Genetic Variability as Identified by AP‐PCR and Reaction to Mid‐Stem Infection of Sclerotinia sclerotiorum among Interspecific Sunflower (Helianthus annuus L.) Hybrid Progenies

Abstract

Various diseases limit productivity in the majority of sunflower (Helianthus annuus L.) growing areas. Sunflower cultivars lack acceptable levels of resistance to Sclerotinia sclerotiorum (Lib.) de Bary, which is a major pathogen in sunflower production. Several wild Helianthus species are potential sources of genes for disease resistance and can be used in interspecific crosses to increase the genetic variability of cultivated sunflower. Progenies of interspecific hybrids between cultivated sunflower lines and Helianthus mollis Lam., H. decapetalus L., H. maximiliani Schrader, H. giganteus L., H. tuberosus L., and H. pauciflorus Nutt were tested for their mid‐stem Sclerotinia reaction by an artificial infection method. Compared with the susceptible commercial hybrid check cv. Frankasol, interspecific hybrid progenies were selected that showed reduced Sclerotinia infection. It could be demonstrated by results of AP‐PCR fingerprinting that interspecific hybrids can be a valuable tool for broadening genetic variability in sunflower. In total, 20 AP‐PCR primers were used for the characterization of interspecific hybrid progenies. It was possible to discriminate between the H. annuus parents 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 exhibited a large genetic distance from the parental sunflower inbred lines and form their own distinct genetic pool.