The pH signalling transcription factor PacC modulate growth, development, stress response and pathogenicity of Trichothecium roseum

Abstract

pH is one of the important environmental factors that affect the growth, development and pathogenicity of postharvest pathogen. The transcription factor PacC dominates the pH signal pathway. PacC in Trichothecium roseum showed three typical conserved zinc finger domains and closest homology to Fusarium graminearum. T. roseum increased the environmental pH both in vitro and in vivo. Expression patterns of TrpacC under different pH showed that at increasing pH from 3 to 5, the wild-type (WT) strain induced the expression of TrPacC in parallel to increased fungal growth; however, TrPacC expression decline at higer pH than 5, while fungal growth continued to increase. Development of a ΔTrPacC mutant down-regulated the expression of TrbrlA, TrabaA and TrwetA, reduced sporulation and delayed spore germination, resulting in smaller spores and sparse hyphae. ΔTrPacC mutant was sensitive to ionic stress, oxidative stress and cell wall integrity stress compared to the WT strain, especially the ionic stress. In addition, ΔTrPacC mutant showed reduced pathogenicity to muskmelon and tomato fruits. Taken together, T. roseum is an alkalinizing fungus, and the acidic environment could induce TrPacC expression. TrPacC positively regulates fungal growth and development as well as pathogenicity showing effect on fungal response to different stresses.

Liamocin biosynthesis is induced by an autogenous host acid activation in Aureobasidium melanogenum

“…Under such acid environment, polygalacturonase secretion was enhanced and pectin in fruits was actively hydrolyzed and fruit decay occurred. Wang et al [13] also reported that at acidic environment (pH 4.0), expression the TrPacC gene encoding the same pH signaling transcriptional activator PacC in Trichothecium roseum was promoted. The tissue acidification is a significant factor in determining virulence of P. expansum.…”

“…The results were constant with those reported by Saur et al [6] and Wang et al [7] However, it has been reported that the acidic environment (pH 3.0) inhibits the growth of Trichothecium roseum. [13] Barad et al [35] also reported that the GOX2 gene responsible for glucose oxidase was highly expressed under alkaline conditions, leading to secretion of high level of gluconic acid and drop in pH in the medium. Under such acid environment, polygalacturonase secretion was enhanced and pectin in fruits was actively hydrolyzed and fruit decay occurred.…”

“…Wang et al. [ 13 ] also reported that at acidic environment (pH 4.0), expression the TrPacC gene encoding the same pH signaling transcriptional activator PacC in Trichothecium roseum was promoted. The tissue acidification is a significant factor in determining virulence of P. expansum .…”

“…[8] On contrast, in some fungi such as Penicillium spp., Trichothecium roseum and A. nidulans, the signaling pathway may be switched on by acidic pH (by producing gluconic acid, citric acid, oxalic acid and fumaric acid) via the transcription factor PacC. [11][12][13][14] For example, PacC activates expression of the gene encoding acid phosphatase expressed under acidic growth conditions and the PACC gene is itself an alkaline expressed gene subject to autogenous regulation. [15] Unfortunately, the detailed mechanism for acid-expression mediated by PacC is still completely unknown.…”

Biocontrol action of Trichothecium roseum against the wheat powdery mildew fungus Blumeria graminis f. sp. tritici

“…Previously, the transformation of T. roseum with fluorescent proteins was based on the PEG-mediated protoplast transformation method (Dai et al, 2019(Dai et al, , 2020Wang et al, 2022). Agrobacterium tumefaciens-mediated transformation (ATMT) methods were repeatedly utilized for transfer GFP into biocontrol agents to reveal the interactions between parasites and powdery mildews (Németh et al, 2019).…”