Somatic Instability Caused by a Cysteine-Sensitive Gene in Arabidopsis.

A recessive gene immutans (im) is responsible for abnormal chloroplast development which results in variegation in Arabidopsis plants. Somatic mutability is simulated, though only functional disorder is involved. Cysteine and low temperature favor normal function, while homocysteine interferes with chloroplast development without producing an adverse effect on the growth of the mutant.