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Hemileia vastatrix
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Hemileia vastatrix
Hemileia vastatrix is a multicellular basidiomycete fungus of the order Pucciniales (previously also known as Uredinales) that causes coffee leaf rust (CLR), a disease affecting the coffee plant. Coffee serves as the obligate host of coffee rust, that is, the rust must have access to and come into physical contact with coffee (Coffea sp.) in order to survive.
CLR is one of the most economically important diseases of coffee, worldwide. Previous epidemics have destroyed coffee production of entire countries. In more recent history, an epidemic in Central America in 2012 reduced the region's coffee output by 16%.
The primary pathological mechanism of the fungus is a reduction in the plant's ability to derive energy through photosynthesis by covering the leaves with fungus spores and/or causing leaves to drop from the plant. The reduction in photosynthetic ability (plant's metabolism) results in a reduction in quantity and quality of flower and fruit production, which ultimately reduces the beverage quality.
The mycelium with uredinia looks yellow-orange and powdery, and appears on the underside of leaves as points ~0.1 mm in diameter. Young lesions appear as chlorotic or pale yellow spots some millimetres in diameter, the older being a few centimetres in diameter. Hyphae are club-shaped with tips bearing numerous pedicels on which clusters of urediniospores are produced.
Telia are pale yellowish teliospores often produced in uredinia; teliospores more or less spherical to limoniform, 26–40 × 20–30 μm in diameter, wall hyaline to yellowish, smooth, 1 μm thick, thicker at the apex, pedicel hyaline.
Urediniospores are more or less reniform, 26–40 × 18-28 μm, with hyaline to pale yellowish wall, 1–2 μm thick, strongly warted on the convex side, smooth on the straight or concave side, warts frequently longer (3–7 μm) on spore edges.
There have been no known reports of a host capable of supporting an aecial stage of the fungus.
Hemileia's life cycle begins with the germination of uredospores through germ pores in the spore. It mainly attacks the leaves and is only rarely found on young stems and fruit. Appressoria are produced, which in turn produce vesicles, from which entry into the substomatal cavity is gained. Within 24–48 hours, infection is completed. After successful infection, the leaf blade is colonized and sporulation will occur through the stomata. One lesion produces 4–6 spore crops over a 3–5 month period releasing 300–400,000 spores.
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Hemileia vastatrix
Hemileia vastatrix is a multicellular basidiomycete fungus of the order Pucciniales (previously also known as Uredinales) that causes coffee leaf rust (CLR), a disease affecting the coffee plant. Coffee serves as the obligate host of coffee rust, that is, the rust must have access to and come into physical contact with coffee (Coffea sp.) in order to survive.
CLR is one of the most economically important diseases of coffee, worldwide. Previous epidemics have destroyed coffee production of entire countries. In more recent history, an epidemic in Central America in 2012 reduced the region's coffee output by 16%.
The primary pathological mechanism of the fungus is a reduction in the plant's ability to derive energy through photosynthesis by covering the leaves with fungus spores and/or causing leaves to drop from the plant. The reduction in photosynthetic ability (plant's metabolism) results in a reduction in quantity and quality of flower and fruit production, which ultimately reduces the beverage quality.
The mycelium with uredinia looks yellow-orange and powdery, and appears on the underside of leaves as points ~0.1 mm in diameter. Young lesions appear as chlorotic or pale yellow spots some millimetres in diameter, the older being a few centimetres in diameter. Hyphae are club-shaped with tips bearing numerous pedicels on which clusters of urediniospores are produced.
Telia are pale yellowish teliospores often produced in uredinia; teliospores more or less spherical to limoniform, 26–40 × 20–30 μm in diameter, wall hyaline to yellowish, smooth, 1 μm thick, thicker at the apex, pedicel hyaline.
Urediniospores are more or less reniform, 26–40 × 18-28 μm, with hyaline to pale yellowish wall, 1–2 μm thick, strongly warted on the convex side, smooth on the straight or concave side, warts frequently longer (3–7 μm) on spore edges.
There have been no known reports of a host capable of supporting an aecial stage of the fungus.
Hemileia's life cycle begins with the germination of uredospores through germ pores in the spore. It mainly attacks the leaves and is only rarely found on young stems and fruit. Appressoria are produced, which in turn produce vesicles, from which entry into the substomatal cavity is gained. Within 24–48 hours, infection is completed. After successful infection, the leaf blade is colonized and sporulation will occur through the stomata. One lesion produces 4–6 spore crops over a 3–5 month period releasing 300–400,000 spores.
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