OBSERVATIONS ON THE DYNAMICS OF STARCH DURING OVULAR DEVELOPMENT IN Vicia faba L.
Wang Yao-zhi, Wang Li-hong, and Gong Kui(Department of Biology, Lanzhou University, Lanzhou 730000)
The dynamics of starch during ovular development in Vicia faba has been investigated by the PAS reaction,the results are summarized as follows; 1. No starch reaction was found at the initial stage of ovular development. As the ovule develops starch grains appeared first in the ehalazal region, and then extended toward the micropylar end. 2.Starch grains were present in nucellus, inner and outer integuments, especially the quantity and size of starch grains in the inner integument around the embryo sac increased rapidly, at anthesis it seems that the nutrients were absorbed from adjacent tissue via entire surface of embryo sac. 3. Some specialised nucellar cells between the vascular bundle and the chalazal end of embryo sac were often present and elongated, this might facilitate nutrient absorption of embryo sac throughchalazal end. 4. A large amount of starch deposit found in functional megaspore and nucellar cells are presumably as the nutrient source in the developmental process of embryo sac. 5. After fertilization, the starch within zygote increased obviously in size and content, and completely disappeared at later stage of proembryo. 6. There was no starch in endosperm at any developmental stage. 7. After differentiation of embryo, the starch deposit reappeared gradually within cotyledon, embryonalaxis and etc. it's content and size increased rapidly within cotyledon.