IDENTIFICATION OF GENES INDUCED IN ALKALOID PRODUCING CULTURES OF CLAVICEPS SP

In order to identify genes which are expressed during alkaloid synthes is in an axenic culture of Claviceps sp. (strain ATCC 26245), a cDNA l ibrary from a producing culture was differentially screened with cDNA from producing (cDNA+) and non-producing (cDNA-) cultures, respectivel y. Altogether, ten cDNA clones were obtained, the alkaloid-synthesis-c orrelated expression of which was confirmed by Northern analyses. Eval uation of their nucleotide and derived amino-acid sequences identified one gene unequivocally, coding for dimethylallyltryptophan-synthase ( DMAT-S), the initial enzyme of the specific alkaloid pathway. For two other genes significant homologies to known fungal genes were detected : one clone showed homology to the Neurospora crassa ccg1 gene, coding for a clock-regulated putative general stress protein; seven cDNA clo nes, derived from the same gene, which is highly expressed under these conditions, contained typical hydrophobin domains and long stretches of asparagine/glycine repeats (like QID3 from Trichoderma harzianum), thus probably representing a cell-wall constituent. These data show th at this is not only a successful approach to clone genes specific for the alkaloid-pathway of C. purpurea, but also of genes which might be involved in the differentiation of sclerotial hyphae, the prerequisite for alkaloid synthesis.