Salt-Induced Stabilization of EIN3/EIL1 Confers Salinity Tolerance by Deterring ROS Accumulation in Arabidopsis

Abstract

Ethylene has been regarded as a stress hormone to regulate myriad stress responses. Salinity stress is one of the most serious abiotic stresses limiting plant growth and development. But how ethylene signaling is involved in plant response to salt stress is poorly understood. Here we showed that Arabidopsis plants pretreated with ethylene exhibited enhanced tolerance to salt stress. Gain- and loss-of-function studies demonstrated that EIN3 (ETHYLENE INSENSITIVE 3) and EIL1 (EIN3-LIKE 1), two ethylene-activated transcription factors, are necessary and sufficient for the enhanced salt tolerance. High salinity induced the accumulation of EIN3/EIL1 proteins by promoting the proteasomal degradation of two EIN3/EIL1-targeting F-box proteins, EBF1 and EBF2, in an EIN2-independent manner. Whole-genome transcriptome analysis identified a list of SIED (Salt-Induced and EIN3/EIL1-Dependent) genes that participate in salt stress responses, including several genes encoding reactive oxygen species (ROS) scavengers. We performed a genetic screen for ein3 eil1-like salt-hypersensitive mutants and identified 5 EIN3 direct target genes including a previously unknown gene, SIED1 (At5g22270), which encodes a 93-amino acid polypeptide involved in ROS dismissal. We also found that activation of EIN3 increased peroxidase (POD) activity through the direct transcriptional regulation of PODs expression. Accordingly, ethylene pretreatment or EIN3 activation was able to preclude excess ROS accumulation and increased tolerance to salt stress. Taken together, our study provides new insights into the molecular action of ethylene signaling to enhance plant salt tolerance, and elucidates the transcriptional network of EIN3 in salt stress response.

ZINC FINGER OF ARABIDOPSIS THALIANA12 (ZAT12) Interacts with FER-LIKE IRON DEFICIENCY-INDUCED TRANSCRIPTION FACTOR (FIT) Linking Iron Deficiency and Oxidative Stress Responses

“…In this respect, the possibility exists that the positive or negative regulation of Fe uptake depends on a competition between the positive regulators EIN3/EIL1 and the negative regulator ZAT12 for the same interaction site in the C terminus of FIT. Additionally, the ZAT12 promoter is a direct target of EIN3 (Peng et al, 2014), which hints toward the existence of multiple level connections between the regulators involved in the FIT interaction network.…”

“…zat12 loss-of-function plants exhibited higher sensitivity to light, H 2 O 2 , salinity, osmotic, and heat stress, whereas overexpression of ZAT12 conferred tolerance to high-light, oxidative, osmotic, and cold stress (Rizhsky et al, 2004;Davletova et al, 2005b;Vogel et al, 2005). ZAT12 was identified as a direct target of EIN3, and ZAT12 transcript levels were up-regulated in EIN3ox (Peng et al, 2014).…”

The LSM1-7 Complex Differentially Regulates Arabidopsis Tolerance to Abiotic Stress Conditions by Promoting Selective mRNA Decapping

“…The top 1000 downregulated genes in mutant plants showed at least 2.1-fold lower expression levels than in the wild type (Supplemental Data Set 11). Strikingly, 457 (45.7%) of these genes were salt induced (Kilian et al, 2007) (Supplemental Data Set 12), and some of them, including DFR, PHI1, or CNI1, have been described to be positive regulators of Arabidopsis tolerance to high salt (Cui et al, 2014;Peng et al, 2014). qPCR experiments confirmed that the expression of these and other salt-regulated genes was lower in lsm1a lsm1b than in wild-type plants after salt treatment, validating once again the RNA-seq data ( Figure 3D).…”

Mechanistic Insights in Ethylene Perception and Signal Transduction

“…3A). High salinity enhances proteasomal degradation of F-box proteins EBF1/2, resulting in the accumulation of EIN3/EIL1 proteins, which then activate expression of salt tolerance genes Zhang et al, 2011;Peng et al, 2014), as well as peroxidase genes whose products scavenge reactive oxygen species to reduce the damage imposed by high salt (Peng et al, 2014).…”