''Sarocladium oryzae'' (Sawada) is a plant pathogen causing the sheath rot disease of

rice Rice is the seed of the grass species ''Oryza sativa'' (Asian rice) or less commonly ''Oryza glaberrima ''Oryza glaberrima'', commonly known as African rice, is one of the two domesticated rice species. It was first domesticated and grown i ...

and

bamboo Bamboos are a diverse group of evergreen perennial flowering plants making up the subfamily Bambusoideae of the grass family Poaceae. Giant bamboos are the largest members of the grass family. The origin of the word "bamboo" is uncertain, bu ...

blight in

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an area ...

Taxonomy and morphology

''Sarocladium oryzae'' has irregularly penicillate conidiophores and slimy, 1-celled

conidia A conidium ( ; ), sometimes termed an asexual chlamydospore or chlamydoconidium (), is an asexual, non-motile spore of a fungus. The word ''conidium'' comes from the Ancient Greek word for dust, ('). They are also called mitospores due to the ...

. ''Sarocladium oryzae'' was previously known as ''Acrocylindrium oryzae''. For forty years prior to 2005, the industrial strain used to manufacture the antibiotic

cerulenin Cerulenin is an antifungal antibiotic that inhibits fatty acid and steroid biosynthesis. It was the first natural product antibiotic known to inhibit lipid synthesis. In fatty acid synthesis, it has been reported to bind in equimolar ratio to b- ...

was known under the invalidly published name "''

Cephalosporium ''Acremonium'' is a genus of fungi in the family Hypocreaceae. It used to be known as ''Cephalosporium''. Description ''Acremonium'' species are usually slow-growing and are initially compact and moist. Their hyphae are fine and hyaline, and p ...

caerulens''", but a subculture of the original ''C. caerulens'' strain KF-140 was subsequently shown to be conspecific with ''S. oryzae''.

Physiology and metabolites

axenic In biology, axenic (, ) describes the state of a culture in which only a single species, variety, or strain of organism is present and entirely free of all other contaminating organisms. The earliest axenic cultures were of bacteria or unicellul ...

culture, ''S. oryzae'' produces 0.3–0.627 micrograms of helvolic acid and 0.9–4.8 micrograms of

per milliliter of culture medium. The level of helvolic acid correlated with a higher incidence of sheath rot disease. Rice grains from infected plants were found to contain 2.2 micrograms helvolic acid and 1.75 micrograms of cerulein per gram of infected seeds, which induce chlorosis and reduce the seed viability and seedling health.

Plant disease symptoms

The disease is found in rice plants usually injured by insects or other diseases. Hot () and humid (wet) weather favour the disease. It is also associated with virus-infected plants. Early symptoms are oblong to irregular spots, with gray centers and brown margins. Spots or rotting occur on the leaf sheath that encloses the young panicles. There is discoloration in the sheath. In severe infection, all or part of the young panicles do not emerge and remain within the sheath. Unemerged panicles will soon rot and produce powdery fungus growth inside the leaf sheath. Infection occurs on the uppermost leaf sheath at all stages, but is most damaging when it occurs at late booting stage.

Management

Partners of the CABI-led programme,

Plantwise CABI (legally CAB International, formerly Commonwealth Agricultural Bureaux) is a nonprofit intergovernmental development and information organisation focusing primarily on agricultural and environmental issues in the developing world, and the c ...

including the

General Directorate of Agriculture in Cambodia A general officer is an officer of high rank in the armies, and in some nations' air forces, space forces, and marines or naval infantry. In some usages the term "general officer" refers to a rank above colonel."general, adj. and n.". OED O ...

have suggested reducing the density of planted crops to and removing infected stubble and weeds from the field. They also recommend application of fertilisers including potassium, calcium sulphate and

zinc sulphate Zinc sulfate is an inorganic compound. It is used as a dietary supplement to treat zinc deficiency and to prevent the condition in those at high risk. Side effects of excess supplementation may include abdominal pain, vomiting, headache, and ...

during the tillering stage to strengthen the stem and leaf tissues. The

Bureau of Rice Research and Development Bureau ( ) may refer to: Agencies and organizations * Government agency *Public administration * News bureau, an office for gathering or distributing news, generally for a given geographical location * Bureau (European Parliament), the administra ...

, Rice Department, of Thailand recommends using disease-free seeds and plants, avoiding monocropping with any one variety of rice (planting at least two varieties in the same field), and regular monitoring of fields.

Sources

References

External links

*
USDA ARS Fungal Database
* Rice Diseases in Mississippi: A Guide to Identification] (includes photo of sheath rot) Fungal plant pathogens and diseases Rice diseases Ascomycota enigmatic taxa {{plant-disease-stub