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Acta Botanica Brasilica

Print version ISSN 0102-3306On-line version ISSN 1677-941X

Abstract

RODRIGUES, Daniele M.; TURCHETTO, Caroline; CALLEGARI-JACQUES, Sidia M.  and  FREITAS, Loreta B.. Can the reproductive system of a rare and narrowly endemic plant species explain its high genetic diversity?. Acta Bot. Bras. [online]. 2018, vol.32, n.2, pp.180-187.  Epub Jan 08, 2018. ISSN 0102-3306.  http://dx.doi.org/10.1590/0102-33062017abb0296.

The reproductive system of flowering plants can be highly variable, affecting their biology, gene flow and genetic variability among populations. Petunia secreta is a rare annual endemic species of Pedra do Segredo, located in the municipality of Caçapava do Sul, state of Rio Grande do Sul, Brazil. Although rare, the species possesses a high level of genetic variability. We investigated the reproductive system of P. secreta, including fruit production and seed germinability, in order to determine if its reproductive system can explain its genetic diversity. We sampled five populations and conducted five greenhouse hand-pollination treatments: 1) autonomous apomixis; 2) self-pollination; 3) hand self-pollination; 4) geitonogamy; and 5) cross-pollination. We analysed a total of 40 plants, 468 flowers, and 6,500 seeds. Only autonomous apomixis and self-pollination did not produce fruit. No differences in fruit weight were observed among pollination treatments (P > 0.05). Seeds of two colours were produced, with no differences in germinability. Considering all plants, populations, and treatments, the average germinability was 73 % (range 9 % to 100 %). These results, along with other previous studies, indicate that the reproductive systems of P. secreta, and its large effective population size, can explain its high genetic diversity.

Keywords : endogamy; Pampas; Petunia; reproductive success; reproductive system; seed germinability.

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