Ectopic expression of CisAF7, an Alfin1-like gene from Citrus sinensis, confers tolerance to several abiotic stresses in Escherichia coli

In order to identify the function of a sweet orange (Citrus sinensis (L.) Osbeck cv. Valencia) Alfin1-like (AL) gene, CisAL7, in vitro functional analyses were performed using a procaryotic heterologous expression system (Escherichia coli). CisAL7 was cloned and expressed in a pET28a(+) system. E. coli cells containing the recombinant plasmid or empty vector as a control were treated by multiple stresses. In LB (Luria-Bertani) solid media, Escherichia coli harboring CisAL7 gene was remarkably more tolerant to stresses, including high salinity (0.6 M NaCl or 0.6 M KCl), high temperature (50°C), and low temperature (4°C), than control cells. These results indicate that CisAL7 protein may play a positive role in responsive to abiotic stresses above. This provides the first experimental evidence that AL7 enhances abiotic tolerance of E. coli cells.