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Hubert B, Marchi M, Ly Vu J, Tranchant C, Tarkowski ŁP, Leprince O, Buitink J. A method to determine antifungal activity in seed exudates by nephelometry. PLANT METHODS 2024; 20:16. [PMID: 38287427 PMCID: PMC10826049 DOI: 10.1186/s13007-024-01144-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Accepted: 01/20/2024] [Indexed: 01/31/2024]
Abstract
BACKGROUND One of the levers towards alternative solutions to pesticides is to improve seed defenses against pathogens, but a better understanding is needed on the type and regulation of existing pathways during germination. Dormant seeds are able to defend themselves against microorganisms during cycles of rehydration and dehydration in the soil. During imbibition, seeds leak copious amounts of exudates. Here, we developed a nephelometry method to assay antimicrobial activity (AA) in tomato seed exudates as a proxy to assess level of defenses. RESULTS A protocol is described to determine the level of AA against the nonhost filamentous fungus Alternaria brassicicola in the exudates of tomato seeds and seedlings. The fungal and exudate concentrations can be adjusted to modulate the assay sensitivity, thereby providing a large window of AA detection. We established that AA in dormant seeds depends on the genotype. It ranged from very strong AA to complete absence of AA, even after prolonged imbibition. AA depends also on the stages of germination and seedling emergence. Exudates from germinated seeds and seedlings showed very strong AA, while those from dormant seeds exhibited less activity for the same imbibition time. The exudate AA did not impact the growth of a pathogenic fungus host of tomato, Alternaria alternata, illustrating the adaptation of this fungus to its host. CONCLUSIONS We demonstrate that our nephelometry method is a simple yet powerful bioassay to quantify AA in seed exudates. Different developmental stages from dormant seed to seedlings show different levels of AA in the exudate that vary between genotypes, highlighting a genetic diversity x developmental stage interaction in defense. These findings will be important to identify molecules in the exudates conferring antifungal properties and obtain a better understanding of the regulatory and biosynthetic pathways through the lifecycle of seeds, from dormant seeds until seedling emergence.
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Affiliation(s)
- Benjamin Hubert
- Univ Angers, Institut Agro, INRAE, IRHS, SFR QUASAV, F-49000, Angers, France
| | - Muriel Marchi
- Univ Angers, Institut Agro, INRAE, IRHS, SFR QUASAV, F-49000, Angers, France
| | - Joseph Ly Vu
- Univ Angers, Institut Agro, INRAE, IRHS, SFR QUASAV, F-49000, Angers, France
| | - Camille Tranchant
- Univ Angers, Institut Agro, INRAE, IRHS, SFR QUASAV, F-49000, Angers, France
| | - Łukasz P Tarkowski
- Univ Angers, Institut Agro, INRAE, IRHS, SFR QUASAV, F-49000, Angers, France
- INRAE, Université de Strasbourg, UMR SVQV, Colmar, France
| | - Olivier Leprince
- Univ Angers, Institut Agro, INRAE, IRHS, SFR QUASAV, F-49000, Angers, France
| | - Julia Buitink
- Univ Angers, Institut Agro, INRAE, IRHS, SFR QUASAV, F-49000, Angers, France.
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Liu H, An T, Zhao Y, Du X, Bi X, Zhang Z, Chen Y, Wen J. Benzoxazines in the Root Exudates Responsible for Nonhost Disease Resistance of Maize to Phytophthora sojae. PHYTOPATHOLOGY 2022; 112:1537-1544. [PMID: 35113672 DOI: 10.1094/phyto-12-21-0508-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
It has been reported that the root exudates of nonhost maize inhibit Phytophthora sojae because of the presence of benzoxazines in maize roots. To understand the concentrations of benzoxazines (Bxs) in maize root exudates and the molecular mechanism of P. sojae being inhibited, the transcriptomes of P. sojae responding to three different Bxs, 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one (DIMBOA), 6-methoxy-2-benzoxazolinone (MBOA), and benzoxazolinone (BOA), were analyzed by RNA sequencing method. We detected DIMBOA, MBOA, and BOA with a concentration range of 7 to 126 μg/ml in root exudates of three tested maize cultivars (A6565, Pengyu 1, and Xianyu 696). DIMBOA, MBOA, and BOA inhibited chemotaxis and invasiveness of P. sojae zoospores and mycelial growth. The inhibition was regulated mainly by endocytosis and the calcium signaling pathway, PI3K-Akt signaling pathway, and mTOR signaling pathway; meanwhile, the glutathione signaling pathway was activated to increase the antioxidant capacity and efflux of toxic substances. It was speculated that endocytosis plays an important role in the response of P. sojae to Bxs, and the specific functions of genes in this pathway must be further studied. This result provides new insights into the response mechanisms of P. sojae response to Bxs.
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Affiliation(s)
- Haixu Liu
- Department of Plant Protection, College of Agriculture, Northeast Agricultural University, Harbin 150030, People's Republic of China
| | - Tai An
- Department of Plant Protection, College of Agriculture, Northeast Agricultural University, Harbin 150030, People's Republic of China
| | - Yifan Zhao
- Department of Plant Protection, College of Agriculture, Northeast Agricultural University, Harbin 150030, People's Republic of China
| | - Xiuming Du
- Department of Plant Protection, College of Agriculture, Northeast Agricultural University, Harbin 150030, People's Republic of China
| | - Xiangqi Bi
- Department of Plant Protection, College of Agriculture, Northeast Agricultural University, Harbin 150030, People's Republic of China
| | - Zhuoqun Zhang
- Department of Plant Protection, College of Agriculture, Northeast Agricultural University, Harbin 150030, People's Republic of China
| | - Yufei Chen
- Department of Plant Protection, College of Agriculture, Northeast Agricultural University, Harbin 150030, People's Republic of China
| | - Jingzhi Wen
- Department of Plant Protection, College of Agriculture, Northeast Agricultural University, Harbin 150030, People's Republic of China
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