Global Aspects of pacC Regulation of Pathogenicity Genes inColletotrichum gloeosporioidesas Revealed by Transcriptome Analysis

Abstract

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.

Cloning and characterization of an endo--1,4-xylanase gene from Colletotrichum lindemuthianum and phylogenetic analysis of similar genes from phytopathogenic fungus

“…In the latter, alkalinization during fruit infection is necessary for the conversion of the biotrophic stage into the necrotrophic stage (Kramer-Haimovich et al, 2006). Also, ambient pH has been described as a regulatory factor related to the pathogenesis of S. sclerotiorum (Rollins and Dickman, 2001), C. gloesporoides (Alkan et al, 2013) and C. acutatum (You et al, 2007). Contrary to these findings, an effect of the pH on growth, expression of xyl1 gene and production of XYL activity by C. lindemuthianum was not observed, which is consistent with previous results on PNL activity (Hernández-Silva et al, 2007).…”

How Does Host Carbon Concentration Modulate the Lifestyle of Postharvest Pathogens during Colonization?

“…Thus, it is likely that fungi with different pH preferences contain an arsenal of both alkaline– and acid-regulated genes to exploit changing pH conditions. Alkan et al (2013) characterized alkaline– and acid-expressed genes. Those modulated genes encoded transporters, antioxidants and cell wall-degrading enzymes (CWDEs) (Alkan et al, 2013).…”

“…Alkan et al (2013) characterized alkaline– and acid-expressed genes. Those modulated genes encoded transporters, antioxidants and cell wall-degrading enzymes (CWDEs) (Alkan et al, 2013). Transporters, including those involved in sulfate, potassium, carboxylic acid, and ammonium transport, are likely to be controlled by pH due to the direct pH effect on the charge of inorganic or organic acid ions.…”

“…What is interesting to note is that gene families with members of similar functionality were both up- and downregulated by PacC (Alkan et al, 2013). This indicated that similar functions might occur under alkaline and acidic conditions, including CWDE activity.…”

Draft Genome Sequence of Colletotrichum sublineola , a Destructive Pathogen of Cultivated Sorghum

“…Based on BLAST searches ( e -value threshold of 1 e −3) of the extracellular proteins, 168 (9.23% of the secretome) do not have any sequence similarity to proteins in C. graminicola , and of those 168 proteins, 70 (3.85% of the secretome) do not have any sequence similarity to proteins in other Colletotrichum species (2, 9–11). However, only 60 secreted proteins are unique to C. sublineola when compared to the nr database with BLAST.…”