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Signaling governed by G proteins and cAMP is crucial for growth, secondary metabolism and sexual development in Fusarium fujikuroi.

Studt L, Humpf HU, Tudzynski B - PLoS ONE (2013)

Bottom Line: Here we studied the impact of the heterotrimeric G protein and the cAMP-mediated signaling network, including the regulatory subunits of the cAMP-dependent protein kinase (PKA), to study their effect on colony morphology, sexual development and regulation of bikaverins, fusarubins and GAs.In contrast, bikaverin biosynthesis is significantly reduced in ffg1 and ffg3 deletion mutants and positively regulated by FfAC and FfPKA1, while GA biosynthesis depends on the active FfAC and FfPKA2 in an FfG1- and FfG3-independent manner.In addition, we provide evidence that G Protein-mediated/cAMP signaling is important for growth in F. fujikuroi because deletion of ffg3, ffac and ffpka1 resulted in impaired growth on minimal and rich media.

View Article: PubMed Central - PubMed

Affiliation: Institut für Lebensmittelchemie, Westfälische Wilhelms-Universität, Münster, Germany.

ABSTRACT
The plant-pathogenic fungus Fusarium fujikuroi is a notorious rice pathogen causing hyper-elongation of infected plants due to the production of gibberellic acids (GAs). In addition to GAs, F. fujikuroi produces a wide range of other secondary metabolites, such as fusarins, fusaric acid or the red polyketides bikaverins and fusarubins. The recent availability of the fungal genome sequence for this species has revealed the potential of many more putative secondary metabolite gene clusters whose products remain to be identified. However, the complex regulation of secondary metabolism is far from being understood. Here we studied the impact of the heterotrimeric G protein and the cAMP-mediated signaling network, including the regulatory subunits of the cAMP-dependent protein kinase (PKA), to study their effect on colony morphology, sexual development and regulation of bikaverins, fusarubins and GAs. We demonstrated that fusarubin biosynthesis is negatively regulated by at least two Gα subunits, FfG1 and FfG3, which both function as stimulators of the adenylyl cyclase FfAC. Surprisingly, the primary downstream target of the adenylyl cyclase, the PKA, is not involved in the regulation of fusarubins, suggesting that additional, yet unidentified, cAMP-binding protein(s) exist. In contrast, bikaverin biosynthesis is significantly reduced in ffg1 and ffg3 deletion mutants and positively regulated by FfAC and FfPKA1, while GA biosynthesis depends on the active FfAC and FfPKA2 in an FfG1- and FfG3-independent manner. In addition, we provide evidence that G Protein-mediated/cAMP signaling is important for growth in F. fujikuroi because deletion of ffg3, ffac and ffpka1 resulted in impaired growth on minimal and rich media. Finally, sexual crosses of ffg1 mutants showed the importance of a functional FfG1 protein for development of perithecia in the mating strain that carries the MAT1-1 idiomorph.

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Loss of FfG1 affects perithecial formation.Strains were crossed as described in Materials and Methods. Crosses from left to right were WTxMRC-1995, Δffg1xMRC-1995, WTxMRC-1995/Δffg1, Δffg1xMRC-1995/Δffg1. A) Photographs of crosses after 10 weeks. B) Aerial hyphae were removed prior to microscopy to uncover the fruiting bodies (indicated by black arrows). C) Enlargement of segments high-lighted by black boxes in B). Perithecia are formed during crosses of WTxMRC-1995 and Δffg1xMRC-1995, but not in WTxMRC-1995/Δffg1, Δffg1xMRC-1995/Δffg1. Size standards are shown in the lower left corners.
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pone-0058185-g007: Loss of FfG1 affects perithecial formation.Strains were crossed as described in Materials and Methods. Crosses from left to right were WTxMRC-1995, Δffg1xMRC-1995, WTxMRC-1995/Δffg1, Δffg1xMRC-1995/Δffg1. A) Photographs of crosses after 10 weeks. B) Aerial hyphae were removed prior to microscopy to uncover the fruiting bodies (indicated by black arrows). C) Enlargement of segments high-lighted by black boxes in B). Perithecia are formed during crosses of WTxMRC-1995 and Δffg1xMRC-1995, but not in WTxMRC-1995/Δffg1, Δffg1xMRC-1995/Δffg1. Size standards are shown in the lower left corners.

Mentions: Therefore, ffg1 was also deleted in the mating partner of strain IMI58289, F. fujikuroi MRC-1995, carrying the MAT1-1 idiomorph, using the same targeted deletion strategy. Two independent deletion mutants were obtained, designated MRC-1995/Δffg1_T44 and MRC-1995/Δffg1_T49 (fig. S1F). Crosses were made between both wild types, one of either wild-type strains and the Δffg1 mutant of the respective mating partner as well as between the two Δffg1 mutant strains. When ffg1 is only deleted in F. fujikuroi IMI58289 that carries the MAT1-2 idiomorph, perithecia were normally produced in a cross with MRC-1995, similarly to the cross between the two wild type strains. However, ffg1 deletion in F. fujikuroi MRC-1995 carrying the MAT1-1 idiomorph resulted in total loss of perithecial formation in a cross with IMI58289, as it was the case when ffg1 was deleted in both mating partners. (fig. 7).


Signaling governed by G proteins and cAMP is crucial for growth, secondary metabolism and sexual development in Fusarium fujikuroi.

Studt L, Humpf HU, Tudzynski B - PLoS ONE (2013)

Loss of FfG1 affects perithecial formation.Strains were crossed as described in Materials and Methods. Crosses from left to right were WTxMRC-1995, Δffg1xMRC-1995, WTxMRC-1995/Δffg1, Δffg1xMRC-1995/Δffg1. A) Photographs of crosses after 10 weeks. B) Aerial hyphae were removed prior to microscopy to uncover the fruiting bodies (indicated by black arrows). C) Enlargement of segments high-lighted by black boxes in B). Perithecia are formed during crosses of WTxMRC-1995 and Δffg1xMRC-1995, but not in WTxMRC-1995/Δffg1, Δffg1xMRC-1995/Δffg1. Size standards are shown in the lower left corners.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3585259&req=5

pone-0058185-g007: Loss of FfG1 affects perithecial formation.Strains were crossed as described in Materials and Methods. Crosses from left to right were WTxMRC-1995, Δffg1xMRC-1995, WTxMRC-1995/Δffg1, Δffg1xMRC-1995/Δffg1. A) Photographs of crosses after 10 weeks. B) Aerial hyphae were removed prior to microscopy to uncover the fruiting bodies (indicated by black arrows). C) Enlargement of segments high-lighted by black boxes in B). Perithecia are formed during crosses of WTxMRC-1995 and Δffg1xMRC-1995, but not in WTxMRC-1995/Δffg1, Δffg1xMRC-1995/Δffg1. Size standards are shown in the lower left corners.
Mentions: Therefore, ffg1 was also deleted in the mating partner of strain IMI58289, F. fujikuroi MRC-1995, carrying the MAT1-1 idiomorph, using the same targeted deletion strategy. Two independent deletion mutants were obtained, designated MRC-1995/Δffg1_T44 and MRC-1995/Δffg1_T49 (fig. S1F). Crosses were made between both wild types, one of either wild-type strains and the Δffg1 mutant of the respective mating partner as well as between the two Δffg1 mutant strains. When ffg1 is only deleted in F. fujikuroi IMI58289 that carries the MAT1-2 idiomorph, perithecia were normally produced in a cross with MRC-1995, similarly to the cross between the two wild type strains. However, ffg1 deletion in F. fujikuroi MRC-1995 carrying the MAT1-1 idiomorph resulted in total loss of perithecial formation in a cross with IMI58289, as it was the case when ffg1 was deleted in both mating partners. (fig. 7).

Bottom Line: Here we studied the impact of the heterotrimeric G protein and the cAMP-mediated signaling network, including the regulatory subunits of the cAMP-dependent protein kinase (PKA), to study their effect on colony morphology, sexual development and regulation of bikaverins, fusarubins and GAs.In contrast, bikaverin biosynthesis is significantly reduced in ffg1 and ffg3 deletion mutants and positively regulated by FfAC and FfPKA1, while GA biosynthesis depends on the active FfAC and FfPKA2 in an FfG1- and FfG3-independent manner.In addition, we provide evidence that G Protein-mediated/cAMP signaling is important for growth in F. fujikuroi because deletion of ffg3, ffac and ffpka1 resulted in impaired growth on minimal and rich media.

View Article: PubMed Central - PubMed

Affiliation: Institut für Lebensmittelchemie, Westfälische Wilhelms-Universität, Münster, Germany.

ABSTRACT
The plant-pathogenic fungus Fusarium fujikuroi is a notorious rice pathogen causing hyper-elongation of infected plants due to the production of gibberellic acids (GAs). In addition to GAs, F. fujikuroi produces a wide range of other secondary metabolites, such as fusarins, fusaric acid or the red polyketides bikaverins and fusarubins. The recent availability of the fungal genome sequence for this species has revealed the potential of many more putative secondary metabolite gene clusters whose products remain to be identified. However, the complex regulation of secondary metabolism is far from being understood. Here we studied the impact of the heterotrimeric G protein and the cAMP-mediated signaling network, including the regulatory subunits of the cAMP-dependent protein kinase (PKA), to study their effect on colony morphology, sexual development and regulation of bikaverins, fusarubins and GAs. We demonstrated that fusarubin biosynthesis is negatively regulated by at least two Gα subunits, FfG1 and FfG3, which both function as stimulators of the adenylyl cyclase FfAC. Surprisingly, the primary downstream target of the adenylyl cyclase, the PKA, is not involved in the regulation of fusarubins, suggesting that additional, yet unidentified, cAMP-binding protein(s) exist. In contrast, bikaverin biosynthesis is significantly reduced in ffg1 and ffg3 deletion mutants and positively regulated by FfAC and FfPKA1, while GA biosynthesis depends on the active FfAC and FfPKA2 in an FfG1- and FfG3-independent manner. In addition, we provide evidence that G Protein-mediated/cAMP signaling is important for growth in F. fujikuroi because deletion of ffg3, ffac and ffpka1 resulted in impaired growth on minimal and rich media. Finally, sexual crosses of ffg1 mutants showed the importance of a functional FfG1 protein for development of perithecia in the mating strain that carries the MAT1-1 idiomorph.

Show MeSH
Related in: MedlinePlus