Two mutations in a maize bronze-1 allele caused by transposable elements of the Ac-Ds family alter the quantity and quality of the gene product.
The Dissociation (Ds) mutant, Bz-wm, of the maize bronze-1 (bz) locus conditions a leaky phenotype. Plants carrying this mutant allele synthesize a low amount of an altered Bz gene product, which leads to reduced anthocyanin pigmentation in the seed. The molecular analysis reported here shows that the Bz-wm mutant has a 406-bp Ds1 insertion located 63 bp 5' to the start of Bz transcription. Furthermore, the Bz-wm allele contains three additional base pairs within the second exon, relative to the wild-type Bz allele. These additional nucleotides are believed to be derived from the 8-bp target site duplication created by an Activator (Ac) element in a previous allele in the series. The biochemical and molecular analyses of Bz-wm and revertants of Bz-wm indicate that the three additional nucleotides are responsible for the altered enzyme stability, while the Ds1 element affects the steady-state level of Bz-specific protein and RNA. Since the two mutations present in the Bz-wm mutant were each caused by the action of the Ac-Ds transposable element system, these results provide new insights into the ways that transposable elements can modify maize gene expression.
Schiefelbein
J W
JW
Laboratory of Genetics, University of Wisconsin-Madison 53706.
Furtek
D B
DB
Dooner
H K
HK
Nelson
O E
OE
D000483:Alleles; D000872:Anthocyanins / Q000235:genetics; D001483:Base Sequence; D015139:Blotting, Southern; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D004251:DNA Transposable Elements; D004795:Enzyme Stability; D005786:Gene Expression Regulation; D005964:Glucosyltransferases / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D012313:RNA / Q000096:biosynthesis; D015183:Restriction Mapping; D003313:Zea mays / Q000235:genetics*
D000872:Anthocyanins; D004251:DNA Transposable Elements; D012313:RNA; D004247:DNA; D005964:Glucosyltransferases; C023249:flavonol 3-O-glucosyltransferase