New Alleles of Rice &amp;lt;i&amp;gt;ebisu dwarf&amp;lt;/i&amp;gt; (&amp;lt;i&amp;gt;d&amp;lt;/i&amp;gt;2) Mutant Show both Brassinosteroid-Deficient and -Insensitive Phenotypes

Sakamoto, Tomoaki; Morinaka, Yoichi; Kitano, Hidemi; Fujioka, Shozo

doi:10.4236/ajps.2012.312208

Cited by 5 publications

(9 citation statements)

References 31 publications

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“…2B). 31 We also confirmed the expression levels of three brassinosteroid-related genes, BU1, CYP85A1, and CYP734A2. BU1 is a primary brassinosteroid-responsive gene, and positively regulated by brassinosteroid treatment.…”

Section: Genome-wide Gene Expression Profiling Of Elf1-1supporting

confidence: 71%

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

Sakamoto

Kitano

Fujioka

2017

Plant Signaling & Behavior

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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. These results indicate that less than half of ELF1-regulated genes in rice seedlings are affected by OsBRI1, and suggest that ELF1 acts in a rice brassinosteroid signaling pathway different from that initiated by OsBRI1. Gene expression analysis showed that some stress response-related genes were induced in elf1-1 but not in d61-12, and 8 of 9 genes oppositely regulated in elf1-1 and d61-12 were significantly up- or down-regulated in both elf1-1 and jasmonic acid-treated wild-type. These results imply that ELF1 suppresses stress-induced signalling, and that jasmonic acid signaling is stimulated in elf1-1; therefore, ELF1 may be involved in the brassinosteroid-mediated suppression of jasmonic acid response in rice.

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Section: Genome-wide Gene Expression Profiling Of Elf1-1supporting

confidence: 71%

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

Sakamoto

Kitano

Fujioka

2017

Plant Signaling & Behavior

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“…Interestingly, the level of CYP85A1 mRNA in untreated d2-6 was lower than that of Nipponbare (about 85%), and was further decreased by brassinolide treatment (Figure 6(b)). Because the bioactive brassinosteroid castasterone accumulated in d2-6 mutant [30], we hypothesize that the expression of CYP85A1 may also be regulated directly by its catalytic product, castasterone. On the other hand, the level of CYP85A1 mRNA in d61-1N was 1.3 times that of wild-type Nipponbare and was not affected by brassinolide treatment (Figure 6(b)).…”

Section: Genetic Background Influences Brassinosteroid-related Mutantmentioning

confidence: 99%

“…CYP90D2/ D2 encodes a cytochrome P450 monooxygenase that functions in brassinosteroid C-23 hydroxylase [7]. We have isolated three new d2 alleles derived from a Nipponbare mutant library (d2-3, d2-4, and d2-6), and showed that they produced more severe dwarf phenotypes in the Nipponbare genetic background than did d2-1, a previously characterized null allele from a Taichung 65 mutant library [28], produced in the Taichung 65 genetic background [30]. The phenotype of Taichung 65-derived null allele d2-1 was semi-dwarf: plants reached ~55% (about 60 cm) of the total culm length of wild-type Taichung 65 (about 110 cm; Figures 5(a), (b) and (e)).…”

Section: Different Background-dependent Abnormal Phenotypes Were Alsomentioning

confidence: 99%

Genetic Background Influences Brassinosteroid-Related Mutant Phenotypes in Rice

Sakamoto¹,

Kitano²,

Fujioka³

2013

AJPS

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In two cases, mutations in the same brassinosteroid-related genes caused different phenotypes in japonica varieties Nipponbare and Taichung 65. The mutant phenotypes were less severe in the Taichung 65 background than in the Nipponbare background. Three newly isolated brassinosteroid-insensitive mutants (d61-1N, d61-11, and d61-12) derived from a Nipponbare mutant library were found to be alleles of d61, which represent defects in the OsBRI1 gene. Although the Nipponbare-derived mutant d61-1N had the same nucleotide substitution as the previously characterized Taichung 65-derived mutant d61-1T, these two mutants showed different phenotypes for plant stature, internode elongation pattern, and seed shape; in each case, d61-1N (in the Nipponbare genetic background) had the more severe mutant phenotype. Similar trends were seen for phenotypes caused by mutants of d2, a brassinosteroid biosynthesis gene. Consistent with these phenotypes, the expression of brassinosteroid-responsive genes was lower in the Nipponbare-derived mutants. These results can be explained by our findings that feed-forward up-regulation of OsBRI1 did not occur in the Nipponbare-derived mutants and that an mPing transposon is inserted into the promoter region of Nipponbare OsBRI1. Based on these results, we conclude that the expression of OsBRI1, especially its feed-forward up-regulation, is misregulated in wild-type Nipponbare and in brassinosteroid-related mutants in a Nipponbare genetic background. Although Nipponbare is a model rice genotype, it can be categorized as an OsBRI1 mutant that has reduced sensitivity to brassinosteroid.

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“…of d61, 13 which is caused by mutations in the brassinosteroid receptor gene OsBRI1, and another 3 were alleles of d2, 16 which is caused by mutations in the brassinosteroid biosynthetic enzyme gene CYP90D2/D2. The remaining mutant, elf1-1, was not an allele of the previously identified brassinosteroid-related mutants, so we further characterized this mutant.…”

Section: Elf1-1 Showed Brassinosteroid-insensitive Phenotypesmentioning

confidence: 99%

“…This mutant also had a short-grain phenotype similar to that observed for recently identified d61 and brassinosteroid-deficient d2 alleles. 13,16 elf1-1 also showed various brassinosteroid-related phenotypes including increased levels of an endogenous bioactive brassinosteroid; therefore, we hypothesized that elf1 mutants have defects in novel brassinosteroid signaling components. The ELF1 gene encodes a U-box-containing E3 ubiquitin ligase, and was found to be identical to the recently identified Taihu Dwarf1 (TUD1) gene.…”

Section: Introductionmentioning

confidence: 99%

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

Sakamoto

Kitano

Fujioka

2013

Plant Signaling & Behavior

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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. U-box proteins have been shown to function as E3 ubiquitin ligases; in fact, ELF1 possessed E3 ubiquitin ligase activity in vitro. However, ELF1 itself does not appear to be polyubiquitinated. Mutant phenotypes of 2 more elf1 alleles indicate that the entire ARM repeats is indispensable for ELF1 activity. These results suggest that ELF1 ubiquitinates target proteins through an interaction mediated by ARM repeats. Similarities in the phenotypes of elf1 and d61 mutants (mutants of brassinosteroid receptor gene OsBRI1), and in the regulation of ELF1 and OsBRI1 expression, imply that ELF1 functions as a positive regulator of brassinosteroid signaling in rice.

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New Alleles of Rice <i>ebisu dwarf</i> (<i>d</i>2) Mutant Show both Brassinosteroid-Deficient and -Insensitive Phenotypes

Cited by 5 publications

References 31 publications

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

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

Genetic Background Influences Brassinosteroid-Related Mutant Phenotypes in Rice

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

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