AUTHOR=Bai Xiaotao , Xu Jianmei , Shao Xuemin , Luo Wenchun , Niu Zhimin , Gao Chengyu , Wan Dongshi 

TITLE=A Novel Gene Coding γ-Aminobutyric Acid Transporter May Improve the Tolerance of Populus euphratica to Adverse Environments

JOURNAL=Frontiers in Plant Science

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2019.01083

DOI=10.3389/fpls.2019.01083

ISSN=1664-462X

ABSTRACT=<p>Novel genes provide important genetic resource for organism innovation. However, the evidence from genetic experiment is limited. In plants, γ-aminobutyric acid (GABA) transporters (GATs) primarily transport GABA and further involve in plant growth, development, and response to various stresses. In this study, we have identified the <italic>GATs</italic> family in <italic>Populus</italic> species and characterized their functional evolution and divergence in a desert poplar species (<italic>Populus euphratica</italic>). We found that the <italic>GATs</italic> underwent genus-specific expansion <italic>via</italic> multiple whole-genome duplications in <italic>Populus</italic> species. The purifying selection were identified across those <italic>GATs</italic> evolution and divergence in poplar diversity, except two paralogous <italic>PeuGAT2</italic> and <italic>PeuGAT3</italic> from <italic>P. euphratica</italic>. The both genes arose from a tandem duplication event about 49 million years ago and have experienced strong positive selection, suggesting that the divergence in PeuGAT3 protein function/structure might define gene function better than in expression pattern. Both <italic>PeuGAT</italic> genes were functionally characterized in <italic>Arabidopsis</italic> and poplar, respectively. The overexpression of <italic>PeuGAT3</italic> increased the thickness of xylem cells walls in both <italic>Arabidopsis</italic> and poplar and enhanced the lignin content of xylem tissues and the proline accumulation in poplar leaves, all of which may improve tolerance of salt/drought stress in desert poplars. Our findings help clarify the genetic mechanisms underpinning high tolerance in desert poplars and suggest that <italic>PeuGAT3</italic> could be an attractive candidate gene for engineering trees with improved brown-rot resistance.</p>