Bd. Shaw et Hc. Hoch, Ca2+ regulation of Phyllosticta ampelicida pycnidiospore germination and appressorium formation, FUNGAL G B, 31(1), 2000, pp. 43-53
Phyllosticta ampelicida conidia germinate only after making contact with an
d 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 reduc
ed or abolished with low Ca2+ (less than or equal to nanomolar levers) but
were nearly 100% at millimolar levels of Ca2+. Germination initiation requi
red 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 eve
nts. Gadolinium, a putative stretch-activated Ca2+ channel blocker, abolish
ed both developmental events at nanomolar levels. Calmodulin antagonists, c
ompounds R-24751 and 48/80, abated spore development at micromolar revels.
Together, these results suggest that Ca2+ signaling is involved in both ger
mination and appressorium formation in P. ampelicida pycnidiospores. (C) 20
00 Academic Press.