Introgressing genes for perennial habit into sunflower (Helianthus annuus L.) via wide crosses.
Brent Hulke, University of Minnesota, 411 Borlaug Hall, 1991 Upper Buford Circle, St. Paul, MN 55108 and Donald L. Wyse, Department of Agronomy and Plant Genetics, University of Minnesota, 411 Borlaug Hall, 1991 Upper Buford Circle, St. Paul, MN 55108.
The genus Helianthus contains both annual and perennial species. Only two of these species are currently cultivated: Helianthus annuus L. (the domesticated, annual sunflower; 2n=2x=34) and Helianthus tuberosus L. (the perennial Jerusalem artichoke; 2n=6x=102). These species can cross in nature, and controlled crosses between them produce many perennial F1 offspring (2n=4x=68), some with both male and female fertility. Attempts to produce elite perennial sunflower lines by backcrossing the tetraploid F1 to the annual sunflower have not been successful to date. The reasons for failure include the complexity of the trait and lack of fertility in backcross populations due to aneuploidy. We attempted to improve the backcross technique by using chromosome-doubled sunflower inbred lines as recurrent parents. By crossing these plants with the F1 plants, we were able to produce stable, tetraploid backcross populations. The BC1F1 plants were grown in a field nursery in St. Paul, MN, during the summer of 2006. Variation existed for perennial-like behavior in these plants (extent of rhizomes) with some plants appearing annual in nature. Improvement of these populations will continue using pedigree selection and backcrossing until perennial lines with suitable agronomic and seed characteristics are recovered.