Histochemical Studies on Embryogenesis of Pinus thunbergii Panl

On the mode of embryogenesis in Pinus thunbergii, its course can be divided approximately into six stages.With histochemical methods the appearance and disappearance of proteins and polysaccharides are studied. The localization of these substances in the different stages of embryogenesis is elucidated.In the cells of the middle part of prothallium where the suspensor elongates, abundant starch and proteins begin to appear in the proembryo stage. These substances rapidly increase and reach the maximum state in the case of proteins when the suspensor has elongated to half of its full length, or in the case of starch when the embryo begins to differentiate into two portions. These substances disappear when the cells containing them break down. The proteins completely disappearjust after the embryo initial has formed, and after some intervals the most of starch gradually decreases its amount till the basal portion of embryo begins to differentiate into two parts though a small quantity of them remains in the tissue surrounding the embryo. From the above facts it may be concluded that these substances are converted into soluble state and serve as nutrients for the early development of embryo.Protein granules begin to accumulate in the remaining prothallium from the stage of suspensor elongation and in the embryo from the stage of cotyledon differentiation. These protein granules gradually increase their amounts and in the mature stage of embryo attain to large quantities. Also many starch grains and much of amorphous polysaccharides begin to accumulate in the basal portion of embryo from the stage of cotyledon differentiation. These substances are considered as the storage material for the coming germination.