Cytoplasmic male sterility in two wild Helianthus annuus L. accessions and their fertility restoration

Commercial sunflower hybrids have been produced by means of a single mate-sterile Helianthus petiolaris Nutt. cytoplasm and a few fertility restoration genes. The objectives of this study were to characterize cytoplasmic male-sterility (cms) systems in wild Ii. annuus L. accessions (PI 413178 and PI 413180) and to determine the inheritance of fertility restoration. Male-sterile plants were identified and maintained by backcrossing with inbred line HA89. Male-fertile progenies from crosses between ems plants of the two PIs and USDA inbred lines indicated the presence of fertility restoration genes in P21, RMAX1, and PI 413178 for ems PI 413178 (cms-ANN2), and P21, RHA280, RHA801, RPET2, and PI 413180 for cms PI 413180 (cms-ANN3). All heterozygous male-fertile plants of backcross progenies, except for RHA280, crossed to ems plants resulted in a segregation ratio of one male-fertile to one male sterile, indicating a single dominant gene controlling fertility restoration. The backcross progeny of ems PI 413180/HA89//cms PI 413180/RHA280 had a segregation ratio of one male-fertile to three male sterile, suggesting two complementary dominant genes For fertility restoration. Pollinating male-fertile plants of both accessions with HA89 pollen resulted in male-fertile and male-sterile F-1 plants, suggesting the existence of male-sterile cytoplasm and heterozygosity for restoration genes in the male-fertile plants. In Field tests, male-sterile PI 413178/4*HA89 and PI 413180/4*HA89 plants produced no seed after self-pollination, and 95 and 98% seed set, respectively, under open-pollination indicating complete male-sterility and female fertility. The new ems sources from wild Ii. annuus and corresponding fertility restoration genes provide diversity for sunflower hybrid production.