Interspecific Hybrids Between Helianthus maximiliani Schrad. and H. annuus L.: Effect of Backcrossing on Meiosis, Anther Morphology, and Seed Characteristics1
- Ernest D. P. Whelan and
- D. G. Dorrell2
Substitutions of the nucleus of Helianthus annuus L. (2n = 34; x = 17) into the cytoplasm of the perennial H. maximiliani Schrad. (2n = 84) were obtained by hybridizing H. maximiliani with wild H. annuus, and then backcrossing, using cultivated H. annuus ‘Saturn’ as the recurrent pollen parent. A paracentric inversion, evident in the F1,-was eliminated by one cross with ‘Saturn’, and multivalents were rare after the first backcross. Pollen fertility improved with backcrossing. Trisomic plants occurred in all three progenies investigated, but with differing frequencies. Oil content and 1,000-seed weight increased with backcrossing. Seed weight of trisomic plants was significantly greater than that of diploid sibs; oil content also tended to be higher. Backcrossing also affected anther morphology. Some plants had highly modified and almost vestigial anthers, which contained little or no pollen, but all trisomic plants had normal anthers. If selection for male-sterility, probably cytoplasmic, is desired, trisomics should be avoided when backcrossing.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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