Resumo

PANSERI, Andrea F.; SEIJO, J. Guillermo  e  SOLIS NEFFA, Viviana G.. Analysis of the production and frequency of unreduced microspores in diploids of Turnera sidoides (Turneraceae). Bol. Soc. Argent. Bot. [online]. 2008, vol.43, n.1-2, pp.95-101. ISSN 1851-2372.

Turnera sidoides is a polyploid complex (x= 7) of dystilous perennial rhizomatous herbs that includes five subspecies. Owing to the high frequency of polyploids within the complex, ongoing studies in T. sidoides are focused on the understanding of the mechanisms involved in the origin and the establishment of polyploids in order to provide evidences of the evolutionary patterns in T. sidoides. In this report we investigate the occurrence and frequency of unreduced microspores in diploid plants from nine natural populations of four subspecies of T. sidoides by analyzing the range of variation of pollen volume and the constitution of the sporads. The results obtained showed that almost all the populations studied produced 2x and 4x microspores, both in short and long-styled floral morphs. Furthermore, the analysis performed provided evidences that support the hypothesis of sexual polyploidization as one of the mechanisms involved in the origin of polyploids within this species complex. The role of unreduced pollen in the establishment and persistence of newly formed polyploids within diploid populations of T. sidoides is also discussed.

Palavras-chave : Turnera sidoides; Aautopolyploidy; Unreduced gametes.

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