Mechanisms of Theophylline on Sclerotial Formation Based on cAMP-PKA Pathway
Sclerotia play a core role in the life cycle of Sclerotinia sclerotiorum.Theophylline can act on PDEs in the cAMP-PKA pathway and affect the growth and development of organisms.This study investigates the effects of exogenous theophylline on the production of sclerotia and related factors in the pathway,with the aim of providing a reference for the development of new fungicides.Different concentrations of theophylline were added externally to evaluate its effect on the growth inhibition rate and sclerotial formation of mycelium,and then the effect of theophylline on the cAMP content in mycelium was investigated using a reagent kit.Finally,the changes in relevant factors in the cAMP-PKA pathway were detected by qRT-PCR.The results showed that the addition of exogenous theophylline at a final concentration of 1 mmol/L to 2.5 mmol/L inhibited the growth rate of hyphae and the formation of sclerotia,while theophylline at a final concentration of 0.5 mmol/L had al-most no effect on the growth rate of hyphae.The exogenous addition of theophylline mainly enhanced the intracel-lular cAMP content during the S4 stage of sclerotia primordia formation and the S5 stage of sclerotia maturation,while there was no difference in the intracellular cAMP content between the SI～S3 stages and the control group.Theophylline increased the intracellular cAMP content by inhibiting the expression level of PDE2,while the ex-pression levels of the downstream genes PKA and RAS also decreased accordingly.The expression level of ATG8 significantly increased after the exogenous addition of theophylline.In conclusion,a certain concentration of the-ophylline has an inhibitory effect on the growth rate of Sclerotinia sclerotiorum hyphae and the production of scle-rotia.Exogenous addition of theophylline can increase the intracellular cAMP content by inhibiting the expression of PDE2,resulting in a corresponding decrease in downstream gene expression.
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