Characterization of the complete mitochondrial genome of Cercospora nicotianae (Ellis & Everh, 1893) (Dothideomycetes: Capnodiales)
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ABSTRACT:
SUBMITTER: Lu N
PROVIDER: S-EPMC8725932 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:The photoactivated toxin, cercosporin, produced by Cercospora species, plays an important role in pathogenesis of this fungus to host plants. Cercosporin has almost universal toxicity to cells due to its production of reactive oxygen species including singlet oxygen. For that reason, Cercospora species, which are highly resistant to their own toxin, are good candidates to identify genes for resistance to cercosporin and to the reactive oxygen species it produces. In previous research, the zinc cluster transcription factor CRG1 (cercosporin resistance gene 1) was found to be crucial for Cercospora species' resistance against cercosporin, and subtractive hybridization analysis identified 185 genes differentially expressed between Cercospora nicotianae wild type (wt) and a crg1 mutant. The focus of this work was to identify and characterize the hypothetical proteins that were identified in the Cercospora nicotianae subtractive library as potential resistance factors. Quantitative RT-PCR analysis of the 20 genes encoding hypothetical proteins showed that two, 24cF and 71cR, were induced under conditions of cercosporin toxicity, suggesting a role in resistance. Transformation and expression of 24cF and 71cR in the cercosporin-sensitive fungus, Neurospora crassa, showed that 71cR provided increased resistance to cercosporin toxicity, whereas no significant increase was observed in 24cF transformants. Gene disruption was used to generate C. nicotianae 71cR mutants; these mutants did not differ from wt C. nicotianae in cercosporin resistance or production. Quantitative RT-PCR analysis showed induction of other resistance genes in the 71cR mutant that may compensate for the loss of 71cR. Analysis of 71cR conserved domains and secondary and tertiary structure identify the protein as having an NTF2-like superfamily DUF1348 domain with unknown function, to be intracellular and localized in the cytosol, and to have similarities to proteins in the steroid delta-isomerase family.
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Project description:Abstract In the present study, the complete mitochondrial genome of Pycanum ochraceum was identified for the first time. The entire genome is 17,198 bp in length with 73.6% A + T content. It contains 22 transfer RNA genes (tRNAs), 2 ribosomal RNA genes (rRNAs), 13 protein-coding genes (PCGs) and 1 noncoding control region (D-loop). Phylogenetic analysis showed that Tessaratomidae bugs are monophyletic. This study can provide essential DNA molecular data for further phylogenetic and evolutionary analysis for Heteroptera.
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Project description:We have cloned and sequenced the Cercospora nicotianae gene for the carotenoid biosynthetic enzyme phytoene dehydrogenase. Analysis of the derived amino acid sequence revealed it has greater than 50% identity with its counterpart in Neurospora crassa and approximately 30% identity with prokaryotic phytoene dehydrogenases and is related, but more distantly, to phytoene dehydrogenases from plants and cyanobacteria. Our analysis confirms that phytoene dehydrogenase proteins fall into two groups: those from plants and cyanobacteria and those from eukaryotic and noncyanobacter prokaryotic microbes. Southern analysis indicated that the C. nicotianae phytoene dehydrogenase gene is present in a single copy. Extraction of beta-carotene, the sole carotenoid accumulated by C. nicotianae, showed that both light- and dark-grown cultures synthesize carotenoids, but higher levels accumulate in the light. Northern (RNA) analysis of poly(A)+ RNA, however, showed no differential accumulation of phytoene dehydrogenase mRNA between light- and dark-grown fungal cultures.
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Project description:Corynespora cassiicola is a well-known plant pathogen with a broad host range and diverse lifestyles. In this study, we presented the complete mitochondrial genome (mitogenome) of C. cassiicola for the first time. It has a total length of 40,752 bp, which encodes 17 protein-coding genes (PCGs), 2 ribosomal RNA genes (rRNA), and 27 transfer RNA (tRNA) genes. The nucleotide composition of the mitogenome is: A (36.24%), T (34.62%), G (15.74%), and C (13.39%). Phylogenetic analysis revealed that C. cassiicola has a close relationship with Didymella pinodes from Didymellaceae.
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Project description:Perylenequinones are a class of photoactivated polyketide mycotoxins produced by fungal plant pathogens that notably produce reactive oxygen species with visible light. The best-studied perylenequinone is cercosporin-a product of the Cercospora species. While the cercosporin biosynthetic gene cluster has been described in the tobacco pathogen Cercospora nicotianae, little is known of the metabolite's biosynthesis. Furthermore, in vitro investigations of the polyketide synthase central to cercosporin biosynthesis identified the naphthopyrone nor-toralactone as its direct product-an observation in conflict with published biosynthetic proposals. Here, we present an alternative biosynthetic pathway to cercosporin based on metabolites characterized from a series of biosynthetic gene knockouts. We show that nor-toralactone is the key polyketide intermediate and the substrate for the unusual didomain protein CTB3. We demonstrate the unique oxidative cleavage activity of the CTB3 monooxygenase domain in vitro. These data advance our understanding of perylenequinone biosynthesis and expand the biochemical repertoire of flavin-dependent monooxygenases.
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Project description:Phytophthora nicotianae is one of the most destructive plant pathogens affecting a variety of plants, causing black shank of tobacco, among several other devastating diseases. Herein, we assembled the mitochondrial genome of P. nicotianae and analyzed its gene content and genome structure, performed comparative mitochondrial genomics analysis, and assessed phylogenetic relationships among oomycetes species. The circular mitogenome is 37,561 bp long, with 38 protein-coding genes, 25 transfer RNA (tRNA) genes, and 2 ribosomal RNA genes (rrnl and rrns). The mitochondrial genome showed a biased A/T usage versus G/C. The overall gene content and size of the P. nicotianae mitogenome are identical to those of other published Phytophthora mitogenomes. Interestingly, collinearity analysis using an existing ?10 k inversion region (including 11 genes and 8 tRNAs) revealed that Phytophthora andina, Phytophthora infestans, Phytophthora mirabilis, Phytophthora ipomoeae, and Phytophthora phaseoli differed from Phytophthora nicotianae, Phytophthora sojae, Phytophthora ramorum, and Phytophthora polonica. Moreover, inverted repeat regions were found to be absent among species of the Peronosporales when compared with species from the Pythiales and Saprolegniales. A phylogenomic investigation based on 29 protein-coding genes demonstrated that Phytophthora is monophyletic, and placed P. nicotianae close to the clade including P. mirabilis, P. ipomoeae, P. andina, P. infestans, and P. phaseoli. Furthermore, we discovered six new candidate DNA molecular markers (rpl6, atp8, nad11, rps2, rps3, and rps4) based on these mitogenomes that would be suitable for species identification in the oomycetes, which have the same identification level as the whole mitogenome and ribosomal DNA sequences. These new molecular markers can not only provide a quick preview of the species without mitogenome information, but will also help to gain better understanding of the oomycetes pathogens and developing treatment or monitoring strategies.
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Project description:In this study, the whole mitochondrial genome of the Purple Spot Mantis Shrimp Gonodactylus smithii from the South China Sea was determined using next-generation sequencing. The circular mitogenome of G. smithii is 16,260 bp long and consists of 13 protein-coding genes (PCGs), 22 tRNA genes, and two rRNA genes. The base composition is AT-rich and has an overall AT content of 67.76% (composition of A, G, T, and C was 35.30%, 12.41%, 32.46%, and 19.83%, respectively). Among 13 PCGs, 12 PCGs shared a common ATN as the start codon except COX1 gene using an abnormal putative first codon GCG. 11 PCGs ended with TAA or TAG, while ND6, COX2 gene terminated with a single T and ND3 gene used a special "GAT" as the stop codon. The phylogenetic tree showed that G. smithii was clustered with Gonodactylus chiragra, then together with Gonodactylaceus randalli.
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Project description:The mitochondrial genome has been widely used in the study of phylogeny and species-level evolution. Here, we sequenced and analyzed the full mitogenome of Tetrastichus howardi, an important natural enemy of many lepidopteran pests. The complete mitochondrial genome has 14,791 nucleotides, containing 13 protein-coding genes (PCGs), 2 ribosomal RNA genes (rRNAs), 22 transfer RNA genes (tRNAs), and a partial control region. All the 13 PCGs started with typical ATN (ATA, ATG, and ATT) codon. Among 13 PCGs, nine genes terminated with the stop codon TAA and four genes terminated with T. Our study provides information on comparative mitogenomics of Eulophidae.
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Project description:Fungi in the genus Cercospora cause crop losses world-wide on many crop species. The wide host range and success of these pathogens has been attributed to the production of a photoactivated toxin, cercosporin. We engineered tobacco for resistance to Cercospora nicotianae utilizing two strategies: 1) transformation with cercosporin autoresistance genes isolated from the fungus, and 2) transformation with constructs to silence the production of cercosporin during disease development. Three C. nicotianae cercosporin autoresistance genes were tested: ATR1 and CFP, encoding an ABC and an MFS transporter, respectively, and 71cR, which encodes a hypothetical protein. Resistance to the pathogen was identified in transgenic lines expressing ATR1 and 71cR, but not in lines transformed with CFP. Silencing of the CTB1 polyketide synthase and to a lesser extent the CTB8 pathway regulator in the cercosporin biosynthetic pathway also led to the recovery of resistant lines. All lines tested expressed the transgenes, and a direct correlation between the level of transgene expression and disease resistance was not identified in any line. Resistance was also not correlated with the degree of silencing in the CTB1 and CTB8 silenced lines. We conclude that expression of fungal cercosporin autoresistance genes as well as silencing of the cercosporin pathway are both effective strategies for engineering resistance to Cercospora diseases where cercosporin plays a critical role.
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