Abstract Detail

Reproductive Processes

Mesic, Matea [1], Schlessman, Mark [2].

Fruit maturation, cross pollination, and water stress promote male flower production in andromonoecious Polanisia dodecandra subsp. riograndensis (Cleomaceae).

The origins and maintenance of a wide variety of angiosperm sexual systems is an enduring central question of evolutionary biology, yet our understanding of sex expression in many species is still often minimal.  In a series of controlled environment experiments, we elucidated sex expression of the Rio Grande clammyweed, Polanisia dodecandra subsp. riograndensis, a native annual that has recently been developed (as Zapata Germplasm) for use in range and wildlife management and native landscaping.  We found that P. dodecandra subsp. riograndensis is andromonoecious, bearing both bisexual flowers and male flowers with aborted pistils.  Compared to bisexual flowers, male flowers also have shorter sepals, petals, and stamens, and fewer stamens.  Flowers are borne in a single large terminal raceme and several smaller lateral ones.  When we provided abundant light, water and mineral nutrients, removed lateral raceme buds, and prevented fruit maturation by removing pistils, terminal racemes bore only bisexual flowers.  When we induced fruit maturation by hand-pollination plants eventually switched to production of male flowers, and if allowed to continue growing would then produce alternating zones of bisexual and male flowers.  Plants that were cross-pollinated produced larger fruit and  transitioned to male flower production more rapidly than those that were self-pollinated. Halving the amount of water provided did not hasten the initial transition from bisexual to male flowers, but did hasten the second transition.  This is the first report of andromonoecy in P. dodecandra subsp. riograndensis.  The expression of andromonoecy in this subspecies is very similar to that recently reported by our lab for P. dodecandra subsp. trachysperma, and also much like that for certain species of Cleome.  It is likely that many more North American cleomids will be found to be andromonoecious.

1 - Vassar College, Biology, Vassar College, 124 Raymond Ave., Poughkeepsie, New York, 12604, United States
2 - Vassar College, Biology, Box 187, Vassar College, 124 Raymond Ave., Poughkeepsie, New York, 12604, United States


Presentation Type: Poster
Session: P, Reproductive Processes Posters
Location: Virtual/Virtual
Date: Thursday, July 30th, 2020
Time: 5:00 PM Time and date to be determined
Number: PRP002
Abstract ID:245
Candidate for Awards:None

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