A pseudoduplication in Lycopersicon pimpinellifolium.
A double-banded variant of Prx-2 encountered in a single wild plant in a previous survey of the peroxidases of Lycopersicon pimpinellifolium was subjected to genetic analysis. Segregations obtained from crosses of this true-breeding type with various alleles of Prx-2 yielded anomalous segregations that are not compatible with a single locus model and suggest activity of alleles of a gene at another, independent locus. A critical test was afforded by studying simultaneous segregation for the apparent duplication and for two alleles at the neighboring Prx-3, a gene which proves to be very tightly linked with Prx-2. The results of the new test revealed independence between the double-banded type and Prx-3, hence also between the former and Prx-2. The most tenable hypothesis stipulates that an independent gene mPx2(1) modifies post-translationally the product coded by Prx-2(+) to yield two electrophoretically separable isozymes. These results reveal the risk of assuming, without appropriate genetic tests, that gene duplication is necessarily the cause of multiple banding.
Department of Vegetable Crops, University of California, Davis, California 95616.
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Rick
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Tanksley
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Fobes