A DExD/H box RNA helicase is important for K+ deprivation responses and tolerance in Arabidopsis thaliana

The molecular mechanism for sensing and transducing the stress signals initiated by K+ deprivation in plants remains unknown. Here, we found that the expression of AtHELPS, an Arabidopsis DExD/H box RNA helicase gene, was induced by low-K+, zeatin and cold treatments, and downregulated by high-K+ stress. To further investigate the expression pattern of AtHELPS, pAtHELPS::GUS transgenic plants were generated. Histochemical staining indicated that AtHELPS is mainly expressed in the young seedlings and vascular tissues of leaves and roots. Using both helps mutants and overexpression lines, we observed that, in the low-K+ condition, AtHELPS affected Arabidopsis seed germination and plant weight. Interestingly, the mRNA levels of AKT1, CBL1/9 and CIPK23 in the helps mutants were much higher than in the overexpression lines under low-K+ stress. Moreover, under low-K+ stress, the helps mutants displayed increased K+ influx, whereas the overexpression line of AtHELPS had a lower flux rate in the roots by the noninvasive micro-test technique. Taken together, these results provide information for the functional analysis of plant DEVH box RNA helicases, and suggest that AtHELPS, as an important negative regulator, plays a role in K+ deprivation stress.