Robert Fluhr,1 and
1Department of Plant Sciences, Weizmann Institute of Science, Rehovot, 76100, Israel; 2Department of Postharvest Science of Fresh Produce, Agricultural Research Organization, the Volcani Center, Bet Dagan 50250, Israel; 3Fruit Tree Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou, 510640, China; 4Centro Hispanoluso de Investigaciones Agrarias (CIALE), Department of Microbiology and Genetics, University of Salamanca, Villamayor 37185, Spain; 5Genomic Unit, Plant Sciences Institute, Agricultural Research Organization, the Volcani Center, Bet Dagan 50250, Israel
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Accepted 13 July 2013.
Colletotrichum gloeosporioides alkalinizes its surroundings during colonization of host tissue. The transcription factor pacC is a regulator of pH-controlled genes and is essential for successful colonization. We present here the sequence assembly of the Colletotrichum fruit pathogen and use it to explore the global regulation of pathogenicity by ambient pH. The assembled genome size was 54 Mb, encoding 18,456 genes. Transcriptomes of the wild type and ΔpacC mutant were established by RNA-seq and explored for their global pH-dependent gene regulation. The analysis showed that pacC upregulates 478 genes and downregulates 483 genes, comprising 5% of the fungal genome, including transporters, antioxidants, and cell-wall-degrading enzymes. Interestingly, gene families with similar functionality are both up- and downregulated by pacC. Global analysis of secreted genes showed significant pacC activation of degradative enzymes at alkaline pH and during fruit infection. Select genes from alkalizing-type pathogen C. gloeosporioides and from acidifying-type pathogen Sclerotinia sclerotiorum were verified by quantitative reverse-transcription polymerase chain reaction analysis at different pH values. Knock out of several pacC-activated genes confirmed their involvement in pathogenic colonization of alkalinized surroundings. The results suggest a global regulation by pacC of key pathogenicity genes during pH change in alkalinizing and acidifying pathogens.
© 2013 The American Phytopathological Society