Genetic variability as identified by AP-PCR and reaction to mid-stem infection of Sclerotinia sclerotiorum among interspecific sunflower (Helianthus annuus L.) hybrid progenies

Various diseases limit productivity in the majority of sunflower (Helianthu s annuus L.) growing areas. Sunflower cultivars lack acceptable levels of r esistance to Sclerotinia sclerotiorum (Lib.) de Bary, which is a major path ogen in sunflower production. Several wild Helianthus species are potential sources of genes for disease resistance and can be used in interspecific c rosses to increase the genetic variability of cultivated sunflower, Progeni es of interspecific hybrids between cultivated sunflower lines and Helianth us mollis Lam., H. decapetalus L., H. maximiliani Schrader, H. giganteus L. , H. tuberosus L., and H. pauciflorus Nutt were tested for their midstem Sc lerotinia reaction by an artificial infection method, Compared with the sus ceptible commercial hybrid check cv. Frankasol, interspecific hybrid progen ies were selected that showed reduced Sclerotinia infection, It could be de monstrated by results of AP-PCR fingerprinting that interspecific hybrids c an be a valuable tool for broadening genetic variability in sunflower. In t otal, 20 AP-PCR primers were used for the characterization of interspecific hybrid progenies. It was possible to discriminate between the H, annuus pa rents and their progenies, where an increased genetic variability resulting from the interspecific hybridizations was detectable. Results of an UPGMA cluster analysis showed that interspecific hybrid progenies which originate in the same cross combination share a common cluster. These lines exhibite d a large genetic distance from the parental sunflower inbred Lines and for m their own distinct genetic pool.