Table 6.
Morphological characters and dimensions (mean ± SD; μm), cardinal temperatures (°C) and temperature-growth relations (mm/d) on V8-juice agar of Phytophthora species from Subclades 10a and 10b. Most discriminating characters are highlighted in bold. Percentages in brackets are ranges of isolate means. – means character not observed.
| Subclade 10a | Subclade 10b | |||||||
|---|---|---|---|---|---|---|---|---|
| P. ludoviciana | P. procera | P. tenuimura | P. afrocarpa | P. gallica | P. intercalaris | P. pseudogallica | P. scandinavica | |
| No. of isolates/source | 2a | 4a | 7a | Bose et al. (2021) | Jung & Nechwatal (2008) | Yang et al. (2016) | 4a | 5a |
| Sporangia | 67 % ovoid-elongated ovoid, 20.5 % tubular, 11 % ellipsoid-elong. ellipsoid (obpyriform) | 50% ovoid-elong. ovoid, 30.7% ellipsoid-elong. ellipsoid, 8% tubular, 8% limoniform (obpyrif.) | 55.2% ovoid-elong. ovoid, 40.8 ellipsoid-elong. ellipsoid (tubular, pyriform, obovoid) | ovoid, elongated ovoid, rarely obpyriform | 35 % obpyriform, 24 % ovoid, 17 % peanut-shaped, 12 % limoniform | ovoid, ellipsoid, pyriform, obpyriform, limoniform | 94.5 % ovoid to broad-ovoid, 4.5 % globose to subglobose (obpyriform) | 70.8 % ovoid, 29.2 % obpyriform |
| apex | nonpapillate | nonpapillate | nonpapillate | nonpapillate | nonpapillate | nonpapillate | nonpapillate | nonpapillate |
| Ixb mean | 41.6 ± 4.7x26.3 ±2.6 | 60.2±11.3x 25.2±3.9 | 45.7±8.4 X 25.0±2.3 | 28±1.2x 18.6±0.7 | 52.5±11 x27±5 | 38.7±5.0 X 27.0±2.9 | 25.2±2.7 x 21.3±2.5 | 52.9±6.6 X 37.1±4.2 |
| range of isolate means | 41.2–42.1 X 25.4–27.1 | 49.3-70.2 X 21.3-27.7 | 40.1-54.5 x 23.6-25.8 | n.a. | 51-54 X 25-29 | n.a. | 24.3-26.7 X 20.1-22.8 | 51.0-55.9 x 36.1-38.3 |
| total range | 30.5–68.9 X 18.3–30.8 | 29.1-92.6 X 12.7-33.5 | 30.6-84.9 X 15.6-30.4 | 13.3-49.5x7.4-31.2 | 30-100 X 19-47.5 | 25.2-52.5 X 19.2-37.0 | 19.4-33.7 X 13.0-29.5 | 35.5-72.4 x 28.3-50.8 |
| l/b ratio | 1.59 ± 0.17 | 2.45 ±0.61 | 1.83 ± 0.34 | 1.5 ±0.01 | 2 ± 0.5 | 1.43 | 1.2 ±0.1 | 1.43 ± 0.14 |
| caducity | – | – | – | – | – | – | – | – |
| pedicels | – | – | – | – | – | – | – | – |
| internal proliferation | extended (rarely nested) | nested and extended | nested and extended | only extended | nested and extended | nested and extended | nested and extended | nested and extended |
| exitpores | 10.4 ± 1.9 | 10.3 ±1.8 | 9.7 ± 2.0 | 7.3 ± 0.7 | 11.5 ± 3 | n.a. | 8.6 ± 1.5 | 13.2 ± 2.6 |
| sympodia | very rare, lax | rare, dense or lax | very rare, lax | frequent | - | infrequent, lax | rare, lax | rare, lax |
| zoospore cysts | 9.2 ± 1.0 | 10.2 ±1.2 | 8.9 ± 1.2 | 5.2-12.6 | n.a. | n.a. | 11.5 ± 1.7 | 13.7 ± 1.4 |
| Breeding system Oogonia | sterile | sterile | homothallic golden-brown with age | sterile | sterile | heterothallic (only A1) all ornamented | sterile | homothallic |
| mean diam | – | – | 42.2 ± 6.3 | – | – | 40.8 ±6.5 | – | 40.5 ± 6.4 |
| range of isolate means | – | – | 39.9-44.7 | – | – | n.a. | – | 38.8-42.5 |
| total range | – | – | 26.1-60.5 | – | – | n.a. | – | 19.1-64.4 |
| tapering base | – | – | 2.0% (0-4%) | – | – | n.a. | – | 5.6% (2-10%) |
| elongated/excentric/ comma-shaped | – | – | 21.5% (12-38%) | – | – | n.a. | – | 33.6% (28-40%) |
| Oospores | – | – | – | – | – | |||
| plerotic oospores | – | – | 98% (96-100%) | – | – | n.a. | – | 13.2% (6-18%) |
| mean diam | – | – | 39.7 ± 5.8 | – | – | 35.8 ±5.2 | – | 39.2 ± 6.8 |
| Total range | – | – | 24.4-54.2 | – | – | n.a. | – | 16.8-51.7 |
| wall diam | – | – | 1.3 ±0.2 | – | – | n.a. | – | 3.1 ±0.9 |
| oospore wall index | – | – | 0.20 ± 0.03 | – | – | n.a. | – | 0.45 ± 0.06 |
| Abortion rate | – | – | 11.0% (6-16%) | – | – | 100% | – | 20% (12-24%) |
| Antheridia | – | – | 100% paragynous | – | – | 100% amphigynous | – | 100% paragynous |
| size | – | – | 15.1±3.5 x 9.7±6.0 | – | – | 20.3 x 15.5 | – | 15.1±2.9 x 11.7±2.1 |
| Chlamydospores | – | – | – | globose, in clusters; dark-brown when mature | globose, pyriform, club-shaped, irregular | globose | 91% globose, 9% sub-globose; golden-brown; multiple lipid globules | - |
| size | – | – | – | 26.2 ± 0.46 | 47.5 ± 7 | 49.8 ±7 | 47.3 ±11.7 | – |
| Hyphal swellings | limoniform, rare; undulating hyphae | limoniform, rare; undulating hyphae | -; undulating hyphae | globose or subglobose; some catenulate | in water; globose or irregular | limoniform or irregular | – | elongated, irregular, limoniform, subglobose |
| Hyphal aggregations | + | – | – | n.a. | n.a. | n.a. | + | - |
| Maximum temperature | >32.5 – <35 | >32.5-<35 | >30-<32.5 | 30 | >30-<32.5 | >32.5-<35 | >25-<27.5 | 27.5-30 (30-32.5) |
| Optimum temperature | 27.5 | 25 | 27.5 | 25 | 20 | 25 | 20 | 20 |
| Growth rate at 20 °C | 0.95 + 0.09 | 0.92 + 0.11 | 0.92 + 0.14 | n.a. | 1.3 + 0.22 | 2.5 | 1.63 + 0.18 | 4.7 ± 0.06 |
| Growth rate at 25 °C | 1.37 ± 0.07 | 1.07 ±0.08 | 1.07 ± 0.19 | n.a. | 1.0 ±0.19 | 3.1 | 1.53 ± 0.23 | 4.6 ± 0.04 |
a Numbers of isolates included in the growth tests: P. ludoviciana = 2; P. procera = 4; P. tenuimura = 7; P. gallica = 3; P. intercalaría = 1 ; P. pseudogallica = 4; P. scandinavica = 5.