AUTHOR=Wu Junpeng , Zong Yaxian , Tu Zhonghua , Yang Lichun , li Wei , Cui Zhengkun , Hao Ziyuan , Li Huogen 

TITLE=Genome-wide identification of XTH genes in Liriodendron chinense and functional characterization of LcXTH21

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.1014339

DOI=10.3389/fpls.2022.1014339

ISSN=1664-462X

ABSTRACT=<p><italic>Liriodendron chinense</italic> is a relic tree species of the family Magnoliaceae with multiple uses in timber production, landscape decoration, and afforestation. <italic>L. chinense</italic> often experiences drought stress in arid areas. However, the molecular basis underlying the drought response of <italic>L. chinense</italic> remains unclear. Many studies have reported that the xyloglucan endotransglucosylase/hydrolase (<italic>XTH</italic>)  family plays an important role in drought stress resistance. Hereby, to explore the drought resistance mechanism of <italic>L. chinense</italic>, we identify <italic>XTH</italic> genes on a genome-wide scale in <italic>L. chinense</italic>. A total of 27 <italic>XTH</italic> genes were identified in <italic>L. chinense</italic>, and these genes were classified into three subfamilies. Drought treatment and RT-qPCR analysis revealed that six <italic>LcXTH</italic> genes significantly responded to drought stress, especially <italic>LcXTH21</italic>. Hence, we cloned the <italic>LcXTH21</italic> gene and overexpressed it in tobacco <italic>via</italic> gene transfer to analyze its function. The roots of transgenic plants were more developed than those of wild-type plants under different polyethylene glycol (PEG) concentration, and further RT-qPCR analysis showed that <italic>LcXTH21</italic> highly expressed in root compared to aboveground organs, indicating that <italic>LcXTH21</italic> may play a role in drought resistance through promoting root development. The results of this study provide new insights into the roles of <italic>LcXTH</italic> genes in the drought stress response. Our findings will also aid future studies of the molecular mechanisms by which <italic>LcXTH</italic> genes contribute to the drought response.</p>