Pollen Stigma Interaction - Stigma

The Stigma After landing on the stigma pollen grain germinates, and produces a pollen tube that carries the male gametes. The stigma has been classified into two principal types depending on the presence or absence of stigmatic exudate at the time of pollination:

1. The wet stigma is covered by a sticky secretion, e.g., Aegle marmelos and Petunia hybrida, and
2. The dry stigma lacks any secretion, e.g., cotton.

EM observations indicate that the exudate is secreted by the ER and it is extruded by exocytosis. The diagrammatic representation of the mechanism involved is shown in Figure. In some plants such as Lilium, the stigma is non-secretory. The exudate which is present on stigma is, in fact, secreted by the stigmatic papillae and those present in the stylar canal emanate from the style.