Rhizophagus irregularis, the model fungus in arbuscular mycorrhiza research, forms dimorphic spores

Vasilis Kokkoris; Claudia Banchini; Louis Paré; Lobna Abdellatif; Sylvie Séguin; Keith Hubbard; Wendy Findlay; Yolande Dalpé; Jeremy Dettman; Nicolas Corradi; Franck Stefani

doi:10.1111/nph.19121

Rhizophagus irregularis, the model fungus in arbuscular mycorrhiza research, forms dimorphic spores

Vasilis Kokkoris, Claudia Banchini, Louis Paré, Lobna Abdellatif, Sylvie Séguin, Keith Hubbard, Wendy Findlay, Yolande Dalpé, Jeremy Dettman, Nicolas Corradi, Franck Stefani^*

^*Corresponding author for this work

Systems Ecology

Research output: Contribution to Journal › Article › Academic › peer-review

Abstract

Rhizophagus irregularis is the model species for arbuscular mycorrhizal fungi (AMF) research and the most widely propagated species for commercial plant biostimulants.
Using asymbiotic and symbiotic cultivation systems initiated from single spores, advanced microscopy, Sanger sequencing of the glomalin gene, and PacBio sequencing of the partial 45S rRNA gene, we show that four strains of R. irregularis produce spores of two distinct morphotypes, one corresponding to the morphotype described in the R. irregularis protologue and the other having the phenotype of R. fasciculatus.
The two spore morphs are easily distinguished by spore colour, thickness of the subtending hypha, thickness of the second wall layer, lamination of the innermost layer, and the dextrinoid reaction of the two outer spore wall layers to Melzer's reagent. The glomalin gene of the two spore morphs is identical and that of the PacBio sequences of the partial SSU-ITS-LSU region (2780 bp) obtained from single spores of the R. cf fasciculatus morphotype has a median pairwise similarity of 99.8% (SD = 0.005%) to the rDNA ribotypes of R. irregularis DAOM 197198.
Based on these results, we conclude that the model AMF species R. irregularis is dimorphic, which has caused taxonomic confusion in culture collections and possibly in AMF research.

Original language	English
Pages (from-to)	1771-1784
Number of pages	14
Journal	New Phytologist
Volume	242
Issue number	4
Early online date	11 Jul 2023
DOIs	https://doi.org/10.1111/nph.19121
Publication status	Published - May 2024

Funding

Our research is kindly supported by the Natural Sciences and Engineering Research Council (RGPIN2020‐05643), a Discovery Accelerator Supplements Program (RGPAS‐2020‐00033), and by Agriculture and Agri‐Food Canada (AAFC) under project J‐002272 (Fungal and Bacterial Biosystematics). NC is a Research Chair at the University of Ottawa, and VK was supported by the MITACS Industrial PDF program (IT16902) to NC, and by Agriculture and Agri‐Food Canada (AAFC) under project J‐002272. We would also like to thank Denise Chabot of the Microscope Laboratory (Ottawa‐RDC, AAFC) for excellent training and technical assistance in all microscopy techniques.

Funders	Funder number
Natural Sciences and Engineering Research Council of Canada	J‐002272, RGPIN2020‐05643, RGPAS‐2020‐00033
Natural Sciences and Engineering Research Council of Canada
Mitacs	IT16902
Mitacs

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title = "Rhizophagus irregularis, the model fungus in arbuscular mycorrhiza research, forms dimorphic spores",

abstract = " Rhizophagus irregularis is the model species for arbuscular mycorrhizal fungi (AMF) research and the most widely propagated species for commercial plant biostimulants. Using asymbiotic and symbiotic cultivation systems initiated from single spores, advanced microscopy, Sanger sequencing of the glomalin gene, and PacBio sequencing of the partial 45S rRNA gene, we show that four strains of R. irregularis produce spores of two distinct morphotypes, one corresponding to the morphotype described in the R. irregularis protologue and the other having the phenotype of R. fasciculatus. The two spore morphs are easily distinguished by spore colour, thickness of the subtending hypha, thickness of the second wall layer, lamination of the innermost layer, and the dextrinoid reaction of the two outer spore wall layers to Melzer's reagent. The glomalin gene of the two spore morphs is identical and that of the PacBio sequences of the partial SSU-ITS-LSU region (2780 bp) obtained from single spores of the R. cf fasciculatus morphotype has a median pairwise similarity of 99.8% (SD = 0.005%) to the rDNA ribotypes of R. irregularis DAOM 197198. Based on these results, we conclude that the model AMF species R. irregularis is dimorphic, which has caused taxonomic confusion in culture collections and possibly in AMF research.",

author = "Vasilis Kokkoris and Claudia Banchini and Louis Par{\'e} and Lobna Abdellatif and Sylvie S{\'e}guin and Keith Hubbard and Wendy Findlay and Yolande Dalp{\'e} and Jeremy Dettman and Nicolas Corradi and Franck Stefani",

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AU - Kokkoris, Vasilis

AU - Banchini, Claudia

AU - Paré, Louis

AU - Abdellatif, Lobna

AU - Séguin, Sylvie

AU - Hubbard, Keith

AU - Findlay, Wendy

AU - Dalpé, Yolande

AU - Dettman, Jeremy

AU - Corradi, Nicolas

AU - Stefani, Franck

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N2 - Rhizophagus irregularis is the model species for arbuscular mycorrhizal fungi (AMF) research and the most widely propagated species for commercial plant biostimulants. Using asymbiotic and symbiotic cultivation systems initiated from single spores, advanced microscopy, Sanger sequencing of the glomalin gene, and PacBio sequencing of the partial 45S rRNA gene, we show that four strains of R. irregularis produce spores of two distinct morphotypes, one corresponding to the morphotype described in the R. irregularis protologue and the other having the phenotype of R. fasciculatus. The two spore morphs are easily distinguished by spore colour, thickness of the subtending hypha, thickness of the second wall layer, lamination of the innermost layer, and the dextrinoid reaction of the two outer spore wall layers to Melzer's reagent. The glomalin gene of the two spore morphs is identical and that of the PacBio sequences of the partial SSU-ITS-LSU region (2780 bp) obtained from single spores of the R. cf fasciculatus morphotype has a median pairwise similarity of 99.8% (SD = 0.005%) to the rDNA ribotypes of R. irregularis DAOM 197198. Based on these results, we conclude that the model AMF species R. irregularis is dimorphic, which has caused taxonomic confusion in culture collections and possibly in AMF research.

AB - Rhizophagus irregularis is the model species for arbuscular mycorrhizal fungi (AMF) research and the most widely propagated species for commercial plant biostimulants. Using asymbiotic and symbiotic cultivation systems initiated from single spores, advanced microscopy, Sanger sequencing of the glomalin gene, and PacBio sequencing of the partial 45S rRNA gene, we show that four strains of R. irregularis produce spores of two distinct morphotypes, one corresponding to the morphotype described in the R. irregularis protologue and the other having the phenotype of R. fasciculatus. The two spore morphs are easily distinguished by spore colour, thickness of the subtending hypha, thickness of the second wall layer, lamination of the innermost layer, and the dextrinoid reaction of the two outer spore wall layers to Melzer's reagent. The glomalin gene of the two spore morphs is identical and that of the PacBio sequences of the partial SSU-ITS-LSU region (2780 bp) obtained from single spores of the R. cf fasciculatus morphotype has a median pairwise similarity of 99.8% (SD = 0.005%) to the rDNA ribotypes of R. irregularis DAOM 197198. Based on these results, we conclude that the model AMF species R. irregularis is dimorphic, which has caused taxonomic confusion in culture collections and possibly in AMF research.

U2 - 10.1111/nph.19121

DO - 10.1111/nph.19121

M3 - Article

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EP - 1784

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JF - New Phytologist

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ER -

Rhizophagus irregularis, the model fungus in arbuscular mycorrhiza research, forms dimorphic spores

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