AUTHOR=Zhang Xingxing , Rui Haiyun , Zhang Fenqin , Hu Zhubing , Xia Yan , Shen Zhenguo 

TITLE=Overexpression of a Functional Vicia sativa PCS1 Homolog Increases Cadmium Tolerance and Phytochelatins Synthesis in Arabidopsis

JOURNAL=Frontiers in Plant Science

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2018.00107

DOI=10.3389/fpls.2018.00107

ISSN=1664-462X

ABSTRACT=<p>Phytochelatins (PCs) catalyzed by phytochelatin synthases (PCS) are important for the detoxification of metals in plants and other living organisms. In this study, we isolated a <italic>PCS</italic> gene (<italic>VsPCS1</italic>) from <italic>Vicia sativa</italic> and investigated its role in regulating cadmium (Cd) tolerance. Expression of <italic>VsPCS1</italic> was induced in roots of <italic>V. sativa</italic> under Cd stress. Analysis of subcellular localization showed that VsPCS1 was localized in the cytoplasm of mesophyll protoplasts of <italic>V. sativa</italic>. Overexpression of <italic>VsPCS1</italic> (<italic>35S::VsPCS1</italic>, in wild-type background) in <italic>Arabidopsis thaliana</italic> could complement the defects of Cd tolerance of <italic>AtPCS1</italic>-deficent mutant (<italic>atpcs1</italic>). Compared with <italic>atpcs1</italic> mutants, <italic>35S::VsPCS1/atpcs1</italic> (in <italic>AtPCS1</italic>-deficent mutant background) transgenic plants significantly lowered Cd-fluorescence intensity in mesophyll cytoplasm, accompanied with enhanced Cd-fluorescence intensity in the vacuoles, demonstrating that the increased Cd tolerance may be attributed to the increased PC-based sequestration of Cd into the vacuole. Furthermore, overexpressing <italic>VsPCS1</italic> could enhance the Cd tolerance in <italic>35S::VsPCS1</italic>, but have no effect on Cd accumulation and distribution, showing the same level of Cd-fluorescence intensity between <italic>35S::VsPCS1</italic> and wild-type (WT) plants. Further analysis indicated this increased tolerance in <italic>35S::VsPCS1</italic> was possibly due to the increased PCs-chelated Cd in cytosol. Taken together, a functional PCS1 homolog from <italic>V. sativa</italic> was identified, which hold a strong catalyzed property for the synthesis of high-order PCs that retained Cd in the cytosol rather the vacuole. These findings enrich the original model of Cd detoxification mediated by PCS in higher plants.</p>