Soybean isoflavones trigger a calcium influx in Phytophthora sojae.
Both the motile zoospores and the hyphal germ tubes of Phytophthora sojae respond chemotropically to the soybean isoflavones daidzein and genistein. The role of Ca(2+) in the cellular response to these host signals was investigated by using X-ray microanalysis of cells to monitor net changes in cellular levels of Ca(2+) and by quantifying the effects of exogenous Ca(2+) and daidzein on the developmental fate of encysted zoospores. Confirmation that isoflavones trigger a net influx of Ca(2+) into the cell was demonstrated by X-ray microanalysis of individual encysted zoospores. Zoospores exposed to 10 mM Ca(2+) and 1 microM daidzein at the time of encystment formed cysts that contained more Ca(2+) than zoospores exposed to Ca(2+) alone. The magnitude of internal Ca(2+) stores appears to be a determining factor affecting the developmental fate of P. sojae cysts.
Connolly
M S
MS
Department of Biological Sciences, Bowling Green State University, Bowling Green, Ohio, 43403, USA.
Williams
N
N
Heckman
C A
CA
Morris
P F
PF
D002118:Calcium / Q000819:agonists / Q000378:metabolism*; D002633:Chemotaxis; D003470:Culture Media / Q000737:chemistry; D004577:Electron Probe Microanalysis; D019833:Genistein / Q000494:pharmacology*; D007529:Isoflavones / Q000494:pharmacology*; D010838:Phytophthora / Q000187:drug effects* / Q000502:physiology; D013025:Glycine max / Q000737:chemistry*; D013170:Spores / Q000737:chemistry / Q000254:growth & development
D003470:Culture Media; D007529:Isoflavones; C004742:daidzein; D019833:Genistein; D002118:Calcium