Over-expression of a cold-induced plasma membrane protein gene (MpRCI) from plantain enhances low temperature-resistance in transgenic tobacco

The plasma membrane is the most direct target of low temperature injury in plants. We have cloned a cold-induced gene (MpRCI) from plantain (Musa paradisiaca L.; ABB Group). Expression of an MpRCI::GFP fusion protein in onion epidermal cells showed localization of the protein product in the plasma membrane. The expression profile of MpRCI was analyzed by RT-PCR and the results indicated that MpRCI is induced by low temperatures in leaves and leafstalk, but not in the shoot meristematic or roots. We also cloned a 1.2 kb fragment upstream of MpRCI, predicted to contain several elements related to abiotic stresses, and demonstrated that the sequence has characteristics of low temperature- and ABA-induced promoter activity. Furthermore, the results of the phenotypic espial and ion leakage assays, using transgenic tobacco containing the gene, indicated that over-expression of the cold-induced plasma membrane protein gene MpRCI enhanced low temperature-resistance in the these plants. These results suggest that MpRCI is involved in maintaining the stability of the plasma membrane at low temperatures.