Inheritance and transmission of plastid alterations in a green–white stripe mutant of pearl millet (Pennisetum americanum)

The breeding behaviour of the GWS-14 stripe mutant of pearl millet was tested in crosses with different normal inbred lines. The F2 segregations revealed two independently assorting recessive nuclear genes controlling the stripe phenotype with variable expressivity. Striping appeared 25 days after germination or later, suggesting the delayed expression of mutant genes. When stripe plants were crossed with pollen from normal inbreds, normal and white F1 progeny were obtained, while reciprocal crosses gave exclusively normal F1 progeny, suggesting that the white plastids are maternally transmitted in the absence of homozygous recessive nuclear genes in homoplastidic (altered plastids) egg cells. The absence of stripe progeny indicates the possible reversion of such plastids in heteroplastidic egg cells.