Ac transposition is impaired by a small terminal deletion.
In maize, the P1-vv allele specifies variegated pericarp and cob pigmentation, and contains an Ac transposable element inserted in the second intron of the P1-rr gene. Starting from P1-vv, we recovered a new allele, called P1-vv5145, which gives an extremely light variegated pericarp and cob phenotype. The P1-vv5145 allele contains an Ac element ( Ac5145) at the same position and in the same orientation as in the progenitor P1-vv allele; however, the P1-vv5145 allele has a 2-bp deletion which removes the last nucleotide (A) from the 3' end of the Ac element, and an adjacent flanking nucleotide (C) from the p1 intron. In crosses with a Ds tester stock, P1-vv5145 shows a normal ability to induce Ds transposition; however, Ac excision from P1-vv5145 is 3800-fold less frequent than from the progenitor P1-vv allele. Our results demonstrate that the alteration of the 3' terminal base strongly impairs Ac transposition. The P1-vv5145 allele thus provides a relatively stable source of Ac transposase for controlling Ds transposition in genetic experiments. In addition, we describe two further alleles ( P1-ww7B8, P1-ww9A146-3) that contain deletions of Ac and flanking p1 gene sequences. These latter deletions are larger and involve the 5' end of the the Ac element. A model is proposed to explain the formation of one-sided deletions as a consequence of Ac transposition during replication of the element.
Xiao
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YL
Interdepartmental Genetics Program, Department of Zoology and Genetics, 2206 Molecular Biology Building, Iowa State University, Ames, IA 50011, USA.
Peterson
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T
D000483:Alleles; D001483:Base Sequence; D019175:DNA Methylation; D004261:DNA Replication / Q000235:genetics; D004251:DNA Transposable Elements / Q000235:genetics*; D018744:DNA, Plant / Q000737:chemistry / Q000235:genetics; D020440:Gene Duplication; D017343:Genes, Plant; D008957:Models, Genetic; D010858:Pigmentation / Q000235:genetics; D017384:Sequence Deletion; D015533:Transcriptional Activation; D003313:Zea mays / Q000235:genetics*
D004251:DNA Transposable Elements; D018744:DNA, Plant