Submitted to: Proceedings Sunflower Research Workshop
Publication Type: Proceedings
Publication Acceptance Date: 2/29/2000
Publication Date: N/A
Citation: Interpretive Summary: The vulnerability of using a single Helianthus petiolaris male-sterile cytoplasm (cms) for worldwide sunflower production has been recognized. None of the 62 cms sources reported are being used for sunflower hybrids, primarily due to the incomplete expression of some cms , and the difficulties of identifying simple and complete nuclear fertility restoration genes. This paper presents study of a cms source derived from perennial species H. rigidus (cms-RIG2) obtained from the former Soviet Union in 1988, with regard to its stability and expression, identification and inheritance of fertility restoration genes, and to compare it with another H. rigidus derived cms-RIG1. The cms-RIG2 was shown to be stable and expressed typical cms characteristics of no anther extrusion and no pollen production. Restoration genes were found in cultivated lines and complete fertility was restored by 2-complementary genes. The same genes restored both cms-RIG1 and cms-RIG2, suggesting the same cms of the two sources. These cms-RIG and restoration gene combinations provide additional sources for hybrid sunflower production.
Technical Abstract: The cms-RIG2 has the characteristic cytoplasmic male sterility property of producing no visible anther during flowering, similar to the cms-PET1 used in all commercial hybrids. After crossing with 20 restoration testers, only crosses with testers Luch and RCMG1 produced male-fertile (MF) progeny. The respective testcross and self-pollinated F2 progeny segregation ratios of 1 MF:3 MS and 9MF: 7MS plants were obtained for both Luch and RCMG1 restoration sources closely fit the expected segregation ratio of a 2-complementary-gene control mechanism. Pollen stainability of MF testcross progenies averaged 91 and 53% for Luch and the RCMG1 sources, respectively, and the large variation of pollen stainability (33 to 91%) in progenies of the RCMG1 sources suggests potential for further selection. In the 1990 field test, average seed set was 99% for open- pollination and 0% for selfing male-sterile plants, suggesting complete female fertility and male sterility of cms-RIG2. The identical testcross and F2 segregation of cms-RIG1 cytoplasm to the restoration genes identified specifically for cms-RIG2 suggested that these two cms sources are the same. The vigor reducing effects of perennial Helianthus species with annual HA89 nuclear genes were observed and could be easily restored by a single dominant gene. The common existence of vigor restoration genes in cultivated lines enhances the utilization of cms-RIG for sunflower hybrids when a breeder can focus on only the selection of fertility restoration genes.