Ethylene Stimulates Nutations That Are Dependent on the ETR1 Receptor

Abstract

Ethylene influences a number of processes in Arabidopsis (Arabidopsis thaliana) through the action of five receptors. In this study, we used high-resolution, time-lapse imaging to examine the long-term effects of ethylene on growing, etiolated Arabidopsis seedlings. These measurements revealed that ethylene stimulates nutations of the hypocotyls with an average delay in onset of over 6 h. The nutation response was constitutive in ctr1-2 mutants maintained in air, whereas ein2-1 mutants failed to nutate when treated with ethylene. Ethylene-stimulated nutations were also eliminated in etr1-7 loss-of-function mutants. Transformation of the etr1-7 mutant with a wild-type genomic ETR1 transgene rescued the nutation phenotype, further supporting a requirement for ETR1. Loss-of-function mutations in the other receptor isoforms had no effect on ethylene-stimulated nutations. However, the double ers1-2 ers2-3 and triple etr2-3 ers2-3 ein4-4 loss-of-function mutants constitutively nutated in air. These results support a model where all the receptors are involved in ethylene-stimulated nutations, but the ETR1 receptor is required and has a contrasting role from the other receptor isoforms in this nutation phenotype. Naphthylphthalamic acid eliminated ethylenestimulated nutations but had no effect on growth inhibition caused by ethylene, pointing to a role for auxin transport in the nutation phenotype.

Differential Control of Ethylene Responses byGREEN-RIPEandGREEN-RIPE LIKE1Provides Evidence for Distinct Ethylene Signaling Modules in Tomato

“…For example, EIN3 and EIL1 proteins act semiredundantly to influence separate ethylene responses associated with seedling growth and stem and leaf expansion in Arabidopsis, and individual ETH-YLENE RESPONSE FACTOR genes mediate distinct responses to environmental stress (Hattori et al, 2009;An et al, 2010;Zhang et al, 2011). Subfunctionalization also occurs at the level of the ethylene receptors, with specific or more prevalent roles for individual receptors and receptor subfamilies identified, even though, in general, the ethylene receptors act redundantly (Tieman et al, 2000;Binder et al, 2006Binder et al, , 2012Qu et al, 2007;Plett et al, 2009;Wuriyanghan et al, 2009).…”

“…Loss-of-function analyses indicate that the receptors act in a semiredundant manner to negatively regulate ethylene responses, although the ETR1 receptor appears to play more of a significant role in mediating ethylene responses than the other Arabidopsis receptors Cancel and Larsen, 2002;Hall and Bleecker, 2003;Wang et al, 2003;Binder et al, 2006;Qu et al, 2007). In the absence of ethylene, the receptors actively suppress downstream responses through direct binding of CONSTITUTIVE TRIPLE RESPONSE1 (CTR1), a Ser/Thr mitogen-activated protein kinase kinase kinase that acts as a negative regulator of the pathway (Kieber et al, 1993;Clark et al, 1998;Gao et al, 2003;Huang et al, 2003).…”

Identification of Regions in the Receiver Domain of the ETHYLENE RESPONSE1 Ethylene Receptor of Arabidopsis Important for Functional Divergence

“…signaling-independent roles (Gamble et al, 1998;Beaudoin et al, 2000;Desikan et al, 2005;Binder et al, 2006;Wilson et al, 2014aWilson et al, , 2014b, which may underlie these observations. Determining the basis for noncanonical receptor signaling is of wide interest because noncanonical signal transduction has been observed in other signal transduction pathways, including Hedgehog and Wingless/int-1) signaling in animal cells (Jenkins, 2009;Miller and McCrea, 2010) and quorum sensing in bacteria (Federle and Bassler, 2003).…”

“…The etr1-6;etr2-3;ein4-4 triple mutants and the triple mutants transformed with gETR1, cETR1, D659A, cetr1-DR, and 1114 have previously been described Wang et al, 2003;Binder et al, 2004bBinder et al, , 2006Kim et al, 2011). The D659A mutant was previously referred to as getr1-[D] (Binder et al, 2004b;Kim et al, 2011).…”

Dissecting the Role of CHITINASE-LIKE1 in Nitrate-Dependent Changes in Root Architecture

“…Mutants in the ethylene perception and signaling pathway, like constitutive triple response (Gao et al, 2003;Huang et al, 2003;, ethylene receptor1 (etr1/ein1; Binder et al, 2006), ethylene insensitive2 (ein2; Alonso et al, 1999), and ein7 (Roman et al, 1995), as well as ethylene overproducers like ethylene overproducer2 (eto2; Vogel et al, 1998) and eto3 (Chae et al, 2003), were plated on moderate (6 mM) and high (60 mM) nitrate concentrations ( Fig. 1; Supplemental Fig.…”