Inheritance and allelic relationships of fertility restoration genes for seven new sources of male-sterile cytoplasm in sunflower
Jan, C.C. | Vick, B.A.
The inheritance of fertility restoration of six mitomycin C and streptomycin-induced cytoplasmic male-sterile (cms) mutants and one cms line derived from Native American cultivar PI 432513 in sunflower was evaluated. These seven new cms sources were also compared with the commercially used cms PET1 (Helianthus petiolaris Nutt.) cytoplasm, using USDA inbred lines with restoration genes (Rf₁) specific for cms PET1 and new restoration lines identified for cms PI 432513. Restoration genes for cms PI 432513 were found in 'Armavir', VNIIMK, P21 and male-fertile (MF) plants of PI 432513. F₂ and F₃ segregation ratios of crosses between cms PI 432513 and these restoration sources indicated a single dominant gene controlled fertility restoration. Progenies of cms PI 432513 testcrossed with F₁'s of half-diallel crosses among the respective four homozygous restoration lines and RHA 274 suggested that the restoration genes of RHA 274, VNIIMK, P21 and PI 432513 were at the same locus. Restoration genes from VNIIMK, P21 and PI 432513 satisfactorily restored pollen stainability in the heterozygous condition. A very weak expression of the Rf gene in 'Armavir' was observed in the heterozygous condition. Fertility restoration capability of these genes for the six mutant cms HA 89 and cms HA 89 (in PET1 cytoplasm) was observed. The mutant cms HA 89 lines were also restored completely by RHA 266, RHA 274, RHA 280 and RHA 296, and F₂'s segregation ratios indicated single dominant gene control, implying a common cytoplasmic male sterility in all lines. F₁'s of half-diallel crosses among RHA 266, RHA 273, RHA 274, RHA 280 and RHA 296 were testcrossed onto the cms lines, and their all MF progenies among lines, except RHA 280, confirmed that fertility restoration was controlled by a single Rf₁ gene locus. The restoration gene in confection line RHA 280, namely Rf₃, was at a different locus than Rf₁ and was equally capable of restoring all the cms lines. Cms HA 89 mutants and cms PI 432513 are in H. annuus cytoplasm, and are agronomically equal in hybrid performance to the cms PET1 used in commercial sunflower hybrids. These new cms lines will provide immediate alternative cms sources for reducing the genetic vulnerability resulting from the exclusive use of the single cms source PET1 in sunflower hybrid production.Show more [+] Less [-]