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Home • Blumeria graminis f. sp. hordei DH14
powdery mildew (Blumeria graminis)
powdery mildew (Blumeria graminis)
from Clemson University - USDA Cooperative Extension Slide Series, Bugwood.org used under a Creative Commons Attribution 3.0 License.
A colony of the barley powdery mildew fungus (Blumeria graminis f. sp. hordei) growing on the leaf surface. The network of hyphae expanding over the leaf surface is visible in the foreground. The erect conidiophores generate masses of airborne conidia visible to the naked eye as a dry powdery mass that is easily dispersed by air currents. Picture by Pietro D. Spanu
A colony of the barley powdery mildew fungus (Blumeria graminis f. sp. hordei) growing on the leaf surface. The network of hyphae expanding over the leaf surface is visible in the foreground. The erect conidiophores generate masses of airborne conidia visible to the naked eye as a dry powdery mass that is easily dispersed by air currents. Picture by Pietro D. Spanu

The genome sequence and gene prediction of Blumeria graminis f. sp. hordei DH14 have not been determined by the Joint Genome Institute (JGI), but were obtained from Lamprinos Frantzeskakis. In order to allow comparative analyses with other fungal genomes sequenced by the JGI, a copy of this genome is incorporated into Mycocosm. Please note that this copy of the genome is not maintained by Frantzeskakis et. al. and is therefore not automatically updated. JGI tools were used to automatically annotate predicted proteins.

Blumeria graminis causes powdery mildews in grasses, including the common cereals wheat and barley. Host specificity of the “formae specialis” is high: for example f. sp. hordei is capable of infecting barley but not wheat, whist the f. sp. tritici grows only on wheat. Like all powdery mildew fungi, B. graminis is an obligate biotroph: it requires a living host to grow and reproduce. No significant development has been ever observed in axenic culture. On a host, the mildew fungi conidium germinates to produce a hypha that differentiates an appressorium and a peg that penetrates directly into the epidermal cell. Once inside the cell, the hypha develops a multidigitate haustorium, surrounded by a matrix and a membrane continuous with the host plasma membrane. The haustorium takes up nutrients from the host and is believed to deliver effectors to target the plant’s metabolism and immune system. The haustoria effectively feed the rest of the colony which expands on the surface of the plant, first as a network of branched hyphae (which produce further, secondary haustoria and then develops conidiophores which grow perpendicular to the leaf surface and generate masses of conidiophores that are visible as a white powdery mass (hence the name of the disease). The conidia are dispersed by air currents.

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