Phytophthora

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Phytophthora

Phytophthora (from Greek

Greek language

Greek is an Indo-European languages native to the southern Balkan peninsula, the language of the Greek people. It forms an independent branch within Indo-European....
phytón, “plant” and phthorá, “destruction”; “the plant-destroyer”) is a genus

Genus

A genus is a low-level taxonomic rank used in the classification of living and fossil organisms. The taxonomic ranks are domain , kingdom , phylum, class , order , family , genus, and species....
of plant-damaging Protist

Protist

Protists ; eukaryote microorganisms. Historically, protists were treated as the kingdom Protista but this group is no longer recognized in modern taxonomy....
s of the Oomycetes
Water mould

Oomycota also known as Water molds are a group of filamentous, unicellular Heterokonts, physically resembling fungus. They are microscopic, absorptive organisms that reproduce both sexually and asexually and are composed of mycelia, or a tube-like vegetative body ....
(water molds). Heinrich Anton de Bary

Anton de Bary

Heinrich Anton de Bary was a Germany surgery, botanist, microbiologist, and mycologist .He is considered a founding father of plant pathology as well as the founder of modern mycology....
described it for the first time in 1875.

hytophthoras are mostly pathogens of dicotyledon

Dicotyledon

Dicotyledons, or "dicots", is a name for a group of flowering plants whose seed typically has two embryonic leaves or cotyledons. There are around 199,350 species within this group....
s, and are relatively host-specific parasites. Many species of Phytophthora are plant

Plant

Plants are Life organisms belonging to the Kingdom Plantae. They include familiar organisms such as trees, herbs, bushes, grasses, vines, ferns, mosses, and green algae....
pathogen

Pathogen

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Encyclopedia

Phytophthora (from Greek

Greek language

Genus

Protist

Anton de Bary

Pathogens

Phytophthoras are mostly pathogens of dicotyledon

Dicotyledon

Plant

Plants are Life organisms belonging to the Kingdom Plantae. They include familiar organisms such as trees, herbs, bushes, grasses, vines, ferns, mosses, and green algae....
pathogen

Pathogen

A pathogen , infectious agent, or germ, is a biological agent that causes disease or illness to its Host .There are several substrates and pathways whereby pathogens can invade a host; the principal pathways have different episodic time frames, but soil contamination has the longest or most persistent potential for harboring...
s of considerable economic importance. Phytophthora infestans
Phytophthora infestans

Phytophthora infestans is an oomycete that causes the serious potato disease known as late blight or potato blight. . It was a major culprit in the Irish Potato Famine and Highland Potato Famine potato famines....
was the infective agent of the potato blight that caused the Great Irish Famine (1845-1849). Plant diseases caused by this genus are difficult to control chemically, thus resistant cultivar

Cultivar

A cultivar is a cultivated plant that has been selected and given a unique name because of its decorative or useful characteristics; it is usually distinct from similar plants and when Plant propagation it retains those characteristics....
s are grown as a management strategy. Research beginning in the 1990s has placed some of the responsibility for European forest die-back on the activity of imported Asian Phytophthoras.

Other important Phytophthora diseases are:

Phytophthora alni
Phytophthora alni

Phytophthora alni is an oomycete plant pathogen that causes causes alder root rot....
– causes alder root rot
Phytophthora cactorum
Phytophthora cactorum

Phytophthora cactorum is a plant pathogen that causes root rot on rhododendron and many other species....
– causes rhododendron root rot affecting rhododendrons, azaleas and causes bleeding canker in hardwood trees
Phytophthora cinnamomi
Phytophthora cinnamomi

Phytophthora cinnamomi is a soil-borne water mould that produces an infection which causes a condition in plants called "root rot" or "dieback"....
- causes cinnamon root rot affecting woody ornamentals including arborvitae, azalea, Chamaecyparis, dogwood, forsythia, Fraser fir, hemlock, Japanese holly, juniper, Pieris, rhododendron, Taxus, white pine, and American chestnut
Phytophthora fragariae
Phytophthora fragariae

Phytophthora fragariae is a plant pathogen that causes red stele, otherwise known as Lanarkshire disease, in strawberry. Symptoms of red stele can include a red core in the roots, wilting of leaves, reduced flowering, stunting, and bitter fruit....
- causes red root rot affecting strawberries
Phytophthora kernoviae - pathogen of beech and rhododendron, also occurring on other trees and shrubs including oak, and holm oak. First seen in Cornwall, UK, in 2003.
Phytophthora palmivora
Phytophthora palmivora

Phytophthora palmivora causes bud-rot of palms, fruit-rot or kole-roga of coconut and arecanut. These are among the most serious diseases caused by fungi and moulds in South India....
- causes fruit rot in coconuts and betel nuts
Phytophthora ramorum
Sudden oak death

Sudden Oak Death is the common name of a disease caused by the oomycete plant pathogen Phytophthora ramorum. The disease kills oak and other species of tree and has had devastating effects on the oak populations in California and Oregon as well as also being present in Europe....
– infects over 60 plant genera and over 100 host species - causes Sudden Oak Death
Sudden oak death

Sudden Oak Death is the common name of a disease caused by the oomycete plant pathogen Phytophthora ramorum. The disease kills oak and other species of tree and has had devastating effects on the oak populations in California and Oregon as well as also being present in Europe....
Phytophthora quercina – causes oak death
Phytophthora sojae
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....
- causes soybean root rot

Fungi resemblance

Phytophthora is sometimes referred to as a fungal-like organism but it is classified under a different kingdom altogether: Chromalveolata (formerly Stramenopila

Heterokont

The heterokonts or stramenopiles are a major line of eukaryotes presently containing about 10,500 known species. Most are algae, ranging from the giant multicellular kelp to the unicellular diatoms, which are a primary component of plankton....
and previously Chromista

Chromista

The Chromista are a eukaryote supergroup, probably polyphyletic, which may be treated as a separate kingdom or included among the Protista. They include all algae whose chloroplasts contain chlorophylls a and c, as well as various colorless forms that are closely related to them....
). This is a good example of convergent evolution

Convergent evolution

Convergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action....
: Phytophthora is morphologically very similar to true fungi yet its evolutionary history is quite distinct. In contrast to fungi, stramenopiles are more closely related to plants than animals. Whereas fungal cell walls are made primarily of chitin

Chitin

Chitin n is a long-chain polymer of a N-acetylglucosamine, a derivative of glucose, and is found in many places throughout the natural world....
, stramenopile cell walls are constructed mostly of cellulose

Cellulose

File:Cellulose Sessel.svgCellulose is an organic compound with the chemical formula , a polysaccharide consisting of a linear chain of several hundred to over ten thousand ? linked D-glucose units....
. Ploidy levels are different between these two kingdoms as are biochemical pathways.

Biology

Phytophthoras 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, 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 which produce zoospores. Chlamydospores are usually spherical and pigmented, and may have a thickened cell wall to aid in its role as a survival structure. Sporangia may be retained by the subtending hyphae (non-caducous) or be shed readily by wind or water tension (caducous) acting as dispersal structures. Also, sporangia may release zoospores, which have two unlike flagella which they use to swim towards a host plant.

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