Abstract

Although the impact of polymorphism on crossover has been well established at the fine scale, little is known about its effect in a genome-wide manner. I am interested in exploring the influence of natural genetic variation on CO patterns in the model plant Arabidopsis thaliana. We have developed high-throughput systems for measuring recombination frequency using linked transgenes expressing distinct colours of fluorescent protein via (i) flow cytometry-based analysis in pollen and (ii) and fluorescence microscopy in seed. Both techniques enable us to analyze 1,000s-100,000s of recombination events within a relatively short time and obtain robust measures of CO frequency, and genetic interference. We have crossing natural A. thaliana accessions with the standard laboratory accession Col-0 lines bearing our reporter transgenes. In F1 plants we observe a change in genetic distance, but its relationship with the degree of genetic polymorphism is not straightforward. We have generated an F2 population in one case and observed extensive variation in CO rate between individuals. Interesting, by genetic mapping we found a strong correlation between CO frequency in the interval and homo- / heterozygosity along the chromosome. Our further investigations shows it is chromosomal location independent. At the moment we are working to dissect the molecular mechanism that are responsible for this effect. This research will elucidate mechanisms that regulate meiotic recombination frequency in natural populations of plants.