''Pythium myriotylum'' is a soil-borne

oomycete Oomycota forms a distinct phylogenetic lineage of fungus-like eukaryotic microorganisms, called oomycetes (). They are filamentous and heterotrophic, and can reproduce both sexually and asexually. Sexual reproduction of an oospore is the resul ...

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), pindar (US) or monkey nut (UK), is a legume crop grown mainly for its edible Seed, seeds. It is widely grown in the tropics and subtropics, important to both small ...

tomato The tomato is the edible berry of the plant ''Solanum lycopersicum'', commonly known as the tomato plant. The species originated in western South America, Mexico, and Central America. The Mexican Nahuatl word gave rise to the Spanish word , ...

rye Rye (''Secale cereale'') is a grass grown extensively as a grain, a cover crop and a forage crop. It is a member of the wheat tribe (Triticeae) and is closely related to both wheat (''Triticum'') and barley (genus ''Hordeum''). Rye grain is u ...

wheat Wheat is a grass widely cultivated for its seed, a cereal grain that is a worldwide staple food. The many species of wheat together make up the genus ''Triticum'' ; the most widely grown is common wheat (''T. aestivum''). The archaeolog ...

oat The oat (''Avena sativa''), sometimes called the common oat, is a species of cereal grain grown for its seed, which is known by the same name (usually in the plural, unlike other cereals and pseudocereals). While oats are suitable for human co ...

cucumber Cucumber (''Cucumis sativus'') is a widely-cultivated creeping vine plant in the Cucurbitaceae family that bears usually cylindrical 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, which has numerous uses. Traditional unfermented food uses of soybeans include soy milk, from which tofu ...

sorghum ''Sorghum'' () is a genus of about 25 species of flowering plants in the grass family ( Poaceae). Some of these species are grown as cereals for human consumption and some in pastures for animals. One species is grown for grain, while many ot ...

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 ch ...

, cabbage, and

maize Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn ( North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. ...

. ''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 a ...

, 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 surrounding some types of cells, just outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with both structural support and protection, and also acts as a filtering mec ...

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

mycelium Mycelium (plural mycelia) is a root-like structure of a fungus consisting of a mass of branching, thread-like hyphae. Fungal colonies composed of mycelium are found in and on soil and many other substrates. A typical single spore germinates in ...

that produce

sporangia A sporangium (; from Late Latin, ) is an enclosure in which spores are formed. It can be composed of a single cell or can be multicellular. Virtually all plants, fungi, and many other lineages form sporangia at some point in their life cyc ...

. These sporangia germinate by producing

zoospore A zoospore is a motile asexual spore that uses a flagellum for locomotion. Also called a swarm spore, these spores are created by some protists, bacteria, and fungi to propagate themselves. Diversity Flagella types Zoospores may possess one or m ...

s with two

flagella A flagellum (; ) is a hairlike appendage that protrudes from certain plant and animal sperm cells, and from a wide range of microorganisms to provide motility. Many protists with flagella are termed as flagellates. A microorganism may have f ...

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 (plural 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 larg ...

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. Androecium is also ...

. This produces a thick-walled structure called an

oospore An oospore is a thick-walled sexual spore that develops from a fertilized oosphere in some algae, fungi, and oomycetes. They are believed to have evolved either through the Somatic fusion, fusion of two species or the chemically-induced stimulat ...

. ''Pythium myriotylum'' has an over-wintering 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

External links

{{Taxonbar, from=Q7263891 Water mould plant pathogens and diseases myriotylum Soybean diseases

Hosts and symptoms

Disease cycle

Environment

See also

References

External links