During hybdrid development using male sterility R line is used to

During hybrid development using male sterility R line is used to bring fertility in male sterile plants.
The restorer line is used to restore the fertility in the hybrid after crossing with the ms A line in the hybrid production plot. The availability of fertility restorer sources in sorghum made it easy to develop hybrids and to commercially use the CMS source in producing fertile hybrid seeds.
Rf (R line) is a dominant allele for restoring male fertility and rf is its recessive allele inducing male sterility, in the presence of a male-sterile cytoplasm.