Soybean Breeding for Asian Soybean Rust Resistance in South America

摘要

Imports account for most of Japan's domestic soybean consumption; therefore, it is very important that soybean production in South America, which supplies most of the soybean in the world market, remains stable. Development of soybean cultivars that show durable resistance to Asian soybean rust (ASR), a major soybean disease, will help reduce its huge control costs, which in turn will result to improved soybean productivity and farmers' profits. However, as mentioned in the previous report, titled "Analysis of Pathogenic Variation of Soybean Rust in South America," the pathogenicity of ASR pathogens in South America is diverse and strong. Thus, we may not expect stable and durable resistance in the resistant varieties, which were developed by introducing one of six known ASR resistance genes (Rppl - Rpp6). In order to cope with the peculiar characteristics of ASR pathogens in South America, four schemes were considered, namely, 1) using new ASR resistance genes in soybean; 2) pyramiding known ASR resistance genes; 3) using field resistance or tolerance against ASR; or 4) using disease-resistant genes isolated from other species. We then carried out research studies on each of these four schemes for developing new ASR resistant cultivars in South America.