yucca6, a Dominant Mutation in Arabidopsis, Affects Auxin Accumulation and Auxin-Related Phenotypes

Abstract

Auxin plays critical roles in many aspects of plant growth and development. Although a number of auxin biosynthetic pathways have been identified, their overlapping nature has prevented a clear elucidation of auxin biosynthesis. Recently, Arabidopsis (Arabidopsis thaliana) mutants with supernormal auxin phenotypes have been reported. These mutants exhibit hyperactivation of genes belonging to the YUCCA family, encoding putative flavin monooxygenase enzymes that result in increased endogenous auxin levels. Here, we report the discovery of fertile dominant Arabidopsis hypertall1-1D and hypertall1-2D (yucca6-1D, -2D) mutants that exhibit typical auxin overproduction phenotypic alterations, such as epinastic cotyledons, increased apical dominance, and curled leaves. However, unlike other auxin overproduction mutants, yucca6 plants do not display short or hairy root phenotypes and lack morphological changes under dark conditions. In addition, yucca6-1D and yucca6-2D have extremely tall (.1 m) inflorescences with extreme apical dominance and twisted cauline leaves. Microarray analyses revealed that expression of several indole-3-acetic acid-inducible genes, including Aux/IAA, SMALL AUXIN-UP RNA, and GH3, is severalfold higher in yucca6 mutants than in the wild type. Tryptophan (Trp) analog feeding experiments and catalytic activity assays with recombinant YUCCA6 indicate that YUCCA6 is involved in a Trp-dependent auxin biosynthesis pathway. YUCCA6:GREEN FLUORESCENT PROTEIN fusion protein indicates YUCCA6 protein exhibits a nonplastidial subcellular localization in an unidentified intracellular compartment. Taken together, our results identify YUCCA6 as a functional member of the YUCCA family with unique roles in growth and development.

Leaf Epinasty in Chrysanthemum: Enabling Breeding Against an Adverse Trait by Physiological Research

“…This process cannot explain directly the phenomenon of leaf epinasty, but indicates the tight relationship between light, auxin metabolism and differential growth. Next to that, the suggestion that auxin is involved is supported by findings that application of auxins exogenously could induce leaf epinasty (Keller and VanVolkenburgh, 1997;Jones et al, 1998;Keller and Van Volkenburgh, 1998;Keller, 2007) and that auxin-overproducing plants show a similar type of same leaf epinasty (Klee et al, 1987;Romano et al, 1993;Romano et al, 1995;Kim et al, 2007).…”

Recognition of AvrBs3-Like Proteins Is Mediated by Specific Binding to Promoters of Matching Pepper Bs3 Alleles

“…Overexpression of YUCCA-like genes leads to phenotypes characteristic of auxin-overproducing mutants but not to an HR, as in the case of the Bs3 cds (Zhao et al, 2001;Kim et al, 2007;Rö mer et al, 2007). Hence, YUCCA-like proteins and Bs3 are functionally distinct.…”

A transcriptional view on somatic embryogenesis

“…The importance of endogenous auxin production for 2,4‐D‐induced SE was demonstrated using yuc knockout mutants, which show a reduced response in 2,4‐D‐treated secondary somatic embryo cultures (Bai, Su, Yuan, & Zhang, 2013; Wojcikowska et al., 2013), but its significance for LEC‐induced SE is not known. YUC overexpression in seedlings is not sufficient to trigger spontaneous SE in seedlings, but rather induces epinastic cotyledon growth (Cheng, Dai, & Zhao, 2006; Kim et al., 2007; Woodward et al., 2005), a typical auxin overproduction phenotype. This suggests that the competence of the underlying tissue is an important determinant for SE induction.…”