Plant Systematics and Evolution (2018) 304:343–355
Unusual diversity of apomictic mechanisms in a species of Miconia,
Ana Paula S. Caetano
· Priscila A. Cortez
· Simone P. Teixeira
· Paulo E. Oliveira
Sandra M. Carmello‑Guerreiro
Received: 4 July 2017 / Accepted: 7 November 2017 / Published online: 5 December 2017
© Springer-Verlag GmbH Austria, part of Springer Nature 2017
Apomixis, the asexual formation of seeds, seems to be a reproductive alternative for many angiosperms, involving various
pathways with diﬀerent genetic and ecological consequences. It is common in some megadiverse tropical groups such as
Melastomataceae, of which approximately 70% of the species studied so far in the tribe Miconieae are autonomous apom‑
ictics. Hence, Miconia appears to be a good model for the study of the embryological pathways associated with apomixis.
In the present study, we analyzed the polyploid and autonomous apomictic M. fallax and compared its embryology to that
of the diploid and sexual M. pepericarpa, both treelets species common in the Cerrado, the Neotropical savanna areas of
Central Brazil. Ovule structure and basic megasporogenesis and megagametogenesis events were similar in both species.
However, M. fallax showed exclusive features associated with apomixis: aposporous embryo sac development, with the par‑
thenogenetic development of unreduced egg cells, autonomous endosperm formation, nucellar embryony and polyembryony.
Moreover, both gametophytic and sporophytic apomixis occurred in parallel to the development of a sexual embryo sac, a
rarely described condition, which probably confers a great reproductive ﬂexibility to the species.
Keywords Adventitious embryony · Apospory · Autonomous apomixis · Megagametogenesis · Megasporogenesis ·
Despite the prevalence of sexual reproduction, apomixis—
the asexual production of seeds—is an alternative that seems
to have been important for the evolution and diversiﬁcation
of the angiosperms (Asker and Jerling 1992; Hojsgaard et al.
2014). In general, the apomictic process bypasses important
steps of sexual reproduction, notably both meiosis and egg
cell fertilization, and has been viewed as a temporal and
spatial deregulation of the sexual developmental program
(Koltunow 1993; Koltunow and Grossniklaus 2003; Hand
and Koltunow 2014). Currently, apomixis is considered an
important reproductive strategy often associated with geo‑
graphical parthenogenesis and polyploidy (Carman 1997;
Hörandl et al. 2008; Santos et al. 2012).
The seeds that result from the apomictic process can have
embryos originating from a somatic cell of the ovule (sporo‑
phytic apomixis or adventitious embryony) or from an unfer‑
tilized egg cell of an unreduced embryo sac (gametophytic
apomixis). In the latter case, the unreduced embryo sac orig‑
inates from a megaspore mother cell in which meiosis was
Handling editor: Hans de Jong.
* Ana Paula S. Caetano
Programa de Pós‑Graduação em Ecologia e Conservação
de Recursos Naturais, Instituto de Biologia, Universidade
Federal de Uberlândia, Uberlândia, Minas Gerais, Brazil
Programa de Pós‑Graduação em Biologia Vegetal, Instituto
de Biologia, Universidade Estadual de Campinas, Campinas,
São Paulo, Brazil
Centro de Microscopia Eletrônica, Departamento de Ciências
Biológicas, Universidade Estadual de Santa Cruz, Ilhéus,
Departamento de Ciências Farmacêuticas, Faculdade de
Ciências Farmacêuticas de Ribeirão Preto, Universidade de
São Paulo, Ribeirão Preto, São Paulo, Brazil
Instituto de Biologia, Universidade Federal de Uberlândia,
Uberlândia, Minas Gerais, Brazil
Departamento de Biologia Vegetal, Instituto de Biologia,
Universidade Estadual de Campinas, Campinas, São Paulo,