Analysis of Cytoplasmically Inherited Mutants

Abstract

Although cytoplasmic mutants have been documented in higher plants, they have not been studied as well as in lower eukaryotes, such as yeast and Chlamydomonas. Very few potential chloroplast mutations have been described in maize, in contrast to several in Chlamydomonas and some in other higher plants. (See Börner and Sears 1986.) The only examples of cytoplasmically inherited, defective plastids in maize appear to result from the action of nuclear genes, such as iojap. (See Walbot and Coe 1979.) In plants homozygous for iojap, some plastids show a loss of chloroplast pigments and ribosomes. The ribosome-less plastids are then inherited maternally. Other nuclear gene mutations that affect photosynthetic function have been identified on the basis of a high chlorophyll fluorescence phenotype (hcf; Miles 1982). Over one hundred nuclear hcf mutations have now been identified in maize, and they are all inherited as typical, recessive Mendelian factors (Miles and Metz 1985).