Genetic studies on radiation-induced chlorina and variegated mutants of okra (Abelmoschus esculentus (L.) Moench) revealed the existence of an unstable gene. The normal green color of the leaves is controlled by duplicate genes C1 and C2, either of which produces the green colour. The chlorina plants are C 1 C 1 C 2 C 2. The allele c 1 (v) is dominant to both C 1 and C 2 but is unstable. The homozygote c 1 (v) c 1 (v) c 2 c 2 is a normal green while the heterozygote c i (v) c 1 c 2 c 2 has a variegated phenotype as a result of the mutation of c 1 (v) to c 1 during development. In green plants with a c 1 (v) c{sh1/v}c 2 c 2 genotype, the autonomous mutation of one of the c 1 (v) alleles to c 1 may take place at the pre-meiotic stage. In the variegated genotype (c 1 (v) c 1 c 2 c 2), the mutation of c 1 to c 1 (v) may take place in early ontogeny, thus producing green plants. The allele C 1, when associated with c 1 (v) in a heterozygous condition, mutates to c 1 at the pre-meiotic stage even in the presence of the allele C 2.