Reactivation of Mutator transposable elements of maize by ultraviolet light.
After epigenetic loss of Mutator activity, the family of Mu elements in Zea mays becomes immobile and highly methylated; in addition, Mu9, the presumptive autonomous regulatory element, is transcriptionally silent and its copy number decreases in successive crosses to non-Mutator lines. Spontaneous reactivation, scored as restoration of somatic instability of potentially mutable alleles of Bronze-2, of such cryptic Mutator lines is rare, occurring with a frequency of about 10(-4). Irradiation of pollen with 254 nm ultraviolet light increases reactivation rate in the progeny kernels by up to 40-fold. Accompanying reactivation, the copy number of Mu9 elements increased, two-fold in one line and 20 to 40-fold in a second line. Reactivation may involve direct DNA damage or immediate physiological stress in the treated pollen.
Walbot
V
V
Department of Biological Sciences, Stanford University, CA 94305-5020.
D004247:DNA / Q000378:metabolism / Q000528:radiation effects; D004251:DNA Transposable Elements / Q000528:radiation effects*; D008745:Methylation; D009154:Mutation; D011058:Pollen / Q000528:radiation effects; D014466:Ultraviolet Rays; D003313:Zea mays / Q000235:genetics*
D004251:DNA Transposable Elements; D004247:DNA