Functional Genomic Analysis of theAUXIN/INDOLE-3-ACETIC ACIDGene Family Members inArabidopsis thaliana [W]

Abstract

Auxin regulates various aspects of plant growth and development. The AUXIN/INDOLE-3-ACETIC ACID (Aux/IAA) genes encode short-lived transcriptional repressors that are targeted by the TRANSPORT INHIBITOR RESPONSE1/AUXIN RECEPTOR F-BOX proteins. The Aux/IAA proteins regulate auxin-mediated gene expression by interacting with members of the AUXIN RESPONSE FACTOR protein family. Aux/IAA function is poorly understood; herein, we report the identification and characterization of insertion mutants in 12 of the 29 Aux/IAA family members. The mutants show no visible developmental defects compared with the wild type. Double or triple mutants of closely related Aux/IAA genes, such as iaa8-1 iaa9-1 or iaa5-1 iaa6-1 iaa19-1, also exhibit wild-type phenotypes. Global gene expression analysis reveals that the molecular phenotypes of auxin-treated and untreated light-grown seedlings are unaffected in the iaa17-6 and iaa5-1 iaa6-1 iaa19-1 mutants. By contrast, similar analysis with the gain-of-function axr3-1/iaa17-1 mutant seedlings reveals dramatic changes in basal and auxin-induced gene expression compared with the wild type. Expression of several type-A ARABIDOPSIS RESPONSE REGULATOR genes and a number of genes involved in cell wall biosynthesis and degradation is repressed in axr3-1/iaa17-1. The data suggest extensive functional redundancy among Aux/IAA gene family members and that enhanced stability of the AXR3/IAA17 protein severely alters the molecular phenotype, resulting in developmental defects.

Global Expression Profiling Applied to the Analysis of Arabidopsis Stamen Development

“…Two of the T-DNA insertion lines (for genes At2g40850 and At5g62320) and one of the RNAi lines (for gene At2g42940) showed specific defects in microspore formation, while all others had no discernable mutant phenotypes. The lack of a mutant phenotype for most of the genes we analyzed by reverse genetics is likely a consequence of the high degree of functional redundancy found in Arabidopsis, especially among duplicated genes (Nawy et al, 2005;Overvoorde et al, 2005). In fact, for most of the genes tested, we found paralogs in the Arabidopsis genome (data not shown).…”

Large-scale analysis of the GRAS gene family in Arabidopsis thaliana

“…After the completion of sequencing of the Arabidopsis genome, there have been several large-scale analyses of the Arabidopsis TFs (Czechowski et al 2004;Gong et al 2004;Tian et al 2004;Guo et al 2005;Iida et al 2005;Okushima et al 2005;Overvoorde et al 2005). Previously, functional genomic analyses on two well-known transcription regulator gene families, AUXIN RESPONSE FACTOR (ARF) and AUXIN/INDOLE-3-ACETIC ACID (AUX/IAA), provided insights into the unique and overlapping functions of the members of these two families Overvoorde et al 2005).…”

“…Previously, functional genomic analyses on two well-known transcription regulator gene families, AUXIN RESPONSE FACTOR (ARF) and AUXIN/INDOLE-3-ACETIC ACID (AUX/IAA), provided insights into the unique and overlapping functions of the members of these two families Overvoorde et al 2005).…”

“…However, our knowledge of the biological roles and the biochemical properties of the majority of Arabidopsis TFs are fragmented. In recent years, there have been various attempts to analyzing the Arabidopsis TFs at a large scale (Czechowski et al 2004;Gong et al 2004;Tian et al 2004;Guo et al 2005;Iida et al 2005;Okushima et al 2005;Overvoorde et al 2005).…”

Root system architecture: insights fromArabidopsisand cereal crops

“…This control is achieved by fine-tuning the auxin response pathway through AUX/IAA-ARF pairs. Different combinations of these partially account for the diversity in phenotypic responses generated in response to a generic auxin signal [54,55]. SLR/IAA14 paired with ARF7-ARF19 is one such auxin response module, which directs transcription of the early auxin response LATERAL ORGAN BOUNDARIES/ASYM-METRIC LEAVES-LIKE (LBD/ASL) genes, which encode transcription factors for a set of genes controlling cell proliferation and patterning.…”