ISHS Acta Horticulturae 751: IV International Symposium on Rose Research and Cultivation
NBS-LRR-RGAS IN ROSES: DIVERSITY, GENOMIC ORGANIZATION, EXPRESSION AND CHROMOSOMAL LOCATION |
| Authors: | A. Hattendorf, T. Debener |
| Keywords: | Resistance Gene Analogs (RGAs), black spot, powdery mildew, resistance genes, evolution, mapping |
| Abstract:
Degenerate oligonucleotide primers targeting conserved motifs within the NBS region of nucleotide binding site (NBS)-leucine-rich repeat (LRR) resistance (R) genes were used to isolate resistance gene analogs (RGAs) from roses. A large RGA sublibrary consisting of 7000 clones was established. Sixty-seven percent of this sublibrary has been characterized and contains at least 40 unique RGA families of variable sizes, which could be subdivided further into the TIR (toll-/ interleukin-1 receptor) and the LZ (leucine zipper) group. TIR- and LZ-RGAs show a clear phylogenetic separation, while distances between the single members of the LZ group are larger. The RGAs were organized as single-, low- and multicopy loci in the rose genome, but none of the analyzed sequences was conserved in Prunus cerasus. We studied the expression of some of the rose RGAs in a black spot resistant rose genotype and identified several candidates probably involved directly in the resistance reaction against black spot or in general stress responses. Finally, we integrated the RGAs into two different rose chromosome maps, which also contain the single dominant R genes Rdr1 against black spot and Rpp1 against powdery mildew (PM) and several QTL (quantitative trait loci) involved in PM resistance. We identified some RGAs in chromosomal regions together with QTL for PM resistance as well as a number of RGA clusters probably indicating genomic regions containing not yet identified R genes. | |
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