Constitutive and salt-inducible expression of SlBADH gene in transgenic tomato (Solanum lycopersicum L. cv. Micro-Tom) enhances salt tolerance.

To improve the stress tolerance of crops, many genes, including transcription factors, have been expressed in transgenic plants using either constitutive or stress-inducible promoters. However, transgenic plants that show strong constitutive expression of transcription factors often suffer from many undesirable phenotypes, such as stunted growth and reduced yield. In the present study, the betaine aldehyde dehydrogenase (BADH) gene, cloned from Suaeda liaotungensis and, controlled by the Cauliflower mosaic virus (CaMV) 35S promoter or stress-inducible promoter of BADH (P5: -300 to +62 bp), was transformed into tomato (Solanum lycopersicum). The transformants with single copy of SlBADH were determined by real time PCR. Expression of SlBADH in the P5:BADH transgenic plants exhibited salt induced and was higher than that in CaMV35S:BADH under salt stress. The SlBADH enhanced salt tolerance of P5:BADH and CaMV35S:BADH transformants. And SlBADH in P5:BADH plants did not affect the growth of transformants. Consequently, we conclude that the P5 promoter can drive increased expression of SlBADH in transgenic tomato under salt stress and increase salt tolerance without affecting plant growth.