Ochratoxin A biosynthetic genes in Aspergillus ochraceus are differentially regulated by pH and nutritional stimuli

O’Callaghan, J.R.; Stapleton, Patricia; Dobson, Alan D. W.

doi:10.1016/j.fgb.2005.11.005

Cited by 76 publications

(54 citation statements)

References 59 publications

(60 reference statements)

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“…In A. nidulans, low pH is required for sterigmatocystin production, whereas an alkaline pH is required for penicillin production by the same fungus (Keller et al, 1997a;Shah et al, 1991). Low pH is also conducive to the production of fumonisin by Fusarium proliferatum (Keller et al, 1997b) and ochratoxin by Aspergillus ochraceus (O'Callaghan et al, 2006). The regulation of secondary metabolism by pH in filamentous fungi is mediated by the highly conserved global pH regulatory system that consists of the transcriptional regulator PacC and a signal cascade (components of which are encoded by palA, palB, palC, palF, palH and palI) to mediate the activity of PacC (reviewed by Peñalva et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Low pH regulates the production of deoxynivalenol by Fusarium graminearum

et al. 2009

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Fusarium graminearum, which causes the globally important head blight disease of wheat, is responsible for the production of the harmful mycotoxin deoxynivalenol (DON) in infected grain. The production of DON by F. graminearum occurs at much higher levels during infection than during axenic growth, and it is therefore important to understand how DON production is regulated in the fungus. Recently, we have identified amines as potent inducers of in vitro DON production in F. graminearum. Although amines strongly induced expression of the key DON biosynthesis gene TRI5 and DON production to levels equivalent to those observed during infection, the timing of this induction suggested that other factors are also likely to be important for the regulation of DON biosynthesis. Here we demonstrate that low extracellular pH both promotes and is required for DON production in F. graminearum. A combination of low pH and amines results in significantly enhanced expression of the TRI5 gene and increased DON production during axenic growth. A better understanding of DON production in F. graminearum would have implications in developing future toxin management strategies.

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Section: Introductionmentioning

confidence: 99%

Low pH regulates the production of deoxynivalenol by Fusarium graminearum

et al. 2009

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“…We did not identify any gene sequences previously substantiate to be involved in the biosynthetic pathway of OTA in A. westerdijkiae (= A. ochraceus) [3,6,13]. However among all of the ESTs here identified, three of them (EST4, EST5 and EST9) particularly attracted our attention.…”

Section: Resultsmentioning

confidence: 64%

“…Exhaustive studies on aflatoxin B 1 (AFB 1 ) biosynthesis revealed that six CYPs are involved [18]. As mentioned, it has also been suggested that two putative p450-type monooxygenase genes, p450-H11 and p450-B03, may be involved in OTA biosynthesis in A. ochraceus [6]. On the other hand, cytochrome P450 may be accumulated in response to mycotoxins because chemical detoxifications are important mechanisms to protect fungal cells against self-toxicity [19].…”

Section: Resultsmentioning

confidence: 99%

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Identification of Genes Differentially Expressed Between Ochratoxin-Producing and Non-Producing Strains of Aspergillus westerdijkiae

et al. 2013

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Approximately 70 % of Aspergillus westerdijkiae strains are able to produce ochratoxin A (OTA), a nephrotoxic and carcinogenic mycotoxin which have been found in cereal and food commodities. Despite of its importance there is, up to now, no information available about which genes are differentially expressed between A. westerdijkiae ochratoxin-producing and non-producing strains. Using cDNA RDA approach we successfully sequenced 231 raw ESTs expected to be enriched in the ochratoxin-producing strain. BLASTX searches against the public databases showed that of these, 205 ESTs (79 %) exhibited significant similarities with proteins of known functions, 28 ESTs (11 %) had matches to hypothetical proteins, and the remaining 27 ESTs (10 %) had no significant hits. EST alignment resulted in a total of 14 non-redundant consensus sequences. Three putative genes encoding oxidoreductases were validated as upexpressed in the OTA producer strain using RT-qPCR approach. The expression of the putative genes encoding a cytochrome P450 family protein, 3-hydroxyphenylacetate-6-hydroxylase, and endoplasmic reticulum oxidoreductin were higher (32-, 2.8-and 20-fold respectively) in the OTA producer strain compared to the non-producer strain.

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“…The values were normalized against the housekeeping gene glyceraldehyde-3-phosphate-dehydrogenase (G3PDH). The primers for amplification of cDNA for A. carbonarius G3PDH were g3pdh-bf (5'-TCGTCAACGGCAAGAAGATT) and g3pdh-br (5'-TAGCAAGGGGAGCAAGGCAGT), as described by O'Callaghan et al (2006b). The analysis of relative expression results in real time PCR was performed using the REST-MCS © software (www.gene-quantification.info) (Pfaffl et al, 2002).…”

Section: Rt-real Time Pcr Analysismentioning

confidence: 99%