Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: 3/16/2008
Publication Date: 3/16/2008
Citation: Baldo, A.M., Volk, G.M., Iezzoni, A., Olmstead, J., Aldwinckle, H., Weber, C., Samuelian, S., Malnoy, M. 2008. Resistance Gene Analogs in Rosaceae: Family-wide Classification Including Raspberry, Cherry, and Wild Apples. Abstract. International Rosaceae Genomics Conference. March 16 - 19, 2008. Pucon, Chile. p. 43.
Technical Abstract: Genetic studies have shown that NBS-LRR Resistance Gene Analogs (RGAs)tend to occur in clusters and often map to major resistance genes or QTLs. The identification and use of specific RGAs as molecular markers among plant material displaying different resistance phenotypes has the potential to directly identify the genes/genomic regions responsible for disease resistance. We undertook a comprehensive analysis of the RGAs found in Rosaceae to revise our earlier classification and identify classes associated with disease resistance. 500 Rosaceae RGA amino acid sequences were downloaded from NCBI. Additional conceptually translated sequences from our studies include 75 RGAs from raspberry germplasm, 90 from cherry germplasm, and almost 300 from various wild apple species. These RGA's represent both major classes (TIR and non-TIR subfamilies) and some have striking sequence similarity to genes previously associated with pest resistance in other rosaceous species. For example, two TIR RGA's from one of the cherry leaf spot resistant parents match an apple sequence associated with apple scab resistance. Another cherry NTIR RGA sequence matches a peach sequence that maps near a nematode resistance gene. Finally, another RGA sequence from the cherry powdery mildew resistant parent is nearly identical to a peach sequence that co-locates on the peach map with powdery mildew and sharka resistance QTLs. These results suggest that using an RGA approach in fruit crops has the potential to not only "tag" resistance gene regions but also identify potential parents among germplasm collections and provide insight into the evolutionary conservation of RGA's and their location within the Rosaceae.