Increased tolerance to salt- and water-deficit stress in transgenic lettuce (Lactuca sativa L.) by constitutive expression of LEA

A late embryogenesis abundant ( LEA) protein gene, ME-leaN4, from rape ( Brassica napus) was successfully introduced into lettuce ( Lactuca sativa L.) using Agrobacterium tumefaciens-mediated transformation. Infection by Agrobacterium strain EHA101 containing the binary vector pIG121-LEA was applied. Six independent transgenic lettuce plants were generated as a result. Transgenic lettuce demonstrated enhanced growth ability as compared to non-transformed control plants under salt-stress and water-deficit stress conditions. After 10-day growth under 100 mM NaCl condition in the hydroponics, average plant length and fresh weight of transgenic lettuce were 2.8 cm and 2.5 g plant(-1), while control plants were only 0.2 cm and 0.3 g plant(-1), respectively. The increased tolerance was also reflected by delayed wilting of leaves caused by water-deficit stress. These results suggest that growth characteristics were improved in transgenic lettuce plants constitutively expressing the rape LEA gene in response to salt- and water-deficit stress.