Development of cytoplasmic‐genic male sterility in safflower

Abstract

AbstractAn interspecific cross was made between Carthamaus oxyacantha and the cultivated species C. tinctorius to develop a cytoplasmic‐genic male sterility (CMS) system in safflower. C. oxyacantha was the donor of sterile cytoplasm. The 3: 1 segregation pattern observed in BC1F2 suggested single gene control with dominance of male‐fertility over male‐sterility. The information obtained from crossing male sterile X male fertile plants in BC1F3 and BC1F4 generations showed statistically significant single gene (1: 1) segregation for male sterility vs. male fertility. The results demonstrated that C. tinctorius possesses a nuclear fertility restorer gene and that a single dominant allele restored fertility (Rf) in progeny carrying CMS cytoplasm of C. oxyacantha. Male sterility occurred with the homozygous recessive condition (rfrf) in a sterile C. oxyacantha cytoplasm background and not in the normal cytoplasm of C. tinctorius. The genetic background of different restorer lines of C. tinctorius having normal cytoplasm did not effect fertility restoration. The absence of male sterile plants in C. tinctorius populations ruled out the possibility of genetic male sterility. Normal meiosis in F1 and BC1F2 ruled out a cytogenetic basis for the occurrence of male sterility.