A Blumeria graminis gene family encoding proteins with a C-terminal variable region with homologues in pathogenic fungi

Abstract

In a study aimed at characterising, at the molecular level, the obligate biotrophic fungus Blumeria graminis f. sp. hordei ( Bgh), we have identified a novel group of genes, the Egh16H genes, and shown that two of these are up-regulated during primary infection of barley leaves. The genes have partial homology to a previously characterised Bgh gene family, Egh16. Egh16 and Egh16H are subfamilies of a larger multigene family with presently about 15 members identified in Bgh. Egh16H has about ten members, and we show that five of these are expressed as highly conserved mRNAs that are predicted to encode proteins with a C-terminal variable region. Egh16H has high homology to sequences in Magnaporthe grisea and other plant pathogenic fungi, as well as sequences of both the insect pathogen Metarhizium anisopliae and the human pathogen Aspergillus fumigatus. No close homologues of Egh16H were found in the non-pathogenic fungi Neurospora crassa and Aspergillus nidulans. We predict that Egh16H plays a general role in the interaction between pathogenic fungi and their hosts. At present, the large number of gene family members with C-terminal variation appears to be unique for Bgh, and the Egh16/ Egh16H gene family is to our knowledge the largest gene family so far characterised in this fungus.