Overexpression of a maize SNF-related protein kinase gene,ZmSnRK2.11, reduces salt and drought tolerance in Arabidopsis

Sucrose non-fermenting-1 related protein kinase 2(Sn RK2) is a unique family of protein kinases associated with abiotic stress signal transduction in plants. In this study, a maize Sn RK2 gene Zm Sn RK2.11 was cloned and characterized. The results showed that Zm Sn RK2.11 is up-regulated by high-salinity and dehydration treatment, and it is expressed mainly in maize mature leaf. A transient expression assay using onion epidermal cells revealed that ZmS nR K2.11-GFP fusion proteins are localized to both the nucleus and cytoplasm. Overexpressing-Zm Sn RK2.11 in Arabidopsis resulted in salt and drought sensitivity phenotypes that exhibited an increased rate of water loss, reduced relative water content, delayed stoma closure, accumulated less free proline content and increased malondialdehyde(MDA) content relative to the phenotypes observed in wild-type(WT) control. Furthermore, overexpression of Zm Sn RK2.11 up-regulated the expression of the genes ABI1 and ABI2 and decreased the expression of DREB2 A and P5CS1. Taken together, our results suggest that Zm Sn RK2.11 is a possible negative regulator involved in the salt and drought stress signal transduction pathways in plants.