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Two Cdc2 Kinase Genes with Distinct Functions in Vegetative and Infectious Hyphae in Fusarium graminearum.

Liu H, Zhang S, Ma J, Dai Y, Li C, Lyu X, Wang C, Xu JR - PLoS Pathog. (2015)

Bottom Line: However, whereas the cdc2B mutant was normal, the cdc2A mutant was significantly reduced in virulence and rarely produced ascospores.Although deletion of CDC2A had no obvious effect on the formation of penetration branches or hyphopodia, the cdc2A mutant was limited in the differentiation and growth of infectious growth in wheat tissues.Overall, our data indicate that cell cycle regulation is different between vegetative and infectious hyphae in F. graminearum and Cdc2A, possibly by interacting with a stage-specific cyclin, plays a more important role than Cdc2B during ascosporogenesis and plant infection.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest Agriculture and Forestry University, Yangling, Shaanxi, China; Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, United States of America.

ABSTRACT
Eukaryotic cell cycle involves a number of protein kinases important for the onset and progression through mitosis, most of which are well characterized in the budding and fission yeasts and conserved in other fungi. However, unlike the model yeast and filamentous fungi that have a single Cdc2 essential for cell cycle progression, the wheat scab fungus Fusarium graminearum contains two CDC2 orthologs. The cdc2A and cdc2B mutants had no obvious defects in growth rate and conidiation but deletion of both of them is lethal, indicating that these two CDC2 orthologs have redundant functions during vegetative growth and asexual reproduction. However, whereas the cdc2B mutant was normal, the cdc2A mutant was significantly reduced in virulence and rarely produced ascospores. Although deletion of CDC2A had no obvious effect on the formation of penetration branches or hyphopodia, the cdc2A mutant was limited in the differentiation and growth of infectious growth in wheat tissues. Therefore, CDC2A plays stage-specific roles in cell cycle regulation during infectious growth and sexual reproduction. Both CDC2A and CDC2B are constitutively expressed but only CDC2A was up-regulated during plant infection and ascosporogenesis. Localization of Cdc2A- GFP to the nucleus but not Cdc2B-GFP was observed in vegetative hyphae, ascospores, and infectious hyphae. Complementation assays with chimeric fusion constructs showed that both the N- and C-terminal regions of Cdc2A are important for its functions in pathogenesis and ascosporogenesis but only the N-terminal region is important for its subcellular localization. Among the Sordariomycetes, only three Fusarium species closely related to F. graminearum have two CDC2 genes. Furthermore, F. graminearum uniquely has two Aurora kinase genes and one additional putative cyclin gene, and its orthologs of CAK1 and other four essential mitotic kinases in the budding yeast are dispensable for viability. Overall, our data indicate that cell cycle regulation is different between vegetative and infectious hyphae in F. graminearum and Cdc2A, possibly by interacting with a stage-specific cyclin, plays a more important role than Cdc2B during ascosporogenesis and plant infection.

No MeSH data available.


Related in: MedlinePlus

Infection assays with the cdc2A and cdc2B mutants.(A) Flowering wheat heads were drop-inoculated with conidia of the wild type (PH-1), the cdc2A and cdc2B mutants (C2A1 and C2B1), and corresponding complemented transformants (C2A-N4 and C2B-N2). Black dots mark the inoculated spikelets. Photographs were taken 14 days post-inoculation (dpi). (B) Eight-week-old corn stalks were punctured with toothpicks dipped in conidia suspensions of the same set of strains. Photographs were taken 14 dpi. (C) Corn silks were inoculated with culture blocks of the same set of strains and examined 6 dpi.
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ppat.1004913.g003: Infection assays with the cdc2A and cdc2B mutants.(A) Flowering wheat heads were drop-inoculated with conidia of the wild type (PH-1), the cdc2A and cdc2B mutants (C2A1 and C2B1), and corresponding complemented transformants (C2A-N4 and C2B-N2). Black dots mark the inoculated spikelets. Photographs were taken 14 days post-inoculation (dpi). (B) Eight-week-old corn stalks were punctured with toothpicks dipped in conidia suspensions of the same set of strains. Photographs were taken 14 dpi. (C) Corn silks were inoculated with culture blocks of the same set of strains and examined 6 dpi.

Mentions: We also assayed the defects of the cdc2A and cdc2B mutants in plant infection. On flowering wheat heads, the cdc2B mutant was as virulent as the wild type. In contrast, the cdc2A mutant caused only limited symptoms on the inoculated kernels in infection assays with flowering wheat heads (Fig 3A). On average, the disease index for PH-1 and the cdc2A mutant was 13.9 and 1.4, respectively.


Two Cdc2 Kinase Genes with Distinct Functions in Vegetative and Infectious Hyphae in Fusarium graminearum.

Liu H, Zhang S, Ma J, Dai Y, Li C, Lyu X, Wang C, Xu JR - PLoS Pathog. (2015)

Infection assays with the cdc2A and cdc2B mutants.(A) Flowering wheat heads were drop-inoculated with conidia of the wild type (PH-1), the cdc2A and cdc2B mutants (C2A1 and C2B1), and corresponding complemented transformants (C2A-N4 and C2B-N2). Black dots mark the inoculated spikelets. Photographs were taken 14 days post-inoculation (dpi). (B) Eight-week-old corn stalks were punctured with toothpicks dipped in conidia suspensions of the same set of strains. Photographs were taken 14 dpi. (C) Corn silks were inoculated with culture blocks of the same set of strains and examined 6 dpi.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4470668&req=5

ppat.1004913.g003: Infection assays with the cdc2A and cdc2B mutants.(A) Flowering wheat heads were drop-inoculated with conidia of the wild type (PH-1), the cdc2A and cdc2B mutants (C2A1 and C2B1), and corresponding complemented transformants (C2A-N4 and C2B-N2). Black dots mark the inoculated spikelets. Photographs were taken 14 days post-inoculation (dpi). (B) Eight-week-old corn stalks were punctured with toothpicks dipped in conidia suspensions of the same set of strains. Photographs were taken 14 dpi. (C) Corn silks were inoculated with culture blocks of the same set of strains and examined 6 dpi.
Mentions: We also assayed the defects of the cdc2A and cdc2B mutants in plant infection. On flowering wheat heads, the cdc2B mutant was as virulent as the wild type. In contrast, the cdc2A mutant caused only limited symptoms on the inoculated kernels in infection assays with flowering wheat heads (Fig 3A). On average, the disease index for PH-1 and the cdc2A mutant was 13.9 and 1.4, respectively.

Bottom Line: However, whereas the cdc2B mutant was normal, the cdc2A mutant was significantly reduced in virulence and rarely produced ascospores.Although deletion of CDC2A had no obvious effect on the formation of penetration branches or hyphopodia, the cdc2A mutant was limited in the differentiation and growth of infectious growth in wheat tissues.Overall, our data indicate that cell cycle regulation is different between vegetative and infectious hyphae in F. graminearum and Cdc2A, possibly by interacting with a stage-specific cyclin, plays a more important role than Cdc2B during ascosporogenesis and plant infection.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest Agriculture and Forestry University, Yangling, Shaanxi, China; Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, United States of America.

ABSTRACT
Eukaryotic cell cycle involves a number of protein kinases important for the onset and progression through mitosis, most of which are well characterized in the budding and fission yeasts and conserved in other fungi. However, unlike the model yeast and filamentous fungi that have a single Cdc2 essential for cell cycle progression, the wheat scab fungus Fusarium graminearum contains two CDC2 orthologs. The cdc2A and cdc2B mutants had no obvious defects in growth rate and conidiation but deletion of both of them is lethal, indicating that these two CDC2 orthologs have redundant functions during vegetative growth and asexual reproduction. However, whereas the cdc2B mutant was normal, the cdc2A mutant was significantly reduced in virulence and rarely produced ascospores. Although deletion of CDC2A had no obvious effect on the formation of penetration branches or hyphopodia, the cdc2A mutant was limited in the differentiation and growth of infectious growth in wheat tissues. Therefore, CDC2A plays stage-specific roles in cell cycle regulation during infectious growth and sexual reproduction. Both CDC2A and CDC2B are constitutively expressed but only CDC2A was up-regulated during plant infection and ascosporogenesis. Localization of Cdc2A- GFP to the nucleus but not Cdc2B-GFP was observed in vegetative hyphae, ascospores, and infectious hyphae. Complementation assays with chimeric fusion constructs showed that both the N- and C-terminal regions of Cdc2A are important for its functions in pathogenesis and ascosporogenesis but only the N-terminal region is important for its subcellular localization. Among the Sordariomycetes, only three Fusarium species closely related to F. graminearum have two CDC2 genes. Furthermore, F. graminearum uniquely has two Aurora kinase genes and one additional putative cyclin gene, and its orthologs of CAK1 and other four essential mitotic kinases in the budding yeast are dispensable for viability. Overall, our data indicate that cell cycle regulation is different between vegetative and infectious hyphae in F. graminearum and Cdc2A, possibly by interacting with a stage-specific cyclin, plays a more important role than Cdc2B during ascosporogenesis and plant infection.

No MeSH data available.


Related in: MedlinePlus