scholarly journals A polyketide synthase gene cluster required for pathogenicity of Pseudocercospora fijiensis on banana

PLoS ONE ◽  
2021 ◽  
Vol 16 (10) ◽  
pp. e0258981
Author(s):  
Elizabeth Thomas ◽  
Roslyn D. Noar ◽  
Margaret E. Daub

Pseudocercospora fijiensis is the causal agent of the highly destructive black Sigatoka disease of banana. Previous research has focused on polyketide synthase gene clusters in the fungus, given the importance of polyketide pathways in related plant pathogenic fungi. A time course study of expression of the previously identified PKS7-1, PKS8-2, and PKS10-2 gene clusters showed high expression of all three PKS genes and the associated clustered genes in infected banana plants from 2 weeks post-inoculation through 9 weeks. Engineered transformants silenced for PKS8-2 and PKS10-2 were developed and tested for pathogenicity. Inoculation of banana plants with silencing transformants for PKS10-2 showed significant reduction in disease symptoms and severity that correlated with the degree of silencing in the conidia used for inoculation, supporting a critical role for PKS10-2 in disease development. Unlike PKS10-2, a clear role for PKS8-2 could not be determined. Two of four PKS8-2 silencing transformants showed reduced disease development, but disease did not correlate with the degree of PKS8-2 silencing in the transformants. Overall, the degree of silencing obtained for the PKS8-2 transformants was less than that obtained for the PKS10-2 transformants, which may have limited the utility of the silencing strategy to identify a role for PKS8-2 in disease. Orthologous PKS10-2 clusters had previously been identified in the related banana pathogens Pseudocercospora musae and Pseudocercospora eumusae. Genome analysis identified orthologous gene clusters to that of PKS10-2 in the newly sequenced genomes of Pseudocercospora fuligena and Pseudocercospora cruenta, pathogens of tomato and cowpea, respectively. Our results support an important role for the PKS10-2 polyketide pathway in pathogenicity of Pseudocercospora fijiensis, and suggest a possible role for this pathway in disease development by other Pseudocercospora species.

2007 ◽  
Vol 6 (7) ◽  
pp. 1210-1218 ◽  
Author(s):  
Daren W. Brown ◽  
Robert A. E. Butchko ◽  
Mark Busman ◽  
Robert H. Proctor

ABSTRACT Fumonisins are mycotoxins produced by some Fusarium species and can contaminate maize or maize products. Ingestion of fumonisins is associated with diseases, including cancer and neural tube defects, in humans and animals. In fungi, genes involved in the synthesis of mycotoxins and other secondary metabolites are often located adjacent to each other in gene clusters. Such genes can encode structural enzymes, regulatory proteins, and/or proteins that provide self-protection. The fumonisin biosynthetic gene cluster includes 16 genes, none of which appear to play a role in regulation. In this study, we identified a previously undescribed gene (FUM21) located adjacent to the fumonisin polyketide synthase gene, FUM1. The presence of a Zn(II)2Cys6 DNA-binding domain in the predicted protein suggested that FUM21 was involved in transcriptional regulation. FUM21 deletion (Δfum21) mutants produce little to no fumonisin in cracked maize cultures but some FUM1 and FUM8 transcripts in a liquid GYAM medium. Complementation of a Δfum21 mutant with a wild-type copy of the gene restored fumonisin production. Analysis of FUM21 cDNAs identified four alternative splice forms (ASFs), and microarray analysis indicated the ASFs were differentially expressed. Based on these data, we present a model for how FUM21 ASFs may regulate fumonisin biosynthesis.


2016 ◽  
Vol 69 (9) ◽  
pp. 712-718 ◽  
Author(s):  
Hisayuki Komaki ◽  
Natsuko Ichikawa ◽  
Tomohiko Tamura ◽  
Akio Oguchi ◽  
Moriyuki Hamada ◽  
...  

2006 ◽  
Vol 188 (11) ◽  
pp. 4024-4036 ◽  
Author(s):  
Xiao-Hua Chen ◽  
Joachim Vater ◽  
Jörn Piel ◽  
Peter Franke ◽  
Romy Scholz ◽  
...  

ABSTRACT Although bacterial polyketides are of considerable biomedical interest, the molecular biology of polyketide biosynthesis in Bacillus spp., one of the richest bacterial sources of bioactive natural products, remains largely unexplored. Here we assign for the first time complete polyketide synthase (PKS) gene clusters to Bacillus antibiotics. Three giant modular PKS systems of the trans-acyltransferase type were identified in Bacillus amyloliquefaciens FZB 42. One of them, pks1, is an ortholog of the pksX operon with a previously unknown function in the sequenced model strain Bacillus subtilis 168, while the pks2 and pks3 clusters are novel gene clusters. Cassette mutagenesis combined with advanced mass spectrometric techniques such as matrix-assisted laser desorption ionization-time of flight mass spectrometry and liquid chromatography-electrospray ionization mass spectrometry revealed that the pks1 (bae) and pks3 (dif) gene clusters encode the biosynthesis of the polyene antibiotics bacillaene and difficidin or oxydifficidin, respectively. In addition, B. subtilis OKB105 (pheA sfp 0), a transformant of the B. subtilis 168 derivative JH642, was shown to produce bacillaene, demonstrating that the pksX gene cluster directs the synthesis of that polyketide.


2011 ◽  
Vol 77 (19) ◽  
pp. 7031-7039 ◽  
Author(s):  
Jessica M. Koczan ◽  
Bryan R. Lenneman ◽  
Molly J. McGrath ◽  
George W. Sundin

ABSTRACTBiofilm formation plays a critical role in the pathogenesis ofErwinia amylovoraand the systemic invasion of plant hosts. The functional role of the exopolysaccharides amylovoran and levan in pathogenesis and biofilm formation has been evaluated. However, the role of biofilm formation, independent of exopolysaccharide production, in pathogenesis and movement within plants has not been studied previously. Evaluation of the role of attachment inE. amylovorabiofilm formation and virulence was examined through the analysis of deletion mutants lacking genes encoding structures postulated to function in attachment to surfaces or in cellular aggregation. The genes and gene clusters studied were selected based onin silicoanalyses. Microscopic analyses and quantitative assays demonstrated that attachment structures such as fimbriae and pili are involved in the attachment ofE. amylovorato surfaces and are necessary for the production of mature biofilms. A time course assay indicated that type I fimbriae function earlier in attachment, while type IV pilus structures appear to function later in attachment. Our results indicate that multiple attachment structures are needed for mature biofilm formation and full virulence and that biofilm formation facilitates entry and is necessary for the buildup of large populations ofE. amylovoracells in xylem tissue.


2012 ◽  
Vol 78 (23) ◽  
pp. 8234-8244 ◽  
Author(s):  
Jennifer Gerke ◽  
Özgür Bayram ◽  
Kirstin Feussner ◽  
Manuel Landesfeind ◽  
Ekaterina Shelest ◽  
...  

ABSTRACTThe genomes of filamentous fungi comprise numerous putative gene clusters coding for the biosynthesis of chemically and structurally diverse secondary metabolites (SMs), which are rarely expressed under laboratory conditions. Previous approaches to activate these genes were based primarily on artificially targeting the cellular protein synthesis apparatus. Here, we applied an alternative approach of genetically impairing the protein degradation apparatus of the model fungusAspergillus nidulansby deleting the conserved eukaryoticcsnE/CSN5deneddylase subunit of the COP9 signalosome. This defect in protein degradation results in the activation of a previously silenced gene cluster comprising a polyketide synthase gene producing the antibiotic 2,4-dihydroxy-3-methyl-6-(2-oxopropyl)benzaldehyde (DHMBA). ThecsnE/CSN5gene is highly conserved in fungi, and therefore, the deletion is a feasible approach for the identification of new SMs.


PLoS ONE ◽  
2019 ◽  
Vol 14 (7) ◽  
pp. e0220319
Author(s):  
Roslyn D. Noar ◽  
Elizabeth Thomas ◽  
De-Yu Xie ◽  
Morgan E. Carter ◽  
Dongming Ma ◽  
...  

2003 ◽  
Vol 66 (11) ◽  
pp. 2116-2122 ◽  
Author(s):  
WON-BO SHIM ◽  
JOSEPH E. FLAHERTY ◽  
CHARLES P. WOLOSHUK

Fusarium verticillioides produces a group of mycotoxins known as fumonisins in maize kernels. Fumonisins are associated with a variety of mycotoxicoses in humans and animals; thus, their presence in food is a considerable safety issue. This study addressed fumonisin B1 (FB1) production in two components of the maize kernel, namely the germ tissues and the degermed kernel. Growth of F. verticillioides was similar in colonized germ tissue and degermed kernels, but FB1 production was at least five times higher in degermed maize kernels than in germ tissue. Expression of the fumonisin polyketide synthase gene, FUM1, as measured by β-glucuronidase (GUS) and Northern blot analysis, followed the same pattern as FB1 production. Also correlated to FB1 was a concomitant drop in pH of the colonized degermed kernels. A time course experiment showed that degermed kernels inoculated with F. verticillioides became acidified over time (from pH 6.4 to 4.7 after 10 days of incubation), whereas colonized germ tissue became alkaline over the same period (from pH 6.5 to 8.5). Because conditions of acidic pH are conducive to FB1 production and alkaline pH is repressive, the observed correlation between the acidification of degermed kernels and the increase in FB1 provides one explanation for the observed differences in FB1 levels.


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