--Yong Bao Pan and Peter A. Peterson
Recently, a number of mutable defective endosperm mutants (Dee-m) arose in several isolation plots containing active transposable elements. These mutants impair the normal endosperm development leading to sectors of chalky endosperm tissue and, as a result, to colorless sectors of aleurone layer overlying the chalky endosperm tissue (Figure 1). On the other hand, the mutant kernels have normal embryos and grow to normal plants. Genetic tests indicate that the phenotype (chalky-endosperm-and-aleurone-variegation) is a dominant trait and is independent of the genes involved in anthocyanin pathway (Figure 2).
Two of these mutants, Dee*-m857345 and Dee*-m857513 that were recovered as single variegated kernels from a Cy- and an En-containing maize population respectively, have been studied. This report summarizes the relations of these two mutants to several known families of maize transposable elements by using appropriate reporter allele testers (Table).
Figure 1. A chalky-endosperm-and-aleurone-variegation phenotype is shown by side (left) and top (right) views of a sectioned kernel of Dee-m/+ (line C) genotype.
Figure 2. Photographs of two Dee-m kernels showing the Dee-m trait is independent of aleurone coloration. Top: Dee-m/+, C/c-ruq. Bottom: Dee-m/+, c-ruq/c-ruq.
The mutant Dee*-m857345 has active En and Ac elements in addition to Cy, and Dee-m857513 has active Ac in addition to En (Table). Nevertheless, the mutable dee trait is shown not to be correlated to the activity of any of these residing active transposable elements (data not shown).
Table. Transposable element (TE) content of Dee-m857345 and Dee-m857513
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