Over-expression of Chinese cabbage calreticulin 1b, BrCRT1b, induces initiation of organogenesis in Arabidopsis

Abstract

Calreticulin (CRT) is a major Ca2+-binding/buffering protein in the lumen of the endoplasmic reticulum. A cDNA encoding CRT, BrCRT1b (Brassica rapa CRT1b), has been isolated from Chinese cabbage flower bud. Recombinant BrCRT1b(21-418) protein showed Ca-45(2+)-binding and chaperone activity. BrCRT1b transcripts accumulated to high levels in the root, young leaf and flower. Constitutive over-expression of BrCRT1b promoted robust shoot production and root formation at sub-optimal concentrations of auxin/cytokinin. In spite of enhanced regeneration in tissue culture, the seedling and plant growth rates were slightly inhibited in soil. Thus, our findings suggest that BrCRT1b is related to organogenesis during in vitro culture.