Survival of Young Immature Capsella Embryos Cultured in vitro.

The survival rate of immature Capsella embryos cultured in vitro varies according to their length and the mineral solution used. Some elements are toxic while others increase survival. Nevertheless, in spite of an improvement in the composition of the nutritive solution, globular embryos of less than 50 μm do not completely develop up to the plant stage. It could be thought that the medium does not contain the essential elements for perfect embryonic growth. In fact, it seems that mortality is due to rupture of the suspensor. The nature of mineral elements capable of increasing survival rate seems to indicate that, through the breach opened in the suspensor, cellular substances indispensable for embryonic development leak into the medium. The analysis of mineral elements reducing the percentage of survival seems to indicate that it is the sudden penetration of mineral salts into the suspensor which induces the necrosis of a great number of embryonic cells. This degeneration of the suspensor begins from its broken end and moves towards the embryo, provoking the necrosis of its basal cells. The embryos which grow in ovules cultured in vitro show much better survival than when they are inoculated singly onto the medium. All these considerations seem to confirm the fundamental necessity for integrity of the suspensor.