Program Results

Introduction to the event

New insights and control of soybean red crown rot: Studies on seed-associated bacteria and seed rot resistance

Dr. Hao-Xun Chang’s research team continues the core research focus from previous Yushan Young Fellow projects, studying soybean diseases and pathogens in Taiwan and mentoring graduate students to make breakthroughs in plant pathology and disease management strategies. Soybean (Glycine max) is an important global crop, and Taiwan is renowned for its “green gold”—edamame—which generates over NT$2 billion in export value annually. In recent years, the red crown rot (RCR) has frequently occurred in the Kaohsiung–Pingtung region, posing a production risk and reducing farmers’ income. Since 2020, Dr. Chang has supervised Mr. Ping-Hu Wu, a Ph.D. student in the Department of Plant Pathology and Microbiology at National Taiwan University to propose the integrated disease management strategies against RCR with the support from the Yushan Young Fellow project. In addition to fungicide screening tests, the team screened soybean and edamame cultivars in Taiwan and found that only a few had seed rot resistance. However, resistant cultivars such as “Tainan No. 5” lost this resistance after germination; in other words, seedlings remained susceptible to root rot. This led to the hypothesis that seed rot resistance was mediated by seed-associated bacteria rather than by the plant innate immunity. Through antibiotic treatments, microbiome analysis, and isolation and culture of seed-associated bacteria, Dr. Chang’s team discovered that Bacillus altitudinis could antagonize pathogenic fungi. Further research revealed that B. altitudinis must be able to colonize and proliferate on the plant to provide resistance, but it could only colonize the seeds of certain soybean cultivars and failed to persist on roots of all cultivars. This explains why seed-associated bacteria cannot provide lasting root rot resistance. The findings were published in The ISME Journal (International Society for Microbial Ecology, ISME). In 2023, this journal had a 5-year impact factor of 11.8, ranking 2nd of 195 journals in the field of ecology (top 1.0%) and 9th of 161 journals in microbiology (top 5.6%), demonstrating the impact and forward-looking significance of this research.