Abstract
Layia glandulosa (Compositae) and L. discoidea are self-incompatible annual plants native to California which are completely interfertile and appear to be related as progenitor and recent derivative. L. glandulosa has sunflower-like heads (capitula) with showy female rays, each subtended by an involucral bract which enfolds the ovary. L. discoidea lacks both rays and enfolding bracts. We describe the results of a breeding programme to identify specific genes that control these and associated morphological traits. The differences in capitulum type are governed primarily by two genes, partially confirming the conclusions of Clausen, Keck and Hiesey (1947). Recombination of these genes produced a novel phenotype with “gibbous” florets in place of rays. Gibbous florets have aspects of both ray and disk florets as well as unique traits. They are fertile and consistent in expression, demonstrating that new combinations of developmental processes may be assimilated without evident adverse effects. Another recombinant genotype confers on ray florets traits such as ovary pubescence and pappus, normally found only on disk florets. Despite the absence of ray florets, L. discoidea has a polymorphism that affects ray presence/absence and additional genes modifying ray floret number, size, shape and colour. Thus, differences in floral morphology between the species depend on a complex assemblage of genes with significant and specific morphological consequences.
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Bachmann, K. 1983. Evolutionary genetics and the genetic control of morphogenesis in flowering plants. Evolutionary Biology, 16, 157–208.
Clausen, J, Keck, D D, and Hiesey, W M. 1947. Heredity of geographically and ecologically isolated races. Am Nat, 81, 114–133.
Fick, G N. 1967. Genetics of floral color and morphology in sunflowers. J Hered, 67, 227–230.
Ford, V S, and Gottlieb, L D. Morphological evolution in Layia (Compositae): Character recombination in hybrids between L. discoidea and L. glandulosa. Syst Bot, 14, 284–296.
Gottlieb, L D. 1984. Genetics and morphological evolution in plants. Am Nat, 123, 681–709.
Gottlieb, L D, and Ford, V S. 1987. Genetic and develop-mental studies of the absence of ray florets in Layia dis-coidea. In Thomas, H. and Grierson, D. (eds) Develop-mental Mutants in Higher Plants, Cambridge University Press, Cambridge.
Gottlieb, L D, Warwick, S I, and Ford, V S. 1985. Morphological and electrophoretic divergence between Layia discoidea and L. glandulosa. Syst Bot, 10, 484–495.
Ingram, R, and Taylor, L. 1982. The genetic control of a non-radiate condition in Senecio squalidus L. and some observations on the role of ray florets in the Compositae. New Phytol, 91, 749–756.
Jackson, R C, and Dimas, C T. 1981. Experimental evidence for systematic placement of the Haplopappus phyllocephalus complex (Compositae). Syst Bot, 6, 8–14.
Mitchison, G J. 1977. Phyllotaxis and the Fibonacci series. Science, 196, 270–275.
Trow, A H. 1912. On the inheritance of certain characters in the common groundsel-Senecio vulgaris L.-and its segre-gates. J Genet, 2, 239–276.
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Ford, V., Gottlieb, L. Genetic studies of floral evolution in Layia. Heredity 64, 29–44 (1990). https://doi.org/10.1038/hdy.1990.5
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DOI: https://doi.org/10.1038/hdy.1990.5
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