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ARS Home » Pacific West Area » Logan, Utah » Poisonous Plant Research » Research » Publications at this Location » Publication #296784
Title: Production of the alkaloid swainsonine by a fungal endosymbiont of the ascomycete order Chaetothyriales in the host Ipomoea carnea.

Author
item Cook, Daniel
item BEAULIEU, W - Indiana University
item Mott, Ivan
item RIET-CORREA, F - Federal University Of Campina Grande
item Gardner, Dale
item Grum, Daniel
item Pfister, James
item CLAY, J - Indiana University
item MARCOLONGO-PEREIRA, C - Federal University Of Campina Grande

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/2/2013
Publication Date: 4/2/2013
Publication URL: https://handle.nal.usda.gov/10113/5491323
Citation: Cook, D., Beaulieu, W.T., Mott, I.W., Grum, D.S., Riet-Correa, F., Gardner, D.R., Pfister, J.A., Clay, J., Marcolongo-Pereira, C. 2013. Production of the alkaloid swainsonine by a fungal endosymbiont of the ascomycete order Chaetothyriales in the host Ipomoea carnea. Journal of Agricultural and Food Chemistry. 61: 3797-803.

Interpretive Summary: Some plant species within the Convolvulaceae (morning glory family) from South America, Africa, and Australia cause a neurologic disease in grazing livestock caused by swainsonine. These convolvulaceous species including Ipomoea carnea contain the the glycosidase inhibitors swainsonine and the calystegines. Swainsonine has been shown to be produced by a fungal endosymbiont in legumes of the Astragalus and Oxytropis genera, which causes a similar neurologic disease in grazing livestock called locoism. Here we demonstrate that I. carnea plants are infected with a fungal endosymbiont that was cultured from its seeds and which produced swainsonine in pure culture but not the calystegines. The same fungal endosymbiont was detected by PCR and by culturing in I. carnea plants containing swainsonine. The fungal endosymbiont belongs to the Ascomycete order Chaetothyriales. Plants derived from fungicide-treated seeds lacked swainsonine, but calystegines concentrations were unaltered. These results suggest that swainsonine is produced by a fungal endosymbiont while the calystegines are produced by the plant.

Technical Abstract: Some plant species within the Convolvulaceae (morning glory family) from South America, Africa, and Australia cause a neurologic disease in grazing livestock caused by swainsonine. These convolvulaceous species including Ipomoea carnea contain the indolizidine alkaloid swainsonine, an inhibitor of a-mannosidase and mannosidase II, and polyhydroxy nortropane alkaloids, the calystegines which are glycosidase inhibitors. Swainsonine has been shown to be produced by a fungal endosymbiont in legumes of the Astragalus and Oxytropis genera, which causes a similar neurologic disease in grazing livestock called locoism. Here we demonstrate that I. carnea plants are infected with a fungal endosymbiont that was cultured from its seeds and which produced swainsonine in pure culture but not the calystegines. The same fungal endosymbiont was detected by PCR and by culturing in I. carnea plants containing swainsonine. The fungal endosymbiont belongs to the Ascomycete order Chaetothyriales. Plants derived from fungicide-treated seeds lacked swainsonine, but calystegines concentrations were unaltered.