3. Genic induction of plastid mutation.

A second case, resembling that of the iojap gene, has been found where a specific gene induces irreversible plastid mutations. This new gene is cloiely linked with R and is probably an allele of luteus‑1 judging by its interaction with albino genes. Plants homozygous for this gene, and not carrying other chlorophyll mutants, have broad sectors of green and yellow tissue. Ear buds arising from the luteus sectors give all luteus populations when outcrossed by green males; ears from green sectors give all green seedlings irrespective of the constitution of the male parent. In many ways this new gene seems to be better suited for the study of gene‑cytoplasm interaction than is the iojap gene.