Identification of resistance gene analos expressed in the absence of pathogen in tall fescue and bermudagrass /

Official URL: http://risc01.sabanciuniv.edu/record=b1158353 (Table of Contents)

Kinase la and GLPL motifs are two of the most highly-conserved regions in the nucleotide-binding domain found in most resistance (R) proteins. In this study, degenerate primers that target these two conserved motifs were used to isolate R gene analogs (RGAs) from root and shoot cDNA of tall fescue {Festuca arunlmacea) and bemudagrass {Cynodon dactylon) grown in a pathogen-free environment A total of 35 clones1 were sequenced: four of them were found to be homologous to known R genes and RGAs. Three of these four sequences were obtained from bemudagrass root cDNA and are identical to one another. The fourth one was obtained from tall fescue shoot cDNA and is highly similar to the three bermudagrass sequences. The high similarity of these four sequences suggests that they may represent two alleles of the same RGA. The deduced amino acid sequence of this RGA was compared to the sequence of 27 R proteins. The five proteins that gave the closest match were MLA13 from barley. Pi-ta from rice. GPA2 from potato. RPP13 from Arabidopsis, and SW5 from tomato. Comparison of the secondary structure prediction for the RGA identified in this study and that for MLA13 of barley revealed similarities in protein structure at the sites of some conserved motifs. Determining the complete mRNA sequence of the RGA and cloning it in an expression system to isolate the protein for structural analyses should provide further insight into the nature of this recently-identified RGA.