Genetic Improvement of Lettuce for Salt and Drought Stress Tolerance by Gene Transfer of an Arabidopsis Transcription Factor DREB1A.

Abstract

A cDNA encoding a transcription factor DREB1A was introduced into lettuce (Lactuca sativa L.) by Agrobacterium tumefaciens-mediated transformation to improve salt and drought stress tolerance. First we analyzed activity of CaMV35S and rd29A promoters using a GUS reporter gene. GUS activity driven by the rd29A promoter was induced by dehydration and that driven by the 35S promoter showed constitutive induction. We also generated transgenic plants overexpressing DREB1A using the 35S and rd29A promoters. The 35S:DREB1A-18 transgenic plants showed enhanced survivability under salt stress condition by 200mM NaCl compared to control plants. The rd29A:DREB1A-31 plants are likely to increase the drought stress tolerance. Expression of DREB1A target genes was analyzed by hetero-probed micro array and some of the genes were induced by DREB1A overexpression. These results indicate that the Arabidopsis rd29A promoter and DREB1A gene might be useful for improvement of salt and drought stress tolerance in transgenic lettuce.