Résumé
In this study, we analyzed the physical interactions of the dominant negative isoform of MoYpt7. Our results show that MoYpt7 interacts with MoGdi1. The dominant negative isoform of MoYpt7 (dominant negative isoform, N125I) is essential for colony morphology, conidiation, and pathogenicity in the rice blast fungus. These results further demonstrate the biological functions of MoYpt7 in Magnaporthe oryzae.
Sujets)
Analyse de mutations d'ADN , Protéines fongiques/métabolisme , Régulation de l'expression des gènes fongiques , Gènes fongiques , Protéines à fluorescence verte/métabolisme , Magnaporthe/génétique , Microscopie de fluorescence , Mutation , Oryza/microbiologie , Phénotype , Maladies des plantes/microbiologie , Isoformes de protéinesRésumé
Fallen leaves of Ficus altissima, F. virens, F. benjamina, F. fistulosa and F. semicordata, were collected in Chiang Mai Province in northern Thailand and examined for fungi. Eighty taxa were identified, comprising 56 anamorphic taxa, 23 ascomycetes and 1 basidiomycete. Common fungal species occurring on five host species with high frequency of occurrence were Beltraniella nilgirica, Lasiodiplodia theobromae, Ophioceras leptosporum, Periconia byssoides and Septonema harknessi. Colletotrichum and Stachybotrys were also common genera. The leaves of different Ficus species supported diverse fungal taxa, and the fungal assemblages on the different hosts showed varying overlap. The fungal diversity of saprobes at the host species level is discussed.
Sujets)
Ascomycota , Basidiomycota , Écosystème , Ficus , Microbiologie , Champignons , Classification , Deuteromycota , Feuilles de plante , Microbiologie , Spécificité d'espèce , ThaïlandeRésumé
Appressorium formation is an important event in establishing a successful interaction between the rice blast fungus, Magnaporthe oryzae, and its host plant, rice. An understanding of molecular events occurring in appressorium differentiation will give new strategies to control rice blast. A quick and reliable method to extract total RNA from appressorium is essential for studying gene expression during appressorium formation and its mechanism. We found that duplicate film is an efficient substratum for appressorium formation, even when inoculated with high density conidia. When inoculated with conidia at 1x10(6) ml(-1), the percentages of conidium germination and appressorium formation were (97.98+/-0.67)% and (97.88+/-0.45)%, respectively. We applied Trizol before appressorium collection for total RNA isolation, and as much as 113.6 microg total RNA was isolated from the mature appressoria at 24 h after inoculation. Functional analysis of two genes, MNH6 and MgATG1, isolated from the cDNA subtractive library, revealed that the quantity of RNA was good enough to construct a cDNA (complementary DNA) library or a cDNA subtractive library. This method may be also applicable for the appressorium RNA isolation of other pathogenic fungi in which conidia differentiate into appressoria in the early stages of host infection.
Sujets)
ADN complémentaire , Génétique , ADN fongique , Génétique , Banque de gènes , Gènes fongiques , Magnaporthe , Génétique , Virulence , Oryza , Microbiologie , Maladies des plantes , Microbiologie , ARN fongique , GénétiqueRésumé
The peroxisomal matrix proteins involved in many important biological metabolism pathways in eukaryotic cells are encoded by nucleal genes, synthesized in the cytoplasm and then transported into the organelles. Targeting and import of these proteins depend on their two peroxisomal targeting signals (PTS1 and PTS2) in sequence as we have known so far. The vectors of the fluorescent fusions with PTS, i.e., green fluorescence protein (GFP)-PTS1, GFP-PTS2 and red fluorescence protein (RFP)-PTS1, were constructed and introduced into Magnaporthe oryzae Guy11 cells. Transformants containing these fusions emitted fluorescence in a punctate pattern, and the locations of the red and green fluorescence overlapped exactly in RFP-PTS1 and GFP-PTS2 co-transformed strains. These data indicated that both PTS1 and PTS2 fusions were imported into peroxisomes. A probable higher efficiency of PTS1 machinery was revealed by comparing the fluorescence backgrounds in GFP-PTS1 and GFP-PTS2 transformants. By introducing both RFP-PTS1 and GFP-PTS2 into Deltamgpex6 mutants, the involvement of MGPEX6 gene in both PTS1 and PTS2 pathways was proved. In addition, using these transformants, the inducement of peroxisomes and the dynamic of peroxisomal number during the pre-penetration processes were investigated as well. In summary, by the localization and co-localization of PTS1 and PTS2, we provided a useful tool to evaluate the biological roles of the peroxisomes and the related genes.
Sujets)
Séquence nucléotidique , Amorces ADN , Génétique , ADN fongique , Génétique , Protéines fongiques , Génétique , Métabolisme , Gènes fongiques , Vecteurs génétiques , Protéines à fluorescence verte , Génétique , Métabolisme , Protéines luminescentes , Génétique , Métabolisme , Magnaporthe , Génétique , Métabolisme , Microscopie de fluorescence , Mutation , Récepteur de la séquence-2 d'adressage au peroxysome , Récepteur de la séquence-1 d'adressage au peroxysome , Péroxysomes , Métabolisme , Récepteurs cytoplasmiques et nucléaires , Génétique , Métabolisme , Protéines de fusion recombinantes , Génétique , Métabolisme , Transformation génétiqueRésumé
Sporidesmiopsis zhejiangensis sp. nov. and Spadicoides americana were found on submerged wood from streams in Zhejiang Province, China. Sporidesmiopsis zhejiangensis is characterized by obclavate to fusiform, 5-6-distoseptate, versicolorous, verruculose conidia with an apical mucilaginous sheath. Spadicoides americana is a new record to China. These taxa are described and illustrated, and morphological differences between these species and their similar species were summarized.
Sujets)
Ascomycota , Classification , Chine , Eau douce , Microbiologie , Deuteromycota , Classification , Spécificité d'espèce , Bois , MicrobiologieRésumé
Magnaporthe oryzae has been used as a primary model organism for investigating fungus-plant interaction. Many researches focused on molecular mechanisms of appressorium formation to restrain this fungal pathogen. Autophagy is a very high conserved process in eukaryotic cells. Recently, autophagy has been considered as a key process in development and differentiation in M. oryzae. In this report, we present and discuss the current state of our knowledge on gene expression in appressorium formation and the progress in autophagy of rice blast fungi.
Sujets)
Autophagie , Génétique , Expression des gènes , Gènes fongiques , Interactions hôte-pathogène , Magnaporthe , Génétique , Virulence , Physiologie , Oryza , Microbiologie , Maladies des plantes , MicrobiologieRésumé
Chinese soft-shelled turtles (Trionyx sinens) in culture farms using an artificial warming system in Zhejiang, China, often show typical signs of white-spot disease such as white spots on their bodies, skin lesions, anorexia and eventually death. The sick turtles were mostly 5~80 g in weight. A suspected fungal pathogen was isolated from the sick turtles and verified as Paecilomyces lilacinus by sequence analysis of the internal transcribed spacer (ITS) of its ribosomal DNA (rDNA). Detailed morphological examinations were also conducted to confirm the white-spot disease.
Sujets)
Animaux , Paecilomyces , Tortues , MicrobiologieRésumé
In this study the MTP1 gene, encoding a type III integral transmembrane protein, was isolated from the rice blast fungus Magnaporthe oryzae. The Mtp1 protein is 520 amino acids long and is comparable to the Ytp1 protein of Saccharomyces cerevisiae with 46% sequence similarity. Prediction programs and MTP1-GFP (green fluorescent protein) fusion expression results indicate that Mtp1 is a protein located at several membranes in the cytoplasm. The functions of the MTP1 gene in the growth and development of the fungus were studied using an MTP1 gene knockout mutant. The MTP1 gene was primarily expressed at the hyphal and conidial stages and is necessary for conidiation and conidial germination, but is not required for pathogenicity. The Deltamtp1 mutant grew more efficiently than the wild type strain on non-fermentable carbon sources, implying that the MTP1 gene has a unique role in respiratory growth and carbon source use.
Sujets)
Protéines fongiques , Génétique , Physiologie , Gènes fongiques , Magnaporthe , Génétique , Protéines membranaires , Génétique , Oryza , Microbiologie , Régions promotrices (génétique)Résumé
The promoter of NAR gene in Magnaporthe grisea was isolated and sequenced. The promoter sequences contained the "TATA" box, the "CAAT" box, and binding sites for fungal regulatory proteins. Programs that predict promoter sequences indicated that promoter sequence lies between locations 430 and 857 of the NAR promoter fragment. GFP expression under the NAR promoter and NAR transcript analysis revealed that this promoter is activated primarily at the mycelial stage in the rice blast fungus and could be used to express native or extrinsic genes in the mycelia of the rice blast fungus.
Sujets)
Séquence nucléotidique , Clonage moléculaire , Protéines fongiques , Génétique , Expression des gènes , Génétique , Hyphae , Génétique , Magnaporthe , Génétique , Données de séquences moléculaires , Régions promotrices (génétique) , Génétique , Activation de la transcription , GénétiqueRésumé
Application of promoter trapping based on transformation in Magnaporthe grisea is reported in this paper. Two promoter-trapping vectors, designated as pCBGFP and pEGFPHPH, were constructed and transformed into protoplasts of M. grisea. A library of 1,077 transformants resistant to hygromycin B was generated. Of which, 448 transformants were found to express eGFP gene in different structures of M. grisea. Three transformants grew slowly, 5 transformants decreased in conidiation and 7 transformants reduced in pathogenicity greatly among these 448 transformants. Eleven transformants were checked by genomic southern blot randomly, and 9 of which were single-copy insertions. The promoter trapping technique has been applied successfully in M. grisea and can be used as a tool for functional genomic analysis.
Sujets)
Protéines fongiques , Génétique , Régulation de l'expression des gènes fongiques , Génétique , Gènes rapporteurs , Génétique , Vecteurs génétiques , Génétique , Protéines à fluorescence verte , Génétique , Métabolisme , Magnaporthe , Génétique , Métabolisme , Régions promotrices (génétique) , Génétique , Ingénierie des protéines , Méthodes , Protéines recombinantes , MétabolismeRésumé
MGTA1, a putative fungal Zn(II)(2)Cys(6) transcriptional activator-encoding gene, was isolated from rice blast pathogen Magnaporthe grisea, which is homologous to CLTA1 from Colletotrichum lindemuthianum with 51% identity at protein level. MGTA1 cassette contains a 2370 bp open reading frame, consisting of 6 exons, coding a 790 amino acid peptide. MGTA1 gene exists as a single copy in genomes of 7 strains of M. grisea, and is expressed in tip hyphae, conidia, and mature appressoria of strain Guy11.
Sujets)
Séquence d'acides aminés , Analyse de profil d'expression de gènes , Régulation de l'expression des gènes fongiques , Physiologie , Magnaporthe , Génétique , Métabolisme , Données de séquences moléculaires , Oryza , Microbiologie , Analyse de séquence de protéineRésumé
A mature appressorium cDNA library of rice blast fungus, Magnaporthe grisea, was constructed in a lambdaTriplEx2 vector by SMART cDNA library containing 2.37x10(6) independent clones about 100% of which harbor foreign cDNA inserts with average size of 660 bp. Of 9 randomly selected clones, 2 expressed sequence tags (ESTs) sequences did not have homologous EST sequences of M. grisea in GenBank. The appressorium cDNA library is suitable for gene expression analysis and function analysis of the late stages of appressorium formation and the early stages of penetration of M. grisea.