The over-expression of calmodulin from Antarctic notothenioid fish increases cold tolerance in tobacco.

Abstract: Genes involved in the calcium signalling pathway have a relationship with cold tolerance in many plants. The primary reaction to many different environmental stresses is an increase in the cytoplasmic Ca2+ concentration. Such variations in the Ca2+ concentration could change the activity of Ca2+-dependent protein functions, further regulating the expression of stress-related genes; therefore, the Ca2+ signalling pathway is involved in the biological stress reaction. The expression of the calcium-modulated protein gene, calmodulin, in Antarctic notothenioid fish (Dissostichus mawsoni) accounts for 0.23% of all transcripts, which is a very high level of expression in this cold-water fish. To elucidate the function of calmodulin (CaM) from Antarctic notothenioid fishes, we introduced the calmodulin (CaM) gene into tobacco plants using a viral vector based on pea early browning virus (PEBV). RT-PCR and Western blot results confirmed that the CaM gene was over-expressed in tobacco. Under low-temperature stress, the CaM transgenic plants exhibited faster growth than wild-type plants. The physiological and biochemical effects of the high-level expression of CaM in tobacco were analysed, and the changes in the electrolyte leakage activity and malondialdehyde content showed that CaM over-expression in tobacco increased the cold tolerance of the plants. These results demonstrate that CaM can possibly be used to enhance the low-temperature tolerance of plants. [Copyright &y& Elsevier]