The pH regulator PacC: a host‐dependent virulence factor in Botrytis cinerea

Abstract

The phytopathogenic fungus Botrytis cinerea is able to infect a wide variety of plants and plant tissues with differing chemical compositions. During its interaction with the host, this pathogen modulates its ambient pH by secreting acids or ammonia. In this work, we examined the Pal/Pac pathway, the fungal ambient pH-responsive signalling circuit, and investigated the role of the PacC transcription factor. Characterization of the BcpacC deletion mutant revealed an alteration of both fungal growth and virulence depending on the pH of the culture medium or of the host tissue. The pathogenicity of the mutant was altered on plants exhibiting a neutral pH and not on plants with acidic tissues. The capacity of the mutant to acidify its environment and, more particularly, to produce oxalic acid was affected, as was production of reactive oxygen species. Finally, proteomic profiling of the mutant secretome revealed significant changes in plant cell wall polysaccharides proteins and lipid degradation and oxidoreduction, highlighting the importance of BcPacC in the necrotrophic lifestyle of B. cinerea.

Botrytis cinerea differentially induces postharvest antioxidant responses in ‘Braeburn’ and ‘Golden Delicious’ apple fruit

“…Botrytis cinerea produces phytotoxic compounds, such as botrydial and botcinolides, as well as cell‐wall‐degrading enzymes . B. cinerea like other postharvest pathogens modulate the host pH environment during infection, and low pH is conducive to gray mold development . Botrytis cinerea secretes a number of organic acids, of which citric acid appears to play an important role in its interaction with host plant tissue .…”

“…Botrytis cinerea secretes a number of organic acids, of which citric acid appears to play an important role in its interaction with host plant tissue . Oxalic acid, another organic acid that is implicated in virulence in Sclerotinia sclerotiorum , a close relative to B. cinerea , does not appear to be involved in the gray mold‐apple interaction …”

“…40,41 B. cinerea like other postharvest pathogens modulate the host pH environment during infection, and low pH is conducive to gray mold development. 42,43 Botrytis cinerea secretes a number of organic acids, of which citric acid appears to play an important role in its interaction with host plant tissue. 44 Oxalic acid, another organic acid that is implicated in virulence in Sclerotinia sclerotiorum, a close relative to B. cinerea, does not appear to be involved in the gray mold-apple interaction.…”

“…44 Oxalic acid, another organic acid that is implicated in virulence in Sclerotinia sclerotiorum, a close relative to B. cinerea, does not appear to be involved in the gray mold-apple interaction. 43,44 Based on the current view of the strategy of B. cinerea to deal with ROS during pathogenesis, it is reasonable to suggest that the observed increase in antioxidant enzyme activity (SOD and APX) in the susceptible apple tissues were of apple origin. Particularly at the last time point, both host and pathogen would have attempted to maintain cellular redox homeostasis and they would therefore have tried to activate effective antioxidant systems.…”

The PAC-3 transcription factor critically regulates phenotype-associated genes in Neurospora crassa

“…Using mutant strains carrying the Δ pac-3 (or rim101 / pacC ) revealed that the PAC-3 transcription factor correlates with fungal traits beyond pH signaling, impacting fundamental biological processes, including cell morphology, hyphae growth, conidiation, and adaptation to the host or nutritional variances ( Ferreira-Nozawa et al , 2006 ; Mendes et al , 2012 ; O'Meara et al , 2014 ; Martins et al , 2018 , 2019 ; Rascle et al , 2018 ). In Neurospora crassa , the deletion of pac-3 and the pal cascade-associated genes, except for Δ pal-9 / palI, diminished aerial growth, reduced conidiation, and resulted in high production of melanin, in comparison with that in the wild-type strain ( Virgilio et al , 2016 ).…”