Image credit: A. McCoy.
Abstract
Plant disease resistance genes are widely used in agriculture to reduce disease outbreaks and epidemics and ensure global food security. In soybean, Rps (Resistance to Phytophthora sojae) genes are used to manage Phytophthora sojae, a major oomycete pathogen that causes Phytophthora stem and root rot worldwide. This study aimed to identify temporal changes in P. sojae pathotype complexity, diversity, and Rps gene efficacy. Pathotype data were collected from 5,121 isolates of P. sojae derived from 29 surveys conducted between 1990 and 2019 across the United States, Argentina, Canada, and China. This systematic review shows a loss of efficacy of specific Rps genes utilized for disease management and a significant increase in pathotype diversity over time. The most widely deployed Rps genes used to manage Phytophthora stem and root rot globally, Rps1a, Rps1c, and Rps1k, are no longer effective in the United States, Argentina, and Canada. This study emphasizes the need to broadly introduce new sources of resistance to P. sojae, such as Rps3a, Rps6, or Rps11, into commercial cultivars to effectively manage disease risk going forward.