Incompatibility in Dendrobium (Orchidaceae)

JOHANSEN, B., 1990. Incompatibility in Dendrobium (Orchidaceae). A unique self‐incompatibility system in Dendrobium is demonstrated by more than 1700 pollination experiments. The majority (72%) of the 61 species that were self‐pollinated showed self‐sterility. In contrast with many other orchid genera Dendrobium showed high incompatibility in interspecific pollinations. Self‐and interspecific incompatibility is expressed by flower abscission and not by inhibition of pollen germination or pollen tube growth. The incompatibility system is gametophytic and complementary, and it is likely that the auxin content in the pollinia triggers the incompatibility reaction. Microscopical investigations on the detached cells of the stigma (here called eleutherocytes) after compatible and incompatible pollinations, suggest that the incompatibility response is probably controlled by these cells.