Subject(s)
Fungi/genetics , Fungi/pathogenicity , Phytophthora/genetics , Phytophthora/pathogenicity , Plant Diseases/microbiology , Algal Proteins/genetics , Amino Acid Sequence , Cluster Analysis , Codon/genetics , DNA, Algal/genetics , DNA, Complementary/genetics , DNA, Fungal/genetics , Evolution, Molecular , Expressed Sequence Tags , Fungi/metabolism , Gene Library , Lysine/biosynthesis , Molecular Sequence Data , Phylogeny , Phytophthora/metabolism , Polysaccharide-Lyases/genetics , Sequence Homology, Amino Acid , Species Specificity , Virulence/geneticsABSTRACT
Zoospores are a critical component of the disease cycles of most oomycete pathogens. To better understand this stage, genes induced during zoosporogenesis were identified from Phytophthora infestans, the potato late blight pathogen. Using cDNA arrays representing 2,600 genes expressed during zoosporogenesis, 69 genes showing >fourfold increases in mRNA levels were identified, of which 22 exhibited >100-fold induction. Included were putative protein kinases, transcription factors, ion channels, and other regulators. The expression of 15 genes was characterized in detail using zoosporogenesis time courses, other developmental stages, different temperature regimes, and tissue treated with signaling inhibitors. The latter were of interest because zoosporogenesis is known to be cold induced and inhibited by calcium channel blockers such as verapamil; moreover, in this study, inhibitors of phospholipase C (U-73122) and inositol trisphosphate receptor-gated calcium channels (2-aminoethoxydiphenyl borate) also were shown to block zoosporogenesis. The results indicated that the cytoplasmic and transcriptional changes occurring during zoosporogenesis are regulated by several pathways. For example, verapamil inhibited zoosporogenesis but not the up-regulation of most genes; the induction of some genes required while others were independent of calcium or phospholipid signaling; and, although most genes were induced in sporangia at 10 degrees C but not 24 degrees C, one was induced at both temperatures.
Subject(s)
Phytophthora/genetics , Signal Transduction/genetics , Spores, Fungal/genetics , Boron Compounds/pharmacology , Calcium Channel Blockers/pharmacology , DNA, Complementary/chemistry , DNA, Complementary/genetics , Estrenes/pharmacology , Gene Expression Regulation, Developmental/drug effects , Gene Expression Regulation, Fungal/drug effects , Molecular Sequence Data , Phytophthora/growth & development , Pyrrolidinones/pharmacology , Reproduction/drug effects , Reproduction/genetics , Sequence Analysis, DNA , Signal Transduction/drug effects , Spores, Fungal/drug effects , Spores, Fungal/growth & development , Temperature , Type C Phospholipases/antagonists & inhibitors , Verapamil/pharmacologyABSTRACT
We cloned and sequenced the cDNA and the gene encoding the catalytic subunit of protein phosphatase 1 from the filamentous fungus Neurospora crassa. The gene, designated ppp-1 (phosphoprotein phosphatase 1), was mapped by restriction fragment length polymorphism to linkage group III, in the vicinity of con-7 and trp-1. The expression of the gene was monitored by reverse transcriptase and polymerase chain reactions, by Western blotting, and by protein phosphatase activity assays in synchronized cultures. Transcripts of ppp-1 were detected in the dormant conidia. The abundance of ppp-1 mRNA, Ppp-1 protein, and the activity of protein phosphatase 1 increased during germination and subsequent hyphal elongation as well as during the early stages of aerial mycelium formation.
