Differential Gene Expression During Conidiation in the Grape Powdery Mildew Pathogen, Erysiphe necator

• Published in: Phytopathology 2011-07, Vol.101 (7), p.839-846
• Main Authors: Wakefield, Laura, Gadoury, David M, Seem, Robert C, Milgroom, Michael G, Sun, Qi, Cadle-Davidson, Lance
• Format: Article
• Language: English
• Subjects: amplified fragment length polymorphism; Amplified Fragment Length Polymorphism Analysis; Ascomycota - genetics; Ascomycota - growth & development; Biological and medical sciences; cDNA libraries; complementary DNA; conidiation; DNA, Complementary - genetics; Erysiphe necator; Fundamental and applied biological sciences. Psychology; Fungal plant pathogens; fungi; G-proteins; gene expression regulation; Gene Expression Regulation, Fungal; Gene Library; genes; Genes, Fungal; grapes; importins; lifestyle; metabolism; Molecular Sequence Annotation; morphogenesis; pathogens; Phytopathology. Animal pests. Plant and forest protection; Plant Diseases - genetics; Plant Diseases - microbiology; powdery mildew; Reverse Transcriptase Polymerase Chain Reaction; RNA, Plant; sequence analysis; Sequence Analysis, DNA; Signal Transduction; Spores, Fungal - genetics; Spores, Fungal - growth & development; transcriptome; Uncinula necator; vegetative growth; Vitis - microbiology
• ISSN: 0031-949X; 1943-7684
• DOI: 10.1094/PHYTO-11-10-0295

Asexual sporulation (conidiation) is coordinately regulated in the grape powdery mildew pathogen Erysiphe necator but nothing is known about its genetic regulation. We hypothesized that genes required for conidiation in other fungi would be upregulated at conidiophore initiation or full conidiation (relative to preconidiation vegetative growth and development of mature ascocarps), and that the obligate biotrophic lifestyle of E. necator would necessitate some novel gene regulation. cDNA amplified fragment length polymorphism analysis with 45 selective primer combinations produced approximately equal to 1,600 transcript-derived fragments (TDFs), of which 620 (39%) showed differential expression. TDF sequences were annotated using BLAST analysis of GenBank and of a reference transcriptome for E. necator developed by 454-FLX pyrosequencing of a normalized cDNA library. One-fourth of the differentially expressed, annotated sequences had similarity to fungal genes of unknown function. The remaining genes had annotated function in metabolism, signaling, transcription, transport, and protein fate. As expected, a portion of orthologs known in other fungi to be involved in developmental regulation was upregulated immediately prior to or during conidiation; particularly noteworthy were several genes associated with the light-dependent VeA regulatory system, G-protein signaling (Pth11 and a kelch repeat), and nuclear transport (importin-beta and Ran). This work represents the first investigation into differential gene expression during morphogenesis in E. necator and identifies candidate genes and hypotheses for characterization in powdery mildews. Our results indicate that, although control of conidiation in powdery mildews may share some basic elements with established systems, there are significant points of divergence as well, perhaps due, in part, to the obligate biotrophic lifestyle of powdery mildews.