Poster: Plant Pathogen/Symbiont Interactions

Abs # 708: Using Synthetic RPP gene clusters to model R gene evolution by meiotic unequal crossing-over

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

Paralogous disease resistance genes (R genes) are frequently organized as gene clusters. This organization facilitates the evolution of the R gene cluster by a process of unequal crossing-over between different linked paralogs resulting in chimeric R genes. The resulting chimeric R genes could have an altered or entirely new pathogen recognition specificity. Identification of chimeric R genes is difficult in standard mutant screens because loss of a pathogen resistance phenotype can occur by many different mechanisms and gain of a new pathogen resistance specificity requires either prior knowledge of which new pathogen specificity will arise or a large collection of susceptible pathogens which to challenge thousands of plants. In contrast, we are utilizing synthetic gene cluster technology to rapidly identify chimeric R genes by coupling chimeric gene formation to the activation of the Firefly Luciferase gene, thereby imparting a bioluminescent phenotype to the plant. This enables the rapid screening of millions of seedlings to quickly identify chimeric R genes formed by rare meiotic events. We will report progress on the construction of a synthetic RPP8 and a synthetic RPP1 gene cluster in Arabidopsis thaliana that will be used to model meiotic recombination between paralogous RPP genes. These synthetic R gene clusters will provide new insights into the frequency and character of unequal crossing-over, as well as structure-function relationships of the resulting chimeric R gene products. Note, SS & BW equally contributed to this work.