Phytophthora (from Greek language φυτόν ( phytón), "plant" and φθορά (), "destruction"; "the plant-destroyer") is a genus of plant-damaging (water molds), whose member species cause economic losses on crops worldwide, as well as environmental damage in natural . The cell wall of Phytophthora is made up of cellulose. The genus was first described by Heinrich Anton de Bary in 1875. Approximately 210 species have been described, although 100–500 undiscovered Phytophthora species are estimated to exist.[Brasier CM, 2009. Phytophthora biodiversity: how many Phytohthora species are there? In: Goheen EM, Frankel SJ, eds. Phytophthoras in Forest and Natural Ecosystems. Albany, CA, USA: USDA Forest Service: General Technical Rep rt PSW-GTR-221, 101–15.]
Pathogenicity
Phytophthora species are mostly pathogens of
, and many are relatively host-specific parasites.
P. cinnamomi, though, infects thousands of species ranging from
,
,
,
,
,
lily, to members of many dicotyledonous families. Many species of
Phytophthora are
plant of considerable economic importance.
P. infestans was the infective agent of the potato blight that caused the Great Famine of Ireland, and still remains the most destructive pathogen of
Solanaceae crops, including tomato and potato.
[Ristaino, J. B., Cooke, D.E.L., Acuña, I., Muñoz, M. 2020. The Threat of Late Blight to Global Food Security. Pages 101-133 in: In Emerging Plant Disease and Global Food Security. A. Records and J. B. Ristaino, eds. American Phytopathological Society Press, St. Paul. https://doi.org/10.1094/9780890546383.006] The soya bean root and stem rot agent,
P. sojae, caused longstanding problems for the agricultural industry. In general, plant diseases caused by this genus are difficult to control chemically, thus the growth of resistant
is the main management strategy. Other important
Phytophthora diseases are:
-
P. agathidicida—causes collar-rot on New Zealand kauri ( Agathis australis), New Zealand's most voluminous tree, an otherwise successful survivor of the Jurassic
-
P. cactorum—causes rhododendron root rot affecting rhododendrons, azaleas, and orchids, and causes bleeding canker in hardwood trees
-
P. capsici—infects Cucurbitaceae fruits, such as and squash
-
P. cinnamomi—causes cinnamon root rot affecting forest and fruit trees, and woody ornamentals including , azalea, Chamaecyparis, dogwood, forsythia, Fraser fir, Tsuga, Japanese holly, juniper, Pieris, rhododendron, Taxus, white pine, American chestnut and Australian woody plants, especially eucalypt and banksia.
-
P. citricola—causes root rot and stem cankers in citrus trees
-
P. fragariae—causes red root rot affecting strawberries
-
P. infestans causes the serious disease known as potato (late) blight: responsible for the Great Famine of Ireland.
-
P. kernoviae—pathogen of beech and rhododendron, also occurring on other trees and shrubs including oak, and Quercus ilex. First seen in Cornwall, UK, in 2003.
-
P. lateralis—causes cedar root disease in Port Orford cedar trees
-
P. megakarya—one of the cocoa black pod disease species, is invasive species and probably responsible for the greatest Theobroma cacao crop loss in Africa
-
P. multivora—discovered in analysis of isolates with P. cinnamomi dieback infections of of Southwest Australia, which were previously diagnosed as P. citricola. The species was found occurring on many other taxa, so named multivora.
-
P. nicotianae—infects tobacco and
-
P. palmivora—causes fruit rot in and
-
P. ramorum—infects over 60 plant genera and over 100 host species; causes sudden oak death
[ "APHIS List of Regulated Hosts and PlantsAssociated with Phytophthora ramorum" U.S. Animal and Plant Health Inspection Services ; ]
-
P. quercina—causes oak death
-
P. sojae—causes soybean root rot
Research beginning in the 1990s placed some of the responsibility for European forest die-back on the activity of imported Asian Phytophthoras.[ " Phytophthora: Asiatischer Pilz lässt die Bäume sterben" Süddeutschen Zeitung 11 Ma 2005]
In 2019, scientists in Connecticut were conducting experiments testing various methods to grow healthier Fraser trees when they accidentally discovered a new species of Phytophthora, which they called P. abietivora. The fact that these scientists so readily discovered a new species further suggests that there could be many more species waiting to be discovered.
Reproduction
Phytophthora species may reproduce sexually or asexually. In many species, sexual structures have never been observed, or have only been observed in laboratory matings. In
homothallic species, sexual structures occur in single culture.
Heterothallic species have mating strains, designated as A1 and A2. When mated,
Antheridium introduce gametes into
Oogonium, either by the oogonium passing through the antheridium (amphigyny) or by the antheridium attaching to the proximal (lower) half of the oogonium (paragyny), and the union producing oospores. Like animals, but not like most true fungi,
gametic meiosis, and somatic nuclei are diploid.
Asexual (mitotic) spore types are
, and
sporangium which produce
. Chlamydospores are usually spherical and pigmented, and may have a thickened cell wall to aid in their role as a survival structure. Sporangia may be retained by the subtending hyphae (noncaducous) or be shed readily by wind or water tension (caducous) acting as dispersal structures. Also, sporangia may release zoospores, which have two unlike
flagellum which they use to swim towards a host plant.
Zoospores (and zoospores of Pythium, also in the Peronosporales) recognize not only hosts but particular locations on hosts.
Evolution and resemblance to fungi
Phytophthora is sometimes referred to as a
fungi-like organism, but it is classified under a different
clade altogether:
SAR supergroup (Harosa) (also under
heterokont and previously under
Chromista). This is a good example of convergent evolution:
Phytophthora is morphologically very similar to true fungi yet its evolutionary history is completely distinct. In contrast to fungi, SAR supergroup is more closely related to plants than to animals. Whereas fungal cell walls are made primarily of
chitin,
Phytophthora cell walls are constructed mostly of
cellulose.
Ploidy levels are different between these two groups;
Phytophthora species have
diploid (paired) chromosomes in the vegetative (growing, nonreproductive) stage of life, whereas fungi are almost always
haploid in this stage. Biochemical pathways also differ, notably the highly conserved
lysine synthesis path..
Species
The NCBI lists:
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Phytophthora acerina
-
Phytophthora afrocarpa
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Phytophthora agathidicida
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Phytophthora aleatoria
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Phytophthora alni
-
Phytophthora × alni
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Phytophthora alpina
-
Phytophthora alticola
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Phytophthora amaranthi
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Phytophthora amnicola
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Phytophthora amnicola × moyootj
-
Phytophthora xandina
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Phytophthora aquimorbida
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Phytophthora arecae
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Phytophthora arenaria
-
Phytophthora cf. arenaria
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Phytophthora aff. arenaria
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Phytophthora asiatica
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Phytophthora asparagi
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Phytophthora aff. asparagi
-
Phytophthora attenuata
-
Phytophthora austrocedrae
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Phytophthora balyanboodja
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Phytophthora batemanensis syn. Halophytophthora batemanensis
Phytophthora betacei
-
Phytophthora bilorbang
-
Phytophthora bishii
-
Phytophthora boehmeriae
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Phytophthora boodjera
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Phytophthora borealis
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Phytophthora botryosa
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Phytophthora cf. botryosa
-
Phytophthora aff. botryosa
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Phytophthora brassicae
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Phytophthora cactorum
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Phytophthora cactorum var. applanata
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Phytophthora cactorum × hedraiandra
-
Phytophthora cajani
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Phytophthora × cambivora
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Phytophthora capensis
-
Phytophthora capsici
-
Phytophthora aff. capsici
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Phytophthora captiosa
-
Phytophthora castaneae
-
Phytophthora castanetorum
-
Phytophthora chesapeakensis
[Man in 't Veld, W.A. et al. 2019. Multiple Halophytophthora spp. and Phytophthora spp. including P. gemini, P. inundata and P. chesapeakensis sp. nov. isolated from the seagrass Zostera marina in the Northern hemisphere. Eur J Plant Pathol 153: 341-357. ]
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Phytophthora chlamydospora
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Phytophthora chrysanthemi
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Phytophthora cichorii
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Phytophthora aff. cichorii
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Phytophthora cinnamomi
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Phytophthora cinnamomi var. cinnamomi
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Phytophthora cinnamomi var. parvispora
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Phytophthora cinnamomi var. robiniae
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Phytophthora citricola
-
Phytophthora aff. citricola
-
Phytophthora citrophthora
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Phytophthora citrophthora var. clementina
-
Phytophthora aff. citrophthora
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Phytophthora clandestina
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Phytophthora cocois
-
Phytophthora colocasiae
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Phytophthora condilina
-
Phytophthora constricta
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Phytophthora cooljarloo
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Phytophthora crassamura
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Phytophthora cryptogea
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Phytophthora aff. cryptogea
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Phytophthora cuyabensis
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Phytophthora cyperi
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Phytophthora dauci
-
Phytophthora aff. dauci
-
Phytophthora drechsleri
-
Phytophthora drechsleri var. cajani
-
Phytophthora elongata
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Phytophthora cf. elongata
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Phytophthora erythroseptica
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Phytophthora erythroseptica var. pisi
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Phytophthora aff. erythroseptica
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Phytophthora estuarina
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Phytophthora europaea
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Phytophthora fallax
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Phytophthora flexuosa
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Phytophthora fluvialis
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Phytophthora fluvialis × moyootj
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Phytophthora foliorum
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Phytophthora formosa
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Phytophthora formosana
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Phytophthora fragariae
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Phytophthora fragariaefolia
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Phytophthora frigida
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Phytophthora gallica
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Phytophthora gemini
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Phytophthora gibbosa
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Phytophthora glovera
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Phytophthora gonapodyides
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Phytophthora gondwanensis
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Phytophthora gregata
-
Phytophthora cf. gregata
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Phytophthora hedraiandra
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Phytophthora aff. hedraiandra
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Phytophthora × heterohybrida
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Phytophthora heveae
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Phytophthora hibernalis
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Phytophthora himalayensis
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Phytophthora himalsilva
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Phytophthora aff. himalsilva
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Phytophthora humicola
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Phytophthora aff. humicola
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Phytophthora hydrogena
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Phytophthora hydropathica Hong, C. & Gallegly, M. 2010
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Phytophthora idaei
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Phytophthora ilicis
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Phytophthora × incrassata
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Phytophthora infestans
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Phytophthora aff. infestans
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Phytophthora inflata
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Phytophthora insolita
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Phytophthora cf. insolita
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Phytophthora intercalaris
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Phytophthora intricata
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Phytophthora inundata
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Phytophthora ipomoeae
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Phytophthora iranica
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Phytophthora irrigata
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Phytophthora katsurae
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Phytophthora kelmania
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Phytophthora kernoviae
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Phytophthora kwongonina
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Phytophthora lactucae
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Phytophthora lacustris
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Phytophthora lacustris × riparia
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Phytophthora lateralis
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Phytophthora lilii
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Phytophthora litchii
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Phytophthora litoralis
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Phytophthora litoralis × moyootj
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Phytophthora macilentosa
-
Phytophthora macrochlamydospora
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Phytophthora meadii
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Phytophthora aff. meadii
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Phytophthora medicaginis
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Phytophthora medicaginis × cryptogea
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Phytophthora mediterranea
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Phytophthora megakarya
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Phytophthora megasperma
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Phytophthora melonis
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Phytophthora mengei
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Phytophthora mexicana
-
Phytophthora cf. mexicana
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Phytophthora mirabilis
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Phytophthora mississippiae
-
Phytophthora morindae
-
Phytophthora moyootj
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Phytophthora moyootj × fluvialis
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Phytophthora moyootj × litoralis
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Phytophthora moyootj × thermophila
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Phytophthora × multiformis
-
Phytophthora multivesiculata
-
Phytophthora multivora
-
Phytophthora nagaii
-
Phytophthora nemorosa
-
Phytophthora nicotianae
-
Phytophthora nicotianae var. parasitica
-
Phytophthora nicotianae × cactorum
-
Phytophthora niederhauserii
-
Phytophthora cf. niederhauserii
-
Phytophthora obscura
-
Phytophthora occultans
-
Phytophthora oleae
-
Phytophthora ornamentata
-
Phytophthora pachypleura
-
Phytophthora palmivora
-
Phytophthora palmivora var. palmivora
-
Phytophthora parasitica
-
Phytophthora parasitica var. nicotianae
-
Phytophthora parasitica var. piperina
-
Phytophthora parsiana
-
Phytophthora aff. parsiana
-
Phytophthora parvispora
-
Phytophthora × pelgrandis
-
Phytophthora phaseoli
-
Phytophthora pini
-
Phytophthora pinifolia
-
Phytophthora pisi
-
Phytophthora pistaciae
-
Phytophthora plurivora
-
Phytophthora pluvialis
-
Phytophthora polonica
-
Phytophthora porri
-
Phytophthora primulae
-
Phytophthora aff. primulae
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Phytophthora pseudocryptogea
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Phytophthora pseudolactucae
-
Phytophthora pseudorosacearum
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Phytophthora pseudosyringae
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Phytophthora pseudotsugae
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Phytophthora aff. pseudotsugae
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Phytophthora psychrophila
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Phytophthora quercetorum
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Phytophthora quercina
-
Phytophthora quininea
-
Phytophthora ramorum Werres, De Cock & Man in’t Veld 2001
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Phytophthora rhizophorae
-
Phytophthora richardiae
-
Phytophthora riparia
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Phytophthora rosacearum
-
Phytophthora aff. rosacearum
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Phytophthora rubi
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Phytophthora sansomea
-
Phytophthora sansomeana
-
Phytophthora aff. sansomeana
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Phytophthora × serendipita
-
Phytophthora sinensis
-
Phytophthora siskiyouensis
-
Phytophthora sojae
-
Phytophthora stricta
-
Phytophthora sulawesiensis
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Phytophthora syringae
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Phytophthora tabaci
-
Phytophthora tentaculata
-
Phytophthora terminalis
-
Phytophthora thermophila
-
Phytophthora thermophila × amnicola
-
Phytophthora thermophila × moyootj
-
Phytophthora tonkinensis
-
Phytophthora trifolii
-
Phytophthora tropicalis
-
Phytophthora cf. tropicalis
-
Phytophthora tubulina
-
Phytophthora tyrrhenica
-
Phytophthora uliginosa
-
Phytophthora undulata
-
Phytophthora uniformis
-
Phytophthora vignae
-
Phytophthora vignae f. sp. adzukicola
-
Phytophthora virginiana
-
Phytophthora vulcanica
[Coomber, A., Saville, A., Carbone, I. and Ristaino, J. 2023. An open T base phylogeny for emerging Phytophthora species. Plos One: https://doi.org/10.1371/journal.pone.0283540
]
Further reading
-
Lucas, J.A. et al. (eds.) (1991) Phytophthora based n a symposium held at Trinity College, Dublin, Ireland September 1200. British Mycologic l Society, Cambridge University Press, Cambridge, UK, ;
-
Erwin, Donald C. and Ribe ro, Olaf K. (1996) Phytophthora Diseases Worldwide American Phytopathological Society Press, St Paul, Minnesota,
-
Erwin, Donald C. (1983) Phytophthora: its biology, ta onomy, ecology, and pathology American Phytopathological Society Press, St. Paul, Minnesota,
-
"APHIS List of Regulated Hosts and Plants Associated with Phytophthora ram rum" U.S. Animal and Plant Health Inspection Services
-
"Dieback" Department of Env ronment and Conservation, Western Australia
External links
