Cytohistochemical analysis of Malus domestica Borkh. seeds from shedding and nonshedding fruits

A histological, cytochemical, and ultrastructural investigation of seeds of control (nonshedding) and shedding fruits of Malus domestica Borkh. showed differences in the pattern of nutrient distribution. The kind and amount o f storage compounds in the two seeds also differed. Protein bodies and star ch were abundant in the control seeds and nearly absent in the seeds of she dding fruit. In the latter, there was a great abundance of phenols that exh ibited a specific distribution in different tissues of the chalazal region. A cuticle was present on the inner side of the inner integument of the see ds of both control and shedding fruits. This cuticle was interrupted in the chalaza and formed a pathway for nutrient translocation, what we termed th e "window." Cell wan changes observed in the chalazal window were probably associated with the different distribution pattern of storage compounds and with the control of nutrient routing. The delayed and variable development of the embryos of seeds in shed fruits may be related to both the altered pattern of storage substances and their translocation to the embryo.