteroid biosynthetic gene DWARF4. In gul3-D/dwf4-D , the Jasmonate and Salicylate signaling pathways were relatively activated and suppressed, respectively. Energy allocation between growth and defense is elegantly balanced to achieve optimal development in plants.

Homeostasis of brassinosteroids regulated by DRL1, a putative acyltransferase in Arabidopsis.

Brassinosteroids (BRs) play essential roles in regulating various aspects of plant growth and development and in responding to diverse environmental cues, and their metabolism is an important way to regulate their homeostasis in plants. Here, we identified a dominant mutant, dwarf and round leaf-1 (drl1-D), which exhibits weak BR-deficient or BR-insensitive mutant phenotypes, including short and round leaves, prolonged senescence, dwarfed shape, and altered expression levels of the BR-responsive genes. Hypocotyl length and root inhibition assays suggest that the drl1-D mutant responds to BRs normally, but has decreased BR signaling outputs.

Auxin signal transcription factor regulates expression of the brassinosteroid receptor gene in rice.

The phytohormones auxins and brassinosteroids are both essential regulators of physiological and developmental processes, and it has been suggested that they act inter-dependently and synergistically. In rice (Oryza sativa), auxin co-application improves the brassinosteroid response in the rice lamina inclination bioassay. Here, we showed that auxins stimulate brassinosteroid perception by regulating the level of brassinosteroid receptor.

Arabidopsis PIZZA has the capacity to acylate brassinosteroids.

Brassinosteroids (BRs) affect a wide range of developmental processes in plants and compromised production or signalling of BRs causes severe growth defects. To identify new regulators of plant organ growth, we searched the Arabidopsis FOX (Full-length cDNA Over-eXpressor gene) collection for mutants with altered organ size and isolated two overexpression lines that display typical BR deficient dwarf phenotypes. The phenotype of these lines, caused by an overexpression of a putative acyltransferase gene PIZZA (PIZ), was partly rescued by supplying exogenous brassinolide (BL) and castasterone (CS), indicating that endogenous BR levels are rate-limiting for the growth of PIZ overexpression lines.

BAT1, a putative acyltransferase, modulates brassinosteroid levels in Arabidopsis.

Brassinosteroids (BRs) are essential for various aspects of plant development. Cellular BR homeostasis is critical for proper growth and development of plants; however, its regulatory mechanism remains largely unknown. BAT1 (BR-related acyltransferase 1), a gene encoding a putative acyltransferase, was found to be involved in vascular bundle development in a full-length cDNA over-expressor (FOX) screen.

Constitutive activation of brassinosteroid signaling in the Arabidopsis elongated-D/bak1 mutant.

Defects in brassinosteroid (BR) biosynthetic or signaling genes result in dwarfed plants, whereas overexpression of these genes increases overall stature. An Arabidopsis elongated-D (elg-D) mutant shares phenotypic similarities with BR overexpression lines, suggesting its implication in BR pathways. Here, we determine how elg-D affects BR signaling.