Abstract
To elucidate the molecular mechanisms of disease susceptibility in plants, we identified NbPAP (Nicotiana benthamiana phosphatidic acid phosphatase), which is specifically expressed in Nicotiana plants by inoculation with pathogenic strain of Ralstonia solanacearum (RsOE1-1). In NbPAP-silenced plants, expression of a maker gene for jasmonic acid (JA) signaling PR-4 and generation of reactive oxygen species (ROS) were accelerated by RsOE1-1 inoculation. Silencing of NbPAP reduced growth of RsOE1-1 and appearance of bacterial wilt, suggesting the enhancement of resistance by NbPAP-silencing. The enhanced-resistance was partially compromised by double silencing of NbPAP with either COI1 or RbohB. In contrast, the enhanced-resistance was hardly affected in salicylic acid deficient NahG plant. Moreover, NbPAP-silenced plants also showed highly resistance to pathogenic bacteria Pseudomonas syringae pv. tabaci and P. syringae pv. mellea compared with control plants.
These results indicate that NbPAP acts as a negative regulator of JA- and ROS-signaling in a response to RsOE1-1 infection. Collectively, NbPAP might be a host disease-susceptibility gene for bacterial disease in Nicotiana.
