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Abstract Detail

Reproductive Processes

Pratt, Donald B. [1], Espericueta, Ramiro [1].

Masters of Their Own Reproductive Fate? Variation of Reproductive Allocation in Amaranthus spinosus.

Approximately 10% of Angiosperms produce unisexual flowers (including, among others, the monoecious and dioecious breeding systems). Further, monoecy has been proposed as part of an evolutionary transformation series leading to dioecy. The genus Amaranthus provides a model system for the study of breeding system evolution as both monoecy and dioecy occur within the genus and a phylogeny of the genus has recently been provided. The monoecious species of Amaranthus tend to have mixed dichasia in which the terminal flower is staminate and the remaining flowers are pistillate. Dichasia in Amaranthus are frequently further aggregated onto an elongating thyrse. One monoecious species, Amaranthus spinosus, breaks the pattern of forming mixed dichasia. Rather, in this species, unisexual pistillate dichasia occur basipetally in relation to unisexual staminate dichasia that are located acropetally along the thyrse. Changes in inflorescence architecture such as those reported for A. spinosus have been suggested to be indicative of an adaptation for increased outcrossing and may be an intermediary step in the evolution of dioecy. We analyzed the ratio of pistillate to staminate dichasia along the thyrse in A. spinosus using herbarium specimens. We found that the ratio of pistillate : staminate area along the thyrse varies per specimen, indicating that there is not a fixed ratio for this species. We speculate that individuals of A. spinosus are able to control the production ratio of pistillate and staminate flowers in order to optimize male and female reproductive output in response to the availability of outcrossed pollen.

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1 - Stephen F. Austin State University, Box 13003 SFA Station, Nacogdoches, TX, 75962, USA

Breeding Systems

Presentation Type: Poster
Session: P, Reproductive Processes
Location: Exhibit Hall/Omni Hotel
Date: Monday, June 26th, 2017
Time: 5:30 PM This poster will be presented at 5:30 pm. The Poster Session runs from 5:30 pm to 7:00 pm. Posters with odd poster numbers are presented at 5:30 pm, and posters with even poster numbers are presented at 6:15 pm.
Number: PRP001
Abstract ID:314
Candidate for Awards:None

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