NbHB1, Nicotiana benthamiana homeobox 1, is a jasmonic acid‐dependent positive regulator of pathogen‐induced plant cell death

Abstract

Summary 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.

Overcompensation of herbivore reproduction through hyper‐suppression of plant defenses in response to competition

“…When overexpressed in Nicotiana benthamiana , Te28 , Te84 , Tu28 and Tu84 each suppress SA defenses (Villarroel et al ., ). To test if these effectors also affect induced JA defenses, we used Agrobacterium tumefaciens for the transient overexpression of the effector‐encoding genes in N. benthamiana leaves and assessed transcript levels of the JA‐responsive trypsin proteinase inhibitor ( TPI ) (Yoon et al ., ) after the induction of JA defenses in agro‐infiltrated leaves by wounding and subsequent application of Manduca sexta oral secretions to the wounds (W + OS treatment; Methods S3). Compared with the empty vector control, the transient overexpression of Te28 , Te84 , Tu28 or Tu84 significantly reduced the transcript accumulation of TPI in W + OS‐treated leaves (Fig.…”

A common plant cell‐wall protein HyPRP1 has dual roles as a positive regulator of cell death and a negative regulator of basal defense against pathogens

“…To evaluate the effects of HyPRP1 silencing on cell death, avirulent P. syringae pv. tomato T1 ( Pst T1, incompatible) was infiltrated into Nb HyPRP1 ‐silenced N. benthamiana (Yoon et al. , 2009).…”

Morphological Classification of Trichomes Associated with Possible Biotic Stress Resistance in the Genus Capsicum

“…Chili pepper is one of the most important vegetable crop in the world, and quite a few studies were undertaken in molecular biology, genetics and breeding (Kim et al, 2010;Yoon et al, 2009;Yeom et al, 2011;Oh et al, 2008). Because of the association of trichome-forming phenotype with multiple biotic stress resistances, studies on genetic analysis of trichome-formation in pepper plants were performed (Kim et al, 2010).…”