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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

Expression levels of CDC2A and CDC2B assayed by qRT-PCR.(A) Relative expression levels of CDC2A and CDC2B in germlings and vegetative hyphae. The expression level of each gene in 18 h germlings was arbitrarily set to 1. (B) Relative expression levels of CDC2A and CDC2B in mating cultures at different day-post-fertilization (dpf). Their expression level at 0 dpf was arbitrarily set to 1. (C) Relative expression levels of CDC2A and CDC2B at 3 and 5 days post-inoculation (dpi). Their expression level at 3 dpi was arbitrarily set to 1. Error bar indicates standard deviation (SD) calculated from data of three replicates.
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ppat.1004913.g005: Expression levels of CDC2A and CDC2B assayed by qRT-PCR.(A) Relative expression levels of CDC2A and CDC2B in germlings and vegetative hyphae. The expression level of each gene in 18 h germlings was arbitrarily set to 1. (B) Relative expression levels of CDC2A and CDC2B in mating cultures at different day-post-fertilization (dpf). Their expression level at 0 dpf was arbitrarily set to 1. (C) Relative expression levels of CDC2A and CDC2B at 3 and 5 days post-inoculation (dpi). Their expression level at 3 dpi was arbitrarily set to 1. Error bar indicates standard deviation (SD) calculated from data of three replicates.

Mentions: When assayed by qRT-PCR, transcripts of CDC2A and CDC2B were detectable in germ tubes, vegetative hyphae, mating cultures, and infected wheat heads (Fig 5). Therefore, the lack of detectable phenotypes in the cdc2B mutant is not related to its stage-specific expression. Interestingly, CDC2B expression was reduced after carrot agar cultures were fertilized. The expression of CDC2A was not significantly affected in early stages of sexual reproduction but up-regulated at 14 dpf (Fig 5B). During plant infection, both CDC2A and CDC2B were up-regulated at 5 dpi in comparison with their expression at 3 dpi. However, the expression of CDC2A increased much more significantly than that of CDC2B (Fig 5C). These expression data are consistent with the importance of Cdc2A during ascosporogenesis and plant infection.


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)

Expression levels of CDC2A and CDC2B assayed by qRT-PCR.(A) Relative expression levels of CDC2A and CDC2B in germlings and vegetative hyphae. The expression level of each gene in 18 h germlings was arbitrarily set to 1. (B) Relative expression levels of CDC2A and CDC2B in mating cultures at different day-post-fertilization (dpf). Their expression level at 0 dpf was arbitrarily set to 1. (C) Relative expression levels of CDC2A and CDC2B at 3 and 5 days post-inoculation (dpi). Their expression level at 3 dpi was arbitrarily set to 1. Error bar indicates standard deviation (SD) calculated from data of three replicates.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4470668&req=5

ppat.1004913.g005: Expression levels of CDC2A and CDC2B assayed by qRT-PCR.(A) Relative expression levels of CDC2A and CDC2B in germlings and vegetative hyphae. The expression level of each gene in 18 h germlings was arbitrarily set to 1. (B) Relative expression levels of CDC2A and CDC2B in mating cultures at different day-post-fertilization (dpf). Their expression level at 0 dpf was arbitrarily set to 1. (C) Relative expression levels of CDC2A and CDC2B at 3 and 5 days post-inoculation (dpi). Their expression level at 3 dpi was arbitrarily set to 1. Error bar indicates standard deviation (SD) calculated from data of three replicates.
Mentions: When assayed by qRT-PCR, transcripts of CDC2A and CDC2B were detectable in germ tubes, vegetative hyphae, mating cultures, and infected wheat heads (Fig 5). Therefore, the lack of detectable phenotypes in the cdc2B mutant is not related to its stage-specific expression. Interestingly, CDC2B expression was reduced after carrot agar cultures were fertilized. The expression of CDC2A was not significantly affected in early stages of sexual reproduction but up-regulated at 14 dpf (Fig 5B). During plant infection, both CDC2A and CDC2B were up-regulated at 5 dpi in comparison with their expression at 3 dpi. However, the expression of CDC2A increased much more significantly than that of CDC2B (Fig 5C). These expression data are consistent with the importance of Cdc2A during ascosporogenesis and plant infection.

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