Gamma irradiation of Prunus avium L. flower buds: effects on stylar development – an ultrastructural study

An attempt has been made to analyse the effects of acute gamma irradiation on stylar development in Prunus avium. The treatment was applied to meiotic buds. The observations with electron microscopy were made on styles collected from the flowers one day after anthesis. The data showed that in the irradiated plants, some cells of the stigma were partially degenerated. The transmitting tissue in the style contained not only the cells with normal cytoplasm, but also the cells having cytoplasm at different stages of degeneration. Empty zones, similar to vacuoles, are present in the intercellular stylar substance, probably due to poor secretion activity of the cells. Further, in the irradiated plants the cells of the tramsmitting tissue contained exclusively free ribosomes and there was considerable decrease in the activity of RER and Golgi bodies indicating a decreased synthetic cellular activity of the transmitting tissue. The possible implications of the radiation effects on the stylar transmitting tissue in relation to the incompatibility mechanism are discussed in the light of the results obtained in the present study.