AUTHOR=Skibbe David S., Fernandes John F., Walbot Virginia 

TITLE=Mu killer-Mediated and Spontaneous Silencing of Zea mays Mutator Family Transposable Elements Define Distinctive Paths of Epigenetic Inactivation

JOURNAL=Frontiers in Plant Science

VOLUME=3

YEAR=2012

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2012.00212

DOI=10.3389/fpls.2012.00212

ISSN=1664-462X

ABSTRACT=<p><italic>Mu killer</italic> contains a partial inverted duplication of the <italic>mudrA</italic> transposase gene and two copies of the terminal inverted repeat A (TIRA) region of the master <italic>MuDR</italic> element of maize. <italic>Mu killer</italic> can effectively silence single copy <italic>MuDR/Mu</italic> lines, and it is proposed that a ∼4 kb hairpin RNA is generated by read through transcription from a flanking gene and that this transcript serves as a substrate for siRNA production. <italic>Mu killer</italic> was sequenced, except for a recalcitrant portion in the center of the locus, and shown to be co-linear with <italic>mudrA</italic> as originally proposed. The ability of the dominant <italic>Mu killer</italic> locus to silence a standard high copy number <italic>MuDR/Mu</italic> transposon line was evaluated. After two generations of exposure, about three quarters of individuals were silenced indicating reasonable effectiveness as measured by the absence of <italic>mudrA</italic> transposase transcripts. <italic>Mu killer</italic> individuals that effectively silenced <italic>MuDR</italic> expressed two short antisense transcripts. In contrast, <italic>Mu killer</italic> individuals that failed to silence <italic>MuDR</italic> expressed multiple sense transcripts, derived from read through transcription initiating in a flanking gene, but no antisense transcripts were detected.</p>