The role of vacuolar processing enzyme (VPE) from Nicotiana benthamiana in the elicitor-triggered hypersensitive response and stomatal closure.
Elicitors/pathogen-associated molecular patterns (PAMPs) trigger the plant immune system, leading to rapid programmed cell death (hypersensitive response, HR) and stomatal closure. Previous reports have shown that the vacuolar processing enzyme (VPE), a cysteine proteinase responsible for the maturation of vacuolar proteins, has caspase-1-like activity and mediates TMV- and mycotoxin-induced cell death. The role of VPE from Nicotiana benthamiana in the response to three elicitors: bacterial harpin, fungal Nep1, and oomycete boehmerin, is described here. Single-silenced (NbVPE1a or NbVPE1b) and dual-silenced (NbVPE1a/1b) N. benthamiana plants were produced by virus-induced gene silencing. Although NbVPE silencing does not affect H(2)O(2) accumulation triggered by boehmerin, harpin, or Nep1, the HR is absent in NbVPE1a- and NbVPE1a/1b-silenced plants treated with harpin alone. However, NbVPE-silenced plants develop a normal HR after boehmerin and Nep1 treatment. These results suggest that harpin-triggered HR is VPE-dependent. Surprisingly, all gene-silenced plants show significantly impaired elicitor-induced stomatal closure and elicitor-promoted nitric oxide (NO) production in guard cells. Dual-silenced plants show increased elicitor-triggered AOS production in guard cells. The accumulation of transcripts associated with defence and cell redox is modified by VPE silencing in elicitor signalling. Overall, these results indicate that VPE from N. benthamiana functions not only in elicitor-induced HR, but also in elicitor-induced stomatal closure, suggesting that VPE may be involved in elicitor-triggered immunity.
Zhang
Huajian
H
Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing, 210095, China.
Dong
Suomeng
S
Wang
Meifang
M
Wang
Wei
W
Song
Wenwen
W
Dou
Xianying
X
Zheng
Xiaobo
X
Zhang
Zhengguang
Z
D000975:Antioxidants / Q000494:pharmacology; D001425:Bacterial Outer Membrane Proteins / Q000494:pharmacology; D016923:Cell Death / Q000187:drug effects / Q000502:physiology*; D003546:Cysteine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D005656:Fungal Proteins / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D020868:Gene Silencing; D006706:Homeostasis / Q000235:genetics; D006861:Hydrogen Peroxide / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D010575:Pesticides / Q000494:pharmacology; D054046:Plant Stomata / Q000187:drug effects / Q000378:metabolism*; D011794:Quercetin / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D014026:Nicotiana / Q000166:cytology / Q000201:enzymology* / Q000235:genetics; D014027:Tobacco Mosaic Virus / Q000378:metabolism
D000975:Antioxidants; D001425:Bacterial Outer Membrane Proteins; D005656:Fungal Proteins; D010575:Pesticides; D017382:Reactive Oxygen Species; C075462:harpin protein, Erwinia amylovora; D009569:Nitric Oxide; C009856:boehmerin; D011794:Quercetin; D006861:Hydrogen Peroxide; D003546:Cysteine Endopeptidases; C089278:vacuolar processing enzyme