Okushima, Y. et al. Functional genomic analysis of the AUXIN RESPONSE FACTOR gene family members in Arabidopsis thaliana: unique and overlapping functions of ARF7 and ARF19. Plant Cell 17, 444-463

Salk Institute, لا هویا, California, United States
The Plant Cell (Impact Factor: 9.34). 03/2005; 17(2):444-63. DOI: 10.1105/tpc.104.028316
Source: PubMed


The AUXIN RESPONSE FACTOR (ARF) gene family products, together with the AUXIN/INDOLE-3-ACETIC ACID proteins, regulate auxin-mediated transcriptional activation/repression. The biological function(s) of most ARFs is poorly understood. Here, we report the identification and characterization of T-DNA insertion lines for 18 of the 23 ARF gene family members in Arabidopsis thaliana. Most of the lines fail to show an obvious growth phenotype except of the previously identified arf2/hss, arf3/ett, arf5/mp, and arf7/nph4 mutants, suggesting that there are functional redundancies among the ARF proteins. Subsequently, we generated double mutants. arf7 arf19 has a strong auxin-related phenotype not observed in the arf7 and arf19 single mutants, including severely impaired lateral root formation and abnormal gravitropism in both hypocotyl and root. Global gene expression analysis revealed that auxin-induced gene expression is severely impaired in the arf7 single and arf7 arf19 double mutants. For example, the expression of several genes, such as those encoding members of LATERAL ORGAN BOUNDARIES domain proteins and AUXIN-REGULATED GENE INVOLVED IN ORGAN SIZE, are disrupted in the double mutant. The data suggest that the ARF7 and ARF19 proteins play essential roles in auxin-mediated plant development by regulating both unique and partially overlapping sets of target genes. These observations provide molecular insight into the unique and overlapping functions of ARF gene family members in Arabidopsis.

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    • "Zhao et al. (2002) reported that IAA inducible genes such as IAA5 increased in response to CYP79B2 overexpression. However, with the exception of PIN1, there was no detectable variation in the transcript levels of the auxinregulated genes, IAA5, DFL1, LAX1, LAX3, ARF5, PID, and ATR1, in the igi1 mutants (Okushima et al. 2005). PIN1 expression levels decreased in the 25-day-old mutants. "

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    • "In lateral root founder cells, negative regulators of auxin signaling, such as IAA14/Solitary Root (slr) (Fukaki et al., 2002), IAA3/SHY2 (Tian and Reed, 1999), IAA19/Massugu2 (MSG2) (Tatematsu et al., 2004), and IAA28 (Rogg et al., 2001), are first degraded, resulting in the activation of the developmental pathway for lateral root morphogenesis. Downstream of IAA14/SLR are ARF7 and ARF19, which are positive regulators of lateral root formation (Okushima et al., 2005;Weijers et al., 2005;Wilmoth et al., 2005). ARF7 and ARF19 in turn activate LBD16/ASL18 (Okushima et al., 2007), LBD18/ASL20 (Lee et al., 2009), and LBDL29/ASL16 (Feng et al., 2012). "
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    ABSTRACT: Sugars promote lateral root formation at low levels but become inhibitory at high C/N or C/P ratios. How sugars suppress lateral root formation is unclear, however. Here we report that WOX7, a member of the WOX family transcription factors, inhibits lateral root development in a sugar-dependent manner. The number of lateral root primordia increased in wox7 mutants but decreased in plants over-expressing WOX7. Plants expressing the WOX7-VP16 fusion protein produced even more lateral roots than wox7, suggesting that WOX7 acts as a transcriptional repressor in lateral root development. WOX7 is expressed at all stages of lateral root development, but it is primarily involved in lateral root initiation. Consistent with this, the wox7 mutant had a higher mitotic activity only at early stages of lateral root development. Further studies suggest that WOX7 regulates lateral root development through direct repression of cell cycle genes, particularly CYCD6;1. WOX7 expression was enhanced by sugar, reduced by auxin, but did not respond to salt and mannitol. In the wox7 mutant, the effect of sugar on lateral root formation was mitigated. These results together suggest that WOX7 has an important role in coupling the lateral root development program and sugar status in plants.
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    • "The tir1 mutant was obtained from the Arabidopsis Biological Stock Center. The slr and arf7-1 arf19-1 mutants have been described previously (Fukaki et al. 2002; Okushima et al. 2005; Copyright © 2015 The Japanese Society for Plant Cell and Molecular Biology Okushima et al. 2007). After being sterilized for 15 min with 95% ethanol, seeds were sown on a gellan gum plate ( "
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    ABSTRACT: LAZY1 is a protein involved in gravity signaling of shoot gravitropism of rice, maize and Arabidopsis. Although the lazy1 mutants have been well-characterized, the function of the LAZY1 protein is still largely unknown. In this study, we used fluorescence microscopy to examine the subcellular localization of Arabidopsis LAZY1 (AtLAZY1) and its truncated proteins fused to GFP in tobacco leaves. We found that AtLAZY1 localizes to the plasma membrane through the C-terminal region, suggesting that the putative trans-membrane domain in the N-terminal half is not required for localization. Next, we took a biochemical approach to investigate the membrane association of AtLAZY1. Transiently expressed AtLAZY1 in transgenic Arabidopsis was fractionated in an insoluble fraction that contained membranous compartments. AtLAZY1 was solubilized by a non-ionic detergent or at a high pH condition, suggesting that AtLAZY1 is a peripheral membrane protein. We also found that when expressed in tobacco the C-terminal part of AtLAZY1 co-localized with microtubules. A microtubule binding assay showed that the C-terminal half of AtLAZY1, which localized to the plasma membrane, interacted with microtubules in vitro. These results suggest that AtLAZY1 may function with microtubules at the periphery of the plasma membrane in the gravity signaling process.
    Preview · Article · Mar 2015 · Plant Biotechnology
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