Root interactions in a maize/soybean intercropping system control soybean soil-borne disease, red crown rot

• Published in: PloS one 2014-05, Vol.9 (5), p.e95031-e95031
• Main Authors: Gao, Xiang, Wu, Man, Xu, Ruineng, Wang, Xiurong, Pan, Ruqian, Kim, Hye-Ji, Liao, Hong
• Format: Article
• Language: English
• Subjects: Acids; Agricultural management; Agricultural practices; Agricultural production; Agriculture; Aluminum; Ascomycota; Biology and Life Sciences; Cinnamic acid; Control systems; Corn; Crop diseases; Cropping systems; Crops; Crops, Agricultural - microbiology; Crown rot; Disease control; Ecology and Environmental Sciences; Experiments; Exudates; Exudation; Field tests; Flowers & plants; Fungi; Fusarium oxysporum; Gene expression; Glycine max; Glycine max - microbiology; Intercropping; Laboratories; Monoculture; Mycoses - microbiology; Nutrient status; Oryza; Phenolic acids; Phenols; Phosphorus; Physiology; Plant biology; Plant diseases; Plant Diseases - microbiology; Plant Roots - microbiology; Quantitative research; Red crown rot; Research and Analysis Methods; Soil Microbiology; Soil sciences; Soil-borne diseases; Soils; Soybeans; Sustainability management; Sustainable agriculture; Zea mays - microbiology
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0095031

Within-field multiple crop species intercropping is well documented and used for disease control, but the underlying mechanisms are still unclear. As roots are the primary organ for perceiving signals in the soil from neighboring plants, root behavior may play an important role in soil-borne disease control. In two years of field experiments, maize/soybean intercropping suppressed the occurrence of soybean red crown rot, a severe soil-borne disease caused by Cylindrocladium parasiticum (C. parasiticum). The suppressive effects decreased with increasing distance between intercropped plants under both low P and high P supply, suggesting that root interactions play a significant role independent of nutrient status. Further detailed quantitative studies revealed that the diversity and intensity of root interactions altered the expression of important soybean PR genes, as well as, the activity of corresponding enzymes in both P treatments. Furthermore, 5 phenolic acids were detected in root exudates of maize/soybean intercropped plants. Among these phenolic acids, cinnamic acid was released in significantly greater concentrations when intercropped maize with soybean compared to either crop grown in monoculture, and this spike in cinnamic acid was found dramatically constrain C. parasiticum growth in vitro. To the best of our knowledge, this study is the first report to demonstrate that intercropping with maize can promote resistance in soybean to red crown rot in a root-dependent manner. This supports the point that intercropping may be an efficient ecological strategy to control soil-borne plant disease and should be incorporated in sustainable agricultural management practices.