The Diversification of Downy Mildew Species Was Not Driven by the Loss of Mycorrhizal Associations or the Evolution of C4 Photosynthesis
There are approximately 700 obligate biotrophic species grouped into 20 genera (Oomycota, Peronosporaceae) that cause downy mildew diseases. In 2001, Dick hypothesized that diversification of downy mildew species was driven in part by host plant secondary metabolites. Dick further speculated that th...
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| Format: | Article |
| Language: | English |
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The American Phytopathological Society
2022-02-01
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| Series: | PhytoFrontiers |
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| Online Access: | https://apsjournals.apsnet.org/doi/10.1094/PHYTOFR-04-21-0027-R |
| _version_ | 1827095679141412864 |
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| author | William J. Davis Jo Anne Crouch |
| author_facet | William J. Davis Jo Anne Crouch |
| author_sort | William J. Davis |
| collection | DOAJ |
| description | There are approximately 700 obligate biotrophic species grouped into 20 genera (Oomycota, Peronosporaceae) that cause downy mildew diseases. In 2001, Dick hypothesized that diversification of downy mildew species was driven in part by host plant secondary metabolites. Dick further speculated that this was driven by the transition of host plants away from mycorrhizal associations or the evolution of C4 photosynthesis. Specifically, loss of mycorrhizal associations or the use of C4 photosynthesis would result in more free carbon that the plants could then use to produce more secondary metabolites. If true, then there should be more downy mildew species that infect hosts from plant lineages that lack mycorrhizal associations or use C4 photosynthesis. However, analysis of 677 downy mildew species for host plant mycorrhizal associations and host plant photosynthetic pathway type shows that this is not what occurred. Seventy percent of downy mildew species parasitize hosts that form mycorrhizal associations, and 94% of downy mildew species parasitize hosts that use C3 photosynthesis. From this, it is concluded that the diversification of downy mildew species was not driven by the loss of mycorrhizal associations or the evolution of C4 photosynthesis. However, 85% of downy mildew species that parasitize Poaceae (grasses) parasitize C4 hosts. Thus, it is possible that C4 photosynthesis plays a role in the diversification of these genera. [Figure: see text] The author(s) have dedicated the work to the public domain under the Creative Commons CC0 “No Rights Reserved” license by waiving all of his or her rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law, 2022. |
| first_indexed | 2024-03-08T06:36:24Z |
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| institution | Directory Open Access Journal |
| issn | 2690-5442 |
| language | English |
| last_indexed | 2025-03-20T07:03:42Z |
| publishDate | 2022-02-01 |
| publisher | The American Phytopathological Society |
| record_format | Article |
| series | PhytoFrontiers |
| spelling | doaj.art-7714287ea3ce42b6ae9cce97eb3ddfdd2024-10-01T12:35:45ZengThe American Phytopathological SocietyPhytoFrontiers2690-54422022-02-0121606510.1094/PHYTOFR-04-21-0027-RThe Diversification of Downy Mildew Species Was Not Driven by the Loss of Mycorrhizal Associations or the Evolution of C4 PhotosynthesisWilliam J. Davis0Jo Anne Crouch1United States Department of Agriculture, Agricultural Research Service (USDA-ARS), Mycology and Nematology Genetic Diversity and Biology Laboratory, Beltsville, MD 20705United States Department of Agriculture, Agricultural Research Service (USDA-ARS), Mycology and Nematology Genetic Diversity and Biology Laboratory, Beltsville, MD 20705There are approximately 700 obligate biotrophic species grouped into 20 genera (Oomycota, Peronosporaceae) that cause downy mildew diseases. In 2001, Dick hypothesized that diversification of downy mildew species was driven in part by host plant secondary metabolites. Dick further speculated that this was driven by the transition of host plants away from mycorrhizal associations or the evolution of C4 photosynthesis. Specifically, loss of mycorrhizal associations or the use of C4 photosynthesis would result in more free carbon that the plants could then use to produce more secondary metabolites. If true, then there should be more downy mildew species that infect hosts from plant lineages that lack mycorrhizal associations or use C4 photosynthesis. However, analysis of 677 downy mildew species for host plant mycorrhizal associations and host plant photosynthetic pathway type shows that this is not what occurred. Seventy percent of downy mildew species parasitize hosts that form mycorrhizal associations, and 94% of downy mildew species parasitize hosts that use C3 photosynthesis. From this, it is concluded that the diversification of downy mildew species was not driven by the loss of mycorrhizal associations or the evolution of C4 photosynthesis. However, 85% of downy mildew species that parasitize Poaceae (grasses) parasitize C4 hosts. Thus, it is possible that C4 photosynthesis plays a role in the diversification of these genera. [Figure: see text] The author(s) have dedicated the work to the public domain under the Creative Commons CC0 “No Rights Reserved” license by waiving all of his or her rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law, 2022.https://apsjournals.apsnet.org/doi/10.1094/PHYTOFR-04-21-0027-Rbiodiversitygraminicolous downy mildewsHyaloperonosporaPeronosporaPeronosclerosporaPlasmopara |
| spellingShingle | William J. Davis Jo Anne Crouch The Diversification of Downy Mildew Species Was Not Driven by the Loss of Mycorrhizal Associations or the Evolution of C4 Photosynthesis PhytoFrontiers biodiversity graminicolous downy mildews Hyaloperonospora Peronospora Peronosclerospora Plasmopara |
| title | The Diversification of Downy Mildew Species Was Not Driven by the Loss of Mycorrhizal Associations or the Evolution of C4 Photosynthesis |
| title_full | The Diversification of Downy Mildew Species Was Not Driven by the Loss of Mycorrhizal Associations or the Evolution of C4 Photosynthesis |
| title_fullStr | The Diversification of Downy Mildew Species Was Not Driven by the Loss of Mycorrhizal Associations or the Evolution of C4 Photosynthesis |
| title_full_unstemmed | The Diversification of Downy Mildew Species Was Not Driven by the Loss of Mycorrhizal Associations or the Evolution of C4 Photosynthesis |
| title_short | The Diversification of Downy Mildew Species Was Not Driven by the Loss of Mycorrhizal Associations or the Evolution of C4 Photosynthesis |
| title_sort | diversification of downy mildew species was not driven by the loss of mycorrhizal associations or the evolution of c4 photosynthesis |
| topic | biodiversity graminicolous downy mildews Hyaloperonospora Peronospora Peronosclerospora Plasmopara |
| url | https://apsjournals.apsnet.org/doi/10.1094/PHYTOFR-04-21-0027-R |
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