NbHB1, Nicotiana benthamiana homeobox 1, is a jasmonic acid-dependent positive regulator of pathogen-induced plant cell death.
Induction of cell death is an important component of plant defense against pathogens. There have been many reports on the role of phytohormones in pathogen-induced cell death, but jasmonic acid (JA) has not been implicated as a regulator of the response. Here, we report the function of NbHB1, Nicotiana benthamiana homeobox1, in pathogen-induced cell death in connection with JA signaling. Involvement of NbHB1 in cell death was analysed by gain- and loss-of-function studies using Agrobacterium-mediated transient overexpression and virus-induced gene silencing, respectively. Expression of NbHB1 following pathogen inoculations and various treatments was monitored by reverse transcription polymerase chain reaction. Transcript levels of NbHB1 were upregulated by infection with virulent and avirulent bacterial pathogens. Ectopic expression of NbHB1 accelerated cell death following treatment with darkness, methyl jasmonate, or pathogen inoculation. Conversely, when NbHB1 was silenced, pathogen-induced cell death was delayed. NbHB1-induced cell death was also delayed by silencing of NbCOI1, indicating a requirement for JA-mediated signaling. Overexpression of the domain-deleted proteins of NbHB1 revealed that the homeodomain, leucine zipper, and part of the variable N-terminal region were necessary for NbHB1 functionality. These results strongly suggest the role of NbHB1 in pathogen-induced plant cell death via the JA-mediated signaling pathway.
Yoon
Joonseon
J
Department of Biological Sciences, KAIST, Daejeon, 305-701, Republic of Korea.|Department of Plant Science, Plant Genomics and Breeding Institute and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, 151-921, Republic of Korea.
Chung
Won-Il
WI
Department of Biological Sciences, KAIST, Daejeon, 305-701, Republic of Korea.
Choi
Doil
D
Department of Plant Science, Plant Genomics and Breeding Institute and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, 151-921, Republic of Korea.
D000595:Amino Acid Sequence; D016923:Cell Death / Q000187:drug effects; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D003517:Cyclopentanes / Q000494:pharmacology*; D003624:Darkness; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D020868:Gene Silencing / Q000187:drug effects; D018398:Homeodomain Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D054884:Host-Pathogen Interactions / Q000187:drug effects* / Q000235:genetics; D008969:Molecular Sequence Data; D054883:Oxylipins / Q000494:pharmacology*; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000187:drug effects; D011549:Pseudomonas / Q000187:drug effects / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D020539:Sequence Analysis, Protein; D015398:Signal Transduction / Q000187:drug effects; D013312:Stress, Physiological / Q000187:drug effects; D014026:Nicotiana / Q000166:cytology* / Q000235:genetics / Q000382:microbiology*
D003517:Cyclopentanes; D018398:Homeodomain Proteins; D054883:Oxylipins; D010940:Plant Proteins; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; C011006:jasmonic acid