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:Walnut anthracnose caused by Colletotrichum gloeosporioides (Penz.) Penz. and Sacc. is a major disease affecting walnut production in China. Although the long non-coding RNAs (lncRNAs) are important for plant disease resistance , the molecular mechanisms underlying resistance to C. gloeosporioides in walnut remain poorly understood.The anthracnose-resistant F26 fruits from the B26 clone and the anthracnose susceptible F423 fruits from the 4-23 clone of walnut were used as the test materials. Specifically, we performed a comparative transcriptome analysis of F26 fruit bracts and F423 to identify differentially expressed LncRNAs (DELs) at five time-points (tissues at 0 hpi, pathological tissues at 24 hpi, 48 hpi, 72 hpi, and distal uninoculated tissues at 120 hpi). Compared with F423, a total of 14525 DELs were identified, including 10645 upregulated lncRNAs and 3846 downregulated lncRNAs in F26. The number of upregulated lncRNAs in F26 compared to in F423 was significantly higher at the early stages of C. gloeosporioides infection. A total of 5 modules related to disease resistance were screened by WGCNA and the target genes of lncRNAs were obtained. Bioinformatic analysis showed that the target genes of upregulated lncRNAs were enriched in immune-related processes during the infection of C. gloeosporioides , such as activation of innate immune response, defense response to bacterium, incompatible interaction and immune system process, and enriched in plant hormone signal transduction, phenylpropanoid biosynthesis and other pathways. And 124 known target genes for 96 hub lncRNAs were predicted, including 10 known resistance genes. The expression of 5 lncRNAs and 5 target genes was confirmed by qPCR, which was consistent with the RNA-seq data.The results of this study provide the basis for future functional characterizations of lncRNAs regarding the C. gloeosporioides resistance of walnut fruit bracts.