STABLE NON-MUTATOR STOCKS OF MAIZE HAVE SEQUENCES HOMOLOGOUS TO THE Mu1 TRANSPOSABLE ELEMENT

Genetics ◽  
1986 ◽  
Vol 114 (3) ◽  
pp. 1007-1021
Author(s):  
Vicki Chandler ◽  
Carol Rivin ◽  
Virginia Walbot
Keyword(s):  
Transposable Element ◽  
Mutation Rate ◽  
Current Evidence ◽  
Mutator Activity ◽  
Restriction Sites ◽  
Initial Characterization ◽  
Element System ◽  
Intact Element ◽  
Internal Probe

ABSTRACT Mutator stocks of maize produce mutants at many loci at rates 20- to 50-fold above spontaneous levels. Current evidence suggests that this high mutation rate is mediated by an active transposable element system, Mu. Members of this transposable element family are found in ~10-60 copies in Mutator stocks. We report here an initial characterization of previously undetected sequences homologous to Mu elements in eight non-Mutator inbred lines and varieties of maize that have a normal low mutation rate. All stocks have ~40 copies of sequences homologous only to the terminal repeat and show weak homology to an internal probe. In addition, several of the stocks contain an intact Mu element. One intact Mu element and two terminal-specific clones have been isolated from one non-Mutator line, B37. The cloned sequences have been used to demonstrate that in genomic DNA the intact element, termed Mu1.4B37, is modified, such that restriction sites in its termini are not accessible to cleavage by the HinfI restriction enzyme. This modification is similar to that observed in Mutator lines that have lost activity. We hypothesize that the DNA modification of the Mu-like element may contribute to the lack of Mutator activity in B37.

scholarly journals Cloning of the Mutator transposable element MuA2, a putative regulator of somatic mutability of the a1-Mum2 allele in maize.

Genetics ◽  
1991 ◽  
Vol 129 (3) ◽  
pp. 845-854 ◽  
Author(s):  
M M Qin ◽  
D S Robertson ◽  
A H Ellingboe
Keyword(s):  
Transposable Elements ◽  
Transposable Element ◽  
Copy Number ◽  
Inverted Repeats ◽  
Terminal Inverted Repeats ◽  
Somatic Instability ◽  
Mutator Activity ◽  
Element System ◽  
Lines Of Evidence

Abstract The identification of the autonomous or transposase-encoding element of the Mutator (Mu) transposable element system of maize is necessary to the characterization of the system. We reported previously that a transcript homologous to the internal region of the MuA element is associated with activity of the Mutator system. We describe here the cloning of another Mu element, designated MuA2, that cosegregates with Mutator activity as assayed by somatic instability of the a1-Mum2 allele. The MuA2 element has features typical of the transposable elements of the Mutator family, including the 210-bp terminal inverted repeats. Several lines of evidence suggest that MuA2 is an autonomous or transposase-encoding element of the Mu family: (1) MuA2 cosegregates with a genetically defined element that regulates somatic mutability of the a1-Mum2 allele; (2) MuA2 is hypomethylated while most other MuA2-hybridizing sequences in the genome are extensively methylated; (3) the increase of the copy number of MuA2 is concomitant with the increase of regulator elements; (4) MuA2-like elements are found in Mutator lines but not in non-Mutator inbreds. We propose that autonomous or transposase-encoding elements of the Mu family may be structurally conserved and MuA2-like.

scholarly journals Identification of a regulatory transposon that controls the Mutator transposable element system in maize.

Genetics ◽  
1991 ◽  
Vol 129 (1) ◽  
pp. 261-270 ◽  
Author(s):  
P Chomet ◽  
D Lisch ◽  
K J Hardeman ◽  
V L Chandler ◽  
M Freeling
Keyword(s):  
Transposable Elements ◽  
Transposable Element ◽  
Restriction Fragment ◽  
Distinct Element ◽  
Single Locus ◽  
Inverted Repeats ◽  
Terminal Inverted Repeats ◽  
Mutator Activity ◽  
Element System ◽  
Multiple Copies

Abstract The Mutator system of maize consists of more than eight different classes of transposable elements each of which can be found in multiple copies. All Mu elements share the approximately 220-bp terminal inverted repeats, whereas each distinct element class is defined by its unique internal sequences. The regulation of instability of this system has been difficult to elucidate due to its multigenic inheritance. Here we present genetic experiments which demonstrate that there is a single locus, MuR1, which can regulate the transposition of Mu1 elements. We describe the cloning of members of a novel class of Mu elements, MuR, and demonstrate that a member of the class is the regulator of Mutator activity, MuR1. This conclusion is based on several criteria: MuR1 activity and a MuR-homologous restriction fragment cosegregate; when MuR1 undergoes a duplicative transposition, an additional MuR restriction fragment is observed, and MuR1 activity and the cosegregating MuR fragment are simultaneously lost within clonal somatic sectors. In addition, the MuR element hybridizes to transcripts in plants with Mutator activity. Our genetic experiments demonstrate that the MuR1 transposon is necessary to specify Mutator activity in our lines.

scholarly journals Characterization of the major transcripts encoded by the regulatory MuDR transposable element of maize.

Genetics ◽  
1995 ◽  
Vol 140 (3) ◽  
pp. 1087-1098
Author(s):  
R J Hershberger ◽  
M I Benito ◽  
K J Hardeman ◽  
C Warren ◽  
V L Chandler ◽  
...  
Keyword(s):  
Transposable Element ◽  
Antisense Rna ◽  
Differential Splicing ◽  
Rnase Protection ◽  
Mutator Activity ◽  
Whole Plant ◽  
Polyadenylation Sites ◽  
Exon Junctions ◽  
Plant Level

Abstract The MuDR element controls the transposition of the Mutator transposable element family in maize. Previous studies reported the presence of two major MuDR-homologous transcripts that correlate with Mutator activity. In this study, we describe the structure and processing of these two major transcripts. The transcripts are convergent, initiating from opposite ends of the element within the 220-bp terminal inverted repeats. The convergent transcripts do not overlap, and only 200 bp of internal MuDR sequences are not transcribed. Cloning and sequencing of multiple MuDR cDNAs revealed unusual intron/exon junctions, differential splicing, and multiple polyadenylation sites. RNase protection experiments indicated that some splicing failure occurs in young seedlings, and that a low level of antisense RNA exists for both transcripts. On a whole plant level, the presence of the major MuDR transcripts strictly correlates with Mutator activity in that no MuDR transcripts are observed in non-Mutator or inactive Mutator stocks. Examination of various tissues from active Mutator stocks indicates that the two transcripts are present in all organs and tissues tested, including those with no apparent transposition activity. This suggests that Mutator activity is not simply controlled by the level of the major MuDR transcripts.

scholarly journals Identification and initial characterization of POLIII-driven transcripts by msRNA-sequencing.

RNA Biology ◽  
2021 ◽  
Author(s):  
Peter Zorn ◽  
Danny Misiak ◽  
Michael Gekle ◽  
Marcel Köhn
Keyword(s):  
Initial Characterization

scholarly journals R-STIPPLED MAIZE AS A TRANSPOSABLE ELEMENT SYSTEM

Genetics ◽  
1984 ◽  
Vol 107 (3) ◽  
pp. 477-488
Author(s):  
W M Williams ◽  
K V Satyanarayana ◽  
J L Kermicle
Keyword(s):  
Transposable Element ◽  
Pollen Grains ◽  
Linkage Phase ◽  
Element System ◽  
In Trans ◽  
A Site

ABSTRACT The I-R element at the R locus destabilizes kernel pigmentation giving the variegated pattern known as stippled (R-st). In trans linkage phase with R-st the element was shown to act as a modifier of stippled, intensifying seed spotting in parallel with effects of the dominant linked modifier M-st. Presence of I-R in the genome was, therefore, shown to be detectable as a modifier of R-st. When this test was used, new modifiers resembling M-st were often detected following mutations of R-st to the stable allele R-sc. Such mutations evidently occurred by transposition of I-R away from the R locus to a site where it was identifiable as a modifier. M-st may be such a transposed I-R. Analysis of mutations to R-sc during the second (sperm-forming) mitosis in pollen grains showed that some of the transposed I-R elements were linked with R, whereas others assorted independently. Their strengths varied from barely discernible to a level equal to M-st. Overreplication frequently accompanied transposition at the sperm-forming mitosis, leading to transposed I-R elements in both the mutant and nonmutant sperm.

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