''Aphanomyces euteiches'' f.sp. ''pisi'' is a water mould, or oomycete, plant pathogen responsible for the disease Aphanomyces pea root rot. The species ''Aphanomyces euteiches'' can infect a variety of legumes. Symptoms of the disease can differ among hosts but generally include reduced root volume and function, leading to stunting and chlorotic foliage. ''Aphanomyces'' root rot is an important agricultural disease in the United States, Europe, Australia, New Zealand, and Japan. Management includes using resistant crop varieties and having good soil drainage, as well as testing soil for the pathogen to avoid infected fields.
== Hosts and symptoms ==
Hosts of ''Aphanomyces euteiches'' can be annuals or perennials in the legume family, including: pea (''Pisum sativum''), alfalfa (''Medicago sativa''), snap bean and red kidney bean (''Phaseolus vulgaris''), faba bean (''Vicia faba''), red clover (''Trifolium pratense''), and white clover (''Trifolium repens'').〔Hughes, Teresa J., and Craig R. Grau. 2007. Aphanomyces root rot or common root rot of legumes. The Plant Health Instructor.
http://www.apsnet.org/edcenter/intropp/lessons/fungi/Oomycetes/Pages/Aphanomyces.aspx〕〔Heyman, Frederik. 2008. Root Rot of Pea Caused by Aphanomyces euteiches. Doctoral thesis. Swedish University of Agricultural Sciences, Uppsala.
http://diss-epsilon.slu.se:8080/archive/00001652/01/Avhandling.pdf〕 In North America, genetically distinct populations of ''A. euteiches'' demonstrate host specificity, but such specificity has not been observed in Europe.
Because ''A. euteiches'' is a root-infecting pathogen, primary symptoms occur on roots and stem tissue below the soil line. Infected root often appear gray and water-soaked, eventually becoming soft and honey-brown or blackish-brown in appearance. Infection causes a reduction in root volume and function, including reduced nodulation, leading to decreased water and nutrient up-take, which lead to above-ground secondary symptoms. Symptoms in the above-ground plant tissue can include chlorosis of the cotyledons and necrosis of the epicotyls and/or hypocotyls, stunting, and wilting of foliage.〔〔 Some symptoms can differ among hosts. Infected plants and patterns of infection in the field often correspond to areas in the field with poor soil drainage, which can be the result of soil compaction, soil texture (high clay content), or excessive wetness due to irrigation or rainfall.〔 Symptoms are generally similar among infected legumes, however timing and pattern of disease can differ among hosts and between annuals and perennials. In both peas and beans, lesions tend to progress up the plant tissue, starting with the epicotyls and moving to the hypocotyls, eventually extending above the soil. Lesions on pea epicotyls turn black, eventually creating a pinched region above the cotyledons as the result of pinched tissue. Lesions on beans, on the other hand, have a characteristic water-soaked appearance, are grayish-green in color, and are firm to the touch. In alfalfa symptoms include chlorotic cotyledons which may eventually become necrotic.
Although the symptoms caused by ''A. euteiches'' can be difficult to distinguish from symptoms caused by other root-infecting plant pathogens (such as ''Pythium'', ''Rhizoctonia'', and ''Fusarium''), there are some distinct differences. ''Aphanomyces'' root rot rarely results in seed rot and/or pre-emergent damping-off. The characteristic lesions caused by the different pathogens also differ. ''Fusarium'' infection results in black or reddish vascular tissue, and ''Rhizoctonia'' infection results in sunken, cankerous lesions.〔
''A. euteiches'' exhibits no macroscopic signs, but oogonia and oospores can be seen in root tissue with a compound microscope.〔
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
■ウィキペディアで「Aphanomyces euteiches f.sp. pisi」の詳細全文を読む