Calcium Interference with Zoospore Biology and Infectivity of Phytophthora parasitica in Nutrient Irrigation Solutions

Abstract

von Broembsen, S. L., and Deacon, J. W. 1997. Calcium interference with zoospore biology and infectivity of Phytophthora parasitica in nutrient irrigation solutions. Phytopathology 87:522-528.Calcium, applied as either CaCl 2 or Ca(NO 3 ) 2 to water or calcium-free soluble fertilizer solution (Peters 20-10-20 Peat Lite Special), affected several important stages of Phytophthora parasitica zoospore behavior relevant to infection and disease spread. Release of zoospores from sporangia was suppressed by Ca 2+ concentrations in the range of 10 to 50 meq. These concentrations also curtailed zoospore motility; 20 meq of Ca 2+ in fertilizer solution caused all zoospores to encyst within 4 h, whereas 94% of zoospores remained motile in unamended solution. In addition, Ca 2+ in the range of 10 to 30 meq stimulated zoospore cysts to germinate in the absence of an organic nutrient trigger, while suppressing

Calcium sulphate soil treatments augment the survival of phosphite-sprayed Banksia leptophylla infected with Phytophthora cinnamomi

“…Ca 2+ 10 -30 mM stimulated zoospores to germinate in the absence of an organic nutrient trigger (von Broembsen and Deacon, 1997) Size of internal Ca stores was a determining factor affecting the developmental fate of P. sojae cysts Germination of P. parasitica cysts was prevented by TMB-8, which inhibits the release of Ca 2+ from intracellular stores (Warburton and Deacon, 1998) …”

“…When calcium 50 ions are included in soil or irrigation solutions, plants infected with Phytophthora show increased resistance 51 to disease as judged by symptom development and time to death (von Broembsen and Deacon, 1997; 52 Serrano et al, 2012). However, as with phosphite, there is debate over whether the 53 control of disease by calcium ions is primarily a result of calcium stimulating plant defense (defense 54 priming) , inhibition of sporangiogenesis in Phytophthora spp.…”

“…The initial transient rise in cytosolic free calcium required to induce cytokinesis in 68 zoosporangia in P. cinnamomi (Jackson and Hardham, 1996) is subverted by either a higher internal (or 69 lower external) background calcium ion concentration. High extracellular calcium concentrations are 70 known to interfere with zoosporogenesis in P. parasitica and reduce the ability of zoospores to infect 71 plants (von Broembsen and Deacon, 1997) and Messenger et al (2000) have shown that sporangial 72 production and inoculum load of P. cinnamomi in gypsum (calcium sulphate) amended soil is significantly 73 reduced. Additionally Irving et al (1984) …”

Effects of Inorganic Elements on the In-vitro Growth of Pythium aphanidermatum (Edson) Fitzp.

“…Closed hydroponics, which utilizes a recirculated nutrient solution, can be most effective 9,16) . However, the environmental conditions in a closed hydroponic system favor the spread of zoosporic fungal pathogens [14][15][16][17] . Pythium aphanidermatum (Edson) Fitzp.…”

“…The application of inorganic elements is one possible method for suppressing target pathogens in closed growing systems. There are reports that some inorganic elements have had suppressive effects on Phytophthora spp 2,15,17) . However, no information is available on other pathogenic zoosporic fungi.…”