| Scientific Name | Hyaloperonospora nasturtii-palustris (S. Ito & Tokun.) J.Sung Lee & Y.J. Choi, Mycobiology 45 (3): 145 (2017) |
|---|---|
| Synonyms | Show synonyms≡ Peronospora nasturtii-palustris S. Ito & Tokun.,Transactions of the Sapporo Natural History Society 14: 31(1935).
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| Disease | Downy mildew |
| Taxonomic Rank | |||
|---|---|---|---|
| Order | Peronosporales | Family | Peronosporaceae |
| Host Plant | |||
|---|---|---|---|
| Common Name | Bog yellowcress (속속이풀) | Scientific Name | Rorippa islandica |
| Distribution | Japan, Korea |
|---|---|
| Characteristics | Lesions commonly present on leaves, pale green to yellow, polyangular, vein-limited, frequently covering larger areas by coalescing. Down present on the lower leaf surface, whitish, consisting of dense, felt-like conidiophore outgrowth evenly distributed over the affected surface. Haustoria filling the host cell partly to almost completely, lobate. Conidiophores emerging through stomata, 20–30 in a fascicle, hyaline, somewhat stout, straight, (235.2–)224.4–313.3–402.3(–484.9) µm; trunk straight, (100–)150–250(–300) µm long, (9–)11–15(–16) µm wide (n = 30). Ultimate branchlets mostly in pairs, curved to sigmoid, (9.4–)10.3–12.4–14.4(–17.6) µm long, (1.4–)1.8–2.1–2.5(–3.1) µm wide at the base; tip obtuse or subtruncate (n = 30). Conidia hyaline, broadly ellipsoidal to subglobose, 18–23 µm long (av. 19.7), 12–17 µm wide (av. 14.7), a length to width ratio of (1.07–)1.23–1.45(–1.54) (av. 1.34, n = 30). Resting organs not seen. |
| Notes | Two downy mildew species, Hyaloperonospora rorippae-islandicae and H. nasturtii-palustris, have been reported from Rorippa palustris. The latter was previously synonymized with H. rorippae-islandicae because of their similar morphology (Gustavsson 1959). However, the Korean collections were morphologically closer to P. nasturtii-palustris, particularly in conidial size, and molecular phylogenetic analyses supported the two taxa as distinct lineages. Accordingly, P. nasturtii-palustris was transferred to Hyaloperonospora as H. nasturtii-palustris (Lee et al. 2017). |
| Economic importance | No quantitative economic losses caused by H. nasturtii-palustris have been reported. Its host, Rorippa palustris, is primarily a wild or weedy brassicaceous plant. |
| References | Gäumann, E. A. 1918. Beih. Bot. Centralbl. 35:395. Gustavsson, A. 1959. Opera Bot. 3:1. Ito, S., and Tokunaga, Y. 1935. Trans. Sapporo Nat. Hist. Soc. 14:11. Lee, J. S., et al. 2017. Mycobiology 45:139. |
