AUTHOR=Yuan Guang , Nong Tongjia , Hunpatin Oluwaseyi Setonji , Shi Chuhan , Su Xiaoqing , Xu Fangzheng , Wang Yihui , Zhang Zhaoting , Ning Yang , Liu Haobao , Wang Qian 

TITLE=Genome-wide identification of Shaker K+ channel family in Nicotiana tabacum and functional analysis of NtSKOR1B in response to salt stress

JOURNAL=Frontiers in Plant Science

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2024.1378738

DOI=10.3389/fpls.2024.1378738

ISSN=1664-462X

ABSTRACT=<p>Soil salinization poses a mounting global ecological and environmental threat. The identification of genes responsible for negative regulation of salt tolerance and their utilization in crop improvement through gene editing technologies emerges as a swift strategy for the effective utilization of saline-alkali lands. One efficient mechanism of plant salt tolerance is maintaining the proper intracellular K<sup>+</sup>/Na<sup>+</sup> ratio. The Shaker K<sup>+</sup> channels play a crucial role in potassium absorption, transport, and intracellular potassium homeostasis in plant cells. Here, the study presents the first genome-wide identification of Shaker K<sup>+</sup> channels in <italic>Nicotiana tabacum</italic> L., along with a detailed bioinformatic analysis of the 20 identified members. Transcriptome analysis revealed a significant up-regulation of <italic>NtSKOR1B</italic>, an outwardly-rectifying member predominantly expressed in the root tissue of tobacco seedlings, in response to salt stress. This finding was then confirmed by GUS staining of <italic>ProNtSKOR1B::GUS</italic> transgenic lines and RT-qPCR analysis. Subsequently, <italic>NtSKOR1B</italic> knockout mutants (<italic>ntskor1</italic>) were then generated and subjected to salt conditions. It was found that <italic>ntskor1</italic> mutants exhibit enhanced salt tolerance, characterized by increased biomass, higher K<sup>+</sup> content and elevated K<sup>+</sup>/Na<sup>+</sup> ratios in both leaf and root tissues, compared to wild-type plants. These results indicate that <italic>NtSKOR1B</italic> knockout inhibits K<sup>+</sup> efflux in root and leaf tissues of tobacco seedlings under salt stress, thereby maintaining higher K<sup>+</sup>/Na<sup>+</sup> ratios within the cells. Thus, our study identifies <italic>NtSKOR1B</italic> as a negative regulator of salt tolerance in tobacco seedlings.</p>