AUTHOR=Wen Lichao , Liu Tao , Deng Zhichao , Zhang Zenglin , Wang Qi , Wang Weifeng , Li Wei , Guo Yongfeng 

TITLE=Characterization of NAC transcription factor NtNAC028 as a regulator of leaf senescence and stress responses

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.941026

DOI=10.3389/fpls.2022.941026

ISSN=1664-462X

ABSTRACT=<p>NAC proteins constitute one of the largest transcription factor families and are involved in regulation of plant development and stress responses. Our previous transcriptome analyses of tobacco revealed a significant increase in the expression of <italic>NtNAC028</italic> during leaf yellowing. In this study, we found that <italic>NtNAC028</italic> was rapidly upregulated in response to high salinity, dehydration, and abscisic acid (ABA) stresses, suggesting a vital role of this gene in abiotic stress response. <italic>NtNAC028</italic> loss-of-function tobacco plants generated <italic>via</italic> CRISPR-Cas9 showed delayed leaf senescence and increased tolerance to drought and salt stresses. Meanwhile <italic>NtNAC028</italic> overexpression led to precocious leaf senescence and hypersensitivity to abiotic stresses in <italic>Arabidopsis</italic>, indicating that <italic>NtNAC028</italic> functions as a positive regulator of natural leaf senescence and a negative regulator of stress tolerance. Furthermore, <italic>NtNAC028</italic>-overexpressing <italic>Arabidopsis</italic> plants showed lower antioxidant enzyme activities, higher reactive oxygen species (ROS), and H<sub>2</sub>O<sub>2</sub> accumulation under high salinity, resulted in more severe oxidative damage after salt stress treatments. On the other hand, <italic>NtNAC028</italic> mutation in tobacco resulted in upregulated expression of ROS-scavenging and abiotic stress-related genes, higher antioxidant enzyme activities, and enhanced tolerance against abiotic stresses, suggesting that <italic>NtNAC028</italic> might act as a vital regulator for plant stress response likely by mediating ROS scavenging ability. Collectively, our results indicated that the <italic>NtNAC028</italic> plays a key regulatory role in leaf senescence and response to multiple abiotic stresses.</p>