Phytophthora species found in forest stands in Vietnam
In 2016 and 2017, studies on Phytophthora diversity were performed in 25 natural and semi-natural forest stands and 16 rivers in temperate and subtropical montane regions, as well as in tropical lowland regions of Vietnam.
Phytophthora isolates were recovered from soil and water by baiting assays, or from naturally fallen leaves by direct isolation. As a result, 13 described Phytophthora species, 5 informally designated Phytophthora taxa, and 21 previously unknown Phytophthora taxa were isolated (see table below).
Phytophthora species and unknown taxa | Phylogenetic clade |
P. capensis P. citricola VII, VIII, IX, X and XI P. sp. botryosa-like 2, P. sp. meadii-like 1 and 2 P. sp. tropicalis-like 2 P. sp. multivesiculata-like 1 | Clade 2 |
P. castaneae P. heveae | Clade 5 |
P. chlamydospora P. gregata P. sp. bitahaiensis-like P. sp. sylvatica-like 1, 2 and 3 | Clade 6 |
P. cinnamomi (EU Annexes) P. parvispora P. attenuata P. sp. attenuata-like 1, 2 and 3 P. x heterohybrida | Clade 7 |
P. drechsleri P. pseudocryptogea P. ramorum (EPPO A2 List) P. sp. kelmania | Clade 8 |
P. macrochlamydospora P. sp. x insolita-like P. sp. x kunnunara-like P. sp. x virginiana-like s.l. P. sp. quininea-like P. sp. Grenada 3-like P. sp. x Peru 4-like | Clade 9 |
P. sp. gallica-like 1 and 2 | Clade 10 |
It can be noted that this is the first documented report of Phytophthora ramorum (EPPO A2 List) in Asia, and the first record for Vietnam. Until now, only P. cinnamomi (A2 mating type) was associated with severe dieback of montane forests in Northern Vietnam. Most other Phytophthora species, including P. ramorum, were not associated with obvious disease symptoms. It is suggested that Vietnam is within the centre of origin of most Phytophthora taxa listed above, including P. cinnamomi and P. ramorum, and that Phytophthora clades 2, 5, 6, 7, 8, 9, and 10 are native to the Indochina peninsula.
Sources
Jung T, Scanu B, Brasier CM, Webber J, Milenković I, Corcobado T, Tomšovský M, Pánek M, Bakonyi J, Maia C, Bačová A, Raco M, Rees H, Pérez-Sierra A, Horta Jung M (2020) A survey in natural forest ecosystems of Vietnam reveals high diversity of both new and described Phytophthora taxa including P. ramorum. Forests 11(1), 93. https://doi.org/10.3390/f11010093