A method of producing double low restorer line of Brassica napus for Ogura cytoplasmic male sterility (cms) pre-senting radish introgression carrying the Rfo restorer gene deleted of the radish Pgi-2 allele and recombined with the Pgi-2 gene from Brassica oleracea, and having a good agronomic value characterized by female fertility, a good transmission rate of Rfo and a high vegetative vigour. A method of forming Brassica napus hybrid seeds and progeny thereof. The seeds of Brassica napus and use of the combined markers PGIol, PGlunt, PGlint, BolJon and CP418 for characterising.