Meiotic recombination ensures the accurate segregation of homologous chromosomes and reshuffles genetic information to generate new combinations of alleles. In plants, recombination is essential for plant breeding, which allows us to map quantitative traits and introduce desirable traits into elite breeding lines. Sex differences have important consequences for population differentiation, sex chromosome evolution, adaptation, and speciation. Much is known about sex differences in overall recombination rates, but relatively little about how and why sexes differ in recombination. In maize, analysis of female meiosis and embryo sac development is technically challenging, thus hindering the causes of differences in male and female meiosis. To identify the variation, we use the 25 parental inbreds of the maize Nested Association Mapping (NAM) population to compare the recombination frequency between sexes. The NAM lines are fully sequenced and can maximize genetic diversity – likely indicating variation between male and female recombination.
Our central hypothesis is that male and female meiotic recombination differs in different inbred maize lines at both global and local scales, and local DNA sequences and chromatin structures are involved in this process. My working hypothesis was to determine whether and how female and male meiosis differs in a tropical maize line CML228. During this project, I extracted DNA from >500 leaf samples from the two backcrossed populations B73 × CML228/B73 and CML228/B73 × B73. The assembled genome sequences of B73 and CML228 were compared to identify InDel markers used to measure the recombination frequency. Primer3Plus was used to design PCR primers. The primers were then screened to select ones that could amplify the regions with polymorphisms between B73 and CML228.
The long-term goal in our laboratory is to identify novel genetic and epigenetic factors that can influence meiotic recombination to facilitate more rapid breeding and better understand this fundamental process.
Author(s): Sahil Angdembe, Biology and Premedical Studies Major
Advisor(s): Meixia Zhao, Department of Biology
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