Pollen-stigma interaction and cross-incompatibility in the grasses.

The failure of interspecific and intergeneric crosses in the grasses is commonly due to zygotic inviability, embryo abortion, or endosperm abnormalities, all of which occur after fertilization. Often, however, there is difficulty in obtaining fertilization because the pollen tube fails to reach the embryo sac. This article concerns recent research on pollen-stigma interaction in the grasses and the light it is beginning to throw on prefertilization self- and cross-incompatibilities.