The barley dehydrin 4 and stress tolerance: From gene to function

Abstract

Dehydrins constitute a major group among Late Embryogenesis Abundant Proteins, and are known to play a crucial role in water stress tolerance in many plant species. However, little is known regarding their functional relevance in cereals such as barley. In this study, we investigated the function and the expression of the barley DHN4 in response to stress. The DHN4 transcription was strongly induced by salinity, cold and dehydration, in Rihane compared to another barley landrace Manel. Interestingly, we found that CBF1 and CBF6 transcription factors can bind to the RhDHN4 promoter and promote its transcription in yeast cells and in planta. A recombinant RhDHN4 protein was purified and shown to be heat stable and sensitive to protease action, a common feature of intrinsically disordered protein. Moreover, RhDHN4 protects in vitro Lactate Dehydrogenase (LDH) against cold, heat and desiccation and is able to prevent the heat-induced aggregation of leaf’s proteome. RhDHN4 exhibited also in vitro radical scavenging activity, suggesting that the RhDHN4 protein may protects DNA and enzymes during stress. On another hand, the overexpression of RhDHN4 conferred stress tolerance in yeast, an effect that seems to occur via a self dimerization of the protein as it was confirmed by yeast-two hybrid and GST-pull down assays. Our results are in favor of a potential role of RhDHN4 in enhancing stress tolerance in barley.