MOLECULAR CHARACTERIZATION OF A STRESS-RELATED GENE MsTPP IN RELATION TO SOMATIC EMBRYOGENESIS OF ALFALFA

Abstract

Somatic embryogenesis is the most comprehensive form of cell totipotency in plant tissue culture İn vitro, in which plant growth regulator and stress have been regarded as the important factors. In the present work, a full-length cDNA of stress-related trehalose-6-phosphate phosphatase, designated as MsTPP, was isolated and characterized from the nonembryogenetic callus of alfalfa on the medium involved in thidiazuron (TDZ). Homology analysis showed that MsTPP protein contained two conversed phosphatase boxes, which is the typical characterization of all phosphatases. Semiquantitative RT-PCR and real-time PCR demonstrated that MsTPP was expressed specifically in young root of alfalfa seedling and up-regulated by TDZ during the whole stage of somatic embryogenesis of alfalfa. Furthermore, treatments with 0.93 or 50 μM TDZ strongly suppressed embryogenic competence of the callus, while increased transcript levels of MsTPP. Taken together, these results suggest that MsTPP is likely to be associated with obtaining of embryogenetic competence in alfalfa. This study expands our understanding of the molecular mechanism of TDZ on reduction or inhibition of the embryogenic competence of alfalfa callus.