Improvement of Lactuca sativa slat Tolerance by Plastid Transformation with BADH Gene

Salinity is one of the major factors that limits geographical distribution of plants and adversely affects crop productivity and quality. Here high-level expression of betaine aldehyde dehydrogenase (BADH) was reported in cultured explants of lettuce via plastid genetic engineering. Lettuce (Lactuca sativa) plant was primarily experimented for tolerance of betaine aldehyde (BA) and soudium chloride (NaCl) by tissue culture technique and it was found that the wild type lettuce tolerated 10 and 75 mM from each substance respectively. Genes required in this study were amplified by polymerase chain reaction (PCR) technique using specific forward and reverse primers, and these genes were BADH, prrn promoter and many other regulatory genes. Some of these genes were isolated from their hosts and some were obtained from previous work available at Daniell laboratory. All these genes beside many techniques for ligation, extension, sequencing, orientation confirmation were used to construct the cassette vector pLS-BADH-LS which carries the gene of interest. Homoplasmic transgenic plants exhibiting high levels of salt tolerance were regenerated from bombarded cell cultures via somatic embryogenesis. Transgenic lettuce plants expressing BADH grew in the presence of high concentrations of NaCl (up to 150 mM), the highest level of salt tolerance reported so far among genetically modified lettuce, and the tolerance to betaine aldehyde was 30 mM.