DFL2, a New Member of the Arabidopsis GH3 Gene Family, is Involved in Red Light-Specific Hypocotyl Elongation

Abstract

A new GH3-related gene, designated DFL2, causes a short hypocotyl phenotype when overexpressed under red and blue light and a long hypocotyl when antisensed under red light conditions. Higher expression of this gene was observed in continuous white, blue and far-red light but the expression level was low in red light and darkness. DFL2 gene expression was induced transiently with red light pulse treatment. DFL2 transgenic plants exhibited a normal root phenotype including primary root elongation and lateral root formation, although primary root elongation was inhibited in antisense transgenic plants only under red light. The adult phenotypes of sense and antisense transgenic plants were not different from that of wild type. DFL2 promoter activity was observed in the hypocotyl. Our results suggest that DFL2 is located downstream of red light signal transduction and determines the degree of hypocotyl elongation.

GH3-mediated Auxin Homeostasis Links Growth Regulation with Stress Adaptation Response in Arabidopsis

“…1A), and to those of dfl1-D, dfl2-D, and ydk1-D, in which auxin-inducible GH3 genes are overexpressed (22)(23)(24). In contrast, a T-DNA insertional mutant, wes1, was phenotypically indistinguishable from wild type plants but with slightly larger leaves (ϳ6 -7% increase; Fig.…”

“…Several GH3 genes have been studied using mutants with altered gene expression. GH3-overexpressing mutants, such as dfl1-D (22), dfl2-D (23), and ydk1-D (24), display reduced growth and altered light responses, suggesting a role for these GH3 proteins in light-auxin interactions. Recently, the GH3 proteins have been biochemically characterized.…”

Modulating plant hormones by enzyme action

“…27 The other group I GH3 in Arabidopsis, AtGH3-10, is associated with the dfl2 mutant and is involved in red lightspecific hypocotyl elongation, but no enzymatic activity has been reported for this protein. 28 a majority of GH3 proteins in plants remains uncharacterized.…”

Arabidopsis thalianaGH3.9 in Auxin and Jasmonate Cross Talk

“…8,9 Other Group II GH3 gene family members influence primary root growth, hypocotyl elongation, apical dominance, leaf formation and stress responses. [10][11][12][13] No obvious morphological alterations in the aerial tissues were observed in gh3.9 mutants, possibly due to functional redundancy. However, the gh3.9-1 mutant, GH3.9 RNAi transgenics, and additional T-DNA insertion mutants displayed a long-root phenotype, moderate sensitivity to IAA-mediated root growth inhibition, and moderate resistance to MeJA-mediated root growth inhibition.…”