A Survey in Natural Forest Ecosystems of Vietnam Reveals High Diversity of both New and Described Phytophthora Taxa including P. ramorum

• Published in: Forests 2020-01, Vol.11 (1), p.93
• Main Authors: Jung, Thomas, Scanu, Bruno, Brasier, Clive, Webber, Joan, Milenković, Ivan, Corcobado, Tamara, Tomšovský, Michal, Pánek, Matěj, Bakonyi, József, Maia, Cristiana, Bačová, Aneta, Raco, Milica, Rees, Helen, Pérez-Sierra, Ana, Horta Jung, Marília
• Format: Article
• Language: English
• Subjects: Baiting; biogeography; biosecurity; breeding systems; center of origin; Creeks & streams; Dieback; Ecosystems; Flowers & plants; Forest ecosystems; Forests; Geomorphology; hybridization; Immigration; Mating; Mating types; Montane environments; Mountain forests; New taxa; Phylogenetics; Phylogeny; Phytophthora; phytophthora cinnamomi; Plant species; Polls & surveys; Rhizosphere; Ribosomal DNA; Rivers; Signs and symptoms; Species; Taxa; Terrestrial ecosystems; Trees; Wind; Woody plants
• ISSN: 1999-4907; 1999-4907
• DOI: 10.3390/f11010093

In 2016 and 2017, surveys of Phytophthora diversity were performed in 25 natural and semi-natural forest stands and 16 rivers in temperate and subtropical montane and tropical lowland regions of Vietnam. Using baiting assays from soil samples and rivers and direct isolations from naturally fallen leaves, 13 described species, five informally designated taxa and 21 previously unknown taxa of Phytophthora were isolated from 58 of the 91 soil samples (63.7%) taken from the rhizosphere of 52 of the 64 woody plant species sampled (81.3%) in 20 forest stands (83.7%), and from all rivers: 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 and P. sp. multivesiculata-like 1 from Phytophthora major phylogenetic Clade 2; P. castaneae and P. heveae from Clade 5; P. chlamydospora, P. gregata, P. sp. bitahaiensis-like and P. sp. sylvatica-like 1, 2 and 3 from Clade 6; P. cinnamomi (Pc), P. parvispora, P. attenuata, P. sp. attenuata-like 1, 2 and 3 and P. ×heterohybrida from Clade 7; P. drechsleri, P. pseudocryptogea, P. ramorum (Pr) and P. sp. kelmania from Clade 8, P. macrochlamydospora, P. sp. ×insolita-like, P. sp. ×kunnunara-like, P. sp. ×virginiana-like s.l. and three new taxa, P. sp. quininea-like, P. sp. ×Grenada 3-like and P. sp. ×Peru 4-like, from Clade 9; and P. sp. gallica-like 1 and 2 from Clade 10. The A1 and A2 mating types of both Pc and Pr co-occurred. The A2 mating type of Pc was associated with severe dieback of montane forests in northern Vietnam. Most other Phytophthora species, including Pr, were not associated with obvious disease symptoms. It is concluded that (1) Vietnam is within the center of origin of most Phytophthora taxa found including Pc and Pr, and (2) Phytophthora clades 2, 5, 6, 7, 8, 9, and 10 are native to Indochina.