Identification of Novel Variants in Interspecific Derivatives of Helianthus Divaricatus and Cultivated Sunflower

Abstract

Wild Helianthus species serve as potential sources for several desirable characteristics such as resistance to biotic and abiotic stresses, cytoplasmic male sterility, fertility restorer genes and oil quality (Thompson et al., 1981; Seiler, 1992). Among the wild sunflowers, H. divaricatus-a diploid perennial of the section Divaricati-assumes importance owing to its tolerance to diseases like Plasmopara halstedii and Diaporthe helianthi (Korell et al., 1996) and its crossability to cultivated sunflower (Nikolova and Christov, 1990). Screening of Helianthus species for resistance to leaf spot incited by Alternaria helianthi (Hansf.) Tubaki et Nishihara revealed H. divaricatus as a useful source against this pathogen (Sujatha et al., 1997). In an attempt to transfer this trait to cultivated sunflower, interspecific hybridization between cultivars and H. divaricatus was undertaken. The F1 hybrids were highly fertile with formation of 17 regular bivalents. The dominance of wild characters viz., branching, and pointed bracts was observed in the F1 and BC1 generations. At BC2, phenotypically superior plants were selected and intermated to avoid narrowing down of the variability for the polygenically controlled trait like resistance to Alternaria. © 2003, by Walter de Gruyter Berlin/Boston. All rights reserved.