Peer Review #2 of "The genome of the butternut canker pathogen, Ophiognomonia clavigignenti-juglandacearum shows an elevated number of genes associated with secondary metabolism and protection from host resistance responses (v0.1)"

Butternut canker, caused by the fungal pathogen Sirococcus clavigignenti-juglandacearum, is present throughout the range of butternut (Juglans cinerea) and is the primary cause for its decline. A quick and reliable method for identification of S. clavigignenti-juglandacearum would provide a valuable tool for the detection of the pathogen on propagative material to avoid spread, as well as assist studies targeted at the epidemiology of this pathogen, in particular the dissemination of the pathogen by seeds of the butternut. The objective of this study was to develop a diagnostic assay to detect S. clavigignenti-juglandacearum in butternut plant tissue. The primers were developed using an alignment of internal transcribed spacer (ITS) sequences from isolates of S. clavigignenti-juglandacearum and several closely related species. These primers were tested on J. cinerea, 48 isolates of S. clavigignenti-juglandacearum recovered from diseased trees, and 26 species of other fungi recovered from butternut tissue. The primers amplified a product from the DNA of all isolates of S. clavigignenti-juglandacearum, detected its DNA at a concentration as low as 1 pg/μl, and detected the pathogen at a concentration of 1 × 103 spore/ml. The primers developed in this study will be a valuable tool for the detection of S. clavigignenti-juglandacearum present on butternut seeds, and as a rapid diagnostic tool for early detection of the pathogen on butternut trees.

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Transcriptome Analysis of Aspergillus flavus RevealsveA-Dependent Regulation of Secondary Metabolite Gene Clusters, Including the Novel Aflavarin Cluster

Eukaryotic Cell ◽

10.1128/ec.00092-15 ◽

2015 ◽

Vol 14 (10) ◽

pp. 983-997 ◽

Cited By ~ 44

Author(s):

J. W. Cary ◽

Z. Han ◽

Y. Yin ◽

J. M. Lohmar ◽

S. Shantappa ◽

...

Keyword(s):

Secondary Metabolism ◽

Secondary Metabolite ◽

Aspergillus Flavus ◽

Gene Clusters ◽

Fungal Species ◽

The Novel ◽

Content Type ◽

Expression Of Genes ◽

Number Of Genes ◽

Fungal Secondary Metabolism

ABSTRACTThe global regulatoryveAgene governs development and secondary metabolism in numerous fungal species, includingAspergillus flavus. This is especially relevant sinceA. flavusinfects crops of agricultural importance worldwide, contaminating them with potent mycotoxins. The most well-known are aflatoxins, which are cytotoxic and carcinogenic polyketide compounds. The production of aflatoxins and the expression of genes implicated in the production of these mycotoxins areveAdependent. The genes responsible for the synthesis of aflatoxins are clustered, a signature common for genes involved in fungal secondary metabolism. Studies of theA. flavusgenome revealed many gene clusters possibly connected to the synthesis of secondary metabolites. Many of these metabolites are still unknown, or the association between a known metabolite and a particular gene cluster has not yet been established. In the present transcriptome study, we show thatveAis necessary for the expression of a large number of genes. Twenty-eight out of the predicted 56 secondary metabolite gene clusters include at least one gene that is differentially expressed depending on presence or absence ofveA. One of the clusters under the influence ofveAis cluster 39. The absence ofveAresults in a downregulation of the five genes found within this cluster. Interestingly, our results indicate that the cluster is expressed mainly in sclerotia. Chemical analysis of sclerotial extracts revealed that cluster 39 is responsible for the production of aflavarin.

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