Browsing by Author "Cacciola, S. O."
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- Six new Phytophthora species from ITS Clade 7a including two sexually functional heterothallic hybrid species detected in natural ecosystems in TaiwanPublication . Jung, Thomas; Horta, Marília; Scanu, B.; Seress, D.; Kovacs, G. M.; Maia, Cristiana; Perez-Sierra, A.; Chang, T. -T.; Chandelier, A.; Heungens, K.; van Poucke, K.; Abad-Campos, P.; Leon, M.; Cacciola, S. O.; Bakonyi, J.During a survey of Phytophthora diversity in natural ecosystems in Taiwan six new species were detected. Multigene phylogeny based on the nuclear ITS, beta-tubulin and HSP90 and the mitochondrial cox1 and NADH1 gene sequences demonstrated that they belong to ITS Clade 7a with P. europaea, P. uniformis, P. rubi and P. cambivora being their closest relatives. All six new species differed from each other and from related species by a unique combination of morphological characters, the breeding system, cardinal temperatures and growth rates. Four homothallic species, P. attenuata, P. flexuosa, P. formosa and P. intricata, were isolated from rhizosphere soil of healthy forests of Fagus hayatae, Quercus glandulifera, Q. tarokoensis, Castanopsis carlesii, Chamaecyparis formosensis and Araucaria cunninghamii. Two heterothallic species, P. xheterohybrida and P. xincrassata, were exclusively detected in three forest streams. All P. xincrassata isolates belonged to the A2 mating type while isolates of P. xheterohybrida represented both mating types with oospore abortion rates according to Mendelian ratios (4-33 %). Multiple heterozygous positions in their ITS, beta-tubulin and HSP90 gene sequences indicate that P. xheterohybrida, P. xincrassata and P. cambivora are interspecific hybrids. Consequently, P. cambivora is re-described as P. xcambivora without nomenclatural act. Pathogenicity trials on seedlings of Castanea sativa, Fagus sylvatica and Q. suber indicate that all six new species might pose a potential threat to European forests.
- The morphology, behaviour and molecular phylogeny of Phytophthora taxon Salixsoil and its redesignation as Phytophthora lacustris sp nov.Publication . Nechwatal, J.; Bakonyi, J.; Cacciola, S. O.; Cooke, D. E. L.; Jung, Thomas; Nagy, Z. A.; Vannini, A.; Vettraino, A. M.; Brasier, C. M.Since its first isolation from Salix roots in 1972, isolates of a sexually sterile Phytophthora species have been obtained frequently from wet or riparian habitats worldwide and have also been isolated from roots of Alnus and Prunus spp. Although originally assigned to Phytophthora gonapodyides on morphological grounds, it was recognized that these isolates, informally named P.taxon Salixsoil, might represent a separate lineage within ITS Clade 6. Based on phylogenetic analyses and comparisons of morphology, growth-temperature relationships and pathogenicity, this taxon is formally described here as Phytophthora lacustris sp. nov. Isolates of P.lacustris form a clearly resolved cluster in both ITS and mitochondrial cox1 phylogenies, basal to most other Clade 6 taxa. Phytophthora lacustris shares several unusual behavioural properties with other aquatic Clade 6 species, such as sexual sterility and tolerance of high temperatures, that have been suggested as adaptations to riparian conditions. It appears to be widespread in Europe and has also been detected in Australia, New Zealand and the USA. It was shown to be weakly or moderately aggressive on inoculation to Alnus, Prunus and Salix. The extent of P.lacustris' activity as a saprotroph in plant debris in water and as an opportunistic pathogen in riparian habitats needs further investigation. Its pathogenic potential to cultivated fruit trees also deserves attention because P.lacustris has apparently been introduced into the nursery trade.
- Widespread Phytophthora infestations in European nurseries put forest, semi-natural and horticultural ecosystems at high risk of Phytophthora diseasesPublication . Jung, Thomas; Orlikowski, L.; Henricot, B.; Abad-Campos, P.; Aday, A. G.; Aguin Casal, O.; Bakonyi, J.; Cacciola, S. O.; Cech, T.; Chavarriaga, D.; Corcobado, T.; Cravador, A.; Decourcelle, T.; Denton, G.; Diamandis, S.; Dogmus-Lehtijaervi, H. T.; Franceschini, A.; Ginetti, Beatrice; Green, S.; Glavendekic, M.; Hantula, J.; Hartmann, G.; Herrero, M.; Ivic, D.; Horta Jung, Marília; Lilja, A.; Keca, N.; Kramarets, V.; Lyubenova, A.; Machado, H.; Magnano di San Lio, G.; Mansilla Vazquez, P. J.; Marcais, B.; Matsiakh, I.; Milenkovic, I.; Moricca, S.; Nagy, Z. A.; Nechwatal, J.; Olsson, C.; Oszako, T.; Pane, A.; Paplomatas, E. J.; Pintos Varela, C.; Prospero, S.; Rial Martinez, C.; Rigling, D.; Robin, C.; Rytkoenen, A.; Sanchez, M. E.; Sanz Ros, A. V.; Scanu, B.; Schlenzig, A.; Schumacher, J.; Slavov, S.; Solla, A.; Sousa, E.; Stenlid, J.; Talgo, V.; Tomic, Z.; Tsopelas, P.; Vannini, A.; Vettraino, A. M.; Wenneker, M.; Woodward, S.; Perez-Sierra, A.An analysis of incidence of Phytophthora spp. in 732 European nurseries producing forest transplants, larger specimen trees, landscape plants and ornamentals, plus 2525 areas in which trees and shrubs were planted, is presented based on work conducted by 38 research groups in 23 European countries between 1972 and 2013. Forty-nine Phytophthora taxa were recorded in 670 nurseries (91.5%); within these nurseries, 1614 of 1992 nursery stands (81.0%) were infested, although most affected plants appeared healthy. In forest and landscape plantings, 56 Phytophthora taxa were recovered from 1667 of 2525 tested sites (66.0%). Affected plants frequently showed symptoms such as crown thinning, chlorosis and dieback caused by extensive fine root losses and/or collar rot. Many well-known highly damaging host-Phytophthora combinations were frequently detected but 297 and 407 new Phytophthora-host associations were also observed in nurseries and plantings, respectively. On average, 1.3 Phytophthora species/taxa per infested nursery stand and planting site were isolated. At least 47 of the 68 Phytophthora species/taxa detected in nurseries and plantings were exotic species several of which are considered well established in both nurseries and plantings in Europe. Seven known Phytophthora species/taxa were found for the first time in Europe, while 10 taxa had not been previously recorded from nurseries or plantings; in addition, 5 taxa were first detections on woody plant species. Seven Phytophthora taxa were previously unknown to science. The reasons for these failures of plant biosecurity in Europe, implications for forest and semi-natural ecosystems and possible ways to improve biosecurity are discussed.
- Worldwide forest surveys reveal forty-three new species in Phytophthora major Clade 2 with fundamental implications for the evolution and biogeography of the genus and global plant biosecurityPublication . Jung, T.; Milenković, I.; Balci, Y.; Janoušek, J.; Kudláček, T.; Nagy, Z. Á.; Baharuddin, B.; Bakonyi, J.; Broders, K. D.; Cacciola, S. O.; Chang, T.-T.; Chi, N. M.; Corcobado, T.; Cravador, Alfredo; Đorđević, B.; Durán, A.; Ferreira, M.; Fu, C.- H.; Garcia, L.; Hieno, A.; Ho, H.- H.; Hong, C.; Junaid, M.; Kageyama, K.; Kuswinanti, T.; Maia, Cristiana; Májek, T.; Masuya, H.; Magnano di San Lio, G.; Mendieta-Araica, B.; Nasri, N.; Oliveira, L. S. S.; Pane, A.; Pérez-Sierra, A.; Rosmana, A.; Sanfuentes von Stowasser, E.; Scanu, B.; Singh, R.; Stanivuković, Z.; Tarigan, M.; Thu, P. Q.; Tomić, Z.; Tomšovský, M.; Uematsu, S.; Webber, J. F.; Zheng, H.- C.; Zheng, F.- C.; Brasier, C. M.; Horta Jung, M.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.