The Arabidopsis DREB1A gene driven by the stress-inducible rd29A promoter increases salt-stress tolerance in proportion to its copy number in tetrasomic tetraploid potato (Solanum tuberosum)

Abstract

Transgenic potato lines of cv. Desiree containing the DREB1A gene driven by the rd29A promoter were generated using Agrobacterium-mediated transformation. The morphological appearance of the 120 transgenic lines was classified into three categories as determined by in vitro test-tube evaluation. Southern blot analyses of genomic DNA were conducted using the restriction enzymes HindIII and DraI. There were significant differences between the transgenic lines and DSC in the quantitative salinity-tolerance evaluations at 1M NaCl. Two transgenic lines were recognized as highly tolerant to salinity based on Duncan multiple range testing. Furthermore, there was a significant correlation between the mean tolerance level of the transgenic lines and the DREB1A copy number estimated from the Southern hybridization experiments. Northern hybridization experiments were subsequently done using a DREB1A cDNA probe and transgenic lines with different levels of salinity tolerance. Salt-tolerant transgenic lines expressed substantially more of the transgene at 2 to 5 h of salt treatment, after which the expression returned to basal levels. These observations suggest that the gene transfer of rd29A