CSIRO Division of Plant Industry

COLUMBIA, MISSOURI

University of Missouri

Name change for chloroplast mutator

--William C. Taylor, Mary Byrne and E. H. Coe, Jr.

Chloroplast mutator (cm) is a recessive mutation closely linked to R1 that causes a distinct pattern of yellow stripes on leaves. These stripes appear to be clonal, suggesting that cm is active in the apical meristem and during leaf development (Thompson et al., Am. J. Bot. 70:940-950, 1983). As is the case for iojap, cm conditioned plastids are maternally inherited (Stroup, J. Hered. 61:131-141, 1970). Maternal inheritance suggests that the nuclear mutation causes a heritable block in chloroplast development. However, one would expect a wide array of phenotypes from a mutator, rather than the clonal pattern seen in homozygous cm plants. The fact that chloroplast development is blocked at the same stage in cm stripes (Thompson, 1983) is also not what one expects from a mutator. It is formally possible that cm is a mutator in a restricted sense, causing a specific mutation in the chloroplast genome at specific times in development.

In order to remove the confusion surrounding the name mutator, we propose to change the name of this mutation to chloroplast modifier. This general description is likely to be consistent with whatever the cm mutation turns out to be.

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