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(a) Under-bark lesion caused by Phytophthora caryae on a 1-year-old twig of shagbark hickory (Carya ovata) 8 days after inoculation; (b, c) inoculation site on the lower stem of a 3-year-old shagbark hickory, 90 days after inoculation of P. caryae, before and after the bark was removed to reveal orange-coloured lesions in the surrounding sapwood.
Source publication
Members of the P. citricola complex (Phytophthora clade 2c), such as P. plurivora, are destructive pathogens of trees and shrubs in nursery, landscape and forest setting worldwide. During surveys of Phytophthora species from streams and rivers in Massachusetts and North Carolina, a novel species in the P. citricola complex was recovered. Based on s...
Contexts in source publication
Context 1
... 1-year-old twigs of shagbark hickory and black wal- nut, mean lesion size for all three isolates tested was sig- nificantly larger than the control (Table 3; Fig. 3a). For saplings of shagbark hickory and black walnut, no exter- nal symptoms of disease (e.g. oozing sap surrounding the inoculation site, foliar wilt or canopy dieback) were observed at any time during the 90 days following inocu- lation with P. taxon caryae. Destructive sampling of black walnut saplings after 90 days revealed no ...
Context 2
... formation around the inoculation site was robust and P. taxon caryae could not be reisolated from tissue in or immediately adjacent to the inoculation site. However, under-bark lesions were evident on saplings of shagbark hickory upon destructive sampling and lesion area was significantly larger com- pared to the control treatment (Table 4; Fig. 3b,c). Suc- cessful reisolation of P. taxon caryae was accomplished from two of the samples collected, representing two of the four isolates used (NJB2013-AF-08 and NJB2013- MF-21), while saplings inoculated with the remaining two isolates (NJB2013-MF-05 and NJB2014-CC-W1-4) and the control produced no viable cultures. Plant Pathology (2016) ...
Similar publications
Pathogens of Phytophthora genus are common not only in forest nurseries and stands, but also in water courses. Species of Phytophthora spread with plants for plantings (and soil attached to them) and with water courses as well, attacking the plants growing in riparian ecosystems. Several specialized organisms damaging only one tree species were ide...
The presence of both mating types of Phytophthora species in the same pot has not been reported in hosts of commercial nurseries in Mexico. Isolates of Phytophthora were collected in commercial nurseries of Mexico City and Morelos state during 2015. Mating types A1 and A2 of Phytophthora capsici and P. drechsleri were detected on wilted plants of C...
Citations
... citricola complex' using multigene phylogenetic analyses, enlarged Clade 2 to 34 described species. These reside in five evolutionary divergent subclades, Clades 2a-2e (Aragaki & Uchida 2001, Reeser et al. 2007, Abad et al. 2008, 2011, 2023a, Hong et al. 2009, 2011, Jung & Burgess 2009, Scott et al. 2009, Bezuidenhout et al. 2010, Rea et al. 2010, Vettraino et al. 2011, Ginetti et al. 2014, Henricot et al. 2014, Ann et al. 2015, Man In't Veld et al. 2015, Brazee et al. 2017, Crous et al. 2017, Ruano-Rosa et al. 2018, Albuquerque Alves et al. 2019, Burgess et al. 2020, Bose et al. 2021a, Dang et al. 2021, Decloquement et al. 2021, Chen et al. 2022). Half of these species, including P. acaciae, P. acaciivora, P. amaranthi, P. botryosa, P. capsici, P. citricola, P. citrophthora, P. colocasiae, P. frigida, P. gloveri (previously P. glovera; Abad et al. 2011Abad et al. , 2023a, P. meadii, P. mekongensis, P. mengei, P. multibullata, P. oleae, P. theobromicola, P. tropicalis and P. ×vanyenensis cause severe root rots, bark cankers, fruit rots or leaf blights on tropical and subtropical crops, tree crops and plantation trees (Erwin & Ribeiro 1996, Aragaki & Uchida 2001, Drenth & Guest 2004, Abad et al. 2011, Hong et al. 2009, Ann et al. 2015, Crous et al. 2017, Ruano-Rosa et al. 2018, Albuquerque Alves et al. 2019, Burgess et al. 2020, Dang et al. 2021, Decloquement et al. 2021, Brasier et al. 2022, Chen et al. 2022. ...
... The sporangia of the majority of species in Clade 2c have exclusively semipapillate apices, i.e., P. acerina, P. capensis, P. caryae, P. citricola, P. fansipanensis, P. japonensis, P. macroglobulosa, P. multivora, P. nimia, P. obturata, P. pachypleura and P. plurivora, or predominantly semipapillate apices, i.e., P. balkanensis, P. catenulata, P. emzansi, P. excentrica, P. falcata, P. limosa, P. oblonga, P. pini and P. platani (Jung & Burgess 2009, Scott et al. 2009, Ginetti et al. 2014, Henricot et al. 2014, Brazee et al. 2017; Tables S10-S13; Figs 44, 45, 47-56). However, several species are clearly distinguished by producing, in addition to semipapillate sporangia, a significant proportion of either papillate sporangia, i.e., P. curvata (48 %), P. excentrica (13 %), P. falcata (13 %), P. limosa (16.2 %) and P. vacuola (77.3 %), or nonpapillate sporangia, i.e., P. emzansi (10 %), P. excentrica (6 %) and P. oblonga (8 %). ...
... All known and new species in Clade 2c are intrinsically selffertile. Comparatively high proportions of oogonia with tapering instead of rounded bases distinguish P. caryae (53 %), P. curvata (46 %), P. falcata (46 %), P. oblonga (59 %) and P. platani (80.4 %) from other Clade 2c species (Brazee et al. 2017; Tables S10-S13; Figs 44-58). Likewise, a high proportion of excentric, elongated or comma-shaped oogonia discriminate P. curvata (38 %), P. excentrica (53 %), P. falcata (36.5 %), P. limosa (36 %), P. oblonga (51.9 %), P. platani (33.2 %) and P. vacuola (42 %) from other Clade 2c species (Tables S10-S13; Figs 44-58). ...
During 25 surveys of global Phytophthora diversity, conducted between 1998 and 2020, 43 new species were detected in natural ecosystems and,
occasionally, in nurseries and outplantings in Europe, Southeast and East Asia and the Americas. Based on a multigene phylogeny of nine nuclear and four
mitochondrial gene regions they were assigned to five of the six known subclades, 2a–c, e and f, of Phytophthora major Clade 2 and the new subclade 2g.
The evolutionary history of the Clade appears to have involved the pre-Gondwanan divergence of three extant subclades, 2c, 2e and 2f, all having disjunct
natural distributions on separate continents and comprising species with a soilborne and aquatic lifestyle and, in addition, a few partially aerial species in
Clade 2c; and the post-Gondwanan evolution of subclades 2a and 2g in Southeast/East Asia and 2b in South America, respectively, from their common
ancestor. Species in Clade 2g are soilborne whereas Clade 2b comprises both soil-inhabiting and aerial species. Clade 2a has evolved further towards an
aerial lifestyle comprising only species which are predominantly or partially airborne. Based on high nuclear heterozygosity levels ca. 38 % of the taxa in
Clades 2a and 2b could be some form of hybrid, and the hybridity may be favoured by an A1/A2 breeding system and an aerial life style. Circumstantial
evidence suggests the now 93 described species and informally designated taxa in Clade 2 result from both allopatric non-adaptive and sympatric adaptive
radiations. They represent most morphological and physiological characters, breeding systems, lifestyles and forms of host specialism found across the
Phytophthora clades as a whole, demonstrating the strong biological cohesiveness of the genus. The finding of 43 previously unknown species from a single
Phytophthora clade highlight a critical lack of information on the scale of the unknown pathogen threats to forests and natural ecosystems, underlining the
risk of basing plant biosecurity protocols mainly on lists of named organisms. More surveys in natural ecosystems of yet unsurveyed regions in Africa, Asia,
Central and South America are needed to unveil the full diversity of the clade and the factors driving diversity, speciation and adaptation in Phytophthora.
... For example, Yang et al. (2017) included 142 formally described and 43 yet to be described Phytophthora entities in their phylogenetic analyses. Rapid growth in the size of the family reflects increased attention on understanding the diversity in natural ecosystems such as forests (e.g., Vettraino et al. 2002;Jung et al. 2017a) and streams (e.g., Reeser et al. 2007;Yang et al. 2016;Brazee et al. 2017) as well as in regions such as Asia and South America (e.g., Webber et al. 2011;Lee et al. 2017;Jung et al. 2020;Legeay et al. 2020). ...
Members of the Peronosporaceae (Oomycota, Chromista), which currently consists of 25 genera and approximately 1000 recognised species, are responsible for disease on a wide range of plant hosts. Molecular phylogenetic analyses over the last two decades have improved our understanding of evolutionary relationships within Peronosporaceae. To date, 16 numbered and three named clades have been recognised; it is clear from these studies that the current taxonomy does not reflect evolutionary relationships. Whole organelle genome sequences are an increasingly important source of phylogenetic information, and in this study we present comparative and phylogenetic analyses of mitogenome sequences from 15 of the 19 currently recognized clades of Peronosporaceae, including 44 newly assembled sequences. Our analyses suggest strong conservation of mitogenome size and gene content across Peronosporaceae but, as previous studies have suggested, limited conservation of synteny. Specifically, we identified 28 distinct syntenies amongst the 71 examined isolates. Moreover, 19 of the isolates contained inverted or direct repeats, suggesting repeated sequences may be more common than previously thought. In terms of phylogenetic relationships, our analyses of 34 concatenated mitochondrial gene sequences resulted in a topology that was broadly consistent with previous studies. However, unlike previous studies concatenated mitochondrial sequences provided strong support for higher level relationships within the family.
... Many Phytophthora species (Oomycetes, Stramenopila) are devastating plant pathogens in agriculture [9] and natural ecosystems [10], including those in the P. citricola sensu lato complex [11]. The complex includes several morphologically similar but phylogenetically distinct species described in the following order: P. citricola sensu stricto, P. plurivora [11], P. multivora [12], P. pini [13], P. capansis [14], P. pachypleura [15], P. acerina [16], P. caryae [17] and P. emzansi [18]. Many records initially ascribed to P. citricola s.l. ...
Background
global trade in living plants and plant material has significantly increased the geographic distribution of many plant pathogens. As a consequence, several pathogens have been first found and described in their introduced range where they may cause severe damage on naïve host species. Knowing the center of origin and the pathways of spread of a pathogen is of importance for several reasons, including identifying natural enemies and reducing further spread. Several Phytophthora species are well-known invasive pathogens of natural ecosystems, including Phytophthora multivora. Following the description of P. multivora from dying native vegetation in Australia in 2009, the species was subsequently found to be common in South Africa where it does not cause any remarkable disease. There are now reports of P. multivora from many other countries worldwide, but not as a commonly encountered species in natural environments.
Results
a global collection of 335 isolates from North America, Europe, Africa, Australia, the Canary Islands, and New Zealand was used to unravel the worldwide invasion history of P. multivora, using 10 microsatellite markers for all isolates and sequence data from five loci from 94 representative isolates. Our population genetic analysis revealed an extremely low heterozygosity, significant non-random association of loci and substantial genotypic diversity suggesting the spread of P. multivora readily by both asexual and sexual propagules. The P. multivora populations in South Africa, Australia, and New Zealand show the most complex genetic structure, are well established and evolutionary older than those in Europe, North America and the Canary Islands.
Conclusions
according to the conducted analyses, the world invasion of P. multivora most likely commenced from South Africa, which can be considered the center of origin of the species. The pathogen was then introduced to Australia, which acted as bridgehead population for Europe and North America. Our study highlights a complex global invasion pattern of P. multivora , including both direct introductions from the native population and secondary spread/introductions from bridgehead populations.
... In South Europe, P. cinnamomi is frequently isolated from English walnut (Juglans regia) trees showing a sudden development of wilt and is considered an aggressive primary pathogen [14,15]. The P. caryae species isolated from streams and rivers in the United States are pathogenic to shagbark hickory (Carya ovata) [16,17]. In this study, P. cinnamomi was isolated from the necrotic tissue and the soil of diseased C. cathayensis trees with dieback and basal stem canker symptoms. ...
Chinese hickory ( Carya cathayensis Sarg.) is an economically and ecologically important nut plant in China. Dieback and basal stem necrosis have been observed in the plants since 2016, and its recent spread has significantly affected plant growth and nut production. Therefore, a survey was conducted to evaluate the disease incidence at five sites in Linan County, China. The highest incidence was recorded at the Tuankou site at up to 11.39% in 2019. The oomycete, Phytophthora cinnamomi , was isolated from symptomatic plant tissue and plantation soil using baiting and selective media-based detection methods and identified. Artificial infection with the representative P . cinnamomi ST402 isolate produced vertically elongated discolorations in the outer xylem and necrotic symptoms in C . cathayensis seedlings in a greenhouse trial. Molecular detections based on loop-mediated isothermal amplification (LAMP) specific to P . cinnamomi ST402 were conducted. Result indicated that LAMP detection showed a high coherence level with the baiting assays for P . cinnamomi detection in the field. This study provides the evidence of existence of high-pathogenic P . cinnamomi in the C . cathayensis plantation soil in China and the insights into a convenient tool developed for conducting field monitoring of this aggressive pathogen.
... In South Europe, P. cinnamomi is frequently isolated from English walnut (Juglans regia) trees showing a sudden development of wilt and is considered an aggressive primary pathogen [14,15]. The P. caryae species isolated from streams and rivers in the United States are pathogenic to shagbark hickory (Carya ovata) [16,17]. In this study, P. cinnamomi was isolated from the necrotic tissue and the soil of diseased C. cathayensis trees with dieback and basal stem canker symptoms. ...
Chinese hickory ( Carya cathayensis Sarg.) is an economically and ecologically important nut plant in China. Dieback and basal stem necrosis have been observed in the plants since 2016, and its recent spread has significantly affected plant growth and nut production. Therefore, a survey was conducted to evaluate the disease incidence at five sites in Linan County, China. The highest incidence was recorded at the Tuankou site at up to 11.39% in 2019. The oomycete, Phytophthora cinnamomi , was isolated from symptomatic plant tissue and plantation soil using baiting and selective media-based detection methods and identified. Artificial infection with the representative P. cinnamomi ST402 isolate produced vertically elongated discolorations in the outer xylem and necrotic symptoms in C. cathayensis seedlings in a greenhouse trial. Molecular detections based on loop-mediated isothermal amplification (LAMP) specific to P. cinnamomi ST402 were conducted. Result indicated that LAMP detection showed a high coherence level with the baiting assays for P. cinnamomi detection in the field. This study provides the evidence of existence of high-pathogenic P. cinnamomi in the C. cathayensis plantation soil in China and the insights into a convenient tool developed for conducting field monitoring of this aggressive pathogen.
... Hosts-Phytophthora agathidicida (commonly known as kauri dieback), which causes kauri death, is considered as one of the world's most feared fungi ). An extensive survey in previously unexplored ecosystems such as natural forests (Rea et al. 2010;Vettraino et al. 2011;Jung et al. 2011Jung et al. , 2017Reeser et al. 2013), streams (Reeser et al. 2007;Bezuidenhout et al. 2010;Yang et al. 2016;Brazee et al. 2017), riparian ecosystems (Brasier et al. 2003(Brasier et al. , 2004Hansen et al. 2012), and irrigation systems (Hong et al. 2010(Hong et al. , 2012Yang et al. 2014a, b) has led an exponential increase in the number of species. ...
This is a continuation of a series focused on providing a stable platform for the taxonomy of phytopathogenic fungi and fungus-like organisms. This paper focuses on one family: Erysiphaceae and 24 phytopathogenic genera: Armillaria, Barriopsis, Cercospora, Cladosporium, Clinoconidium, Colletotrichum, Cylindrocladiella, Dothidotthia,, Fomitopsis, Ganoderma, Golovinomyces, Heterobasidium, Meliola, Mucor, Neoerysiphe, Nothophoma, Phellinus, Phytophthora, Pseudoseptoria, Pythium, Rhizopus, Stemphylium, Thyrostroma and Wojnowiciella. Each genus is provided with a taxonomic background, distribution, hosts, disease symptoms, and updated backbone trees. Species confirmed with pathogenicity studies are denoted when data are available. Six of the genera are updated from previous entries as many new species have been described.
... Species complexes exist in areas of high Phytophthora diversity (e.g. Brazee et al. 2017), and distinct but related species may have been either pooled together or missed in investigations. In two cases, old taxa were redesignated in light of new genetic information (e.g. ...
Phytophthora is a genus of oomycete plant pathogens consisting of numerous invaders of production and natural systems. To date, only few studies assessed how invasions change over time, and none have examined changes in invasive genera consisting of multiple species. With increasing globalisation, pathogens invade and adapt to new environments and hosts. After establishment, the aggressiveness of pathogens could decrease due to biotic and abiotic factors. Conversely, highly pathogenic genotypes should continuously replace less pathogenic ones. Here, we compiled the disease development data of Phytophthora species from published data and reports that span 105 years to assess how aggressiveness has changed over time. For each aggressiveness trial, we recorded the year of pathogen isolation and a measure of pathogenicity, as well as local environmental variables. Phylogenetic multi-level quantile regression was used to analyse the relationships between aggressiveness and time across pathogen taxa under different environmental conditions. We found that aggressiveness decreased over time. This holds true if only the most commonly isolated taxa, and the most recent isolates, were considered. Highly aggressive pathogens from agriculture and natural ecosystems decreased significantly. However, pathogens from nurseries generally became more aggressive over time, particularly among the most common species. Phytophthora diseases overall are highly pathogenic and have potential to cause outbreaks, especially given that the common species were more aggressive under higher temperature variability. Through a multi-level approach, we uncover how the aggressiveness of pathogens changes globally at the genus-level with continuous emergence and invasion. **The final
publication is available at https://link.springer.com/article/10.1007/s10530-020-02229-1
... The prevalence of two low-temperature species infecting wild olive roots following exceptionally cold winter temperatures 2 years previously, as P. megasperma in 2009 (Gonz alez et al., 2017a) and P. oleae in 2015, could be hypothesized as probably unusual considering the long, hot and dry summers prevailing in the area. However, the ability of some Phytophthora spp. with low optimum temperature, including P. oleae (Ruano-Rosa et al., 2018), to form thick-walled oospores and abundant sporangia, has been described as an adaptation to Mediterranean climates with long, hot and dry summers and wet winters (Brazee et al., 2017;Jung et al., 2017). According to this hypothesis, P. oleae would be able to survive severe summer droughts in its dormant state (oospore) and rapidly resume growth and sporulation after autumn-winter rainfalls, acquiring an advantage to compete for wild olive root infection when temperatures are cooler than usual. ...
Wild olive (Olea europaea subsp. europaea var. sylvestris) is an important component of Mediterranean forests and a key genetic source for olive improvement programs. Since 2009, a severe decline caused by Phytophthora cryptogea and P. megasperma was detected in a protected wild olive forest of high ecological value (Dehesa de Abajo, Seville, Spain). In this natural forest, samplings of roots and soil were done on 25 symptomatic wild‐olives in 2014 and 2015. Apart from the already known P. cryptogea A1 and P. megasperma, a third Phytopththora species was consistently isolated from symptomatic wild‐olive rootlets. These isolates conformed morphologically with the newly described species P. oleae and were confirmed by analysis of their ITS regions and Cox‐1 sequences. Temperature‐growth relationships showed a maximum growth at 19.9°C on CA medium, being the lowest‐temperature Phytophthora spp. infecting wild olive roots. Pathogenicity was confirmed on 1 year‐old healthy wild olive seedlings and was similar respect to the previously known pathogenic Phytophthoras. As temperature requirements are quite different, the three Phytophthora spp. may be active against wild olive roots in different seasons. However, the prevalence of P. oleae infecting wild olives in the last years could be due to its introduction as a new invasive pathogen. The likely invasive nature of P. oleae, together with increasing rain episodes concentrated in short periods frequent in southern Spain, would allow outbreak infections in wild olive forests, also putting at risk cultivated olive orchards.
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... The P. citricola complex was recently split into eight species (P. plurivora, P. pachypleura, P. pini, P. multivora, P. capensis, P. caryae, P. acerina, and P. citricola sensu stricto), and potentially includes other taxa (Bezuidenhout et al. 2010;Brazee et al. 2017;Ginetti et al. 2014;Henricot et al. 2014;Jung and Burgess 2009;Scott et al. 2009). All species formerly part of this species complex are now placed in clade 2 of the Phytophthora genus (Hong et al. 2011). ...
Phytophthora plurivora is a recently described plant pathogen, formerly recognized as P. citricola. Recent sampling of Pacific Northwest nurseries frequently encountered this pathogen, and it has been shown to be among the most damaging Phytophthora pathogens on ornamentals. We characterized the population structure of P. plurivora in a survey of four Oregon nurseries across three different counties with focus on Rhododendron hosts. Isolates were identified to the species level by Sanger sequencing and/or a PCR-RFLP assay of the internal transcribed spacer (ITS) region. We used genotyping-by-sequencing to determine genetic diversity. Variants were called de novo, resulting in 284 high-quality variants for 61 isolates after stringent filtering. Based on Fst and AMOVA, populations were moderately differentiated among nurseries. Overall, population structure suggested presence of one dominant clonal lineage in all nurseries, as well as isolates of cryptic diversity mostly found in one nursery. Within the clonal lineage, there was a broad range of sensitivity to mefenoxam and phosphorous acid. Sensitivity of the two fungicides was correlated. P. plurivora was previously assumed to spread clonally, and the low genotypic diversity observed within and among isolates corroborated this hypothesis. The broad range of fungicide sensitivity within the P. plurivora population found in PNW nurseries has implications for managing disease caused by this important nursery pathogen. These findings provide the first perspective into P. plurivora population structure and phenotypic plasticity in Pacific Northwest nurseries.
... Some species found in aquatic habitats, especially Phytophthora Clade 6 species, appear to be facultative pathogens or aquatic opportunists that have not been associated with plant disease (Hansen et al. 2012;Jung et al. 2011;Marano et al. 2016;van der Plaats-Niterink 1981). Phytopathogens appear to constitute only a small portion of the total species recovered from streams, rivers, and irrigation water reservoirs (Brazee et al. 2017;Choudhary et al. 2016;Copes et al. 2015;Hong et al. 2012Hong et al. , 2008Loyd et al. 2014;MacDonald et al. 1994;Parke et al. 2014;Yang 2013;Yang and Hong 2013;Yang et al. 2012Yang et al. , 2014Yang et al. , 2016. Genus-level identification of Phytophthora, Pythium, and Phytopythium is therefore insufficient to assess the risks posed to plants. ...
Recycling of irrigation water increases disease risks due to spread of waterborne oomycete plant pathogens such as Phytophthora, Pythium and Phytopythium. A comprehensive metabarcoding study was conducted to determine spatial and temporal dynamics of oomycete communities present in irrigation water collected from a creek (main water source), a pond, retention reservoirs, a chlorinated water reservoir, and runoff channels within a commercial container nursery in Oregon over the course of one year. Two methods, filtration and leaf baiting, were compared for the detection of oomycete communities. Oomycete communities in recycled irrigation water were less diverse but highly enriched with biologically active plant pathogens as compared to the creek water. The filtration method captured a larger portion of oomycete diversity, while leaf baiting was more selective for plant-associated oomycete species of Phytophthora and a few Pythium and Phytopythium species. Seasonality strongly influenced oomycete diversity in irrigation water and detection with leaf baiting. Phytophthora was the major colonizer of leaf baits in winter, while all three genera were equally abundant on leaf baits in summer. The metabarcoding approach was highly effective in studying oomycete ecology, however, it failed to distinguish some closely related species. We developed a custom oomycete ITS1 reference database containing shorter sequences flanked by ITS6 and ITS7 primers used in metabarcoding and used it to assemble a list of indistinguishable species complexes and clusters to improve identification. The predominant bait-colonizing species detected in recycled irrigation water were the Phytophthora citricola-complex, P. syringae, P. parsiana-cluster, P. chlamydospora, P. gonapodyides, P. irrigata, P. taxon Oaksoil-cluster, P. citrophthora-cluster, P. megasperma-cluster, Pythium chondricola-complex, Py. dissotocum-cluster, and Phytopythium litorale.
