Surface Ultrastructural Studies on Penetration and Infection Process of Colletotrichum gloeosporioides on Mulberry Leaf Causing Black Spot Disease |
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Authors: | Vineet Kumar V P Gupta A M Babu R K Mishra V Thiagarajan & R K Datta |
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Institution: | Electron Microscopy Unit, Mysore 570 008, Karnataka, India,;Mulberry Pathology Laboratory, Mysore 570 008, Karnataka, India,;Central Sericultural Research and Training Institute, Mysore 570 008, Karnataka, India |
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Abstract: | Unicelled conidia of Colletotrichum gloeosporioides germinated 3 h after inoculation producing single germ tubes. The orientation of the germ tubes and their lateral branches as they grew was towards the open stomata and away from closed stomata. By 24 h post-inoculation, the lateral branches had developed specialized infection vesicles either over the stomata or within the stomatal cavities. The infection vesicles produced primary infection hyphae which entered the leaves through stomatal openings. The disease symptoms became apparent by 6 days post-inoculation when clusters of abundant conidiophores emerged by rupturing the leaf epidermal layer, forming acervuli mostly near the base of idioblasts. The pressure exerted by the emerging conidiophores caused stretching of epidermal layer leading to the widening of the acervuli. The conidia are borne on the tips of the erect conidiophores. |
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Keywords: | Colletotrichum gloeosporioides black leaf spot mulberry penetration infection scanning electron microscopy |
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