Effect of sugars, amino acids, and culture technique on maturation of somatic embryos of Pinus strobus on medium with two gellan gum concentrations

Maturation of five embryogenic lines of Pinus strobus L. was tested on medi a with various sugars and sources of organic nitrogen, and solidified with two gellan gum concentrations (0.6 and 1.0%). Mature somatic embryo product ion was more abundant at 1.0% gellan gum than at 0.6%. Complex combinations of amino acids had little effect on mature embryo production of most teste d embryogenic lines. Increasing glutamine concentration of the maturation m edium from 1.7 to 7.3 g l(-1) was beneficial to one embryogenic line. Incre asing sucrose concentration or substituting part of the sucrose with mannit ol or sorbitol had variable effects on somatic embryo maturation depending on the embryogenic line. A medium with 88 mM sucrose plus 175 mM sorbitol s olidified with 1.0% gellan gum produced high numbers of somatic embryos in four out of five embryogenic lines tested.