Diversity of Phytophthora species in natural ecosystems of Taiwan and association with disease symptoms

Abstract

In 2013 a survey of Phytophthora diversity was performed in 25 natural and semi-natural forest stands and 25 rivers in temperate montane and subtropical lowland regions of Taiwan. Using baiting assays, ten described species and 17 previously unknown taxa of Phytophthora were isolated from 71.5% of the 144 rhizosphere soil samples from 33 of 40 tree species sampled in 24 forest stands ,and from 19 rivers: P. capensis, P. citrophthora, P. plurivora, P. tropicalis, P.citricola VII, P. sp. x botryosa-like, P. sp. x meadii-like and P. sp. occultans-like from Clade 2; P. palmivora from Clade 4; P. castaneae and P. heveae from Clade 5; P. chlamydospora and P. sp.forestsoil-like from Clade 6; P. cinnamomi (Pc), P. parvispora, P. attenuata nom. prov., P. flexuosa nom. prov., P. formosa nom. prov., P. intricata nom. prov., P. x incrassata nom. prov. and P. x heterohybrida nom. prov. from Clade 7; P. sp. palustris and five new hybrid species from Clade 9.The A1 mating type of Pc was widespread in both montane and lowland forests and rarely associated with disease, whereas the A2 mating type was limited to lowland forests and in some cases causing severe dieback. Most other Phytophthora species were not associated with obvious disease symptoms. It is concluded that (1) Taiwan is within the center of origin of most Phytophthora taxa found, (2) PcA2 is an introduced invasive pathogen, and (3) interspecific hybridisations play a major role in speciation and species radiations in diverse natural ecosystems.

Multiple new cryptic pathogenic Phytophthora species from Fagaceae forests in Austria, Italy and Portugal

“…Recently, six new Phytophthora species from Clade 7a occurring in natural ecosystems in Taiwan were described and two other new Clade 7a taxa were informally designated (Jung et al 2017a, b) expanding the number of extant taxa in Clade 7a to 16. Besides the new Taiwanese species, Clade 7a contains several important plant pathogens like the multivorous P. x cambivora and the host-specific P. fragariae , P. rubi , P. uniformis , P. x alni and P. x multiformis , but also cryptic species such as P. europaea and P. uliginosa (Jung et al 2002, 2017b).…”

Phytophthora oleae sp. nov. causing fruit rot of olive in southern Italy

“…The Phytophthora genus contains more than 150 formally described species and about 50 informally designated taxa (Hansen et al ., ; Kroon et al ., ; Jung et al ., ,b,c; Kunadiya et al ., ), of which many are plant pathogens of considerable economic importance. In recent years, an outstanding contribution for the identification of species in this genus, especially those with similar or overlapping morphological features, has arisen from phylogenetic analyses (Cooke et al ., ; Kroon et al ., ).…”

Genotypic Diversity of Phytophthora cinnamomi and P. plurivora in Maryland’s Nurseries and Mid-Atlantic Forests

“…The reason behind this pathological difference is likely related to its ecological adaptations. Unlike P. cinnamomi, P. plurivora is adapted to aquatic environments (e.g., fresh stream water or irrigation water), and can spread to aboveground plant parts through rain splash or overhead irrigation (Brazee et al 2016;Huai et al 2013;Jung et al 2016Jung et al , 2017Nechwatal et al 2011). Ecologically, P. plurivora appears to be not restricted by cold winter temperatures whereas P. cinnamomi is limited in its pathology and spread (Bergot et al 2004;McConnell and Balci 2014).…”

“…P. plurivora is one of eight species once considered part of the P. citricola complex (now delineated into P. capensis, P. caryae, P. citricola, P. pachypleura, P. pini, P. plurivora, P. multivora, and P. acerina) (Bezuidenhout et al 2010, Brazee et al in press, Ginetti et al 2014Henricot et al 2014;Hong et al 2011;Jung and Burgess 2009;Scott et al 2009). Although both species have a worldwide distribution, P. plurivora is potentially of Asian origin and introduced to North America from Europe (Huai et al 2013;Jung and Burgess 2009;Jung et al 2017;Schoebel et al 2014). P. cinnamomi is thought to have originated in Southeast Asia but became a globally well-established species in nursery, agricultural, and forest ecosystems, with records dating back over a century (Arentz and Simpson 1986;Balci et al 2007;Brasier et al 1993;Duan et al 2008;Erwin and Ribeiro 1996;Jung et al 2016Jung et al , 2017Zentmyer 1980).…”

“…Although both species have a worldwide distribution, P. plurivora is potentially of Asian origin and introduced to North America from Europe (Huai et al 2013;Jung and Burgess 2009;Jung et al 2017;Schoebel et al 2014). P. cinnamomi is thought to have originated in Southeast Asia but became a globally well-established species in nursery, agricultural, and forest ecosystems, with records dating back over a century (Arentz and Simpson 1986;Balci et al 2007;Brasier et al 1993;Duan et al 2008;Erwin and Ribeiro 1996;Jung et al 2016Jung et al , 2017Zentmyer 1980). Both species are widespread and differences exist in their pathogenicity, ecology, and mating behavior.…”