Triploidy causes sexual infertility in Cyrtanthus breviflorus (Amaryllidaceae)
Mike Ramsey A C , Glenda Vaughton A , Glendon D. Ascough B and Steven D. Johnson B
+ Author Affiliations
- Author Affiliations
A Botany, University of New England, Armidale, NSW 2351, Australia.
B School of Biological and Conservation Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville, Pietermaritzburg 3209, South Africa.
C Corresponding author. Email: mramsey@une.edu.au
Australian Journal of Botany 59(3) 238-243 https://doi.org/10.1071/BT10272
Submitted: 14 October 2010 Accepted: 28 February 2011 Published: 9 May 2011
Abstract
The balance between sexual and asexual reproduction can vary markedly in clonal plants. At one extreme, plants are sexually infertile and reproduction is solely clonal. Infertility can be caused by environmental and/or genetic factors, but the role of each is often unknown. Here we determine variation in sexual reproduction and explore the underlying factors causing sexual infertility in Cyrtanthus breviflorus Harv. We examined open- and cross-pollinated fruit set, ploidy using flow cytometry, pollen viability, pollinator visits to flowers and pollen deposition onto stigmas. One population was sexually infertile; no plants produced fruit. Three populations were sexually fertile; >98% of plants produced fruit. Percent pollen viability differed between infertile (18%) and fertile (97%) populations. The most likely cause of infertility was unequal ploidy. Plants in the infertile population were triploid, whereas those in fertile populations were diploid. Pollination factors were not related to infertility. In infertile and fertile populations, pollen-collecting insects visited flowers frequently, depositing 4-fold more pollen grains onto stigmas than the number of ovules per flower. Our study is the first to demonstrate infertility and triploidy in C. breviflorus. How triploidy became established despite high levels of pollinator activity remains a challenging question.
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