Registration of One Cytoplasmic Male‐Sterile and Two Fertility Restoration Sunflower Genetic Stocks

Cytoplasmic male-sterile sunflower (Helianthus annuus L.) line, cms RIGX-HA 89 (Reg. no. GS-36, PI 642059), and two corresponding fertility restoration lines, Rf RIGX-Luch (Reg. no. GS-37, PI 642060) and Rf RIGX-RCMG1 (Reg. no. GS-38, PI 642061) were cooperatively developed and released by the USDA-ARS and the North Dakota Agricultural Experiment Station, Fargo, ND, in 2005. New sources of cytoplasmic malesterility and fertility restoration genes will help reduce the genetic vulnerability of commercial sunflower hybrids because of the current use of a single male-sterile cytoplasm, PET1 (French) derived from H. petiolaris Nutt., and a few fertility restoration genes. These new cms and corresponding fertility restoration lines will provide cytoplasmic diversity for hybrid sunflower production. Seed of the cms source RIGX, derived from H. pauciflorus (rigidus) Nutt. in a cultivated background, was obtained through a scientific exchange with the Former Soviet Union (FSU) in 1987, and was increased by crossing with the inbred line HA 89 (PI 599773) and bulked pollen of several wild H. annuus L. (WA) accessions. Crosses between male-sterile plants, with the pedigree of cms-RIGX/HA 89//WA/3/HA 89, and 21 prospective restoration lines indicated the presence of fertility restoration genes in ‘Luch’ and ‘RCMG1’. Luch (PI 371937) is a germplasm developed at the N. F. Vavilov Institute of Plant Industry, the FSU. RCMG1 is an S2 line of sibmated lines among male-fertile plants of the cytoplasmic male-sterile CMG1 germplasm obtained from Dr. E.D.P. Whelan, Morden, MB, Canada, in 1981 (Whelan and Dedio, 1980; Miller and Wolf, 1991). Segregation ratios of one malefertile to three male-sterile in the F2 and nine male-fertile to sevenmale-sterile in testcross progenies indicated fertility restoration was controlled by two complementary dominant genes (Jan et al., 2002). Cms RIGX-HA 89 is a BC7 bulk with the pedigree of cms RIGX/HA 89//WA/3/7*HA 89 and has the cytoplasmic malesterility characteristic of producing no visible anthers during flowering, similar to the cms PET1 currently used in all commercial hybrids. In field tests, cms RIGX-HA 89 plants produced no seeds after self-pollination, and 99% seed set from open-pollination, indicating complete male-sterility and female-fertility. Rf RIGX-Luch is an F6 bulk homozygous for the restoration genes, with the pedigree of cms RIGX/2*HA 89/3/cms RIGX/HA 89//WA/4/2*HA 89/7/cms RIGX/2*HA 89/3/cms RIGX/HA 89//WA/4/2*HA 89/6/cms RIGX/2*HA 89/3/cms RIGX/HA 89//WA/4/HA 89/5/Luch. Rf RIGX-RCMG1 is an F7 bulk homozygous for the restoration genes, with the pedigree of cms RIGX/2*HA 89/3/cms RIGX/HA 89//WA/4/2*HA 89/7/cms RIGX/2*HA 89/3/cms RIGX/HA 89//WA/4/2*HA 89/6/cms RIGX/2*HA 89/3/cms RIGX/HA 89//WA/4/HA 89/ 5/RCMG1. Cms RIGX-HA 89 is nonbranched, with a plant height of 96 cm, flowers 79 d after planting (DAF), and has a head diameter of 12.9 cm. Seeds are black with gray stripes, with a 1000-seed weight of 60 g. Rf RIGX-Luch and Rf RIGXRCMG1 are also nonbranched, with plant heights of 65 and 97 cm, flowers 66 and 68 DAP, and has seed set percentages of 59 and 81%, respectively. Seeds of Rf RIGX-Luch and Rf RIGX-RCMG1 are black with gray stripes, and have 1000-seed weights of 42 and 58 g, respectively. In comparison, HA 89 has a plant height of 132 cm, 73 d to flowering, head diameter of 14.8 cm, black with gray stripes seed color, 1000-seed weight of 69 g, and seed set percentage of 70%. Limited quantities of seed of each genetic stock are available on request from the corresponding author for 5 yr. Recipients of seed are asked to make appropriate recognition of the source of the genetic stocks if they are used in the development of a new cultivar, germplasm, parental line, or genetic stock.