1. Mycosphaerella graminicola infects wheat plants via the stomata. |
2. First growth stage of M. graminicola in a wheat leaf, 48 hours after infection. |
3. First growth stage of M. graminicola between cells in wheat leaves, 48 hours after infection. |
4. During growth of the wheat leaf M. graminicola causes various changes in plant cell metabolism. Shown are strongly swollen chloroplasts. |
5. The second growth stage of M. graminicola between cells in a wheat leaf, 10 days after infection. |
6. Rapid cell death after the second growth stage of M. graminicola, where nutrients are released that enable the fungus to colonise the whole leaf very rapidly. |
7. Leaf of an adult wheat plant showing symptoms of septoria leaf spot disease caused by M. graminicola. The black spots are the pycnidia, each containing thousands of spores that are spread by water droplets. |
8. Seedling leaf with the same symptoms of septoria leaf spot disease caused by M. graminicola. |
9. First stage of the formation of a pycnidium of M. graminicola under the stomate of a wheat leaf. |
10. First stage of the formation of a pycnidium of M. graminicola under a stomate of a wheat leaf. |
11. Continuation of the formation of a pycnidium of M. graminicola under a stomate of a wheat leaf. |
12. Final stage of the formation of pycnidia. The pycnidium has been formed directly underneath the stomate and is filled with thousands of spores. As symptom of the disease the pycnidium looks as one small black spot (see photographs 7 and 8). |
13. The asexual spores of M. graminicola are contained in a viscous substance (cyrrhus) that is pressed from the pycnidia onto the leaf surface under high humidity. |
14 Asexual spores of M. graminicola are pressed through the stomates of the wheat leaf under high humidity and are disseminated via splashing water. |
15. The individual M. graminicola spores in the cyrrhus have several cells, each with one nucleus (coloured here). |
16. In this way they reach a different plant or plant part taking Mycosphaerella graminicola infestation to another level. |
The cycle above can also be watched in a movie:
Biology of Fungal Pathogens - Septoria Leaf Blotch of Wheat
(Information about fungi, how they live, reproduce, and disseminate)
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Pycnidia can also be formed on artificial substrates in petri dishes. |
In the laboratory wheat plants are inoculated by spraying with spores of M. graminicola. |
Infecting plants with spores of M. graminicola is called inoculation. |
After inoculation the plants are placed under low-light conditions for 48 hours in plastic bags to support M. graminicola infection. |
The symptoms of M. graminicola are assessed 21 days after inoculation. |
Assessment of the M. graminicola symptoms. |