Deciphering the molecular bases of chromosome drive using the B chromosome of rye as a model

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B chromosomes, also known as supernumerary chromosomes, are dispensable elements in the genome of many plants, animals, and fungi. Many B chromosomes have evolved one or more drive mechanisms to transmit themselves at a higher frequency than predicted by Mendelian genetics and these mechanisms counteract the tendency of non-essential genetic elements to be lost over time. After unravelling the cellular process of B chromosome drive and identifying the first rye B drive controlling candidate genes, I aim to narrow down the number of drive candidate genes by (I) identifying candidate genes that are highly conserved across diverse drive-positive rye B variants. (II) B drive candidate genes will be functionally analyzed by their transient inactivation in wheat carrying standard rye Bs. (III) A detailed evaluation of the B drive candidate gene NCR28, a microtubule-associated Futsch-like protein, will be done in A. thaliana and N. benthamiana. (IV) An in vitro test will be applied to determine tubulin-binding differences between the B- and A-encoded NCR28 variants to test the hypothesis that overexpression of the B-encoded NCR28 (co)modulates the segregation dynamics (drive) of the B chromosome.