''Pythium myriotylum'' is a soil-borne

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 ...

necrotroph that has a broad host range, this means that it can infect a wide range of plants.

Hosts and symptoms

''Pythium myriotylum'' is a causal agent of soft root rot in economically important crops including

peanut The peanut (''Arachis hypogaea''), also known as the groundnut, goober (US), goober pea, pindar (US) or monkey nut (UK), is a legume crop grown mainly for its edible seeds. It is widely grown in the tropics and subtropics by small and large ...

tomato The tomato (, ), ''Solanum lycopersicum'', is a plant whose fruit is an edible Berry (botany), berry that is eaten as a vegetable. The tomato is a member of the nightshade family that includes tobacco, potato, and chili peppers. It originate ...

rye Rye (''Secale cereale'') is a grass grown extensively as a grain, a cover crop and a forage crop. It is grown principally in an area from Eastern and Northern Europe into Russia. It is much more tolerant of cold weather and poor soil than o ...

wheat Wheat is a group of wild and crop domestication, domesticated Poaceae, grasses of the genus ''Triticum'' (). They are Agriculture, cultivated for their cereal grains, which are staple foods around the world. Well-known Taxonomy of wheat, whe ...

, oats,

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.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 ...

sorghum ''Sorghum bicolor'', commonly called sorghum () and also known as great millet, broomcorn, guinea corn, durra, imphee, jowar, or milo, is a species in the Poaceae, grass genus ''Sorghum (genus), Sorghum'' cultivated for its grain. The grain i ...

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 ...

cabbage Cabbage, comprising several cultivars of '' Brassica oleracea'', is a leafy green, red (purple), or white (pale green) biennial plant grown as an annual vegetable crop for its dense-leaved heads. It is descended from the wild cabbage ( ''B.& ...

, and

maize Maize (; ''Zea mays''), also known as corn in North American English, is a tall stout grass that produces cereal grain. It was domesticated by indigenous peoples in southern Mexico about 9,000 years ago from wild teosinte. Native American ...

. ''Pythium myriotylum'' causes pre-emergence

damping off Damping off (or damping-off) is a horticultural disease or condition, caused by several different pathogens that kill or weaken seeds or seedlings before or after they germinate. It is most prevalent in wet and cool conditions. Symptoms There ar ...

, it infects the seed and causes it to rot before plant growth. This causes the plant seedling to become shriveled, soft, and brown. In a study done on soybeans, some symptoms that were seen were rotting of roots, diseased seedlings in the field, plus rotting and blight of seedlings. ''Pythium myriotylum'' can also cause post-emergence damping off in peanuts, resulting in discoloration of the seedlings and roots along with a water-soaked appearance in certain areas, these symptoms usually result in the death of the seedlings.

Disease cycle

''Pythium myriotylum'' causes disease through direct penetration of the host with appressoria. The oomycete helps invade and colonize the host by secreting cell wall degrading enzymes (CWDEs) this breaks down the plant

cell wall A cell wall is a structural layer that surrounds some Cell type, cell types, found immediately outside the cell membrane. It can be tough, flexible, and sometimes rigid. Primarily, it provides the cell with structural support, shape, protection, ...

. ''P. myriotylum'' has an asexual reproductive cycle that consists of

mycelium Mycelium (: mycelia) is a root-like structure of a fungus consisting of a mass of branching, thread-like hyphae. Its normal form is that of branched, slender, entangled, anastomosing, hyaline threads. Fungal colonies composed of mycelium are fo ...

that produce

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 ...

. These sporangia germinate by producing

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 with two

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 ...

that help with zoospore movement. The zoospores are released during wet conditions so that they can move through the soil to infect new hosts. It also has a sexual reproductive system where mating occurs between the

oogonium 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 large ...

and

antheridium An antheridium is a haploid structure or organ producing and containing male gametes (called ''antherozoids'' or sperm). The plural form is antheridia, and a structure containing one or more antheridia is called an androecium. The androecium is al ...

. This produces a thick-walled structure called an oospore. ''Pythium myriotylum'' has an overwintering stage through the oospore, also known as, the survival structure. This is the initial innoculum that germinates after its resting period. It is difficult to break the dormancy of ''P. myriotylum'' oospores.

Environment

''Pythium myriotylum'' is a soil-borne necrotrophic oomycete. A disease caused by ''Pythium myriotylum'' is increased in warm regions, or in summer months. It thrives in high humid conditions. It prefers wet soil conditions in places of low altitude because this is where the water will sit for long periods of time. In lower altitudes, it can also contaminate irrigation water supplies and spread rapidly to other crops, especially hydroponically grown crops.

References

{{Taxonbar, from=Q7263891 Water mould plant pathogens and diseases myriotylum Soybean diseases Oomycete species Protists described in 1930

Hosts and symptoms

Disease cycle

Environment

See also

References