The effects of glutamine on the maintenance of embryogenic cultures of Cryptomeria japonica

Embryogenic tissues of sugi (Cryptomeria japonica) were induced on a modifi ed Campbell and Durzan (CD) medium containing 1 muM 2,4-dichlorophenoxyacet ic acid (2,4-D) and 600 mg l(-1) glutamine, and subcultured in the medium o f the same composition for over 1 yr. This resulted in a mixed culture of e mbryogenic and non-embryogenic cells. When embryogenic cells were isolated and cultured independently, their capacity to form embryogenic aggregates w as lost. Thus, the non-embryogenic cells present within a mixed culture sys tem were essential to the formation of embryogenic aggregates. When embryog enic tissues were isolated and cultured independently on a high glutamine-c ontaining (2400 mg l(-1)) medium, dry weights and endogenous levels of glut amine increased, and the tissue could generate a large number of embryogeni c aggregates. Amino acid analysis of embryogenic and non-embryogenic cells from the maintenance culture indicated a higher level of glutamine was pres ent in the latter. The high endogenous level of glutamine in the nonembryog enic portion of mixed cell masses may be the supplier of glutamine for main taining the embryogenic property of the tissues.