Resistance Gene Analogs in Six Genera of Rosaceae: A Family-wide Classification

Authors: Baldo, Angela; Volk, Gayle; Henk, Adam; IEZZONI, AMY - MICHIGAN STATE; OLMSTEAD, JIM - WASHINGTON STATE; ALDWINCKLE, HERB - CORNELL UNIV; WEBER, CA - CORNELL UNIV; SAMUELIAN, S - CORNELL UNIV; MALNOY, MA - IASMA ITALY

Submitted to: Plant and Animal Genome Conference
Publication Type: Abstract Only
Publication Acceptance Date: 1/1/2009
Publication Date: 1/10/2009
Citation: Baldo, A.M., Volk, G.M., Henk, A.D., Iezzoni, A., Olmstead, J.W., Aldwinckle, H.S., Weber, C., Samuelian, S., Malnoy, M. 2009. Resistance Gene Analogs in Six Genera of Rosaceae: A Family-wide Classification. Plant & Animal Genome XVII Conference. Annual Conference. January 10-14, 2009. San Diego, CA. pp.182. Meeting Abstract.

Interpretive Summary: 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 plants with different levels of biotic resistance may help us find the genes or genomic regions responsible for this resistance. We have accomplished a comprehensive analysis of the RGAs found in Rosaceae to revise an earlier classification and identify classes of these genes associated with disease resistance. 500 Rosaceae RGA amino acid sequences were downloaded from NCBI. Additional conceptually translated sequences from our studies include 75 unique RGA sequences from raspberry germplasm, 90 from cherry germplasm, and 133 from 23 wild apple species. These RGAs represent both major classes (TIR and non-TIR subfamilies). The new classification retains 18 of our earlier TIR (11) and non-TIR (11) groups that contained multiple genera. Some of the new RGA sequences have striking similarity to genes previously associated with pest resistance in other rosaceous species. For example, an 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 (plum pox) 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.

Technical Abstract: 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 plants with different levels of biotic resistance may help us find the genes or genomic regions responsible for this resistance. We have accomplished a comprehensive analysis of the RGAs found in Rosaceae to revise an earlier classification and identify classes of these genes associated with disease resistance. 500 Rosaceae RGA amino acid sequences were downloaded from NCBI. Additional conceptually translated sequences from our studies include 75 unique RGA sequences from raspberry germplasm, 90 from cherry germplasm, and 133 from 23 wild apple species. These RGAs represent both major classes (TIR and non-TIR subfamilies). The new classification retains 18 of our earlier TIR (11) and non-TIR (11) groups that contained multiple genera. Some of the new RGA sequences have striking similarity to genes previously associated with pest resistance in other rosaceous species. For example, an 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 (plum pox) 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.