Mendelian genetics of apomixis in plants

Apomixis, asexual reproduction through seeds, has the potential to revolutionize agriculture if its genetic basis can be elucidated. However, the genetic control of natural apomixis has remained obscure until quite recently, owing to all the complications of Mendelian genetics, such as epistatic gene interactions, components that are expressed sporophytically and gametophytically, expression modifiers, polyploidy, aneuploidy, segregation distortion, suppressed recombination, etc., that seem to have accumulated during the evolution of apomixis. In this review we show how molecular markers and superior phenotypic methods have been used to clarify the genetics of apomixis in monocots as well as dicots during the past 15 years. Many of the complexities in the genetics of apomixis are likely secondary and have evolved as a consequence of the reproductive process. New mapping techniques, such as comparative mapping, linkage disequilibrium mapping, and deletion mapping, and new high-throughput sequencing methods, will help to penetrate the core of apomixis chromosomal regions. If the evolutionary genetic load can be exposed and removed, the apomixis genes may be used in agriculture as a tool to fix elite genotypes.