EIN2 regulates salt stress response and interacts with a MA3 domain‐containing protein ECIP1 in Arabidopsis

Abstract

Ethylene signalling regulates plant growth and development. However, its roles in salt stress response are less known. Here we studied functions of EIN2, a central membrane protein of ethylene signalling, and its interacting protein ECIP1 in salt stress responses. Mutation of EIN2 led to extreme salt sensitivity as revealed by phenotypic and physiological changes, and overexpression of C-terminus of EIN2 suppressed salt sensitivity in ein2-5, indicating that EIN2 is required for salt tolerance. Downstream components EIN3 and EIL1 are also essential for salt tolerance because ein3-1eil1-1 double mutant showed extreme saltsensitive phenotype. A MA3 domain-containing protein ECIP1 was further identified to interact with EIN2 in yeast two-hybrid assay and GST pull-down assay. Loss-offunction of ECIP1 resulted in enhanced ethylene response but altered salt response during seed germination and plant growth. Double mutant analysis revealed that ein2-1 was epistatic to ecip1, and ecip1 mutation partially suppressed ethylene-insensitivity of etr2-1 and ein4-1. These studies strengthen that interactions between ECIP1 and EIN2 or ethylene receptors regulate ethylene response and stress response.

MRF Family Genes Are Involved in Translation Control, Especially under Energy-Deficient Conditions, and Their Expression and Functions Are Modulated by the TOR Signaling Pathway

“…The Arabidopsis genome contains four genes encoding PDCD4 homologs, and one of them was recently reported to interact with the ethylene signaling protein EIN2; hence, it was designated ECIP1 (EIN2 C TERMINUS-INTERACTING PROTEIN1; AT4G24800). Loss-of-function mutations in ECIP1 have been shown to result in ethylene hypersensitivity (Lei et al, 2011). Apart from these findings, we lack evidence of the cellular functions of these homologs.…”

“…RT-PCR analyses showed that mrf3-2 (ecip1-1) is a null allele, while mrf3-3 (ecip1-2) produces a truncated MRF3 mRNA (Supplemental Figures 3D and 3E;Lei et al, 2011). mrf3-1 has a T-DNA insertion in the promoter region, resulting in a slight decrease in MRF3 mRNA.…”

“…Three T-DNA insertion mutant lines were available for MRF3 (Supplemental Figure 3A); mrf3-3 and mrf3-2 alleles had been previously identified and designated ecip1-1 and ecip1-2, respectively (Lei et al, 2011). RT-PCR analyses showed that mrf3-2 (ecip1-1) is a null allele, while mrf3-3 (ecip1-2) produces a truncated MRF3 mRNA (Supplemental Figures 3D and 3E;Lei et al, 2011).…”

Ethylene Response Factors: A Key Regulatory Hub in Hormone and Stress Signaling

“…In the presence of ethylene, the inactivation of the receptors and CTR1 results in the dephosphorylation and cleavage of the EIN2 C terminus and translocation to the nucleus, where it directly or indirectly regulates EIN3/EIL1 activation (Ju et al, 2012). An MA3 domain-containing protein (ECIP1) interacts with the EIN2 C terminus, leading to enhanced ethylene response (Lei et al, 2011). In the absence of ethylene, the EIN3/EIL1 protein levels are extremely low because of the protein turnover involving the F-box proteins Ethylene Insensitive3-Binding F-Box Protein1 (EBF1) and EBF2.…”

Overexpression of <em>AmRosea1 </em>Gene Confers Drought and Salt Tolerance in Rice

“…Rice has a different ethylene response phenotype in comparison with Arabidopsis and the other monocotyledonous species tested [48]. Meanwhile, unlike the positive roles of EIN2 and EIN3 in salinity response in Arabidopsis, the main positive ethylene signaling components MHZ7/OsEIN2, MHZ6/OsEIL1, and OsEIL2 all negatively regulate the salinity-tolerance of rice seedlings [48][49][50][51][52][53]. In this study, one of component of EBF1/2, EBF1 (Os06t0605900-01) was up-regulated under both drought and salt treatments compared with WT.…”