Tassel seed (ts) and silkless (sk) genes in maize
Maize is monoecious with male inflorescence (tassel) and female inflorescence (silk) located on the same plant. A gene tassel seed (ts) is known, which will convert the tassel into seed bearing inflorescence. Another gene silkless (sk) is responsible for the absence of silks. Therefore, a plant sk/sk will be effectively a male plant and a plant, ts/ts will be effectively a female plant. By using these genes it has been possible to convert maize from a monoecious to a dioecious form, where plants will bear only male or only female inflorescences.
For instance, if we use females with genotype ts ts sk sk (seeds on tassels, silkless) and males with genotype Ts ts sk sk (normal tassel and silkless) on crossing, they will give males and females (having same genotypes as parents) in 1 : 1 ratio. This will be stable dioecious situation.
Transformer gene (tra)in Drosophila
In Drosophila, a transformer gene (tra) has been identified, which if present in homozygous condition (tra/tra) converts a female into a sterile male, but does not act upon normal male individual.
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