Cloning of a NaCl-induced fructose-1, 6-diphosphate aldolase cDNA from Dunaliella salina and its expression in tobacco

Using Rapid Amplification of cDNA ends (RACE) technique, the full-length cDNA encoding a NaCl-induced fructose-1, 6- diphosphate aldolase (DsALDP) was obtained. It was shown that the DsALDP had a relatively high homology (66%-73%) to chloroplast fructose-1, 6-diphos- phate aldolase (AldP) in many plants according to their amino acid sequences. The phylogenetic analysis further confirmed that AldP in alga is the nearest to DsALDP. As to its expression pattern, DsALDP was de novo synthesized by NaCl induction. Its expression level was significantly changed with inducing time. After the selected DsALDP cDNA subcloned into a binary vector pBI121, the new construct was introduced into tobacco by Agrobacterium tumefaciens. The results of Southern blot and RT-PCR analysis of four transgenic T1 plants indicated that DsALDP was integrated into genome of these transgenic plants and effectively expressed. Aldolase activities have been detected in T1-1, T1-2 and T1-3 plants by bioassay under 100-200 mmol/L NaCl. It was also observed that proline contents in them were differentially increased.