Construction And Genetic Analysis Of Mutator Insertional Mutants Pool In Maize

The innovation, improvement and expansion of maize germplasm are a chief step in modern breeding systems and are a long-term stratagem for the commonweal. Mu elements are the transposons with the highest transposition activity and mutation capability discovered so far. Although the mechanism of mutator transposon was not known very clearly, it is useful in constructing large mutant population of maize for creating maize germplasm, obtaining mutant genes, isolating and cloning important maize functional genes. Mu element will be used to mutate and isolate genes in other heterogenous species.In this research, A total of 4218 Ml plants were generated from seeds of crosses between the active mutator transposon donor parents (Q105, WW51, 115F, V26-2 and 919J) and the recipient parents(Hz85 and W328 with B(?) gene). The phenotypes of M1 plants were observed in the field and self-pollinated to establish the mutator insertion-mutagenized M2 seeds pool. The reversion frequency of mutator in the genome was calculated based on the spotted aleurone phenotype of the M2 seeds. The results showed that:(1) The mutation frequency of Ml phenotypes in the filed was 0.154 in the population of Hz85×Mu; the mutation frequency of Ml phenotypes in the filed was 0.071 in the population of W328×Mu; the reversion frequency of the Mu elements was 0.122 in the M2 population of W328×Mu.(2) 99 flanking sequences of mutator transpostion were amplified by modified MuTAIL-PCR, among which 59 sequences about 400 base pair were non-redundant and bioinformatically analyzed.(3) Results showed that 27 sequences could be annotated comparing with the non-redundant nucleotide database of Maize, Rice and Arabidopsis, and that 36 sequences could be located on the genetic map of maize. Hotspot sequences of mutator transposition were found after comparing the homologies among the 9-bp target site duplication of the mutator insertion. Several flanking sequences of mutator insertion were mapped at a single marker locus on the genetic map of maize. The putative functions of 8 flanking sequences of mutator transposition were found to be consistent with the functions of their corresponding marker locus.The mutator insertional mutants pool in maize constructed in the current research will provide a valuable platform for gene discovery and functional genomics study in maize.