Project description:Colletotrichum gloeosporioides, a widely distributed economically important agent in postharvest fruit disease thrives by massive secretion of ammonia to alkalize its environment and activate its pathogenicity genes. We sequenced the C. gloeosporioides transcriptomes of WT and a M-bM-^HM-^FpacC mutant, a major gene regulator under changing pH, under pH 7.0 in order to examine pacC regulation. Transcriptome analysis of the M-bM-^HM-^FpacC strain showed that 468 and 458 genes were up or down regulated, respectively. Both the up and down regulated genes were clustered into similar functions including: transporters to maintain cellular homeostasis, cell wall degrading enzymes to optimize pathogenicity and GATA-like transcription factors. Suggesting that activation of pacC under alkaline condition regulates genes expression to fit their optimal PKa. The transcript level predictions were verified by growth in different pH and fruit infection. Further analyses showed pacC binding sites were over-represented in the promoters of the pacC up-regulated genes but not in the promoters of the down-regulated genes, where instead, GATA-like binding sites were prominent. Evolutionary conservation of pacC control was sought by examining the gene orthologs in 5 fungal genomes whose members display contrasting alkaline or acidifying pathogenicity strategies. The results showed that irrespective of pathogen colonization strategy, only orthologs of up-regulated genes showed over-representation of pacC binding sites. Significantly, the down regulated orthologs revealed cross-genome over-representation of GATA transcription factor binding sites. Thus, pacC is a phylogenetically conserved fungal mechanism exerting dual pH control for maintaining homeostasis and pathogenicity in changing environments. Examination of C. gloeosporioides WT and a M-bM-^HM-^FpacC mutant grown under pH 7.0
Project description:Anthracnose disease is caused by Colletotrichum gloeosporioides, and is common in leaves of the tea plant Camellia sinensis. MicroRNAs (miRNAs) have been known as key modulators of gene expression in defense responses; however, the role of miRNAs in tea plant during defensive responses to C. gloeosporioides remains unexplored. Six miRNA sequencing data sets and two degradome data sets were generated from C. gloeosporioides-inoculated and control tea leaves. A total of 485 conserved and 761 novel miRNAs were identified. Of those, 239 known and 369 novel miRNAs exhibited significantly differential expression under C. gloeosporioides stress. 1134 and 596 mRNAs were identified as targets of 389 and 299 novel and conserved miRNAs by degradome analysis, respectively. The expression levels of twelve miRNAs and their targets were validated by quantitative real-time PCR. The predicted targets of five interesting miRNAs were further validated through 5'RLM-RACE. Furthermore, Gene Ontology and metabolism pathway analysis revealed that most of the target genes were involved in translation, carbohydrate metabolism and signal transduction pathways. This study enriches the resources of defense-responsive miRNAs and their targets in C. sinensis, and thus, provides novel insights into the miRNA-mediated regulatory mechanisms underlying immunity responses to biotic stress in tea plant.
