Abstract
We have developed direct somatic embryo-forming system in which carrot hypocotyl explants are treated with 2,4-D for brief time and then cultured in 2,4-D-free medium. We think that the transition from somatic cells to cells which have embryo-forming function in the earliest events during somatic embryogenesis is firstly promoted by treating with 2,4-D. Thus we search for genes expressed specifically in 2,4-D-treated hypocotyl explants. To find these genes, we prepare three samples as following for differential display method; (1)hypocotyl explants treated with 2,4-D for 48hrs, (2)hypocotyl explants treated with 2,4-D for 24hrs and then cultured in 2,4-D-free medium for 24hrs, (3)hypocotyl explants cultured in 2,4-D-free medium for 48hrs. We obtain three genes, No.130, No.151 and No.209 which are specifically expressed in 2,4-D-treated samples by RT-PCR analysis. In addition, these genes were expressed in cell clusters and blobular embryos, but expressed hardly in the heart- and torpedo-shaped embryos and plantlets.
