ARS | Publication request: Identification and mapping of nucleotide binding site-leucine rich repeat resistance gene analogs in bermudagrass

Submitted to: Journal of the American Society for Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 6, 2010
Publication Date: March 19, 2010
Citation: Harris, K.R., Schwartz, B.M., Paterson, A.H., Brady, J.A. 2010. Identification and mapping of nucleotide binding site-leucine rich repeat resistance gene homologs in bermudagrass. Journal of the American Society Horticultural Science. 135:74-82.

Interpretive Summary: Bermudagrass is a perennial grass used widely for lawns, sports fields, parks, golf courses, pastures, and to prevent soil erosion in most of the warmer environments across the world. Although bermudagrass tolerates a diverse range of environmental conditions, it is susceptible to a wide range of fungi, nematodes, and insects. To date, the development of cultivars with resistance to diseases or pests of interest in many plant species has been accomplished by use of traditional plant breeding, the use of marker-assisted selection (MAS) to transfer resistance genes from a resistant genotype to a cultivar, and by genetic transformation. This study aimed to ‘mine’ disease resistance like genes from diploid, triploid, and hexaploid bermudagrass with resistance to various living organisms. Thirty-one unique disease resistance like genes were identified and mapped onto a bermudagrass genetic map. Genetic regions where these disease resistance genes clustered were identified. Genetic markers were created from these disease resistance like genes and may prove useful for the improvement of disease resistance in bermudagrass.

Technical Abstract: Thirty-one bermudagrass (Cynodon spp.) disease resistance gene homologs (BRGH) were cloned and sequenced from diploid, triploid, and hexaploid bermudagrass using degenerate primers to target the nucleotide binding site (NBS) of the NBS- leucine rich repeat (LRR) resistance gene family. Alignment of deduced amino acid sequences revealed that the conserved motifs of the NBS are present and all sequences have non- Drosophila melanogaster Toll and mammalian interleukin-1 receptor (TIR) motifs. Using a neighbor-joining algorithm, a dendrogram was created and eight BRGH groups were identified. Four BRGH markers and fifteen bermudagrass expressed sequence tags (ESTs) with homology to resistance genes or resistance gene homologs were placed on a bermudagrass genetic map. BRGH and EST markers clustered on T89 linkage groups 1a, 5a, and 19. In addition, three primers made from BRGH groups and ESTs with homology to NBS-LRR resistance genes amplify NBS-LRR homologs in zoysiagrass (Zoysia japonica or Z. matrella) or seashore paspalum (Paspalum vaginatum). This gives evidence of conservation of NBS-LRR homologs among the subfamilies Chloridoideae and Panicoideae. These BRGH and EST markers may be useful in marker-assisted selection for the improvement of disease resistance in bermudagrass.