Enhances Drought and Salt Tolerance Through an ABA-Mediated Pathway in .

The WRKY transcription factors (TFs) are one of the largest families of TFs in plants and play multiple roles in plant development and stress response. In the present study, encoding a WRKY transcription factor in soybean was functionally characterized in Arabidopsis. GmWRKY16 is a nuclear protein that contains a highly conserved WRKY domain and a CH zinc-finger structure, and has the characteristics of transcriptional activation ability, presenting a constitutive expression pattern with relative expression levels of over fourfold in the old leaves, flowers, seeds and roots of soybean. The results of quantitative real time polymerase chain reaction (qRT-PCR) showed that could be induced by salt, alkali, ABA, drought and PEG-6000. As compared with the control, overexpression of in Arabidopsis increased the seed germination rate and root growth of seedlings in transgenic lines under higher concentrations of mannitol, NaCl and ABA. In the meantime, transgenic lines showed over 75% survival rate after rehydration and enhanced Arabidopsis tolerance to salt and drought with higher proline and lower MDA accumulation, less water loss of the detached leaves, and accumulated more endogenous ABA than the control under stress conditions. Further studies showed that , , and were induced in transgenic plants under NaCl treatment. The expressions of the ABA biosynthesis gene (), signaling genes (, , , and ), responsive genes (, , , and ) and stress-related marker genes (, and ) were regulated in transgenic lines under drought stress. In summary, these results suggest that as a WRKY TF may promote tolerance to drought and salt stresses through an ABA-mediated pathway.