Development of cytoplasmic-genic male sterility in safflower

Abstract

An interspecific cross was made between Carthamaus oxyacantha andthe cultivated species C. tinclorius to develop a cytoplasmic-genic malesterility (CMS) system in safflower. C. oxyacantha was the donor ofsterile cytoplasm. The 3 : 1 segregation pattern observed in BC1F2suggested single gene control with dominance of male-fertility overmale-sterility. The information obtained from crossing male ster-ile X male fertile plants in BC1F3 and BC]F4 generations showedstatistically significant single gene (1 : 1) segregation for male sterilityvs. male fertility. The results demonstrated that C. tinctorius possessesa nuclear fertility restorer gene and that a single dominant allelerestored fertility (Rf) in progeny carrying CMS cytoplasm ofC. oxyacantha. Male sterility occurred with the homozygous recessivecondition (rfrf) in a sterile C. oxyacantha cytoplasm background andnot in the normal cytoplasm of C. tinctorius. The genetic backgroundof different restorer lines of C. tinctorius having normal cytoplasm didnot effect fertility restoration. The absence of male sterile plants inC. tinctorius populations ruled out the possibility of genetic malesterility. Normal meiosis in F| and BC1F2 ruled out a cytogenetic basisfor the occurrence of male sterility.