Construction and genetic analysis of mutator insertion mutant population in maize

A total of 26718 M1 plants were obtained by crossing the active mutator transposon donor parents (Q105, WW51, 115F, V26-2 and 919J) with the recipient parents (Hz85,W328 with Bz gene and S-Mo17 Rf3Rf3 ). The phenotypes of M1 plants were observed in the field. M1 plants were self-pollinated to develop the mutator insertion-mutagenized M2 seeds. The transposition frequency of the 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 M1 phenotypes in the field was 0.07 in the population of W328× Mu ; (2) the mutation frequency of spotted aleurone seeds on the M2 ears was 0.122 in the population of W328× Mu ; (3) five S-cytoplasm male-sterile plants were found among 22500 M1 plants of S-Mo17 Rf3Rf3 × Mu , with the transposition frequency about 2.2×10 −4 per locus. 99 flanking sequences of mutator transposition were amplified by the modified MuTAIL-PCR, and 59 non-redundant sequences with length around 400 bp were obtained. After bioinformatic analysis, 27 sequences of them could be annotated, using non-redundant nucleotide database of maize, rice, and Arabidopsis . 36 sequences of them were located on the genetic map of maize by comparative genomics, and several flanking sequences of mutator insertion were mapped on the single marker locus. Hotspot sequences of mutator transposition were revealed by comparing the homologies between the 9-bp target site duplication of the mutator insertion. The putative functions of 8 flanking sequences of mutator transposition had identity with the functions of their corresponding marker. The constructed mutator insertion mutant population in maize will facilitate the new gene discovery and functional genomics study in maize.