Nutrition of Embryo - In Vivo Studies
The young proembryo derives its nutrition from ovular tissues with the help of suspensor. As the embryo develops its suspensor degenerates. Later the chief source of nutrition of the embryo inside the developing seed is the endosperm. By the time the proembryo attains a late globular state, and its suspensor becomes disfunctional, the endosperm is generally already a cellular tissue surrounding the embryo on all sides. The developing seed is a powerful sink for nutrients.
Food materials received through the funicular vascular supply, are absorbed by the endosperm and passed on to the embryo for its growth and development. The central cell wall has transfer cells for absorption of nutrients. Sometimes persistent antipodal cells or special structures such as hypostase and postament of the ovule help in translocation of food to the endosperm. After the embryo is fully grown, the endosperm persists in a large number of plants, particularly monocotyledons, storing starch or oil or protein or all the three. These are used up during seed germination. In other plants no endosperm may persist in the mature seed as the cotyledons store food reserves. Legumes are the best examples and have been the subject matter of research on storage proteins in recent times.