Abstract
In order to identify genes involved in early stage of procambium development, we screened 51,000 Arabidopsis gene trap lines. We isolated a line that exhibited GUS staining pattern preferentially along procambial cells and meristems. We identified Gamma-Glutamyl Hydorolase (GGH) gene, which is known to cleave the polyglutamate chain of folates, as the causal gene. In Arabidopsis genome, three GGH genes are tandemly placed. Overexpression of any of three GGH genes caused similar developmental abnormalities indicating reduction of meristematic activity. Conversely, suppression of all GGH genes caused developmental abnormalities indicating enhancement of meristematic activity. To know the roles of folates in tissue development, we examined the effect of a folate biosynthesis inhibitor and glutamyl conjugated folates on the development of Arabidopsis plant and Zinnia culture cells. Based on the data obtained, we suggest that the GGH gene may regulate the developmental phase transition by cleaving poly-glutamate residue of folates.
