EFFECTS OF THE FUSARIUM SOLANI TOXIN DIHYDROFUSARUBIN ON TOBACCO LEAVES ANDSPINACH CHLOROPLASTS

Authors: ALBRECHT, ARND - UNIV OF MUNICH; SCHNEIDER, INGRID - UNIV OF MUNICH; Baker, Robert; NEMEC, STAN - RETIRED FROM USDA; ELSTNER, ERICH - UNIV OF MUNICH; OSSWALD, WOLFGANG - LM UNIV OF MUNICH

Submitted to: Journal of Plant Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/18/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Dihydrofusrubin is the primary phytotoxic naphthoquinone produced by the soil fungus Fusarium solani. When tested on tobacco leaves and spinach chloroplasts, this toxin caused a light dependent destruction of chlorophyll and production of reactive oxygen species within the chloroplast. This action is comparable to the mode of action of the commercial herbicide Paraquat.

Technical Abstract: The effects of the Fusarium solani toxin dihydrofusarubin on tobacco leaves and on spinach chloroplasts have been studied in comparison with the herbicide methylviologen. Toxin treatment of tobacco leaves and leaf discs resulted in a light dependent chlorophyll degradation and a simultaneous ethane production. Experiments with spinach chloroplasts showed that dihydrofusarubin interacted with the electron transport chain thus forming reactive oxygen species. Experiments with DCMU and DBMIB proved that superoxide was produced on photosystem I in a light dependent reaction. Furthermore we showed that NADPH formation was blocked by dihydrofusarubin. Inhibition started with 10 uM DHF, whereas about 80% inhibition of NADP+-reduction was achieved with 100 uM toxin. Simultaneously to the inhibition of NADPH- formation an increase in ATP- production was measured. Experiments with methylviologen proved that the effects of the Fusarium solani toxin dihydrofusarubin on chloroplasts were comparable with the effects of this herbicide. The significance of the dihydrofusarubin toxin for symptom development on citrus trees infected with Fusarium solani is discussed.