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Two phosphodiesterase genes, PDEL and PDEH, regulate development and pathogenicity by modulating intracellular cyclic AMP levels in Magnaporthe oryzae.

Zhang H, Liu K, Zhang X, Tang W, Wang J, Guo M, Zhao Q, Zheng X, Wang P, Zhang Z - PLoS ONE (2011)

Bottom Line: As a second messenger, cAMP is important in the activation of downstream effector molecules.This is in contrast to PdeH whose mutation resulted in major defects in conidial morphology, cell wall integrity, and surface hydrophobicity, as well as a significant reduction in pathogenicity.Moreover, microarray data revealed new insights into the underlying cAMP regulatory mechanisms that may help to identify potential pathogenicity factors for the development of new disease management strategies.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing, China.

ABSTRACT
Cyclic AMP (cAMP) signaling plays an important role in regulating multiple cellular responses, such as growth, morphogenesis, and/or pathogenicity of eukaryotic organisms such as fungi. As a second messenger, cAMP is important in the activation of downstream effector molecules. The balance of intracellular cAMP levels depends on biosynthesis by adenylyl cyclases (ACs) and hydrolysis by cAMP phosphodiesterases (PDEases). The rice blast fungus Magnaporthe oryzae contains a high-affinity (PdeH/Pde2) and a low-affinity (PdeL/Pde1) PDEases, and a previous study showed that PdeH has a major role in asexual differentiation and pathogenicity. Here, we show that PdeL is required for asexual development and conidial morphology, and it also plays a minor role in regulating cAMP signaling. This is in contrast to PdeH whose mutation resulted in major defects in conidial morphology, cell wall integrity, and surface hydrophobicity, as well as a significant reduction in pathogenicity. Consistent with both PdeH and PdeL functioning in cAMP signaling, disruption of PDEH only partially rescued the mutant phenotype of ΔmagB and Δpka1. Further studies suggest that PdeH might function through a feedback mechanism to regulate the expression of pathogenicity factor Mpg1 during surface hydrophobicity and pathogenic development. Moreover, microarray data revealed new insights into the underlying cAMP regulatory mechanisms that may help to identify potential pathogenicity factors for the development of new disease management strategies.

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Related in: MedlinePlus

Detergent wettable phenotype of ΔpdeH and ΔpdeHΔpdeL mutants.(A) Ten microliters of water or detergent solution containing 0.02% SDS and 5 mM EDTA were placed on the colony surfaces of the wild type and mutants strains and photographed after 5 min. (B) Expression analysis of MPG1 gene in wild type and mutant strains. The error bars indicate SD of three replicates. Asterisk indicates significant differences at P = 0.01.
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pone-0017241-g003: Detergent wettable phenotype of ΔpdeH and ΔpdeHΔpdeL mutants.(A) Ten microliters of water or detergent solution containing 0.02% SDS and 5 mM EDTA were placed on the colony surfaces of the wild type and mutants strains and photographed after 5 min. (B) Expression analysis of MPG1 gene in wild type and mutant strains. The error bars indicate SD of three replicates. Asterisk indicates significant differences at P = 0.01.

Mentions: In previous studies, disruption of several M. oryzae hydrophobin genes, including MPG1 and MHP1, resulted in a water- or detergent-soaked easily wettable phenotype [64], [65], [66], [55], [67], [68], [69]. To determine whether PdeL and PdeH are involved in surface hydrophobicity, the mutant and wild type strains were tested with water and detergent solutions. Unlike Δmpg1, the ΔpdeH mutant did not show an easily wettable phenotype when incubated with water droplets (10 µl) for 24 hours. However, aerial hyphae of ΔpdeH mutants that were grown on CM agar were more readily wettable by a solution containing both 0.02% SDS and 5 mM EDTA within 5 min (Figure 3A), as seen in the Δmhp1 mutant. The detergent-wettable phenotype shown by ΔpdeH mutant was stably maintained up to four successive generations, suggesting that this phenotype is mitotically stable (data not shown). Based on the results described above, we suggested that the surface hydrophobicity defect of ΔpdeH and ΔpdeLΔpdeH mutants might be related to Mpg1 and Mhp1. To assess this, we examined the levels of MPG1 and MHP1 expression in the mutant and wild-type strains. The MPG1 expression level showed a 50% decrease in the ΔpdeL mutant compared with the wild-type control, while the expression reduced more than 90% in the ΔpdeH and ΔpdeLΔpdeH mutants (Figure 3B). In contrast, there was no apparent difference in MHP1 expression in any of the mutants compared with the wild-type control (data not shown). These results indicated that the surface hydrophobicity defects of ΔpdeH and ΔpdeLΔpdeH mutants were likely due to the lowed MPG1 expression.


Two phosphodiesterase genes, PDEL and PDEH, regulate development and pathogenicity by modulating intracellular cyclic AMP levels in Magnaporthe oryzae.

Zhang H, Liu K, Zhang X, Tang W, Wang J, Guo M, Zhao Q, Zheng X, Wang P, Zhang Z - PLoS ONE (2011)

Detergent wettable phenotype of ΔpdeH and ΔpdeHΔpdeL mutants.(A) Ten microliters of water or detergent solution containing 0.02% SDS and 5 mM EDTA were placed on the colony surfaces of the wild type and mutants strains and photographed after 5 min. (B) Expression analysis of MPG1 gene in wild type and mutant strains. The error bars indicate SD of three replicates. Asterisk indicates significant differences at P = 0.01.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3046207&req=5

pone-0017241-g003: Detergent wettable phenotype of ΔpdeH and ΔpdeHΔpdeL mutants.(A) Ten microliters of water or detergent solution containing 0.02% SDS and 5 mM EDTA were placed on the colony surfaces of the wild type and mutants strains and photographed after 5 min. (B) Expression analysis of MPG1 gene in wild type and mutant strains. The error bars indicate SD of three replicates. Asterisk indicates significant differences at P = 0.01.
Mentions: In previous studies, disruption of several M. oryzae hydrophobin genes, including MPG1 and MHP1, resulted in a water- or detergent-soaked easily wettable phenotype [64], [65], [66], [55], [67], [68], [69]. To determine whether PdeL and PdeH are involved in surface hydrophobicity, the mutant and wild type strains were tested with water and detergent solutions. Unlike Δmpg1, the ΔpdeH mutant did not show an easily wettable phenotype when incubated with water droplets (10 µl) for 24 hours. However, aerial hyphae of ΔpdeH mutants that were grown on CM agar were more readily wettable by a solution containing both 0.02% SDS and 5 mM EDTA within 5 min (Figure 3A), as seen in the Δmhp1 mutant. The detergent-wettable phenotype shown by ΔpdeH mutant was stably maintained up to four successive generations, suggesting that this phenotype is mitotically stable (data not shown). Based on the results described above, we suggested that the surface hydrophobicity defect of ΔpdeH and ΔpdeLΔpdeH mutants might be related to Mpg1 and Mhp1. To assess this, we examined the levels of MPG1 and MHP1 expression in the mutant and wild-type strains. The MPG1 expression level showed a 50% decrease in the ΔpdeL mutant compared with the wild-type control, while the expression reduced more than 90% in the ΔpdeH and ΔpdeLΔpdeH mutants (Figure 3B). In contrast, there was no apparent difference in MHP1 expression in any of the mutants compared with the wild-type control (data not shown). These results indicated that the surface hydrophobicity defects of ΔpdeH and ΔpdeLΔpdeH mutants were likely due to the lowed MPG1 expression.

Bottom Line: As a second messenger, cAMP is important in the activation of downstream effector molecules.This is in contrast to PdeH whose mutation resulted in major defects in conidial morphology, cell wall integrity, and surface hydrophobicity, as well as a significant reduction in pathogenicity.Moreover, microarray data revealed new insights into the underlying cAMP regulatory mechanisms that may help to identify potential pathogenicity factors for the development of new disease management strategies.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing, China.

ABSTRACT
Cyclic AMP (cAMP) signaling plays an important role in regulating multiple cellular responses, such as growth, morphogenesis, and/or pathogenicity of eukaryotic organisms such as fungi. As a second messenger, cAMP is important in the activation of downstream effector molecules. The balance of intracellular cAMP levels depends on biosynthesis by adenylyl cyclases (ACs) and hydrolysis by cAMP phosphodiesterases (PDEases). The rice blast fungus Magnaporthe oryzae contains a high-affinity (PdeH/Pde2) and a low-affinity (PdeL/Pde1) PDEases, and a previous study showed that PdeH has a major role in asexual differentiation and pathogenicity. Here, we show that PdeL is required for asexual development and conidial morphology, and it also plays a minor role in regulating cAMP signaling. This is in contrast to PdeH whose mutation resulted in major defects in conidial morphology, cell wall integrity, and surface hydrophobicity, as well as a significant reduction in pathogenicity. Consistent with both PdeH and PdeL functioning in cAMP signaling, disruption of PDEH only partially rescued the mutant phenotype of ΔmagB and Δpka1. Further studies suggest that PdeH might function through a feedback mechanism to regulate the expression of pathogenicity factor Mpg1 during surface hydrophobicity and pathogenic development. Moreover, microarray data revealed new insights into the underlying cAMP regulatory mechanisms that may help to identify potential pathogenicity factors for the development of new disease management strategies.

Show MeSH
Related in: MedlinePlus