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Isolation frequency and distribution of the 7 most common Phytophthora species isolated in this study.
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New and emerging Phytophthora-related diseases in small trees, shrubs and herbaceous plants typical of subalpine vegetations have recently been observed in Italy and Slovenia. Diseased plants showed a complex symptomatology including foliar necrosis, fruit rot, shoot blight and branch bleeding cankers. Since little information is available about th...
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... species was isolated from 25 out of the 33 hosts, in 36 sites distributed in all monitored geographic regions. Together with P. cactorum, it is the only species detected in all three types of hosts, while the other Phytophthora species were isolated from only one or two types (Figure 2). Phytophthora plurivora was the second most-isolated species, obtained from 12 hosts in 24 sites. ...
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... pseudosyringae and P. plurivora were the most frequently isolated species in NE Italy and Slovenia (Figure 2). In addition to these two species, some species belonging to clade 1, such as P. alpina and P. cactorum, were frequently isolated from different hosts in the NE Alps. ...
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... addition to these two species, some species belonging to clade 1, such as P. alpina and P. cactorum, were frequently isolated from different hosts in the NE Alps. In the mountainous areas of Sardinia, in addition to P. pseudosyringae, other two species P. ilicis and P. psychrophila belonging to clade 3 were constantly isolated (Figure 2). Table 4. Number of Phytophthora isolates obtained from the different plant hosts. ...
Citations
... The representatives of the genus that are associated with water habitats are mainly saprophytes. However, many Phytophthora species are necrotrophic or hemibiotrophic pathogens and are able to cause root rot diseases on a variety of plant hosts [2]. Some of the most devastating plant pathogens worldwide belong to the genus Phytophthora, including P. infestance [3], P. alni [4] and P. ramorum [5]. ...
... A number of studies on the disease symptoms of Alnus spp. revealed that the causal agent usually is not only one species but an assembly of Phytophthora pathogens [2,20,[25][26][27][28][29]. Therefore, numerous Phytophthora species are associated with the declining of alder, including P. plurivora, P. gonapodyides, P. lacustris, P. cactorum, P. syringae, P. pseudosyringae, P. polonica, P. hydropathica, P. bilorbang, P. acerina, P. siskiyouensis, P. pseudocryptogea, P. × serendipita and P. alpine. ...
... Therefore, numerous Phytophthora species are associated with the declining of alder, including P. plurivora, P. gonapodyides, P. lacustris, P. cactorum, P. syringae, P. pseudosyringae, P. polonica, P. hydropathica, P. bilorbang, P. acerina, P. siskiyouensis, P. pseudocryptogea, P. × serendipita and P. alpine. However, studies of alder are mainly focused on A. glutinosa [2,20,23,24,26,30,31] and rarely concern A. incana [25,27,32,33]. Although several investigations on the health status of alder ecosystems in Europe have been reported recent years, the occurrence, diversity and new distribution sites of the Phytophthora species affecting Alnus spp. ...
A number of Phytophthora species have been identified as destructive plant pathogens and invasive species. They have the potential to affect a wide range of host plants and cause diseases in agricultural and forest ecosystems. Two Phytophthora species from rhizosphere soil samples collected from declining Alnus glutinosa in Bulgaria were isolated in the autumn of 2022. They were identified as Phytophthora polonica and Phytophthora hydropathica according to the DNA sequence analysis of the ITS region, as well as their morphological and physiological characteristics. The pathogenicity of both species to common and gray alder was evaluated by the inoculation of detached leaves and cuttings. Experimental data proved that P. polonica and P. hydropathica are able to cause leaf necrosis not only on A. glutinosa from which they were derived, but also on A. incana. No significant deference in the aggressiveness of the studied isolates from both Phytophthora species against the two tested plants was observed. Therefore, P. polonica and P. hydropathica were determined as potential threats for alder ecosystems in the country. This is the first report for the isolation of P. polonica in Bulgaria and represents the most southeastern point of the species distribution in Europe.
... The genus Phytophthora is a large group of fungus-like organisms, which includes important plant pathogens responsible for severe diseases on herbaceous and woody plants in agriculture, horticulture, natural ecosystems and urban forests (Moralejo et al., 2009;Lamour, 2013;Migliorini et al., 2019;Antonelli et al., 2022;Linaldeddu et al., 2023;Schiffer-Forsyth et al., 2023). To date, there are over 220 formally described Phytophthora species, many of which have been discovered in urban forests or nurseries during the last three decades (Abad et al., 2023;Bregant et al., 2023;Coomber et al., 2023). ...
... nicotianae are cosmopolitan and polyphagous, while others, e.g., Ph. ilicis, Ph. lateralis, and Ph. quercina are associated with few hosts (Jung et al., 1999;Vettraino et al., 2005;Brasier et al., 2010;Bregant et al., 2023). ...
Field surveys conducted in two urban green spaces in Athens (Greece) revealed the presence of Phytophthora-
related diseases on Platanus orientalis and P. x acerifolia trees. Declining trees showed a range of disease symp-
toms including root rot, stem bleeding cankers and extensive canopy dieback. Since there is little information
about the etiology of these diseases, a study was conducted from 2016 to 2021 to define the main pathogens
involved. A total of 71 Phytophthora isolates were obtained from bark tissues and rhizosphere samples collected
from symptomatic plane trees. Based on morphological traits and DNA sequence data, Phytophthora isolates were
identified as Ph. mediterranea (11 isolates) and Ph. nicotianae (60). Over a five-year period 41% of P. orientalis
trees associated with Phytophthora infections died and were removed from the park. Pathogenicity tests
confirmed that all Phytophthora species including Ph. cinnamomi used for comparison, are pathogenic on both
P. orientalis and P. x acerifolia trees. Phytophthora cinnamomi was shown to be the most aggressive species on both
P. orientalis and P. x acerifolia. Phytophthora nicotianae was the dominant species, whereas Ph. mediterranea was
associated with a few trees. Our finding has contributed to expanding knowledge on the host and geographic
range of Ph. mediterranea, an invasive pathogen with a high potential for diffusion in Mediterranean regions and
highlights the importance of enhancing biosecurity measures to prevent and limit the spread of invasive path-
ogens in urban and natural ecosystems.
... Despite the extreme adaptability to rapid environmental modifications, riparian systems appear to be more vulnerable than other forest formations to diseases. In the last decades, severe decline events have severally impacted many riparian ecosystems worldwide [14][15][16][17]. In particular, an increasing number of outbreaks caused by Phytophthora species have been reported on alders [18,19]. ...
... Given the alarming decline and mortality affecting riparian species in Italy [17,19,24,25] and the still limited information on the pathogens involved, a study was conducted in 46 riparian formations distributed from the Mediterranean to the alpine climate to isolate and characterize the main pathogens associated. ...
... PCR was performed in 50 ml reaction mixtures using the GoTaq Hot Start Green Master Mix (Promega) and a SimpliAmp Thermal Cycler (Thermo Fisher Scientific Inc.). Amplification conditions for the three regions were conducted as described in Bregant et al. [17]. ...
Riparian formations encompass a diverse suite of transitional zones between terrestrial and aquatic ecosystems. During the last decades, these formations have been impacted by several emerging diseases. The first outbreaks were detected on alder formations, but have progressively also been observed on other plant species such as Betula pubescens, Nerium oleander, Populus alba, Salix alpina, Salix purpurea and Tamarix gallica. Declining plants showed a plethora of symptoms (leaf spot, shoot blight, bleeding cankers and root rot) indicative of Phytophthora infections. Since there is little information about the aetiology of these pathosystems, from November 2019 to March 2023, an in-depth study was conducted in 46 riparian ecosystems spanning from the Mediterranean to Alpine regions. Overall, 744 symptomatic samples (stem bleeding cankers and root with rhizosphere) from 27 host species were collected for Phytophthora isolation. Based on morphology and DNA sequence data, 20 known Phytophthora species belonging to seven phylogenetic clades have been identified: P. plurivora (202 isolates), P. gonapodyides (156), P. pseudosyringae (84), P. lacustris (57), P. acerina (31), P. idaei (30), P. alpina (20), P. pseudocryptogea (19), P. cambivora (13), P. pseudotsugae (13), P. cactorum (9), P. honggalleglyana (6), P. pseudogregata (6), P. debattistii (4), P. multivora (4), P. cinnamomi (3), P. bilorbang (2) P. crassamura (2), P. ilicis (2) and P. inundata (2). In addition, 26 isolates of a new putative species obtained from Alnus incana and Pinus sylvestris are described here as Phytophthora heteromorpha sp. nov. The new species proved to be pathogenic on grey alder causing symptoms congruent with field observations. This study represents the most comprehensive investigation on the Phytophthora species associated with declining riparian vegetation in Italy and highlights that the polyphagous pathogen P. plurivora represents a growing threat to Mediterranean, temperate and alpine ecosystems.
... Fifteen Phytophthora species belonging to six out the twelve major Phytophthora clades were identified. The genus Phytophthora over the last three decades has expanded rapidly to reach the current 220 species [58], of which 15 have been isolated in this study. The presence of the fifteen species in the Italian regions was discontinuous, suggesting that different Phytophthora species can cause the same symptoms on olive trees. ...
Extensive collar rot, sunken and bleeding cankers, shoot blight, and fruit rot symptoms on olive trees have recently been observed in several orchards in Italy. Since there is little information about the etiology of these diseases and given the high economic relevance of this iconic crop, a study was conducted from autumn 2017 to summer 2022, in four Italian regions, to define the occurrence, distribution and impact of the main pathogens involved. A total of 1064 symptomatic olive samples were collected and processed. Based on colony appearance, micromorphological analysis and DNA sequence data, thirty-eight species, including eighteen Botryosphaeriaceae species belonging to five genera and fifteen Phytophthora species, were isolated and identified, thirteen of which, Diplodia africana, D. fraxini, D. subglobosa, Dothiorella omnivora, Do. sarmentorum, Do. sempervirentis, Sardiniella urbana (Botryosphaeriaceae), Phytophthora cactorum, P. cinnamomi, P. citricola, P. crassamura, P. niederhauserii and P. pseudocryptogea, are reported here for the first time in olive trees. Pathogenicity tests performed on unripe drupes and on potted olive seedlings completed Koch postulates and highlighted that several species of Botryosphaeriaceae and Phytophthora represent a growing threat to olive trees.
Severe pomegranate yield losses due to fruit diseases have recently been observed in several orchards in Veneto (north-eastern Italy). Given the economic relevance of these emerging diseases, an in-depth study was conducted in ten orchards distributed in the main producing areas in order to investigate the aetiology. From autumn 2020 to autumn 2023, eighty-two symptomatic fruits were sampled to isolate the causal agents. Based on morphology, colony appearance and DNA sequence data, seventy-seven isolates were obtained and identified. These included Coniella granati (Fam. Schizoparmaceae, 39 isolates), Neofusicoccum parvum (Fam. Botryosphaeriaceae, 29) and Phytophthora palmivora (Fam. Peronosporaceae, 9). Pathogenicity trials conducted on ripe pomegranate fruits confirmed the aggressiveness of the three species. Results obtained have allowed us to expand knowledge on emerging pomegranate pathogens. Neofusicoccum parvum and P. palmivora are reported here for the first time as fruit rot agents on pomegranate in Italy.
The article and supplementary files are open access and can be downloaded from:
https://bsppjournals.onlinelibrary.wiley.com/doi/10.1111/mpp.13450
Phytophthora pseudosyringae is a self-fertile pathogen of woody plants, particularly associated with tree species from the genera Fagus, Notholithocarpus, Nothofagus and Quercus, which is found across Europe and in parts of North America and Chile. It can behave as a soil pathogen infecting roots and the stem collar region, as well as an aerial pathogen infecting leaves, twigs and stem barks, causing particular damage in the United Kingdom and western North America. The population structure, migration and potential outcrossing of a worldwide collection of isolates were investigated
using genotyping-by-sequencing. Coalescent-based migration analysis revealed that the North American population originated from Europe. Historical gene flow has occurred between the continents in both directions to some extent, yet contemporary
migration is overwhelmingly from Europe to North America. Two broad population clusters dominate the global population of the pathogen, with a subgroup derived from one of the main clusters found only in western North America. Index of association
and network analyses indicate an influential level of outcrossing has occurred in this preferentially inbreeding, homothallic oomycete. Outcrossing between the two main population clusters has created distinct subgroups of admixed individuals that are, however, less common than the main population clusters. Differences in life history
traits between the two main population clusters should be further investigated together with virulence and host range tests to evaluate the risk each population poses to natural environments worldwide.
This article is the 15th contribution in the Fungal Diversity Notes series, wherein 115 taxa from three phyla, nine classes, 28 orders, 48 families, and 64 genera are treated. Fungal taxa described and illustrated in the present study include a new family, five new genera, 61 new species, five new combinations, one synonym, one new variety and 31 records on new hosts or new geographical distributions. Ageratinicolaceae fam. nov. is introduced and accommodated in Pleosporales. The new genera introduced in this study are Ageratinicola, Kevinia, Pseudomultiseptospora (Parabambusicolaceae), Marasmiellomycena, and Vizzinia (Porotheleaceae). Newly described species are Abrothallus altoandinus, Ageratinicola kunmingensis, Allocryptovalsa aceris, Allophoma yuccae, Apiospora cannae, A. elliptica, A. pallidesporae, Boeremia wisteriae, Calycina papaeana, Clypeococcum lichenostigmoides, Coniochaeta riskali-shoyakubovii, Cryphonectria kunmingensis, Diaporthe angustiapiculata, D. campylandrae, D. longipapillata, Diatrypella guangdongense, Dothiorella franceschinii, Endocalyx phoenicis, Epicoccum terminosporum, Fulvifomes karaiensis, F. pannaensis, Ganoderma ghatensis, Hysterobrevium baoshanense, Inocybe avellaneorosea, I. lucida, Jahnula oblonga, Kevinia lignicola, Kirschsteiniothelia guangdongensis, Laboulbenia caprina, L. clavulata, L. cobiae, L. cosmodisci, L. nilotica, L. omalii, L. robusta, L. similis, L. stigmatophora, Laccaria rubriporus, Lasiodiplodia morindae, Lyophyllum agnijum, Marasmiellomycena pseudoomphaliiformis, Melomastia beihaiensis, Nemania guangdongensis, Nigrograna thailandica, Nigrospora ficuum, Oxydothis chinensis, O. yunnanensis, Petriella thailandica, Phaeoacremonium chinensis, Phialocephala chinensis, Phytophthora debattistii, Polyplosphaeria nigrospora, Pronectria loweniae, Seriascoma acutispora, Setoseptoria bambusae, Stictis anomianthi, Tarzetta tibetensis, Tarzetta urceolata, Tetraploa obpyriformis, Trichoglossum beninense, and Tricoderma pyrrosiae. We provide an emendation for Urnula ailaoshanensis Agaricus duplocingulatoides var. brevisporus introduced as a new variety based on morphology and phylogeny.
