Collaborative Proposal: Testing mechanisms and consequences of W chromosome turnover in a dynamic plant system

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This research will test theories of the evolution of the genes and chromosomes that determine whether individuals are male or female. The project will identify processes that lead to changes in the chromosomal location of sex-determining genes in wild ancestors of the cultivated strawberry. The work will advance our knowledge of how these changes affect gene function and whole-plant growth and reproduction. Understanding how genes are arranged on chromosomes will expanding our knowledge of the effects of varied gene location on flower and fruit development, and will inform agricultural practices that ensure food security. Educational and outreach activities will bring knowledge gained by this research to the general public, and contribute to curriculum development for middle school and high school students.Genetic determination of sex is widespread across eukaryotes and the evolutionary dynamics can transcend wide taxonomic boundaries. Changes in either the chromosome pair that determines sex or the location of the sex-determining genes can be an important driver of phenotypic dimorphism, adaptive variation, and speciation. The research will test four leading hypothesized mechanisms for, and phenotypic consequences of, turnover in the W chromosome. The work will leverage the octoploid wild strawberry (Fragaria) where translocation-based turnover has been observed, enabling tests of predicted patterns of genomic fingerprints (changes in linkage disequilibrium and function polymorphisms) characteristic of each turnover mechanism. The work will use a combination of high-throughput sequencing, molecular evolutionary analysis, genetic linkage mapping, transcriptomics, and phenotypic assessment. The research will provide insight into a key dynamic of chromosomal evolution and shed light on a genomic restructuring mechanism that also underlies the evolution of other supergenes affecting complex phenotypes, adaptation, and speciation. The work will contribute to society by expanding knowledge of the effects of chromosomal rearrangement on ecological tolerances in important wild relatives of the cultivated strawberry.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.