Poster: Plant-pathogen interactions

Abs # 551: Using synthetic RPP8 gene clusters to model R gene evolution by meiotic unequal crossing-over

Presenter:	Simon, Stacey A, stsimon@vt.edu
Authors	Simon, Stacey A (A)   Woffenden, Bonnie  (A)   Gilbert, Crystal  (A)   Jelesko, John  (A)   McDowell, John  (A)
Affiliations:	(A): Virginia Tech

Disease resistance genes (R genes) are frequently organized as gene clusters. This organization facilitates the evolution of R genes by unequal crossing-over between different linked paralogs. The resulting chimeric R genes could have an altered or entirely new pathogen recognition specificity. Identification of chimeric R genes is difficult because standard mutant screens are biased towards the loss or gain of a pathogen resistance phenotype. We are utilizing synthetic gene cluster technology to model both the frequency and character of unequal crossing-over within a synthetic RPP8 cluster (synthRPP8). We will identify rare meiotic unequal cross-over events by coupling chimeric gene formation to the activation of the Firefly Luciferase gene. The recombination breakpoints will be mapped and the pathogen resistance specificities of the chimeric RPP8 genes will be tested. We will also address how positional effects of the cluster and stress induced conditions influence the frequency of meiotic recombination. This study will provide new insights into the frequency and character of meiotic unequal crossing-over, as well as structure-function relationships of the resulting chimeric R gene products.