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Front. Plant Sci. | doi: 10.3389/fpls.2018.00258

Identification of STOP1-like Proteins Associated with Aluminum Tolerance in Sweet Sorghum (Sorghum bicolor L.)

  • 1College of Plant Science, Jilin University, China

Aluminum (Al) toxicity in acidic soils affects crop production worldwide. C2H2-type zinc finger transcription factor STOP1/ART1-mediated expression of Al tolerance genes has been shown to be important for Al resistance in Arabidopsis, rice and other crop plants. Here, we identified and characterized four STOP1-like proteins (SbSTOP1a, SbSTOP1b, SbSTOP1c and SbSTOP1d) in sweet sorghum, a variant of grain sorghum (Sorghum bicolor L.). Al induced the transcription of the four SbSTOP1 genes in both time- and Al concentration-dependent manners. All SbSTOP1 proteins localized to the cell nucleus, and they showed transcriptional activity in a yeast expression system. In the HEK 293 coexpression system, SbSTOP1d showed transcriptional regulation of SbSTAR2 and SbMATE, indicating the possible existence of another SbSTOP1 and SbSTAR2-dependent Al tolerance mechanism in sorghum apart from the reported SbMATE-mediated Al exclusion mechanism. A transgenic complementation assay showed that SbSTOP1d significantly rescued the Al-sensitivity characteristic of the Atstop1 mutant. Additionally, yeast two-hybrid and BiFC assays showed that SbSTOP1d interacted with SbSTOP1b and SbSTOP1d itself, suggesting that SbSTOP1 may function as a homodimer and/or heterodimer. These results indicate that STOP1 plays an important role in Al tolerance in sweet sorghum and extend our understanding of the complex regulatory mechanisms of STOP1-like proteins in response to Al toxicity.

Keywords: aluminum toxicity, STOP1, Transcriptional regulation, Al tolerance genes, sweet sorghum

Received: 27 Nov 2017; Accepted: 12 Feb 2018.

Edited by:

Wei Fan, Yunnan Agricultural University, China

Reviewed by:

Jian Li Yang, Zhejiang University, China
Chao-Feng Huang, Shanghai Institutes for Biological Sciences (CAS), China

Copyright: © 2018 Huang, Gao, You, Liang, Guan, Yan, Zhan and Yang. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Prof. Zhenming Yang, Jilin University, College of Plant Science, Changchun, China,