Abstract
Conspicuous asymmetries in forms that are polymorphic within a species can be genetically or environmentally determined. Here, we present a genetic analysis of the inheritance of dimorphic enantiostyly, a sexual polymorphism in which all flowers on a plant have styles that are consistently deflected either to the left or the right side of the floral axis. Using Heteranthera multiflora (Pontederiaceae), a short-lived herb, we conducted crosses within and between left- and right-styled plants and scored progeny ratios of the style morphs in F(1), F(2) and F(3) generations. Crosses conducted in the parental generation between morphs or right-styled plants resulted in right-styled progeny, whereas crosses between left-styled plants resulted in left-styled progeny. When putative heterozygous F(1) plants were selfed, the resulting F(2) segregation ratios were not significantly different from a 3 : 1 ratio for right- and left-styled plants. Crosses between left- and right-styled plants in the F(2) generation yielded F(3) progeny with either a 1 : 1 ratio of left- and right-styled plants or right-styled progeny. Our results are consistent with a model in which a single Mendelian locus with two alleles, with the right-styled allele (R) dominant to the left-styled allele (r), governs stylar deflection. The simple inheritance of dimorphic enantiostyly has implications for the evolution and maintenance of this unusual sexual polymorphism.
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Selected References
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- Capdevila J., Vogan K. J., Tabin C. J., Izpisúa Belmonte J. C. Mechanisms of left-right determination in vertebrates. Cell. 2000 Mar 31;101(1):9–21. doi: 10.1016/S0092-8674(00)80619-4. [DOI] [PubMed] [Google Scholar]
- Coyne J. A. Lack of response to selection for directional asymmetry in Drosophila melanogaster. J Hered. 1987 Mar-Apr;78(2):119–119. doi: 10.1093/oxfordjournals.jhered.a110329. [DOI] [PubMed] [Google Scholar]
- Endress P. K. Evolution of floral symmetry. Curr Opin Plant Biol. 2001 Feb;4(1):86–91. doi: 10.1016/s1369-5266(00)00140-0. [DOI] [PubMed] [Google Scholar]
- Endress PK. Symmetry in Flowers: Diversity and Evolution. Int J Plant Sci. 1999 Nov;160(S6):S3–S23. doi: 10.1086/314211. [DOI] [PubMed] [Google Scholar]
- Hudson A. DEVELOPMENT OF SYMMETRY IN PLANTS. Annu Rev Plant Physiol Plant Mol Biol. 2000 Jun;51(NaN):349–370. doi: 10.1146/annurev.arplant.51.1.349. [DOI] [PubMed] [Google Scholar]
- Jesson Linley K., Barrett Spencer C. H. Solving the puzzle of mirror-image flowers. Nature. 2002 Jun 13;417(6890):707–707. doi: 10.1038/417707a. [DOI] [PubMed] [Google Scholar]
- Murray J., Clarke B. Supergenes in polymorphic land snails. II. Partula suturalis. Heredity (Edinb) 1976 Oct;37(2):271–282. doi: 10.1038/hdy.1976.87. [DOI] [PubMed] [Google Scholar]
- Smith J M, Sondhi K C. The Genetics of a Pattern. Genetics. 1960 Aug;45(8):1039–1050. doi: 10.1093/genetics/45.8.1039. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Tuinstra E. J., De Jong G., Scharloo W. Lack of response to family selection for directional asymmetry in Drosophila melanogaster: left and right are not distinguished in development. Proc Biol Sci. 1990 Aug 22;241(1301):146–152. doi: 10.1098/rspb.1990.0078. [DOI] [PubMed] [Google Scholar]