Table 12.
Morphological characters and dimensions (μm), cardinal temperatures (°C) and temperature-growth relations (mm/d) on V8-juice agara of Nothophytophthora species. Most discriminating characters are highlighted in bold. Percentages in brackets are ranges of isolate means.
| N. amphigynosa | N. caduca | N. chlamydospora | N. valdiviana | N. intricata | N. vietnamensis | |
|---|---|---|---|---|---|---|
| No. of isolates | 8b | 14b | 5b | 5b | 6b | 8b |
| Sporangia | 82 % ovoid, 12 % ellipsoid, 5 % obpyriform (limoniform, mouse-shaped) | 83 % ovoid, 7 % ellipsoid, 4 % limoniform (obpyriform, pyriform, mouse-shaped) | 44 % ovoid, 27.5 % ellipsoid, 22.5 % limoniform (obpyriform, pyriform, mouse-shaped) | 50.5 % ovoid, 40.5 % limoniform, 6 % ellipsoid, (obpyriform, pyriform, mouse-shaped) | 71 % ovoid, 15 % obpyriform, 7 % limoniform, 5 % ellipsoid (pyriform, mouse-shaped) | 91 % ovoid, 6 % ellipsoid, 3 % limoniform |
| l × b mean | 47.0 ± 5.6 × 26.4 ± 1.8 | 37.9 ± 4.6 × 25.7 ± 3.0 | 37.6 ± 4.9 × 22.1 ± 2.5 | 42.7 ± 4.6 × 28.0 ± 3.5 | 38.5 ± 2.8 × 24.8 ± 1.5 | 36.4 ± 12.7 × 29.3 ± 8.1 |
| range of isolate means | 41.5–52.0 × 25.4–27.3 | 34.7–43.1 × 23.3–28.2 | 35.6–38.9 × 20.4–23.2 | 40.4–44.7 × 25.6–29.5 | 37.6–40.5 × 23.4–26.3 | 34.1–37.9 × 24.1–25.8 |
| total range | 33.6–60.6 × 21.3–32.4 | 24.1–54.4 × 18.1–35.9 | 27.4–57.2 × 17.0–30.8 | 30.2–55.7 × 18.6–47.5 | 27.8–49.2 × 18.6–30.2 | 28.4–42.1 × 20.6–28.1 |
| l/b ratio | 1.78 ± 0.17 | 1.48 ± 0.15 | 1.71 ± 0.17 | 1.53 ± 0.14 | 1.55 ± 0.18 | 1.47 ± 0.08 |
| caducity | – | 32.1 % (10–53 %) | 25.2 % (11–41 %) | 6.8 % (4–10 %) | – | 15.8 % (4–36 %) |
| pedicel-like basal plug | 2.9 ± 0.6 | 2.6 ± 0.7 | 2.8 ± 1.6 | 2.4 ± 0.5 | 2.9 ± 0.7 | 2.7 ± 0.7 |
| internal proliferation | – | nested and extended | – | nested and extended | – | – |
| exitpores | 8.9 ± 1.4 | 10.4 ± 2.2 | 8.2 ± 1.7 | 9.4 ± 1.8 | 9.0 ± 1.6 | 7.6 ± 1.5 |
| sympodia | infrequent, lax | frequent, lax | frequent, lax or dense | frequent, lax or dense | infrequent, lax | frequent, lax or dense |
| zoospore cysts | 9.0 ± 1.1 | 7.4 ± 0.6 | 8.6 ± 0.8 | 8.6 ± 1.1 | 8.1 ± 1.1 | 8.4 ± 0.7 |
| sporangiospore swellings | 11.1 ± 2.8; rare | 10.2 ± 2.0; rare | 15.2 ± 6.3; rare | 14.0 ± 2.7; rare | 9.8 ± 1.5; rare | n/a; rare |
| Breeding system | homothallic | self-sterile | self-sterile | self-sterile | homothallic | homothallic |
| Oogonia | ||||||
| mean diam | 25.3 ± 1.7 | – | – | – | 30.1 ± 3.9 | 23.9 ± 3.0 |
| range of isolate means | 24.3–25.5 | – | – | – | 28.1–31.8 | 22.3–27.3 |
| total range | 18.4–29.7 | – | – | – | 16.7–41.8 | 18.6–33.0 |
| tapering base | 2.9 % (0–7.5 %) | – | – | – | 7.5 % (0–30 %) | 75.4 % (42–95 %) |
| thin stalks | 58.3 % (10–100 %) | – | – | – | 29.4 % (2.5–45 %) | 3.1 % (0–12.5 %) |
| curved base | – | – | – | – | 1.3 % (0–5 %) | 24.4 % (7.5–32.5 %) |
| elongated | 12.5 % (5–20 %) | – | – | – | 5.6 % (0–17.5 %) | 70.6 % (60–85 %) |
| Oospores | – | – | – | |||
| plerotic oospores | 99.2 % | – | – | – | 96.9 % (92.5–100 %) | 96.9 % (87.5–100 %) |
| mean diam | 23.4 ± 1.7 | – | – | – | 28.3 ± 3.5 | 22.5 ± 2.4 |
| Total range | 17.2–28.0 | – | – | – | 15.7–38.4 | 17.6–29.5 |
| wall diam | 1.7 ± 0.3 | – | – | – | 2.1 ± 0.4 | 1.8 ± 0.3 |
| oospore wall index | 0.38 ± 0.05 | – | – | – | 0.38 ± 0.06 | 0.42 ± 0.05 |
|
| ||||||
| Abortion rate | 4.2 % (1–25 %) | – | – | – | 10.8 % (1–18 %) | 1.0 % (0–4 %) |
| Antheridia | 87.2 % amphigynous | – | – | – | 100 % paragynous | 100 % paragynous |
| size | 8.5 ± 1.8 × 6.5 ± 0.9 | – | – | – | 10.0 ± 1.9 × 6.9 ± 1.2 | 7.2 ± 1.2 × 4.6 ± 0.9 |
| intricate stalks | 28.8 % (22.5–35 %) | – | – | – | 63.3 % (50–72.5 %) | 46.7 % (42.5–52.5 %) |
| Chlamydospores | – | – | 98.1 % globose, 1.9 % pyriform; radiating, forming clusters 43.7 ± 7.0 | – | – | – |
| Hyphal swellings | – | – | globose, (pyriform, limoniform) 29.2 ± 6.1 | – | – | – |
| Lethal temperature | 28 | 28 or 30 | 26 | 30 | 28 | 29 |
| Maximum temperature | 27 | 26 or 28 | 25 | 28 | 27 | 27 |
| Optimum temperature | 20 | 20 or 25 | 20 | 25 | 25 | 25 |
| Growth rate at 20 °C | 3.1 ± 0.05 | 3.1 ± 0.21 | 3.2 ± 0.05 | 2.9 ± 0.05 | 2.2 ± 0.06 | 2.5 ± 0.04 |
| Growth rate at 25 °C | 3.0 ± 0.06 | 3.6 ± 0.08 | 0.5 ± 0 | 3.1 ± 0.1 | 2.5 ± 0.07 | 2.9 ± 0.05 |
a Oogonia and oospores were studied and measured on carrot agar.
b Numbers of isolates included in the growth tests: N. amphigynosa = 4; N. caduca = 10; N. chlamydospora = 4; N. valdiviana = 4; N. intricata = 5; N. vietnamensis = 8.
– = character not observed.