Localization of Calcium-Dependent Protein Kinase in Potato Microsomal Fraction and its Role in Phytophthora infestans Hyphal Cell Wall Component and Suppressor Signal Transduction

摘要

We investigated localization of calcium-dependent protein kinase (CDPK) in potato microsomal fraction (MF) and its role in relation to hyphal cell wall component (HWC) and suppressor glucan (suppressor) of Phytophthora infestans (Mont.) de Bary in hypersensitive resistance response (HR). Additionally, we studied activity of CDPK from MF in the absence and presence of staurosporine, a kinase inhibitor and okadaic acid, a phosphatase inhibitor. Stimulation of MF kinase activity by the addition of Ca²⁺ supported the presence of CDPKs in MF. This was confirmed when a 70 kDa CDPK was detected in potato MF using western immunoblot analysis. HWC and suppressor stimulated kinase activity of MF within 5-10 min after application. In the presence of staurosporine, HWC stimulated MF kinase activity but suppressor did not. In the presence of okadaic acid, HWC inhibited and suppressor stimulated kinase activity of MF. These results suggest that HWC and suppressor may interact with potato kinase(s) in the MF, initiating a signal leading to the occurrence of HR, or in the case of suppressor, to the inhibition of HR. We suggest that the signal cascades involving HWC and suppressor from P. infestans may be different in incompatible and compatible interactions, respectively, occurring between potato and P. infestans .