Studies on a Maize Mutant Sensitive to Low Temperature II. Chloroplast Structure, Development, and Physiology.

In the Zea mays L. mutant M11 grown in the dark at 15 degrees , the ultrastructure of the etioplast is abnormal. The pigment content of the etioplasts is reduced but the in vivo absorption characteristics suggest that the normal protochlorophyll (ide)-holochrome is present. The lowered synthetic ability of the etioplasts is not primarily due to a reduced complement of plastid ribosomes. The plastids of mutant M11 grown in the light at 15 degrees contain little pigment, are markedly deficient in ribosomes and their ultrastructure is abnormal. In mutant M11 grown at 15 degrees , an extreme sensitivity of the plastid membranes to light was observed.