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Elizabeth Chávez-García, Sonia Vázquez-Santana

Abstract


In this study the development of the male and female fl owers of Begonia gracilis is described, using conventional histological
and microscopic techniques. The aims were to clarify whether just one whorl is initiated on the meristem or if the fl ower
begins as bisexual and later abortion occurs on androecium or gynoecium. The results show that the unisexuality is established in the fl oral meristem, because any fl oral morph develops atrophied organs. The female fl owers develop a style that is trifurcate on the tip, forming three dry, bifi d, papillate, and helically twisted stigmas. The ovule is crassinucellate, bitegmic and anatropous. The micropyle is amphistome. The male fl owers develop free stamens and the gynoecium reminiscences are absent. The microspores tetrads are tetrahedric and isobilateral. The pollen grain is bicellular and tricolporate, with striate and verrugate-striate exine near to the apertures. Based on results we conclude that unisexuality in B. gracilis is established since the fl oral meristem, likely by mutations in homeotic genes that regulate the development of sexual whorls.

Keywords


Begonia; embryology; floral development; monoecy; unisexuality

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DOI: http://dx.doi.org/10.17129/botsci.469

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ISSN: 2007-4476
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