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Increase in Endogenous and Exogenous Cyclic AMP Levels Inhibits Sclerotial Development in Sclerotinia sclerotiorum
Abstract:
Growth and development of a wild-type Sclerotinia sclerotiorum isolate were examined in the presence of various pharmacological compounds to investigate signal transduction pathways that influence the development of sclerotia. Compounds known to increase endogenous cyclic AMP (cAMP) levels in other organisms by inhibiting phosphodiesterase activity (caffeine and 3-isobutyl-1-methyl xanthine) or by activating adenylate cyclase (NaF) reduced or eliminated sclerotial development in S. sclerotiorum. Growth in the presence of 5 mM caffeine correlated with increased levels of endogenous cAMP in mycelia. In addition, incorporation of cAMP into the growth medium decreased or eliminated the production of sclerotia in a concentration-dependent manner and increased the accumulation of oxalic acid. Inhibition of sclerotial development was cAMP specific, as exogenous cyclic GMP, AMP, and ATP did not influence sclerotial development. Transfer of developing cultures to cAMP-containing medium at successive time points demonstrated that cAMP inhibits development prior to or during sclerotial initiation. Together, these results indicate that cAMP plays a role in the early transition between mycelial growth and sclerotial development.
Insights
Cyclic adenosine monophosphate (cAMP) significantly inhibits sclerotial development in Sclerotinia sclerotiorum. This finding reveals cAMP
Area of Science:
- Mycology
- Plant Pathology
- Biochemistry
Background:
- Sclerotinia sclerotiorum is a significant plant pathogen.
- Sclerotial development is crucial for the life cycle and pathogenicity of S. sclerotiorum.
- Signal transduction pathways regulating sclerotial development are not fully understood.
Purpose of the Study:
- To investigate the role of cyclic adenosine monophosphate (cAMP) in regulating sclerotial development in Sclerotinia sclerotiorum.
- To explore signal transduction pathways influencing sclerotia formation.
Main Methods:
- Examining the growth and development of S. sclerotiorum in the presence of pharmacological compounds affecting cAMP levels (caffeine, 3-isobutyl-1-methyl xanthine, NaF).
- Measuring endogenous cAMP levels in mycelia.
- Incorporating exogenous cAMP, cyclic guanosine monophosphate (cGMP), adenosine monophosphate (AMP), and adenosine triphosphate (ATP) into the growth medium.
- Assessing the impact of cAMP on oxalic acid accumulation.
- Monitoring the effect of timed transfer to cAMP-containing medium on development.
Main Results:
- Compounds that increase intracellular cAMP levels (caffeine, NaF) reduced or eliminated sclerotial development.
- Exogenous cAMP incorporation inhibited sclerotia production in a dose-dependent manner.
- cAMP treatment increased oxalic acid accumulation.
- Inhibition was specific to cAMP; other cyclic nucleotides and ATP had no effect.
- cAMP inhibited development before or during the initiation of sclerotia.
Conclusions:
- Cyclic adenosine monophosphate (cAMP) plays a critical role in inhibiting the transition from mycelial growth to sclerotial development in S. sclerotiorum.
- cAMP signaling is a key regulatory mechanism in the early stages of sclerotia formation.
- These findings provide insights into potential targets for controlling S. sclerotiorum through manipulation of cAMP pathways.