Contributed by Edward Braun Dept. of Plant Pathology, Iowa State University Ames, IA firstname.lastname@example.org
Phytophthora sojae is an Oomycete which causes a serious root and stem rot of soybeans. The pathogen can survive for long periods in infected plant tissue or soil as sexual spores called oospores. Asexual reproduction results in the formation of ovoid sporangia that are produced in abundance on rotten root tissues when the soil is flooded. Motile spores called zoospores are formed within the sporangia. Sporangia formation and zoospore release can occur within a few hours in flooded soils. The zoospores lack cell walls and swim by means of two flagella of unequal length. The longer whiplash flagellum is directed forward and the shorter tinsel flagellum extends behind.
Following their release, the zoospores swim in a helical path. The zoospores of P. sojae are attracted by chemicals (the isoflavones daidzein and genistein) released by soybean roots and germinating seeds. Once the zoospores reach the soybean root they adhere to the surface, shed their flagella, and form a cell wall (encyst). The encysted zoospores then germinate and the hyphae penetrate into the root and begin rotting the tissue.
APS publication number: IW000025
Picture your photograph as the APS Featured
Click here to find out more
License to Copy. This
notice hereby grants permission to APS users to copy the image featured for
noncommercial, personal use. All components of APSnet are copyrighted and may
not be reproduced or distributed except by express permission of APS. Copyright
is not claimed for material provided by United States government employees as
part of their work. APS copyright extends to images, text, graphics,
photographs, illustrations, audio, video, computer software, and all other
elements of the site.Instructions to Copy. For PC, position your mouse
cursor on the featured image, click the right mouse button, and choose "Save
Picture As..." or "Save this Image as..." whichever is the case. For Mac, click
the only mouse button and follow the same steps. Users may want to set up a
specific directory and file naming scheme for storing images; otherwise, they
will be saved using your system defaults. Images may be used in any software
application that supports JPEG file format or viewed in an Internet browser as
Get ALL the Latest Updates for CHANGING LANDSCAPES OF PLANT PATHOLOGY. Follow APS!