BTT EAGER: Investigating Genetic, Epigenetic and Environmental Control of Meiotic Recombination using Fluorescent Crossover Reporters in Tomato

Most crop foods, including seeds, grains, fruit and vegetables, are the result of plant sexual reproduction. Successful reproduction requires the interaction of parental chromosomes. The same kind of chromosomal interactions are used by plant breeders to create new combinations of favorable traits. The Copenhaver lab at The University of North Carolina at Chapel Hill together with their collaborators, the Henderson lab from the University of Cambridge previously developed a powerful technique for detecting and quantifying these chromosome interactions in a model plant species related to the mustard plant. In this project the Copenhaver and Henderson labs will extend that technology into a commercial crop species tomato. They will then use that technology to measure the effects of genetic, epigenetic and environmental factors on influencing the number and genomic distribution of these chromosome interactions in order to understand the fundamental biological mechanism that drive plant reproduction, as well as to identify fruitful avenues for accelerating crop breeding. The Copenhaver and Henderson labs will publish their findings in open-access formats, and make the genetic resources they develop available to researchers and industrial colleagues.

Previously, the Copenhaver and Henderson labs developed a visual assay for measuring meiotic recombination frequencies directly in the gametes of Arabidopsis thaliana. They assay, called the FTL system, employs a collection of lines harboring transgenes encoding pollen-specific fluorescent proteins expressed in the quartet (qrt) mutant background, which enable tetrad analysis in a higher plant. In this project they will translate the FTL system into Solanum lycopersicum (tomato). Using the tomato FTL system they will test whether CRISPR/Cas9 induced mutations in recq4 helicase homologs result in genome wide hyper-recombination. They will also test whether CRISPR/Cas9 induced mutations in genes that mediate epigenetic mechanisms such as DNA methylation and small RNA biogenesis can alter recombination frequencies around specific chromosomal domains with distinct chromatin environments such as centromeres. Prior work in Arabidopsis, suggests that exposure to high and low temperatures can significantly modulate recombination frequencies. The Copenhaver and Henderson lab will test whether similar environmental manipulation can alter recombination frequencies in S. lycopersicum. The project will provide training for two postdoctoral fellows as well as independent research experiences for undergraduates in both the Copenhaver and Henderson lab. The research findings will be published in open-access formats, and all genetic resources will be made available to both research and industrial colleagues.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.