Albugo occidentalis

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Albugo occidentalis
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Clade: Diaphoretickes
Clade: SAR
Clade: Stramenopiles
Phylum: Oomycota
Order: Albuginales
Family: Albuginaceae
Genus: Albugo
Species:
A. occidentalis
Binomial name
Albugo occidentalis
G.W. Wilson, (1907)
Synonyms

Cystopus occidentalis(G.W. Wilson) Sacc. & Trotter, (1912)

Contents

Albugo occidentalis, the causal agent of spinach white rust, is an oomycete plant pathogen, although some discussions still treat it as a fungal organism. Albugo occidentalis is one of the most important spinach diseases in North America, found throughout the United States east of the rocky mountains.

Hosts and symptoms

The economically important host of Albugo occidentalis is spinach (Spinacia oleracea); although the oomycete has also been reported to affect plants of the genus Chenopodium , the genus including the crop plant quinoa. [1] This pathogen causes white rust or white blister of spinach. It is unrelated to the basidiomycete rusts biologically, but appears somewhat similar on the surface of the leaf, sometimes causing the plant to form white or yellow blister-like pustules on leaves. The early stage, a milder chlorosis, is found on the on abaxial face, but if the white rust is allowed to thrive, it can blister and be visible on the adaxial surface as well. [2]

Disease cycle

Like all the other species in its genus, Albugo occidentalis is an oomycete. [3] The survival structure is an oospore, which is the result of the karyogamy of two haploid gametes (the oogonium and antheridium). The oospore can overwinter in the soil, and in the spring it produces zoospores which will encyst on the surface of spinach leaves in the presence of water and germinate. Asexual propagation of Albugo occidentalis occurs via the production of sporangia on sporangiophores. These sporangia disperse and form zoospores, which complete the asexual cycle by re-infecting or infecting a new spinach leaf. The asexual oomycete can overwinter in spinach debris. [4]

Environment

Because it is an oomycete, presence of water or atmospheric moisture is essential for infection via motile zoospores. Periods of greatest risk of infection include spring and fall when cool evenings promote dew formation on leaf and days are not hot and dry enough to dry out the leaf surface. [5] Albugo occidentalis is most successful at temperatures between 12° and 18 °C, and in this range the white rust takes about three days to germinate. It takes longer at temperatures outside of this window. [6]

Related Research Articles

<span class="mw-page-title-main">Oomycete</span> Fungus-like eukaryotic microorganism

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 of an oospore is the result of contact between hyphae of male antheridia and female oogonia; these spores can overwinter and are known as resting spores. Asexual reproduction involves the formation of chlamydospores and sporangia, producing motile zoospores. Oomycetes occupy both saprophytic and pathogenic lifestyles, and include some of the most notorious pathogens of plants, causing devastating diseases such as late blight of potato and sudden oak death. One oomycete, the mycoparasite Pythium oligandrum, is used for biocontrol, attacking plant pathogenic fungi. The oomycetes are also often referred to as water molds, although the water-preferring nature which led to that name is not true of most species, which are terrestrial pathogens.

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 zoospores that move in water and are attracted to soybean roots. Zoospores can attach to roots, germinate, and infect the plant tissues. Diseased roots develop lesions that may spread up the stem and eventually kill the entire plant. Phytophthora sojae also produces oospores that can remain dormant in the soil over the winter, or longer, and germinate when conditions are favourable. Oospores may also be spread by animals or machinery.

<i>Albugo candida</i> Species of single-celled organism

Albugo candida, commonly known as white rust or white blister rust, is an obligate plant pathogen in the family Albuginaceae that infects Brassicaceae species. It has a relatively smaller genome than other oomycetes.

Phytophthora citrophthora, also known as brown rot of citrus, is a soil borne oomycete that infects several economically important citrus crops. A diagnostic symptom of P. citrophthora is gummosis, wherein lesions around the base of the tree exude sap. Other common symptoms include dark longitudinal lesions forming at the soil line, a sour smell, and eventual cracking of the bark. Advanced symptoms include yellowing and necrosis of the tree canopy. Girdling action caused by the pathogen around the trunk can often cause the collapse of the tree. Resistant lemon varieties have been developed and their implementation has been effective at controlling the spread of the disease. Fruits that have been infected with P. citrophthora exhibit symptoms of brown rot characterized by a distinct odor. This disease is most active in the moderate temperatures of spring, fall, and winter months, opposite of most other Phytophthora species.

<i>Phytophthora medicaginis</i> Species of single-celled organism

Phytophthora medicaginis is an oomycete plant pathogen that causes root rot in alfalfa and chickpea. It is a major disease of these plants and is found wherever they are grown. P. medicaginis causes failure of stand establishment because of seedling death. Phytophthora medicaginis is part of a species complex with Phytophthora megasperma.

Pythium irregulare is a soil borne oomycete plant pathogen. Oomycetes, also known as "water molds", are fungal-like protists. They are fungal-like because of their similar life cycles, but differ in that the resting stage is diploid, they have coenocytic hyphae, a larger genome, cellulose in their cell walls instead of chitin, and contain zoospores and oospores.

Pythium aphanidermatum is a soil borne plant pathogen. Pythium is a genus in the class Oomycetes, which are also known as water molds. Oomycetes are not true fungi, as their cell walls are made of cellulose instead of chitin, they are diploid in their vegetative state, and they form coenocytic hyphae. Also, they reproduce asexually with motile biflagelette zoospores that require water to move towards and infect a host. Sexually, they reproduce with structures called antheridia, oogonia, and oospores.

Pythium graminicola is a plant pathogen infecting cereals.

Pythium volutum is a plant pathogen infecting wheat, barley, and turfgrass. It is known to be sensitive to some of the compounds typically present in selective media commonly used for isolating Pythium spp., so isolation may require alternative methods.

Sclerophthora macrospora is a protist plant pathogen of the class Oomycota. It causes downy mildew on a vast number of cereal crops including oats, rice, maize, and wheat as well as varieties of turf grass. The common names of the diseases associated with Sclerophthora macrospora include "crazy top disease" on maize and yellow tuft disease on turf grass. The disease is present all over the world, but it is especially persistent in Europe.

<i>Albugo</i> Genus of plant-parasitic oomycetes

Albugo is a genus of plant-parasitic oomycetes. Those are not true fungi (Eumycota), although many discussions of this organism still treat it as a fungus. The taxonomy of this genus is incomplete, but several species are plant pathogens. Albugo is one of three genera currently described in the family Albuginaceae, the taxonomy of many species is still in flux.

<i>Plasmopara viticola</i> Species of single-celled organism

Plasmopara viticola, the causal agent of grapevine downy mildew, is a heterothallic oomycete that overwinters as oospores in leaf litter and soil. In the spring, oospores germinate to produce macrosporangia, which under wet condition release zoospores. Zoospores are splashed by rain into the canopy, where they swim to and infect through stomata. After 7–10 days, yellow lesions appear on foliage. During favorable weather the lesions sporulate and new secondary infections occur.

<i>Pseudoperonospora humuli</i> Species of single-celled organism

Pseudoperonospora humuli is a plant pathogen that causes downy mildew on hops.

<i>Phytophthora capsici</i> Species of single-celled organism

Phytophthora capsici is an oomycete plant pathogen that causes blight and fruit rot of peppers and other important commercial crops. It was first described by L. Leonian at the New Mexico State University Agricultural Experiment Station in Las Cruces in 1922 on a crop of chili peppers. In 1967, a study by M. M. Satour and E. E. Butler found 45 species of cultivated plants and weeds susceptible to P. capsici In Greek, Phytophthora capsici means "plant destroyer of capsicums". P. capsici has a wide range of hosts including members of the families Solanaceae and Cucurbitaceae as well as Fabaceae.

Pythium dissotocum is a plant pathogen infecting strawberry and rice.

White rust is a disease in plants caused by the oomycete Albugo candida or one of its close relatives. Plants susceptible to this disease generally include members of the Brassica family. White rust has been known to cause agricultural losses in fields cultivating members of this family including broccoli, cauliflower, and Indian mustard. Despite the name, it is not considered a true rust.

Globisporangium sylvaticum is a plant pathogen, an oomycete known to cause root rot and damping off in a multitude of species. These species include apples, carrot, cherry laurel, cress, cucumber, garlic, lettuce, pea, rhododendron, and spinach. Symptoms of infection include stunting, wilt, chlorosis, and browning and eventual necrosis of roots. The pathogen can by identified by the presence of thick, microscopic, round spores within the cells of the root.

Phytophthora hydropathica is an oomycete plant pathogen that is found in aquatic environments such as irrigation and river water. The pathogen was previously classified as P. drechsleri Dre II before being categorized as its own distinct species. P. hydropathica has been primarily found in association with ornamental plant nurseries. The pathogen has been isolated throughout the Southern United States, as well as internationally in Mexico, Italy, and Spain.

Black rot on orchids is caused by Pythium and Phytophthora species. Black rot targets a variety of orchids but Cattleya orchids are especially susceptible. Pythium ultimum and Phytophthora cactorum are known to cause black rot in orchids.

References

  1. Correll, James; Morelock, Teddy (1994). "Economically Important Diseases of Spinach". Plant Disease. 78 (7): 653–660. doi:10.1094/pd-78-0653.
  2. "Texas Plant Disease Handbook". Texas A&M. Retrieved 15 November 2016.
  3. Barnes, E. H. (2012). Atlas and Manual of Plant Pathology. Springer Science & Business Media. ISBN   978-1468434958.
  4. "Introduction to the Oomycota". University of California Museum of Paleontology. 1995.
  5. Vakalounakis, D.J.; Doulis, A.G. (September 2013). "First Record of White Rust, Caused by Albugo occidentalis, on Spinach in Greece". Plant Disease. 97 (9): 1253–1254. doi: 10.1094/pdis-02-13-0198-pdn .
  6. Sullivan, M.J.; Damicone, J.P. (2002). "The Effects of Temperature and Wetness Period on the Development of Spinach White Rust". Plant Disease. 96 (7): 753–758. doi: 10.1094/PDIS.2002.86.7.753 .

Further reading

[1]

  1. Vakalounakis, D.J.; Doulis, A.G. (September 2013). "First Record of White Rust, Caused by Albugo occidentalis, on Spinach in Greece". Plant Disease. 97 (9): 1253–1254. doi: 10.1094/pdis-02-13-0198-pdn .