Salinity Stress-Mediated Suppression of Expression of Salt Overly Sensitive Signaling Pathway Genes Suggests Negative Regulation by AtbZIP62 Transcription Factor in Arabidopsis thaliana.

Nkulu Kabange Rolly,Qari Muhammad Imran,Byung-Wook Yun,In-Jung Lee

doi:10.3390/ijms21051726

Nkulu Kabange Rolly, Qari Muhammad Imran + Show 2 more

Open Access

https://doi.org/10.3390/ijms21051726

Copy DOI

Abstract

Salt stress is one of the most serious threats in plants, reducing crop yield and production. The salt overly sensitive (SOS) pathway in plants is a salt-responsive pathway that acts as a janitor of the cell to sweep out Na+ ions. Transcription factors (TFs) are key regulators of expression and/or repression of genes. The basic leucine zipper (bZIP) TF is a large family of TFs regulating various cellular processes in plants. In the current study, we investigated the role of the Arabidopsis thaliana bZIP62 TF in the regulation of SOS signaling pathway by measuring the transcript accumulation of its key genes such as SOS1, 2, and 3, in both wild-type (WT) and atbzip62 knock-out (KO) mutants under salinity stress. We further observed the activation of enzymatic and non-enzymatic antioxidant systems in the wild-type, atbzip62, atcat2 (lacking catalase activity), and atnced3 (lacking 9-cis-epoxycarotenoid dioxygenase involved in the ABA pathway) KO mutants. Our findings revealed that atbzip62 plants exhibited an enhanced salt-sensitive phenotypic response similar to atnced3 and atcat2 compared to WT, 10 days after 150 mM NaCl treatment. Interestingly, the transcriptional levels of SOS1, SOS2, and SOS3 increased significantly over time in the atbzip62 upon NaCl application, while they were downregulated in the wild type. We also measured chlorophyll a and b, pheophytin a and b, total pheophytin, and total carotenoids. We observed that the atbzip62 exhibited an increase in chlorophyll and total carotenoid contents, as well as proline contents, while it exhibited a non-significant increase in catalase activity. Our results suggest that AtbZIP62 negatively regulates the transcriptional events of SOS pathway genes, AtbZIP18 and AtbZIP69 while modulating the antioxidant response to salt tolerance in Arabidopsis.

Highlights

Salinity stress is one of the major challenges threatening food security and restricting crop productivity [1,2,3,4]
Despite being involved in the positive regulation of plant responses to salinity by controlling the Na+/H+ exchange rate, SOS1, SOS2, and SOS3 transcript accumulations were found to be negatively regulated by AtbZIP62 Transcription factors (TFs) per the transcriptional patterns recorded in the atbzip62 loss-of-function mutant exposed to salt stress conditions
The current study investigated the role the Arabidopsis AtbZIP62 encoding a transcription factor in modulating the transcriptional events of the salt overly sensitive pathway genes in response to salt stress

Summary

Introduction

Salinity stress is one of the major challenges threatening food security and restricting crop productivity [1,2,3,4]. This abiotic stress affects the agricultural sector on a global scale. Salt stress induction leads to impaired plant growth and development (i.e., reduced rate of leaf surface expansion, cessation of expansion with the intensification of stress), crop failure, and cytotoxicity due to excessive ions, such as from sodium uptake and nutritional imbalance [5,6]. To cope with salt stress conditions, plants acquired diverse mechanisms that function to maintain a balanced reduction-oxidation state, reduced cellular hyperosmolarity, and ion disequilibrium [7]. Salt stress involves the induction of signals that are influenced by diverse signaling pathways [8,9,10,11,12]

Methods

Results

Discussion

Conclusion