AUTHOR=Chen Meixia , She Zeyuan , Aslam Mohammad , Liu Ting , Wang Zerong , Qi Jianmin , Niu Xiaoping 

TITLE=Genomic insights of the WRKY genes in kenaf (Hibiscus cannabinus L.) reveal that HcWRKY44 improves the plant’s tolerance to the salinity stress

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.984233

DOI=10.3389/fpls.2022.984233

ISSN=1664-462X

ABSTRACT=<p>The WRKY transcription factors (TFs) are among the most diverse TF families of plants. They are implicated in various processes related to plant growth and stress response. Kenaf (<italic>Hibiscus cannabinus</italic> L.), an important fiber crop, has many applications, including the phytoremediation of saline-alkaline soil. However, the roles of WRKY TFs in kenaf are rarely studied. In the present study, 46 kenaf WRKY genes were genome-widely identified and characterized by gene structure, phylogeny and expression pattern analysis. Furthermore, the <italic>HcWRKY44</italic> gene was functionally characterized in <italic>Arabidopsis</italic> under salinity and drought stresses. HcWRKY44 is a nuclear-localized protein that is positively induced by salinity and drought, with roots showing maximum accumulation of its transcripts. Under NaCl and abscisic acid (ABA) stress conditions, plants overexpressing <italic>HcWRKY44</italic> had higher germination rates, better root growth and increased survival than control plants; however, it did not improve the ability to withstand drought stress. Moreover, ABA signaling genes (<italic>ABI1</italic>, <italic>ABI2</italic>, and <italic>ABI5</italic>), ABA-responsive genes (<italic>ABF4</italic>, <italic>RD29B</italic>, <italic>COR15A</italic>, <italic>COR47</italic>, and <italic>RD22</italic>), stress-related genes (<italic>STZ</italic>, <italic>P5CS</italic>, and <italic>KIN1</italic>), and ionic homeostasis-related genes (<italic>SOS1</italic>, <italic>AHA1</italic>, <italic>AHA2</italic>, and <italic>HKT1</italic>) were positively induced in <italic>HcWRKY44</italic> transgenic plants under NaCl treatment. These results suggest that <italic>HcWRKY44</italic> improved plant’s tolerance to salt stress but not osmotic stress through an ABA-mediated pathway. In summary, this study provides provided comprehensive information about <italic>HcWRKY</italic> genes and revealed that <italic>HcWRKY44</italic> is involved in salinity tolerance and ABA signaling.</p>