INVESTIGADORES
PIECKENSTAIN Fernando Luis
congresos y reuniones científicas
Título:
Inhibition of polyamine biosynthesis in the phytopathogenic fungus Sclerotinia sclerotiorum
Autor/es:
PIECKENSTAIN FL, A GARRIZ, E CHORNOMAZ, D SÁNCHEZ, OA RUIZ
Lugar:
Rimini, Italia
Reunión:
Conferencia; Polyamines 2000, II Europeaen Polyamine Conference; 2000
Resumen:
In many fungi, growth and developmental events are associated with changes in polyamine metabolism. In addition, inhibition of polyamine biosynthesis of phytopathogenic fungi can lead to the control of fungal plant diseases. Sclerotinia sclerotiorum is an important and widely distributed soil-borne plant pathogen highly destructive to many crops. In diseased tissues, mycelium aggregates to form sclerotia, which act as survival structures in soil and plant debris. Sclerotia can germinate carpogenically, producing ascospores with the potential to infect further crops. Germinating ascospores colonize dead or senescing tissues in the phyllosphere and the resulting mycelium invades adjacent living tissue and initiates disease. Sclerotia may also germinate myceliogenically, causing root rot and wilt of plants. We used inhibitors that act on different steps of polyamine biosynthesis to test the effect of perturbation of polyamine metabolism on growth and differentiation of S. sclerotiorum in vitro. The following compounds were used: DFMO and DAB (inhibitors of ODC), DFMA (inhibitor of ADC) and CHA (Inhibitor of Spd synthase). We evaluated their effect on mycelial growth, sclerotia formation, ascospore germination and the level of free polyamines. Spermidine was the most abundant polyamine in mycelium of control cultures. DFMO reduced Put and Spd levels, mycelial growth and sclerotia formation. CHA reduced Spd levels and caused an increase of putrescine levels. In these conditions, sclerotia formation decreased drastically, but mycelial growth was not affected at all. The inhibitors did not affect ascospore germination. The effect of DFMA was similar to that of DFMO. It can be concluded that spermidine biosynthesis is necessary for sclerotial development, while mycelial growth can be supported either by putrescine or spermidine. Inhibition caused by DFMA may be due to its conversion into DFMO as a consequence of arginase activity. Alternatively, this effect could be due to the presence of ADC activity. Current work is in progress in order to elucidate this point.