Figure 1.

Endosperm defects in response to interploidy and interspecies hybridizations. Interploidy and interspecies hybridizations cause endosperm defects leading to embryo arrest. In species forming nuclear endosperm, paternal excess crosses delay endosperm cellularization, while maternal excess crosses lead to precocious endosperm cellularization. In species with the cellular type of endosperm development, paternal excess crosses lead to the formation of fewer and enlarged cells, while maternal excess crosses cause the formation of small endosperm cells. EBN, Endosperm balance number.