ydk1‐D, an auxin‐responsive GH3 mutant that is involved in hypocotyl and root elongation

Abstract

SummaryTo study the GH3 gene family of Arabidopsis, we investigated a¯anking sequence database of Arabidopsis activation-tagged lines. We found a dwarf mutant, named yadokari 1-D (ydk1-D), that had a T-DNA insertion proximal to a GH3 gene. ydk1-D is dominant and has a short hypocotyl not only in light but also in darkness. Moreover, ydk1-D has a short primary root, a reduced lateral root number, and reduced apical dominance. A GH3 gene, named YDK1, was upregulated in ydk1-D, and YDK1 transgenic plants showed the ydk1-D phenotype. YDK1 gene expression was induced by exogenously applied auxin and regulated by auxinresponse factor (ARF)7. In addition, YDK1 gene expression was downregulated by blue and far-red (FR) lights. Strong promoter activity of YDK1 was observed in roots and¯owers. These results suggest that YDK1 may function as a negative component in auxin signaling by regulating auxin activity.

Activation of the Indole-3-Acetic Acid–Amido Synthetase GH3-8 Suppresses Expansin Expression and Promotes Salicylate- and Jasmonate-Independent Basal Immunity in Rice

“…The T1 progeny of D25UM8-27 that showed a high level of GH3-8 transcripts produced shorter roots and fewer adventitious roots than the negative segregates (Figure 1F). Similar abnormal morphology was also observed in auxin-deficient Arabidopsis (Nakazawa et al, 2001;Takase et al, 2004). GH3-8-overexpressing plants also showed abnormal leaf formation.…”

“…The expressional characteristics of GH3-8 indicate that its function is restricted to vegetative and early reproductive development. Thus, constitutive overexpression of GH3-8 suppressed auxin action, which resulted in abnormal morphology similar to that reported in auxindeficient plants (Nakazawa et al, 2001;Takase et al, 2004). Xoo is a vascular pathogen.…”

MicroRNA-Directed Regulation of ArabidopsisAUXIN RESPONSE FACTOR17Is Essential for Proper Development and Modulates Expression of Early Auxin Response Genes

“…Dominant ydk1-D mutants, which overexpress YDK1, have hypocotyl and root phenotypes (Takase et al, 2004) similar to 5mARF17 plants ( Figure 4M). Both 5mARF17 and ydk1-D plants display reduced primary root length, lateral root number, hypocotyl length, and stature.…”

Modulating plant hormones by enzyme action

“…For AtGH3-2, a gain-of-function mutant ydk1-D was found through a short primary root, reduced lateral root number and reduced apical dominance phenotype. 29 AtGH3-5 appears to be involved in both IAA and salicylic acid (SA) action. 14,30-31 AtGH3-5 was first characterized in a promoter trap line that exhibited light-dependent reporter gene expression 32 and later by the loss-of-function mutant wes1 and two gain-of-function mutants wes1-D and gh3.5-1D.…”