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Abnormal chromosome IO and R paramutation in maize

1969; Elsevier BV; Volume: 8; Issue: 2 Linguagem: Inglês

10.1016/0027-5107(69)90008-6

1873-135X

R. A. Brink,

Plant Gene Expression Analysis

Abnormal chromosome IO (KIO) carries a large, heterochromatic segment of unknown origin at the end of the long arm and beyond sr-2, a locus 35 crossover units distal to R (conditioning anthocyanin in seed and plant). It is found that insertion of a paramutable R into a KIO chromosome regularly results in reduced sensitivity of the allele to paramutation in Rst (stippled) heterozygotes. The reduction persists, in part, when R is returned by crossing-over to a structurally normal chromosome IO, showing that KIO induces an alteration at, or near, the R locus. KIO does not affect R in repulsion. Passage of an RKIO chromosome through 3 successive generations of Rst heterozygotes progressively lowers R pigmenting potential, demonstrating that KIO retards, but does not block, paramutation. The KIO-retarding effect was duplicated by inserting R into T2-IOa a reciprocal translocation involving a break in IOL. Bearing of the results on the nature of unstable loci in higher plants is discussed.