Ca2+ regulation of Phyllosticta ampelicida pycnidiospore germination and appressorium Formation

Fungal Genet Biol. 2000 Oct;31(1):43-53. doi: 10.1006/fgbi.2000.1223.

Abstract

Phyllosticta ampelicida conidia germinate only after making contact with and attaching to a substratum. Previous studies suggested a role for Ca2+ in this process. A Ca2+ buffering system was used to control the external free Ca2+ concentration. Both germination and appressorium formation were reduced or abolished with low Ca2+ (less than or equal to nanomolar levels) but were nearly 100% at millimolar levels of Ca2+. Germination initiation required Ca2+ within 10-25 min after the spore made contact with the substratum. Appressorium initiation required Ca2+ 90-120 min following initial contact. Ca2+ channel blockers nicardipine and lanthanum abated spore development. TMB-8, a blocker of internal Ca2+ channels, reduced both developmental events. Gadolinium, a putative stretch-activated Ca2+ channel blocker, abolished both developmental events at nanomolar levels. Calmodulin antagonists, compounds R-24751 and 48/80, abated spore development at micromolar levels. Together, these results suggest that Ca2+ signaling is involved in both germination and appressorium formation in P. ampelicida pycnidiospores.

MeSH terms

  • Ascomycota / drug effects
  • Ascomycota / physiology*
  • Calcium / metabolism*
  • Calcium / pharmacology
  • Calcium Channel Blockers / pharmacology
  • Calmodulin / antagonists & inhibitors
  • Calmodulin / pharmacology
  • Signal Transduction
  • Spores, Fungal / drug effects
  • Spores, Fungal / physiology*

Substances

  • Calcium Channel Blockers
  • Calmodulin
  • Calcium