The Glycine soja NAC transcription factor GsNAC019 mediates the regulation of plant alkaline tolerance and ABA sensitivity
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Overexpression of Gshdz4 or GsNAC019 enhanced alkaline tolerance in transgenic Arabidopsis. We proved that Gshdz4 up-regulated both GsNAC019 and GsRD29B but GsNAC019 may repress the GsRD29B expression under alkaline stress.
Wild soybean (Glycine soja) has a high tolerance to environmental challenges. It is a model species for dissecting the molecular mechanisms of salt-alkaline stresses. Although many NAC transcription factors play important roles in response to multiple abiotic stresses, such as salt, osmotic and cold, their mode of action in alkaline stress resistance is largely unknown. In our study, we identified a G. soja NAC gene, GsNAC019, which is a homolog of the Arabidopsis AtNAC019 gene. GsNAC019 was highly up-regulated by 50 mM NaHCO3 treatment in the roots of wild soybean. Further investigation showed that a well-characterized transcription factor, Gshdz4 protein, bound the cis-acting element sequences (CAATA/TA), which are located in the promoter of the AtNAC019/GsNAC019 genes. Overexpression of Gshdz4 positively regulated AtNAC019 expression in transgenic Arabidopsis, implying that AtNAC019/GsNAC019 may be the target genes of Gshdz4. GsNAC019 was demonstrated to be a nuclear-localized protein in onion epidermal cells and possessed transactivation activity in yeast cells. Moreover, overexpression of GsNAC019 in Arabidopsis resulted in enhanced tolerance to alkaline stress at the seedling and mature stages, but reduced ABA sensitivity. The closest Arabidopsis homolog mutant plants of Gshdz4, GsNAC019 and GsRD29B containing athb40, atnac019 and atrd29b were sensitive to alkaline stress. Overexpression or the closest Arabidopsis homolog mutant plants of the GsNAC019 gene in Arabidopsis positively or negatively regulated the expression of stress-related genes, such as AHA2, RD29A/B and KIN1. Moreover, this mutation could phenotypically promoted or compromised plant growth under alkaline stress, implying that GsNAC019 may contribute to alkaline stress tolerance via the ABA signal transduction pathway and regulate expression of the downstream stress-related genes.
KeywordsNAC HD-ZIP Glycine soja Arabidopsis Alkaline stress
Cold-regulated gene 47
Green fluorescent protein
NAC binding sites
NADP-dependent malic enzyme
Responsive to dehydration 22
Responsive to dehydration 29A
Responsive to dehydration 29B
Synthetically defined medium
Uracil-specific excision reagent
We would like to thank Dr. Guanzheng Qu for the service of confocal laser-scanning microscope in Northeast Forestry University.
This work was supported by the National Natural Science Foundation of China (31670272 to XD) and the Technological Innovation Team Building Program of the College of Heilongjiang Province (2011TD005) and NEAU starting grant to XD. This work was also supported by the National Natural Science Foundation of China (31501331).
Experiment design LC, YZ. Experiment performance and data analyses LC, FY, YY, DZ, XS, XD, KY. Manuscript drafting LC, BL, XD.
Compliance with ethical standards
Conflict of interest
The authors have read and approved the manuscript and declare that they have no conflict of interest.
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