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Asexual reproduction is widespread in land plants, including ferns where 10% of all species are obligate asexuals. In these ferns, apogamous sporophytes are generated directly from gametophytes, bypassing fertilization. In the model fern Ceratopteris richardii, a sexual species, apogamy can be induced by culture on high sugar media. BABY BOOM ( BBM) genes in angiosperms are known to promote somatic embryogenesis, which like apogamy produce sporophytes without fertilization. Here, a Brassica napus BBM ( Bn BBM) was used to investigate genetic similarity between apogamy in ferns and somatic embryogenesis in angiosperms. A C. richardii transcriptome was constructed from which one AINTEGUMENTA- LIKE unigene, Cr ANT, was identified. Whole mount in situ hybridization showed that Cr ANT is expressed in sperm and fertilized eggs. Phylogenetic analysis grouped Cr ANT with other non-seed-plant ANT genes to the eu ANT clade but in a branch separate from BBM genes. Overexpression of Cr ANT or Bn BBM promotes apogamy in C. richardii without sugar supplement. Cr ANT knockdown gametophytes responded weakly to sugar for apogamy promotion. Theses results suggest some genetic conservation between apogamy and somatic embryogenesis and that such asexual reproduction may be ancient. [ABSTRACT FROM AUTHOR]