Ca2+ regulation of Phyllosticta ampelicida pycnidiospore germination and appressorium Formation.
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.
Shaw
B D
BD
Department of Plant Pathology, Cornell University, Geneva, New York 14456, USA.
Hoch
H C
HC
D001203:Ascomycota / Q000187:drug effects / Q000502:physiology*; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002147:Calmodulin / Q000037:antagonists & inhibitors / Q000494:pharmacology; D015398:Signal Transduction; D013172:Spores, Fungal / Q000187:drug effects / Q000502:physiology*
D002121:Calcium Channel Blockers; D002147:Calmodulin; D002118:Calcium