AUTHOR=Khedia Jackson , Agarwal Parinita , Agarwal Pradeep K. 

TITLE=AlNAC4 Transcription Factor From Halophyte Aeluropus lagopoides Mitigates Oxidative Stress by Maintaining ROS Homeostasis in Transgenic Tobacco

JOURNAL=Frontiers in Plant Science

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2018.01522

DOI=10.3389/fpls.2018.01522

ISSN=1664-462X

ABSTRACT=<p>NAC proteins are a large family of plant-specific transcription factors which regulate both ABA-dependent and -independent gene expression. These transcription factors participate in biotic and abiotic stress-response through intricate regulation at transcriptional, post-transcriptional and post-translational levels. In the present study, AlNAC4 transcription factor was isolated from a salt excreting halophyte <italic>Aeluropus lagopoides</italic>. The <italic>AlNAC4</italic> has an open reading frame of 936 bp, encoding a protein of 312 amino acid, with an estimated molecular mass of 34.9 kDa. The <italic>AlNAC4</italic> showed close homology to monocot NACs in the phylogenetic tree. <italic>In silico</italic> analysis revealed that AlNAC4 possess the characteristic A-E subdomains within the NAC domain. The AlNAC4 showed sixteen post-translational phosphorylation sites. The <italic>AlNAC4</italic> transcript was significantly upregulated with dehydration and H<sub>2</sub>O<sub>2</sub> treatments, showing its role in osmotic and oxidative stress, respectively. The recombinant protein showed binding to mono as well as tandem repeats of NAC recognition sequence (NACRS) of the <italic>erd1</italic> promoter. This is the first report mentioning that overexpression of <italic>AlNAC4</italic> improved oxidative stress tolerance in tobacco transgenics. The transgenics maintained ROS homeostasis during H<sub>2</sub>O<sub>2</sub> treatment. The transgenics showed regulation of stress-responsive genes including <italic>CAT, SOD</italic>, <italic>LEA5</italic>, <italic>PLC3</italic>, <italic>ERD10B</italic>, <italic>THT1</italic> and transcription factors like <italic>AP2</italic>, <italic>ZFP</italic> during oxidative stress.</p><p><bold>Key Message:</bold> The AlNAC4 transcription factor from recretohalophyte Aeluropus showed regulation with abiotic stresses and binding to NACRS elements of <italic>erd1</italic> promoter. The <italic>AlNAC4</italic> tobacco transgenics showed improved growth with oxidative stress.</p>