Functional analysis of TaDi19A, a salt-responsive gene in wheat.

A salinity stress upregulated expressed sequence tag (EST) was selected from a suppression subtractive hybridization cDNA library, constructed from the salinity-tolerant wheat cultivar Shanrong No. 3. Sequence analysis showed that the corresponding gene (named TaDi19A) belonged to the Di19 family. TaDi19A was constitutively expressed in both the root and leaf of wheat seedlings grown under non-stressed conditions, but was substantially up-regulated by the imposition of stress (salinity, osmotic stress and cold), or the supply of stress-related hormones [abscisic acid (ABA) and ethylene]. The heterologous over-expression of TaDi19A in Arabidopsis thaliana increased the plants' sensitivity to salinity stress, ABA and mannitol during the germination stage. Root elongation in these transgenic lines showed a reduced tolerance to salinity stress and a reduced sensitivity to ethophon. The expression of the ABA signal pathway genes ABI1, RAB18, ERD15 and ABF3, and SOS2 (SOS pathway) was altered in the transgenic lines. TaDi19A plays a role in the plant's response to abiotic stress, and some possible mechanisms of its action are proposed.