Submitted to: Helia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/22/2004
Publication Date: 12/31/2004
Citation: Nikolova, L., Christov, M., Seiler, G.J. 2004. Interspecific hybridization between H. pumilus nutt. and H. annuus L. and their potential for cultivated sunflower improvement. Helia. 27(41):151-162. Interpretive Summary: The genus Helianthus is composed of 51 species, 37 perennial and 14 annual. Wild sunflower species constitute the basic genetic stock from which cultivated sunflower originated. The diverse species represent considerable genetic variability which can be utilized for the improvement of cultivated sunflower. The objective of this paper was to describe the interspecific hybrids obtained from a cross of cultivated sunflower and a wild perennial dwarfish sunflower (Helianthus pumilus), and their potential for improving cultivated sunflower. Successful interspecific hybridization was carried out between the wild perennial species and cultivated sunflower. The cross-compatibility between wild species and cultivated sunflower was much higher when the wild species was used as the male parent in the crosses. Seed set was very low, regardless of the parentage. Considerable variability in the first generation was observed for morphological traits such as plant height, head diameter, number of disk flowers and fertility. These traits segregated in the second generation indicating that they have a genetic basis and can be selected for in future generations. One of the most important finding of this research was the identification of genes for resistance to the following pathogens, downy mildew, broomrape, and Phomopsis stem canker which were found in the segregating progenies of the interspecific hybrids. Further research will be needed to determine the inheritance of the disease resistance genes.
Technical Abstract: Successful interspecific hybridization was carried our between the wild perennial diploid species Helianthus pumilus Nutt. accession GT-M-172, and cultivated H. annuus L. The cross-compatibility between H. pumilus and H. annuus was much higher when the wild species was used as the male in the crosses. Seed set was very low in both directions. In order to prove the presence of considerable variability in the early F1 generation, some statistical methods were used for evaluation of morphological traits such as plant height, head diameter, number of disk flowers and fertility. Heterosis was detected for plant height. Cases of partial to complete dominance of the cultivated parent prevailed. A high level of segregation was observed in the F2 generation; therefore, trait depression and transgression were evaluated for plant height, head diameter, number of florets and seed set. A triple phenotypic correlation appeared between three characters in sunflower and one of them was confirmed on the genetic level as well. Resistance to Plasmopara helianthi, Orobanche cumana and Phomopsis helianthi was discovered in different progenies of the interspecific hybrids of H. pumilus.