Cultivars of Nicotiana tabacum L. normally have pink flowers and brown seeds. A white flowered and white seeded mutant occurred in a cultivar known as Jayalakshmi (JL). These associated mutant characters were recessive to pink flower and brown seed colours in F₁ progenies. F₂ populations of crosses involving JL with three normal cultivars gave segregation ratios of 15 pink flowered, brown seeded: 1 white flowered. white seeded plants. Testcross populations gave 3:1 ratios. In a fourth cross (16/103 ×JL), ratios of 3:1 in F₂ and 1.1 in the testcross were obtained. Results show that the white flower and white seed characters are governed by duplicate recessive genes. Of the four varieties used in crosses with JL, three had both genes in dominant condition, whereas in the fourth cultivar (16/103) one of the genes seems to exist in the mutated condition. The duplicate recessive genes are designated as wfs₁ and wfs₂ for white flower and white seed.

(Full article published with kind permission from "Tobacco International")