Wheat rhizosphere-derived bacteria protect soybean from soilborne diseases

Authors: Yin, Chuntao; LARSON, MATT - South Dakota State University; Lahr, Nathan; Paulitz, Timothy

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/14/2023
Publication Date: 12/14/2023
Citation: Yin, C., Larson, M., Lahr, N.D., Paulitz, T.C. 2023. Wheat rhizosphere-derived bacteria protect soybean from soilborne diseases. Plant Disease. 108(6):1565-1576. https://doi.org/10.1094/PDIS-08-23-1713-RE.
DOI: https://doi.org/10.1094/PDIS-08-23-1713-RE

Interpretive Summary: Soybean comprises 90 percent of U.S. oilseed production. Soybean and corn rotation is a widely used agricultural practice by Midwest farmers. Three damaging soybean diseases, soybean cyst nematode (SCN), white mold, and soybean root rot, are destructive to production of soybean and pulse crops. The current disease control strategies, such as resistant varieties, chemical regents, and tillage, are either limited, ineffective against these pathogens, or have negative impacts on the ecosystem. In this study, 61 bacterial strains were used to examine their antagonistic activities against these pathogens. We found that six strains reduced the growth of the pathogen that causes Fusarium root rot. Two bacterial strains also inhibited the growth of the fungal pathogen Sclerotinia in cultural medium, respectively. Three of them increased the mortality rate of the SCN second-stage juveniles. Further greenhouse testing demonstrated that some of them significantly reduced soybean diseases in plants, including soybean root rot, SCN, and white mold. Their biocontrol abilities will be tested in the field.

Technical Abstract: Soybean [Glycine max (L.) Merr.] is an important oilseed crop with a high economic value. However, three damaging soybean diseases, soybean cyst nematode (Heterodera glycines Ichinohe), Sclerotinia stem rot caused by fungus Sclerotinia sclerotiorum (Lid.) de Bary, and soybean root rot caused by Fusarium spp., are major constraints to production in the Great Plains. Current disease management options, including resistant or tolerant varieties, fungicides, nematicides, and agricultural practices (crop rotation and tillage), have limited efficacy for these pathogens or have adverse effects on the ecosystem. Microbe with antagonistic activity is a promising option to control soybean diseases with the advantage of being environmentally friendly and sustainable. In this study, 61 bacterial strains isolated from wheat rhizospheres were examined for their antagonistic abilities against three soybean pathogens. Six strains significantly inhibited the growth of Fusarium graminearum in the dual-culture assay. These bacterial strains were identified as Chryseobacterium ginsengisoli, Chryseobacterium indologenes, Pseudomonas poae, two Pseudomonas spp., and Delftia acidovorans by 16S rRNA gene sequencing. Moreover, C. ginsengisoli, C. indologenes, and P. poae significantly increased the mortality of the SCN second-stage juvenile (J2) in vitro. Two Pseudomonas spp. inhibited the growth of S. sclerotiorum in vitro. Further greenhouse tests found that C. ginsengisoli and C.indologenes reduced soybean Fusarium root rot disease. C. ginsengisoli and P. poae dramatically decreased SCN egg number on SCN susceptible soybean Williams 82. Two Pseudomonas spp. protected soybean plants from leaf damage and collapsing after being infected by S. sclerotiorum. These bacteria exhibit versatile antagonistic potential. This work lays the foundation for further research on the field control of soybean pathogens.