Main content area

Gene expression profiling of the endophytic fungus Neotyphodium lolii in association with its host plant perennial ryegrass

Khan, Anar, Bassett, Shalome, Voisey, Christine, Gaborit, Charlotte, Johnson, Linda, Christensen, Mike, McCulloch, Alan, Bryan, Gregory, Johnson, Richard
Australasian plant pathology 2010 v.39 no.5 pp. 467-476
symbionts, protein transport, mammals, endophytes, intercellular spaces, perennials, Epichloe festucae var. lolii, gene expression, photosynthesis, gene expression regulation, virulence, grasses, Lolium perenne, host plants, models, suppression subtractive hybridization, protein synthesis, symbiosis, expressed sequence tags, fungi
Endophytes of the Neotyphodium/Epichloƫ complex are filamentous fungi that typically form mutualistic associations with temperate grasses. The endophytes systemically colonise the intercellular spaces of their grass hosts and confer several biotic and abiotic attributes, but can also cause mammalian toxicoses. These symbioses are therefore of significant agricultural importance, and furthermore, the symbioses represent models to understand how such symbioses are established and maintained. To gain a greater understanding of the Neotyphodium lolii-perennial ryegrass (Lolium perenne) symbiosis, we have generated, sequenced and analysed four in planta expressed sequence tag libraries, enriched for genes differentially expressed during symbiosis via suppression subtractive hybridisation. Subtracted libraries were largely comprised of perennial ryegrass sequences, and comparative functional profiling of endophyte-infected ryegrass libraries with endophyte-free ryegrass libraries revealed downregulation of carbohydrate metabolism and photosynthesis during symbiosis, the latter confirming observations made in previous studies. Functional categories upregulated in the plant host in association with endophyte infection included cellular protein transport and protein synthesis and turnover. We also identified 24 N. lolii transcripts expressed during symbiosis, some of which were homologous to demonstrated pathogenicity/virulence genes, and others with proven roles in endophyte secondary metabolism. This study offers insights into biological processes underlying the N. lolii-perennial ryegrass symbiosis, and provides a list of novel candidate genes from both symbionts, which will form the basis for future investigations.