Characterization of the ABC transporter genes MgAtr1 and MgAtr2 from the wheat pathogen Mycosphaerella graminicola

ATP-binding cassette (ABC) transporters are membrane-bound transporters inv olved in various physiological processes. In this paper we describe the clo ning of the ABC transporter encoding genes MgAtr1 and MgAtr2 from the wheat pathogen Mycosphaerella graminicola (anamorph Septoria tritici). Both dedu ced proteins MgAtr1 and MgAtr2 are highly homologous to other fungal ABC tr ansporters, RT-PCR revealed that the MgAtr2 mRNA population consists of par tially and fully spliced transcripts, Putative substrates of ABC transporte rs, modulators of ABC transporter activity, and inducers of ABC transporter gene transcription were analyzed for their potential to induce expression of MgAtr1 and MgAtr2 in m. graminicola. The genes are differently upregulat ed by compounds such as the plant secondary metabolites eugenol and reserpi ne, Similar results are obtained for several antibiotics and the azole fung icides cyproconazole and imazalil, Moreover, a different expression pattern between yeast-like cells and mycelium of this dimorphic fungus was observe d. These results indicate that MgAtr1 and MgAtr2 play a role in protection of m, graminicola against natural toxic compounds and xenobiotics, A putati ve role in protection against plant defense compounds during pathogenesis i s suggested. (C) 2000 Academic Press.