''Phytophthora'' (from

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

(''phytón''), "plant" and (), "destruction"; "the plant-destroyer") is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of plant-damaging

oomycete The Oomycetes (), or Oomycota, form a distinct phylogenetic lineage of fungus-like eukaryotic microorganisms within the Stramenopiles. They are filamentous and heterotrophic, and can reproduce both sexually and asexually. Sexual reproduction o ...

s (water molds), whose member species cause economic losses on crops worldwide, as well as

environmental damage Environment most often refers to: __NOTOC__ * Natural environment, referring respectively to all living and non-living things occurring naturally and the physical and biological factors along with their chemical interactions that affect an organism ...

in natural

ecosystem An ecosystem (or ecological system) is a system formed by Organism, organisms in interaction with their Biophysical environment, environment. The Biotic material, biotic and abiotic components are linked together through nutrient cycles and en ...

s. The cell wall of ''Phytophthora'' is made up of

cellulose Cellulose is an organic compound with the chemical formula, formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of glycosidic bond, β(1→4) linked glucose, D-glucose units. Cellulose is an important s ...

. The genus was first described by

Heinrich Anton de Bary Heinrich Anton de Bary (26 January 183119 January 1888) was a German surgeon, botanist, microbiologist, and mycologist (fungal systematics and physiology). He is considered a founding father of plant pathology (phytopathology) as well as the fou ...

in 1875. Approximately 210 species have been described, although 100–500 undiscovered ''Phytophthora'' species are estimated to exist.

Pathogenicity

''Phytophthora'' spp. are mostly pathogens of

dicotyledon The dicotyledons, also known as dicots (or, more rarely, dicotyls), are one of the two groups into which all the flowering plants (angiosperms) were formerly divided. The name refers to one of the typical characteristics of the group: namely, ...

s, and many are relatively host-specific parasites. '' P. cinnamomi'', though, infects thousands of species ranging from club mosses,

fern The ferns (Polypodiopsida or Polypodiophyta) are a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. They differ from mosses by being vascular, i.e., having specialized tissue ...

cycad Cycads are seed plants that typically have a stout and woody (ligneous) trunk (botany), trunk with a crown (botany), crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious, that is, individual plants o ...

conifer Conifers () are a group of conifer cone, cone-bearing Spermatophyte, seed plants, a subset of gymnosperms. Scientifically, they make up the phylum, division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a sin ...

grass Poaceae ( ), also called Gramineae ( ), is a large and nearly ubiquitous family (biology), family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos, the grasses of natural grassland and spe ...

es, lilies, to members of many dicotyledonous families. Many species of ''Phytophthora'' are

plant Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they are predominantly Photosynthesis, photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with c ...

pathogen In biology, a pathogen (, "suffering", "passion" and , "producer of"), in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a Germ theory of d ...

s 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 solanaceous 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

cultivar A cultivar is a kind of Horticulture, cultivated plant that people have selected for desired phenotypic trait, traits and which retains those traits when Plant propagation, propagated. Methods used to propagate cultivars include division, root a ...

s is the main management strategy. Other important ''Phytophthora'' diseases are: * '' P. agathidicida''—causes collar-rot on

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

kauri (''

Agathis australis ''Agathis australis'', commonly known as kauri, is a species of coniferous tree in the family Araucariaceae, found north of 38°S in the northern regions of New Zealand's North Island. It is the largest (by volume) but not tallest species ...

''), New Zealand's most voluminous tree, an otherwise successful survivor of the

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...

* '' P. cactorum''—causes rhododendron root rot affecting rhododendrons, azaleas, and

orchids Orchids are plants that belong to the family Orchidaceae (), a diverse and widespread group of flowering plants with blooms that are often colourful and fragrant. Orchids are cosmopolitan plants that are found in almost every habitat on Earth ...

, and causes bleeding canker in hardwood trees * '' P. capsici''—infects

Cucurbitaceae The Cucurbitaceae (), also called cucurbits or the gourd family, are a plant family (biology), family consisting of about 965 species in 101 genera.

fruits, such as

cucumber The cucumber (''Cucumis sativus'') is a widely-cultivated creeping vine plant in the family Cucurbitaceae that bears cylindrical to spherical fruits, which are used as culinary vegetables.squash * '' P. cinnamomi''—causes cinnamon root rot affecting forest and fruit trees, and woody ornamentals including arborvitaee,

azalea Azaleas ( ) are flowering shrubs in the genus ''Rhododendron'', particularly the former sections ''Rhododendron sect. Tsutsusi, Tsutsusi'' (evergreen) and ''Pentanthera'' (deciduous). Azaleas bloom in the spring (April and May in the temperate ...

, Chamaecyparis,

dogwood ''Cornus'' is a genus of about 30–60 species of woody plants in the family Cornaceae, commonly known as dogwoods or cornels, which can generally be distinguished by their blossoms, berries, and distinctive bark. Most are deciduous ...

forsythia ''Forsythia'' , is a genus of flowering plants in the olive family Oleaceae. There are about 11 species, mostly native to Eastern Asia, but one native to Southeastern Europe. ''Forsythia'' – also one of the plant's common names – is named ...

, Fraser fir, hemlock, Japanese holly,

juniper Junipers are coniferous trees and shrubs in the genus ''Juniperus'' ( ) of the cypress family Cupressaceae. Depending on the taxonomy, between 50 and 67 species of junipers are widely distributed throughout the Northern Hemisphere as far south ...

, Pieris,

rhododendron ''Rhododendron'' (; : ''rhododendra'') is a very large genus of about 1,024 species of woody plants in the Ericaceae, heath family (Ericaceae). They can be either evergreen or deciduous. Most species are native to eastern Asia and the Himalayan ...

Taxus ''Taxus'' is a genus of coniferous trees or shrubs known as yews in the family Taxaceae. Yews occur around the globe in temperate zones of the northern hemisphere, northernmost in Norway and southernmost in the South Celebes. Some populations ex ...

, white pine,

American chestnut The American chestnut (''Castanea dentata'') is a large, fast-growing deciduous tree of the Fagaceae, beech family native to eastern North America. As is true of all species in the genus ''Chestnut, Castanea'', the American chestnut produces Bur ...

and Australian woody plants, especially

eucalypt Eucalypt is any woody plant with Capsule (fruit), capsule fruiting bodies belonging to one of seven closely related genera (of the tribe Eucalypteae) found across Australia: ''Eucalyptus'', ''Corymbia'', ''Angophora'', ''Stockwellia'', ''Allosyn ...

and

banksia ''Banksia'' is a genus of around 170 species of flowering plants in the family Proteaceae. These Australian wildflowers and popular garden plants are easily recognised by their characteristic flower spikes, and woody fruiting "cones" and head ...

. * '' 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 Beech (genus ''Fagus'') is a genus of deciduous trees in the family Fagaceae, native to subtropical (accessory forest element) and temperate (as dominant element of Mesophyte, mesophytic forests) Eurasia and North America. There are 14 accepted ...

and rhododendron, also occurring on other trees and shrubs including

oak An oak is a hardwood tree or shrub in the genus ''Quercus'' of the beech family. They have spirally arranged leaves, often with lobed edges, and a nut called an acorn, borne within a cup. The genus is widely distributed in the Northern Hemisp ...

, and holm oak. 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 and probably responsible for the greatest cocoa crop loss in Africa * '' P. multivora''—discovered in analysis of isolates with ''P. cinnamomi'' dieback infections of tuart forests 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 Tobacco is the common name of several plants in the genus '' Nicotiana'' of the family Solanaceae, and the general term for any product prepared from the cured leaves of these plants. More than 70 species of tobacco are known, but the ...

and

onion An onion (''Allium cepa'' , from Latin ), also known as the bulb onion or common onion, is a vegetable that is the most widely cultivated species of the genus '' Allium''. The shallot is a botanical variety of the onion which was classifie ...

s * '' P. palmivora''—causes fruit rot in

coconut The coconut tree (''Cocos nucifera'') is a member of the palm tree family (biology), family (Arecaceae) and the only living species of the genus ''Cocos''. The term "coconut" (or the archaic "cocoanut") can refer to the whole coconut palm, ...

s and

betel nut The areca nut ( or ) or betel nut () is the fruit of the areca palm ('' Areca catechu''). The palm is originally native to the Philippines, but was carried widely through the tropics by the Austronesian migrations and trade since at least 1 ...

s * '' P. ramorum''—infects over 60 plant genera and over 100 host species; causes sudden oak death * '' P. quercina''—causes oak death * '' P. sojae''—causes

soybean The soybean, soy bean, or soya bean (''Glycine max'') is a species of legume native to East Asia, widely grown for its edible bean. Soy is a staple crop, the world's most grown legume, and an important animal feed. Soy is a key source o ...

root rot Research beginning in the 1990s placed some of the responsibility for European forest die-back on the activity of imported Asian ''Phytophthoras''. 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, antheridia introduce gametes into

oogonia An oogonium (: oogonia) is a small diploid cell which, upon maturation, forms a primordial follicle in a female fetus or the female (haploid or diploid) gametangium of certain thallophytes. In the mammalian fetus Oogonia are formed in lar ...

, 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, meiosis is gametic, and somatic nuclei are diploid. Asexual (mitotic) spore types are chlamydospores, and

sporangia A sporangium (from Late Latin, ; : sporangia) is an enclosure in which spores are formed. It can be composed of a unicellular organism, single cell or can be multicellular organism, multicellular. Virtually all plants, fungus, fungi, and many ot ...

which produce

zoospore A zoospore is a motile asexual spore that uses a flagellum for locomotion in aqueous or moist environments. Also called a swarm spore, these spores are created by some protists, bacteria, and fungi to propagate themselves. Certain zoospores are ...

s. 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

flagella A flagellum (; : flagella) (Latin for 'whip' or 'scourge') is a hair-like appendage that protrudes from certain plant and animal sperm cells, from fungal spores ( zoospores), and from a wide range of microorganisms to provide motility. Many pr ...

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. ''Phytophthora'' zoospores recognize and attach to specific root surface regions. This is a high degree of specificity at an early stage of cell development.

Evolution and resemblance to fungi

''Phytophthora'' is sometimes referred to as a

fungus A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...

-like organism, but it is classified under a different

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

altogether:

SAR supergroup SAR is a highly diverse clade of eukaryotes, often considered a supergroup, that includes stramenopiles (heterokonts), alveolates, and rhizarians. It is a node-based taxon (under the Sar name), including all descendants of the three groups' ...

(Harosa) (also under Stramenopila and previously under

Chromista Chromista is a proposed but polyphyletic obsolete Biology, biological Kingdom (biology), kingdom, refined from the Chromalveolata, consisting of single-celled and multicellular eukaryotic species that share similar features in their Photosynthesi ...

). This is a good example of

convergent evolution Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last comm ...

: ''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 Chitin (carbon, C8hydrogen, H13oxygen, O5nitrogen, N)n ( ) is a long-chain polymer of N-Acetylglucosamine, ''N''-acetylglucosamine, an amide derivative of glucose. Chitin is the second most abundant polysaccharide in nature (behind only cell ...

, ''Phytophthora'' cell walls are constructed mostly of

Ploidy Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Here ''sets of chromosomes'' refers to the number of maternal and paternal chromosome copies, ...

levels are different between these two groups; ''Phytophthora'' species have

diploid Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Here ''sets of chromosomes'' refers to the number of maternal and paternal chromosome copies, ...

(paired) chromosomes in the vegetative (growing, nonreproductive) stage of life, whereas fungi are almost always

haploid Ploidy () is the number of complete sets of chromosomes in a cell (biology), cell, and hence the number of possible alleles for Autosome, autosomal and Pseudoautosomal region, pseudoautosomal genes. Here ''sets of chromosomes'' refers to the num ...

in this stage. Biochemical pathways also differ, notably the highly conserved

lysine Lysine (symbol Lys or K) is an α-amino acid that is a precursor to many proteins. Lysine contains an α-amino group (which is in the protonated form when the lysine is dissolved in water at physiological pH), an α-carboxylic acid group ( ...

synthesis path..

Species

The NCBI lists: *'' Phytophthora acerina'' *'' Phytophthora afrocarpa'' *''

Phytophthora agathidicida ''Phytophthora'' (from Greek (''phytón''), "plant" and (), "destruction"; "the plant-destroyer") is a genus of plant-damaging oomycetes (water molds), whose member species cause economic losses on crops worldwide, as well as environmental da ...

Phytophthora × incrassata ''Phytophthora'' (from Greek (''phytón''), "plant" and (), "destruction"; "the plant-destroyer") is a genus of plant-damaging oomycetes (water molds), whose member species cause economic losses on crops worldwide, as well as environmental dam ...

'' *''

Phytophthora infestans ''Phytophthora infestans'' is an oomycete or Oomycete, water mold, a fungus-like microorganism that causes the serious potato and tomato disease known as late blight or potato blight. Early blight, caused by ''Alternaria solani'', is also often c ...

Phytophthora porri ''Phytophthora'' (from Greek language, Greek (''phytón''), "plant" and (), "destruction"; "the plant-destroyer") is a genus of plant-damaging oomycetes (water molds), whose member species cause economic losses on crops worldwide, as well as e ...

'' *'' Phytophthora primulae'' *'' Phytophthora aff. primulae'' *'' Phytophthora pseudocryptogea'' *'' Phytophthora pseudolactucae'' *'' Phytophthora pseudorosacearum'' *'' Phytophthora pseudosyringae'' *'' Phytophthora pseudotsugae'' *'' Phytophthora aff. pseudotsugae'' *'' Phytophthora psychrophila'' *'' Phytophthora quercetorum'' *'' Phytophthora quercina'' *'' Phytophthora quininea'' *''

Phytophthora ramorum ''Phytophthora ramorum'' is the oomycete known to cause the disease sudden oak death (SOD). The disease kills oak and other species of trees and has had devastating effects on the oak populations in California and Oregon, as well as being present ...

'' Werres, De Cock & Man in’t Veld 2001 *'' Phytophthora rhizophorae'' *'' Phytophthora richardiae'' *'' Phytophthora riparia'' *'' Phytophthora rosacearum'' *'' Phytophthora aff. rosacearum'' *'' Phytophthora rubi'' *'' Phytophthora sansomea'' *'' Phytophthora sansomeana'' *'' Phytophthora aff. sansomeana'' *'' Phytophthora × serendipita'' *'' Phytophthora sinensis'' *'' Phytophthora siskiyouensis'' *''

Phytophthora sojae ''Phytophthora sojae'' is an oomycete and a soil-borne plant pathogen that causes stem and root rot of soybean. This is a prevalent disease in most soybean growing regions, and a major cause of crop loss. In wet conditions the pathogen produces ...

''References''

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

External links

* ecticut

"''Phytophthora'' Canker – Identification, Biology and Management"
Bartlett TreeExperts Online Resource Library
"''Phytophthora'' Root Rot – Identification, Biology andManagement"
Bartlett Tree Experts Online Resource Library
Dieback Working Group
– Western Australia {{Authority control Phytophthora"> Water mould plant pathogens and diseases Oomycete genera">Water mould plant pathogens and diseases">Phytophthora"> Water mould plant pathogens and diseases Oomycete genera