Abstract:The cloning of fga1, the gene encoding a G protein alpha subunit, was performed by standard PCR techniques and by screening a Fusarium oxysporum genomic library, using the PCR product as a probe. The full-length open reading frame spanned 1,059 nucleotides and the deduced primary structure of the protein (353 amino acid residues) showed high identity to those of G protein alpha(i) family proteins from other filamentous fungi. Disruption of fga1 had no effect on vegetative growth, but reduced the conidiation an… Show more
“…Similar to MgGpa1, the orthologous group I G␣ proteins in C. parasitica, M. grisea, Stagonospora nodorum, F. oxysporum, Colletotrichum trifolii, and B. cinerea affect pathogenicity (7,16,28,41,61,65), whereas the orthologous proteins CGA1 and GPA1 in Cochliobolus heterostrophus and U. maydis, respectively, are dispensable for pathogenicity (24,57). Such a functional dichotomy was also observed for group III G␣ orthologs.…”
Section: Vol 8 2009mentioning
confidence: 77%
“…We observed that all M. graminicola strains were equally thermosensitive, whereas for N. crassa and F. oxysporum, thermotolerance was observed in G␣-encoding mutants and was positively correlated with decreased intracellular cAMP levels (28,29,71). Indeed, constitutive expression of Gna1 in N. crassa resulted in elevated cAMP levels and increased thermosensitivity (26,71).…”
Section: Vol 8 2009mentioning
confidence: 77%
“…For instance, the Cpg-1 gene in C. parasitica negatively regulates the cAMP level, as disruption increased intracellular cAMP levels in this fungus (5). In contrast, the orthologs Gna1 in Neurospora crassa, Fga1 in Fusarium oxysporum, and MagB in M. grisea positively regulate the cAMP pathway, as disruption of these genes decreased intracellular cAMP levels (26,28). In M. grisea, exogenous cAMP restored appressorium formation and pathogenicity of the MagB mutant (41).…”
Section: Discussionmentioning
confidence: 99%
“…Irrespective of the observed numerical variation, G␣ proteins regulate a variety of cellular and developmental responses (4). For plant-pathogenic fungi, G-encoding genes have been characterized functionally (9,14,22,27,31,48,52). Apart from the fact that individual G␣-encoding genes and the G-encoding gene have been demonstrated to regulate growth, reproduction, and virulence, comparative functional characterization of all G␣-encoding genes has been reported only for a few plantpathogenic fungi, including Magnaporthe grisea, Cryphonectria parasitica, and U. maydis (5,41,57).…”
We identified and functionally characterized genes encoding three G␣ proteins and one G protein in the dimorphic fungal wheat pathogen Mycosphaerella graminicola, which we designated MgGpa1, MgGpa2, MgGpa3, and MgGpb1, respectively. Sequence comparisons and phylogenetic analyses showed that MgGPA1 and MgGPA3 are most related to the mammalian G␣ i and G␣ s families, respectively, whereas MgGPA2 is not related to either of these families. On potato dextrose agar (PDA) and in yeast glucose broth (YGB), MgGpa1 mutants produced significantly longer spores than those of the wild type (WT), and these developed into unique fluffy mycelia in the latter medium, indicating that this gene negatively controls filamentation. MgGpa3 mutants showed more pronounced yeast-like growth accompanied with hampered filamentation and secreted a dark-brown pigment into YGB. Germ tubes emerging from spores of MgGpb1 mutants were wavy on water agar and showed a nested type of growth on PDA that was due to hampered filamentation, numerous cell fusions, and increased anastomosis. Intracellular cyclic AMP (cAMP) levels of MgGpb1 and MgGpa3 mutants were decreased, indicating that both genes positively regulate the cAMP pathway, which was confirmed because the WT phenotype was restored by adding cAMP to these mutant cultures. The cAMP levels in MgGpa1 mutants and the WT were not significantly different, suggesting that this gene might be dispensable for cAMP regulation. In planta assays showed that mutants of MgGpa1, MgGpa3, and MgGpb1 are strongly reduced in pathogenicity. We concluded that the heterotrimeric G proteins encoded by MgGpa3 and MgGpb1 regulate the cAMP pathway that is required for development and pathogenicity in M. graminicola.
“…Similar to MgGpa1, the orthologous group I G␣ proteins in C. parasitica, M. grisea, Stagonospora nodorum, F. oxysporum, Colletotrichum trifolii, and B. cinerea affect pathogenicity (7,16,28,41,61,65), whereas the orthologous proteins CGA1 and GPA1 in Cochliobolus heterostrophus and U. maydis, respectively, are dispensable for pathogenicity (24,57). Such a functional dichotomy was also observed for group III G␣ orthologs.…”
Section: Vol 8 2009mentioning
confidence: 77%
“…We observed that all M. graminicola strains were equally thermosensitive, whereas for N. crassa and F. oxysporum, thermotolerance was observed in G␣-encoding mutants and was positively correlated with decreased intracellular cAMP levels (28,29,71). Indeed, constitutive expression of Gna1 in N. crassa resulted in elevated cAMP levels and increased thermosensitivity (26,71).…”
Section: Vol 8 2009mentioning
confidence: 77%
“…For instance, the Cpg-1 gene in C. parasitica negatively regulates the cAMP level, as disruption increased intracellular cAMP levels in this fungus (5). In contrast, the orthologs Gna1 in Neurospora crassa, Fga1 in Fusarium oxysporum, and MagB in M. grisea positively regulate the cAMP pathway, as disruption of these genes decreased intracellular cAMP levels (26,28). In M. grisea, exogenous cAMP restored appressorium formation and pathogenicity of the MagB mutant (41).…”
Section: Discussionmentioning
confidence: 99%
“…Irrespective of the observed numerical variation, G␣ proteins regulate a variety of cellular and developmental responses (4). For plant-pathogenic fungi, G-encoding genes have been characterized functionally (9,14,22,27,31,48,52). Apart from the fact that individual G␣-encoding genes and the G-encoding gene have been demonstrated to regulate growth, reproduction, and virulence, comparative functional characterization of all G␣-encoding genes has been reported only for a few plantpathogenic fungi, including Magnaporthe grisea, Cryphonectria parasitica, and U. maydis (5,41,57).…”
We identified and functionally characterized genes encoding three G␣ proteins and one G protein in the dimorphic fungal wheat pathogen Mycosphaerella graminicola, which we designated MgGpa1, MgGpa2, MgGpa3, and MgGpb1, respectively. Sequence comparisons and phylogenetic analyses showed that MgGPA1 and MgGPA3 are most related to the mammalian G␣ i and G␣ s families, respectively, whereas MgGPA2 is not related to either of these families. On potato dextrose agar (PDA) and in yeast glucose broth (YGB), MgGpa1 mutants produced significantly longer spores than those of the wild type (WT), and these developed into unique fluffy mycelia in the latter medium, indicating that this gene negatively controls filamentation. MgGpa3 mutants showed more pronounced yeast-like growth accompanied with hampered filamentation and secreted a dark-brown pigment into YGB. Germ tubes emerging from spores of MgGpb1 mutants were wavy on water agar and showed a nested type of growth on PDA that was due to hampered filamentation, numerous cell fusions, and increased anastomosis. Intracellular cyclic AMP (cAMP) levels of MgGpb1 and MgGpa3 mutants were decreased, indicating that both genes positively regulate the cAMP pathway, which was confirmed because the WT phenotype was restored by adding cAMP to these mutant cultures. The cAMP levels in MgGpa1 mutants and the WT were not significantly different, suggesting that this gene might be dispensable for cAMP regulation. In planta assays showed that mutants of MgGpa1, MgGpa3, and MgGpb1 are strongly reduced in pathogenicity. We concluded that the heterotrimeric G proteins encoded by MgGpa3 and MgGpb1 regulate the cAMP pathway that is required for development and pathogenicity in M. graminicola.
“…Mitogen-activated protein kinase (MAPK) and cAMP protein kinase A (cAMP-PKA) signal transduction systems control important steps during plant infection. Some MAPK genes, such as Fmk1 , Fga1 and Fgb1, of F. oxysporum play significant roles in the pathogenicity (Di Pietro et al 2001; Jain et al 2002, 2003). RNA-silencing pathways regulate the MAPK and the cAMP-PKA cascades to affect virulence in F. oxysporum at the stage of infection.10.1080/21501203.2015.1027313-F0005Figure 5.Pathogenicity of wild-type Fusarium oxysporum strain A8 and the Δ Qip mutant.…”
Ribonucleic acid (RNA)-silencing mechanisms exist in many eukaryotes to regulate a variety of biological processes. The known molecular components are related to Dicers, Argonautes and RNA-dependent RNA polymerases. Previous biochemical studies have also suggested that Qip, with an exonuclease domain, facilitates the conversion of duplex small interfering RNAs into single strands. In our study, the Qip gene in Fusarium oxysporum was disrupted using homologous recombination technology. The deletion of the Qip gene resulted in a decrease in colony growth rates but increased the number of branches. Additionally, the ΔQip mutant had a reduced pathogenicity in cabbage. Our results show Qip gene in F. oxysporum is required for normal hyphae morphology and virulence. The mutant will be useful for elucidating the relationship between the RNA-silencing mechanism and hyphal growth and development in F. oxysporum.
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