Genetic analysis of variegation mutants of pearl millet, Pennisetum glaucum

Abstract

Intercrosses between different variegated lines of Pennisetum glaucum (L.) R.Br. were made to determine their allelic composition and the number of loci controlling plastid alterations. Self-pollinations of different variegated plants resulted in normal, variegated, and yellow or white progeny. Crosses among yellow stripe mutants (IP 5009, IP 9712, IP 482) resulted in normal and yellow progeny in the F₁, and normal and yellow stripe in the F₂ generations, indicating the complementary interaction of two loci in each cross. Reciprocal crosses between the yellow stripe mutants IP 5009 and IP 13160-1 revealed similarity in their genotypes. Progeny composition from the crosses between the white stripe mutants VCM-36 and GWS-14 indicated their genotypic similarities. Crosses between yellow stripe and white stripe mutants (IP 5009 × VCM-36, IP 482 × VCM-36) indicated differences in their genotypes. Comparison of segregation patterns in the progenies of intercrosses revealed at least 4 independent loci, any one of which in recessive condition leads to mutant phenotype(s) while the development of chlorophyll is accomplished by the complementary interaction of dominant genes at these loci. Among the recessive genotypes in the F₂s from intergenotypic crosses, the mutant phenotypes fell short of expectation, indicating differential penetrance in expression.