Location: Corn Insects and Crop Genetics Research
2019 Annual Report
Accomplishments
1. Convergent evolution of a novel plant disease resistance locus. Plant disease resistance is often mediated by intracellular immune receptors known as nucleotide-binding leucine-rich repeat proteins (NLRs). The primary function of the many NLR-type resistance genes deployed in crop protection is to detect the presence of pathogen-secreted effector proteins. ARS scientists in Ames, Iowa collaborated with colleagues at Cornell University in Ithaca, New York and Indiana University in Bloomington, Indiana to discover that multiple barley varieties recognize and respond to a conserved protease activity mediated by the pathogen effector, designated AvrPphB. Barley reaction to the AvrPphB effector is controlled by a novel NLR disease resistance gene, designated AvrPphB Response 1 (Pbr1). Wheat varieties also possess copies of Pbr1, suggesting that this new disease resistance system can be deployed in cereal grain crops. These results provide the first evidence that host targets of AvrPphB have essential immune functions in both monocot and dicot crops. This knowledge will be used to expand protease effector recognition, creating disease resistant crops.
2. Evaluation of maize silk resistance to corn earworm. Caterpillar pests like corn earworm are among the most damaging to corn because they reduce grain quantity by herbivory and grain quality by vectoring diseases. While present chemical and biochemical technologies are protective, corn with its own genetic resistance mechanisms is important for both organic and future conventional growers. ARS scientists in Ames, Iowa developed a quantitative corn earworm bioassay and applied it to the discovery of new genetic resistance mechanisms found in tropical corn. Because genetic solutions can reduce or eliminate pesticide use, this research offers opportunities to simultaneously lower farm input costs, protect crop health, and prevent damage to the environment.
Review Publications
Carter, M., Helm, M., Chapman, A., Wan, E., Restrepo Sierra, A., Innes, R., Bogdanove, A., Wise, R.P. 2019. Convergent evolution of effector protease recognition by Arabidopsis and barley. Molecular Plant-Microbe Interactions. 32(5):550-565. https://doi.org/10.1094/MPMI-07-18-0202-FI.
Wisser, R.J., Lauter, N.C. 2018. Genomics of fungal disease resistance. In: Bennetzen J., Flint-Garcia S., Hirsch C., Tuberosa R., editors. The Maize Genome. Compendium of Plant Genomes. Cham, Switzerland: Springer International. p. 201-211. https://doi.org/10.1007/978-3-319-97427-9_13.
Lopez, M.D., Dennison, T., Ward, T.M., Yandeau-Nelson, M.D., Abel, C.A., Lauter, N.C. 2019. Development and application of a quantitative bioassay to evaluate maize silk resistance to corn earworm herbivory among progenies derived from Peruvian landrace Piura. PLoS One. 14(4):e0215414. https://doi.org/10.1371/journal.pone.0215414.
Elmore, J.M., Perovic, D., Ordon, F., Schweizer, P., Wise, R.P. 2018. A genomic view of biotic stress resistance. In: Stein, N., Muehlbauer, G., editors. The Barley Genome. Cham, Switzerland: Springer International. p. 233-257. https://doi.org/10.1007/978-3-319-92528-8_14.
Carter, M., Bogdanove, A., Innes, R., Wise, R.P. 2018. A confounding effect of bacterial titer in a type III delivery-based assay of eukaryotic effector function. Molecular Plant-Microbe Interactions. 31(11):1115-1116. https://doi.org/10.1094/MPMI-05-18-0128-LE.
