Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 1/4/2007
Publication Date: 1/10/2007
Citation: Jan, C.C., Feng, J., Seiler, G.J., Rashid, K.Y. 2007. Development of Sclerotinia head rot resistant germplasm utilizing H. maximiliani and H. nuttallii. 5th Annual Sclerotinia Initiative Meeting, January 17-19, 2007, Bloomington, MN. p. 18. Interpretive Summary:
Technical Abstract: Sclerotinia is the most damaging disease with an incidence higher than other major sunflower diseases. Wild Helianthus species have played an important role in establishing sunflower as an important global oilseed crop. However, the present day sunflower germplasm is still represented by a relatively narrow genetic base, which greatly limits its future success as a competitive major oilseed crop. Interspecific hybridization of NMS HA 89 with Sclerotinia head rot resistant wild diploid perennial H. maximiliani and H. nuttallii accessions was successful using embryo rescue. A total of 162 F1 hybrid plants were obtained after rescuing 228 embryos from 70,500 pollinated florets. Most F1 plants had the expected 2n chromosome number of 34. A few F1 hybrids had 2n=51 chromosome which was assumed to have resulted from fertilization of normal gametes with unreduced gametes. Most F1 plants with 2n=34 chromosome had low pollen stainablity of around 1%, and consequently low backcross seed set with only 85 seed from 506 pollinated heads. Backcrosses of 2n=34 F1 plants with HA 441 produced BC1F1 progeny with 2n=34 or 35 chromosome. Sib-pollination among heads with colchicine-induced chromosome doubling also had low seed set with 250 seeds from 425 pollinated heads. These sib-pollinated seeds produced amphiploids with 2n=62 to 68 chromosomes. Backcrossing of 2n=34 to 35 F1 plants with HA 441 is now in progress, as well as sib-pollination of the amphiploids for seed increase. The use of diploid perennial Helianthus accessions is expected to avoid the limitations of using higher ploidy Helianthus species or amphiploids by providing maximum genetic recombination in the F1 generation, minimizing target gene loss, and shorten the breeding time to obtain adequate seed for replicated field disease evaluation.