Recognition of two formae speciales of Erysiphe graminis by wheat cells.

F1 hybrid cultures between Erysiphe graminis f.sp. agropyri (wheatgrass mildew fungus) and E. graminis f.sp. tritici (wheat mildew fungus) were produced by using a common host of the two formae spéciales. When three common wheat cultivars, Triticum aestivum cv. Norin 4, T. aestivum cv. Norin 10, and T. compactum cv. No. 44, were inoculated with a population of F1 cultures, avirulent and virulent cultures segregated in a 3:1 ratio. This indicated that two major genes are involved in the avirulence of E. graminis f.sp. agropyri, Ak-1, on each of the three cultivars. Further analyses revealed that the three pairs of avirulence genes have one gene in common. On T. aestivum cv. Shin-chunaga, T. aestivum cv. Norin 26, and a strain of T. macha, the F1 population segregated in the same pattern as on T. aestivum cv. Norin 4, indicating that the same pair of avirulence genes is operating on these four cultivars. On T. aestivum cv. Red Egyptian the distribution of F1 phenotypes was continuous, suggesting that no major genes are involved in the avirulence of Ak-1 on this cultivar.Key words: powdery mildew, Erysiphe graminis, avirulence, wheat, wheatgrass.

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Isozyme Variation and Genetic Distances of Erysiphe graminis DC. Formae Speciales

Journal of Phytopathology ◽

10.1111/j.1439-0434.1990.tb04292.x ◽

1990 ◽

Vol 129 (2) ◽

pp. 89-101 ◽

Cited By ~ 8

Author(s):

G. Koch ◽

W. Köhler

Keyword(s):

Genetic Distances ◽

Erysiphe Graminis ◽

Isozyme Variation ◽

Formae Speciales

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Cytological aspects of interactions between formae speciales of Erysiphe graminis and genera of gramineous plants, and their evolutionary implications

Canadian Journal of Botany ◽

10.1139/b90-158 ◽

1990 ◽

Vol 68 (6) ◽

pp. 1249-1253 ◽

Cited By ~ 16

Author(s):

Y. Tosa ◽

T. Akiyama ◽

H. Ogura

Keyword(s):

Triticum Aestivum ◽

Cell Wall ◽

Hordeum Vulgare ◽

Secale Cereale ◽

Avena Sativa ◽

Erysiphe Graminis ◽

The Other ◽

Formae Speciales ◽

Ancestral Form ◽

Host Parasite

The progress of infection in leaves of wheat (Triticum aestivum), rye (Secale cereale), wheatgrass (Agropyron tsukushiense), barley (Hordeum vulgare), and oat (Avena sativa) inoculated with Erysiphe graminis f.sp. tritici, secalis, agropyri, and hordei was observed using a fluorescence microscope. Relative compatibility of each host–parasite combination was estimated by the incidence of cell wall penetration. Formae speciales tritici, secalis, and agropyri were highly compatible with any accession of wheat, rye, and wheatgrass, but less compatible with barley. On the other hand, f.sp. hordei was highly compatible with any of these four hosts. The four formae speciales had very low compatibility with oat, although f.sp. hordei was relatively more compatible with this host. These results suggested that (i) f.sp. tritici, secalis, and agropyri are phylogenetically very close; (ii) f.sp. hordei is less close to f.sp. tritici, secalis, and agropyri, and closer than these to the ancestral form of E. graminis; (iii) f.sp. avenae is remote from f.sp. tritici, secalis, agropyri, and hordei, but relatively less remote from f.sp. hordei than from the other three formae speciales.

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