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Rosier A, Pomerleau M, Beauregard PB, Samac DA, Bais HP. Surfactin and Spo0A-Dependent Antagonism by Bacillus subtilis Strain UD1022 against Medicago sativa Phytopathogens. PLANTS (BASEL, SWITZERLAND) 2023; 12:1007. [PMID: 36903868 PMCID: PMC10005099 DOI: 10.3390/plants12051007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 02/13/2023] [Accepted: 02/20/2023] [Indexed: 06/18/2023]
Abstract
Plant growth-promoting rhizobacteria (PGPR) such as the root colonizers Bacillus spp. may be ideal alternatives to chemical crop treatments. This work sought to extend the application of the broadly active PGPR UD1022 to Medicago sativa (alfalfa). Alfalfa is susceptible to many phytopathogens resulting in losses of crop yield and nutrient value. UD1022 was cocultured with four alfalfa pathogen strains to test antagonism. We found UD1022 to be directly antagonistic toward Collectotrichum trifolii, Ascochyta medicaginicola (formerly Phoma medicaginis), and Phytophthora medicaginis, and not toward Fusarium oxysporum f. sp. medicaginis. Using mutant UD1022 strains lacking genes in the nonribosomal peptide (NRP) and biofilm pathways, we tested antagonism against A. medicaginicola StC 306-5 and P. medicaginis A2A1. The NRP surfactin may have a role in the antagonism toward the ascomycete StC 306-5. Antagonism toward A2A1 may be influenced by B. subtilis biofilm pathway components. The B. subtilis central regulator of both surfactin and biofilm pathways Spo0A was required for the antagonism of both phytopathogens. The results of this study indicate that the PGPR UD1022 would be a good candidate for further investigations into its antagonistic activities against C. trifolii, A. medicaginicola, and P. medicaginis in plant and field studies.
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Affiliation(s)
- Amanda Rosier
- Department of Plant and Soil Sciences, University of Delaware, 311 AP Biopharma, 590 Avenue 1743, Newark, DE 19713, USA
| | - Maude Pomerleau
- Département de Biologie, Bureau D8-1014, Université de Sherbrooke, 2500 boul. Université Sherbrooke, Sherbrooke, QC J1K 2R1, Canada
| | - Pascale B. Beauregard
- Département de Biologie, Bureau D8-1014, Université de Sherbrooke, 2500 boul. Université Sherbrooke, Sherbrooke, QC J1K 2R1, Canada
| | - Deborah A. Samac
- USDA-ARS Plant Science Research Unit, 1991 Upper Buford Circle, St. Paul, MN 55108, USA
| | - Harsh P. Bais
- Department of Plant and Soil Sciences, University of Delaware, 311 AP Biopharma, 590 Avenue 1743, Newark, DE 19713, USA
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Karhoff S, Vargas-Garcia C, Lee S, Mian MAR, Graham MA, Dorrance AE, McHale LK. Identification of Candidate Genes for a Major Quantitative Disease Resistance Locus From Soybean PI 427105B for Resistance to Phytophthora sojae. FRONTIERS IN PLANT SCIENCE 2022; 13:893652. [PMID: 35774827 PMCID: PMC9237613 DOI: 10.3389/fpls.2022.893652] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 05/02/2022] [Indexed: 06/15/2023]
Abstract
Phytophthora root and stem rot is a yield-limiting soybean disease caused by the soil-borne oomycete Phytophthora sojae. Although multiple quantitative disease resistance loci (QDRL) have been identified, most explain <10% of the phenotypic variation (PV). The major QDRL explaining up to 45% of the PV were previously identified on chromosome 18 and represent a valuable source of resistance for soybean breeding programs. Resistance alleles from plant introductions 427105B and 427106 significantly increase yield in disease-prone fields and result in no significant yield difference in fields with less to no disease pressure. In this study, high-resolution mapping reduced the QDRL interval to 3.1 cm, and RNA-seq analysis of near-isogenic lines (NILs) varying at QDRL-18 pinpointed a single gene of interest which was downregulated in inoculated NILs carrying the resistant allele compared to inoculated NILs with the susceptible allele. This gene of interest putatively encodes a serine-threonine kinase (STK) related to the AtCR4 family and may be acting as a susceptibility factor, based on the specific increase of jasmonic acid concentration in inoculated NILs. This work facilitates further functional analyses and marker-assisted breeding efforts by prioritizing candidate genes and narrowing the targeted region for introgression.
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Affiliation(s)
- Stephanie Karhoff
- Center for Applied Plant Sciences, The Ohio State University, Columbus, OH, United States
- Center for Soybean Research, The Ohio State University, Columbus, OH, United States
| | - Christian Vargas-Garcia
- Center for Soybean Research, The Ohio State University, Columbus, OH, United States
- Department of Horticulture and Crop Science, The Ohio State University, Columbus, OH, United States
| | - Sungwoo Lee
- Department of Horticulture and Crop Science, The Ohio State University, Columbus, OH, United States
| | - M. A. Rouf Mian
- United States Department of Agriculture-Agricultural Research Service, Soybean Research Unit, Raleigh, NC, United States
| | - Michelle A. Graham
- Department of Agronomy, Iowa State University, Ames, IA, United States
- United States Department of Agriculture-Agricultural Research Service, Corn Insects and Crop Genetics Resources Unit, Ames, IA, United States
| | - Anne E. Dorrance
- Center for Applied Plant Sciences, The Ohio State University, Columbus, OH, United States
- Center for Soybean Research, The Ohio State University, Columbus, OH, United States
- Department of Plant Pathology, The Ohio State University, Wooster, OH, United States
| | - Leah K. McHale
- Center for Applied Plant Sciences, The Ohio State University, Columbus, OH, United States
- Center for Soybean Research, The Ohio State University, Columbus, OH, United States
- Department of Horticulture and Crop Science, The Ohio State University, Columbus, OH, United States
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