The Sequence Characterization of Somatic Excision Footprints from Two-element Transposable System of rMrh/Mrh in Maize
Transposable element insertions and excisions are prevalent forces in driving phenotypic variations,gene mutations and genome evolution.Mrh/rMrh transposons are the components of the first genetically characterized two-element transposon sys-tem from Mutator superfamily in maize,wherein rMrh transposon,the nonautonomous component has been cloned for sequence characterization.Through phenotypic analysis on the segregation ratio of progeny segregants from genetic cross population,we verified the existence of a single copy autonomous Mrh transposon to catalyse the excision of rMrh from the reporter a1 allele in the maize genome.To elucidate the effects of somatic excision and repairing pattern of rMrh on the function of host a1 gene,and the effects of two autonomous Mrh elements from distinct genetic loci on the somatic excision and repairing pattern of rMrh element at the identical a1 locus,PCR amplification and cloning were applied to recover the simple somatic excision products for sequenc-ing.Results suggested two types of major somatic transposition footprints upon the somatic excision of rMrh transposon in maize,one is precise excision repairing,and another is partial retentions of TIRs from rMrh.Meanwhile,under the regulation of Mrh ele-ments from different genetic loci,the repairing patterns of rMrh somatic excision are rather simple at the primary insertion site in maize,and lead to recovery of the function of host gene through precise excision repairing or host gene mutation due to extra base-pair retentions,but the sequences of repairing products are varied between autonomous Mrh elements from different genetic loci regardless.Our results elucidated the excision repairing features of rMrh from the classic Mrh/rMrh two-element transposon sys-tem,enriched the knowledge of genetics characteristics of Mutator transposons,and provided theoretical bases for further explo-ration of Mrh/rMrh transposon system for generating novel maize germplasms and genetic materials for functional genomics.
万方数据
维普
