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PLoS One

Title:		Functional monoecy due to delayed anther dehiscence: a novel mechanism in Pseuduvaria mulgraveana (Annonaceae)
Author(s):		Pang CC; Scharaschkin T; Su YC; Saunders RM;
Address:		"School of Biological Sciences, The University of Hong Kong, Hong Kong, China"
Journal Title:		PLoS One
Year:		2013
Volume:		20130326
Issue:		3
Page Number:		e59951 -
DOI:		10.1371/journal.pone.0059951
ISSN/ISBN:		1932-6203 (Electronic) 1932-6203 (Linking)
Abstract:		"Unlike most genera in the early-divergent angiosperm family Annonaceae, Pseuduvaria exhibits a diversity of floral sex expression. Most species are structurally andromonoecious (or possibly androdioecious), although the hermaphroditic flowers have been inferred to be functionally pistillate, with sterile staminodes. Pseuduvaria presents an ideal model for investigating the evolution of floral sex in early-divergent angiosperms, although detailed empirical studies are currently lacking. The phenology and pollination ecology of the Australian endemic species Pseuduvaria mulgraveana are studied in detail, including evaluations of floral scent chemistry, pollen viability, and floral visitors. Results showed that the flowers are pollinated by small diurnal nitidulid beetles and are protogynous. Pollen from both hermaphroditic and staminate flowers are shown to be equally viable. The structurally hermaphroditic flowers are nevertheless functionally pistillate as anther dehiscence is delayed until after petal abscission and hence after the departure of pollinators. This mechanism to achieve functional unisexuality of flowers has not previously been reported in angiosperms. It is known that protogyny is widespread amongst early-divergent angiosperms, including the Annonaceae, and is effective in preventing autogamy. Delayed anther dehiscence represents a further elaboration of this, and is effective in preventing geitonogamy since very few sexually mature flowers occur simultaneously in an individual. We highlight the necessity for field-based empirical interpretations of functional floral sex expression prior to evaluations of evolutionary processes"
Keywords:		Animals Annonaceae/genetics/*physiology Coleoptera Flowers/*genetics Odorants Pheromones/genetics Plant Physiological Phenomena *Pollen Species Specificity Temperature;
Notes:		"MedlinePang, Chun-Chiu Scharaschkin, Tanya Su, Yvonne C F Saunders, Richard M K eng Research Support, Non-U.S. Gov't 2013/04/05 PLoS One. 2013; 8(3):e59951. doi: 10.1371/journal.pone.0059951. Epub 2013 Mar 26"