A high-throughput screen of cell-death-inducing factors in Nicotiana benthamiana identifies a novel MAPKK that mediates INF1-induced cell death signaling and non-host resistance to Pseudomonas cichorii

作者：Takahashi Yoshihiro; Bin Nasir Khairun Hisam; Ito Akiko; Kanzaki Hiroyuki; Matsumura Hideo; Saitoh Hiromasa; Fujisawa Shizuko; Kamoun Sophien; Terauchi Ryohei^*

来源：Plant Journal, 2007, 49(6): 1030-1040.

DOI：10.1111/j.1365-313X.2006.03022.x

• mitogen-activated protein kinase kinase
• cell death
• phytophthora infestans
• nuclear localization
• virus-induced gene silencing
• non-host resistance

A high-throughput overexpression screen of Nicotiana benthamiana cDNAs identified a gene for a mitogen-activated protein kinase kinase (MAPKK) as a potent inducer of the hypersensitive response (HR)-like cell death. NbMKK1 protein is localized to the nucleus, and the N-terminal putative MAPK docking site of NbMKK1 is required for its function as a cell-death inducer. NbMKK1-mediated leaf-cell death was compromised in leaves where NbSIPK expression was silenced by virus-induced gene silencing. A yeast two-hybrid assay showed that NbMKK1 and NbSIPK physically interact, suggesting that NbSIPK is one of the downstream targets of NbMKK1. Phytophthora infestans INF1 elicitor-mediated HR was delayed in NbMKK1-silenced plants, indicating that NbMKK1 is involved in this HR pathway. Furthermore, the resistance of N. benthamiana to a non-host pathogen Pseudomonas cichorii was compromised in NbMKK1-silenced plants. These results demonstrate that MAPK cascades involving NbMKK1 control non-host resistance including HR cell death.