Cytological and Electrophoretic Investigations of the Origin of ‘Callie’ Bermudagrass
1980
‘Callie’ bermudagrass (Cynodon dactylon var. aridus Harlan et de Wet) is a vigorous, robust form selected as an aberrant plant from a plot of PI 290814 bermudagrass (C. dactylon L. Pets.). Since Callie differed markedly from the original introduction, a cytological and electrophoretic investigation was undertaken in an attempt to determine how it originated. Callie and PI 290814 had a chromosome number of 2n=4x=36. Meiosis was regular in both plants and their chromosome pairing behavior was similar with primarily bivalent pairing. Pollen stainability in Callie was 46%. Seed set ranged from 1.0 to 3.2% in Callie and was 1.0% in PI 290814. Embryo sac development was normal and there was no evidence of ovule abortion in either plant. Thirtythree selfed progeny from Callie showed a considerable range in morphology and vigor, illustrating a high degree of heterozygosity. None were as large or vigorous as Callie, indicating an inbreeding depression after one generation of selling. Electrophoresis demonstrated qualitative differences in the water-soluble proteins in leaf tissue of Callie and PI 290814. This eliminates mutation as a means of Caliie's origin. These findings suggest that Callie probably originated as a natural hybrid between PI 290814 and a giant, tetraploid form of C. dactylon var. aridus. Its size and vigor are probably the result of heterosis as well as characteristics from the pollen parent.
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