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

Abstract

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 explantsof lettuce via plastid genetic engineering. Lettuce (Lactucasativa) plant was primarilyexperimented for tolerance of betaine aldehyde (BA) and soudium chloride(NaCl) by tissue culture technique and it was found that the wild typelettuce tolerated 10 and 75 mM from each substance respectively. Genesrequired in this study were amplified by polymerase chain reaction (PCR)technique using specific forward and reverse primers, and these genes wereBADH, prrn promoter and many other regulatory genes. Some ofthese genes were isolated from their hosts and some were obtained fromprevious work available at Daniell laboratory. All these genes beside manytechniques for ligation, extension, sequencing, orientation confirmationwere used to construct the cassette vector pLS-BADH-LS whichcarries 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 150mM), the highest level of salt tolerance reported so far among genetically modified lettuce, and the tolerance to betaine aldehyde was 30 mM.