AUTHOR=Zhou Yuanyuan , Zhai Hong , He Shaozhen , Zhu Hong , Gao Shaopei , Xing Shihan , Wei Zihao , Zhao Ning , Liu Qingchang 

TITLE=The Sweetpotato BTB-TAZ Protein Gene, IbBT4, Enhances Drought Tolerance in Transgenic Arabidopsis

JOURNAL=Frontiers in Plant Science

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2020.00877

DOI=10.3389/fpls.2020.00877

ISSN=1664-462X

ABSTRACT=<p>BTB-TAZ (BT)-domain proteins regulate plant development and pathogen defense. However, their roles in resistance to abiotic stresses remain largely unknown. In this study, we found that the sweetpotato BT protein-encoding gene <italic>IbBT4</italic> significantly enhanced the drought tolerance of <italic>Arabidopsis</italic>. <italic>IbBT4</italic> expression was induced by PEG6000, H<sub>2</sub>O<sub>2</sub> and brassinosteroids (BRs). The <italic>IbBT4</italic>-overexpressing <italic>Arabidopsis</italic> seeds presented higher germination rates and longer roots in comparison with those of WT under 200 mM mannitol stress. Under drought stress the transgenic <italic>Arabidopsis</italic> plants exhibited significantly increased survival rates and BR and proline contents and decreased water loss rates, MDA content and reactive oxygen species (ROS) levels. <italic>IbBT4</italic> overexpression upregulated the BR signaling pathway and proline biosynthesis genes and activated the ROS-scavenging system under drought stress. Yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays revealed that the IbBT4 protein interacts with BR-ENHANCED EXPRESSION 2 (BEE2). Taken together, these results indicate that the <italic>IbBT4</italic> gene provides drought tolerance by enhancing both the BR signaling pathway and proline biosynthesis and further activating the ROS-scavenging system in transgenic <italic>Arabidopsis</italic>.</p>