Construction And Genetic Analysis Of Mutator Transposon Insertional Population In Maize And Primary Research On A Maize Brittle Mutant

Maize (Zea mays L.) is not only a major cash crop but also an important model system for basic biological research. The finished whole genomic sequencing is likely to make maize one of the most important species for functional genomic studies in cereal crop. Constructing loss-of-function mutants is one of the most direct and efficient way to study the function of gene. While insertional mutagenesis is the easiest strategy, resources based on mutations caused by defined DNA insertions are likely to have an enduring importance in functional genomics. The Mutator transposons in maize hold an advantage of high activity to construct large mutant population, which makes it a powerful and indispensable tool to screen mutations and clone functional gene.In current research, a MuDR-active line was used as the pollen donor to cross with a Chinese elite maize inbred line Z31. The progenies of the cross were self-pollinated to produce the Mutator mutant stocks. After the identification of the mutants in the field and the amplification and analysis of the MuDR flanking sequences, a total genetic analysis of the insertional mutant population was performed. The major results are as follows:1. A total of 886 lines containing 17720 individuals were constructed. The field identification showed that there were 1031 individuals in 536 lines having a distinguishable mutant phenotype, including albino and yellow seedlings, plant height, leaf included angle, the number of ear and tassel, leaf color, pollen sterility, brittleness, ear height and so on.2. Totally,695 specific fragments were amplified and sequenced with a modified MuTAIL-PCR method, among which,374 non-redundant insertion sites were identified.3.298 of the 374 identified non-redundant insertion sites were mapped in silico to a single locus on the integrated maize map. The results revealed some prominent features of the MuDR-related insertions of maize:distribution across the 10 chromosomes, preferential insertion into genic sequences and favoring some classes of functional genes.4. After screening of the mutant population, two brittle stalk mutants were obtained. After back-cross with the parent Z31 and self-pollened, a segregating F2 population was constructed. Phenotype identification result showed that the segregating ratio of wildtype and brittle stalk in this population fitted with 3:1 ratio. Cellulose content in brittle muntant was lower by 50%, while soluble sugar content is markedly increased. Cytological analysis showed that there was no difference in numbers and morphous of vascular bundle, while the vascular bundle sheath cell wall in mutants was thicker than that in wild type, which may lead to the stalk brittleness.5. Through Mu-Illumina sequencing method,48 potential candidate genes were identified from the isolated Mu insertional sites.