SEC14 phospholipid transfer protein is involved in lipid signaling-mediated plant immune responses in Nicotiana benthamiana.

Akinori Kiba,Yasufumi Hikichi,Yuko Hojo,Ivan Galis,Kouhei Ohnishi,Hirofumi Yoshioka,Mark Gijzen

doi:10.1371/journal.pone.0098150

Akinori Kiba, Yasufumi Hikichi + Show 5 more

Open Access

https://doi.org/10.1371/journal.pone.0098150

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Journal: PloS one	Publication Date: May 20, 2014
Citations: 75	License type: CC BY 4.0

Affiliation: Kōchi University, Okayama University, Nagoya University

Abstract

We previously identified a gene related to the SEC14-gene phospholipid transfer protein superfamily that is induced in Nicotiana benthamiana (NbSEC14) in response to infection with Ralstonia solanacearum. We here report that NbSEC14 plays a role in plant immune responses via phospholipid-turnover. NbSEC14-silencing compromised expression of defense–related PR-4 and accumulation of jasmonic acid (JA) and its derivative JA-Ile. Transient expression of NbSEC14 induced PR-4 gene expression. Activities of diacylglycerol kinase, phospholipase C and D, and the synthesis of diacylglycerol and phosphatidic acid elicited by avirulent R. solanacearum were reduced in NbSEC14-silenced plants. Accumulation of signaling lipids and activation of diacylglycerol kinase and phospholipases were enhanced by transient expression of NbSEC14. These results suggest that the NbSEC14 protein plays a role at the interface between lipid signaling-metabolism and plant innate immune responses.

Highlights

Plants have evolved innate immune responses to detect and respond quickly to foreign infections [1]
To determine the role of NbSEC14 in plant innate immunity, we focused on characteristic immune responses, including hypersensitive response (HR), salicylic acid (SA)-dependent and jasmonic acid (JA)-dependent signaling pathways
In control leaves inoculated with Ralstonia solanacearum strains 8107 (Rs8107), expression of NbSEC14 and PR-4, a marker gene for JA signaling, showed peaks of expression at 12 and 24 hours after inoculation (HAI), respectively, but PR-4 transcript levels were greatly reduced in NbSEC14-silenced leaves

Summary

Introduction

Plants have evolved innate immune responses to detect and respond quickly to foreign infections [1]. Intracellular signaling cascades, such as changes in ion fluxes, cytoplasmic Ca2+ levels, oxidative burst, protein phosphorylation, and the production of stress-related hormonal substances, are required for the establishment of plant immune responses [5,6]. In Nicotiana plants, members of the mitogen activated protein kinase (MAPK) family, SIPK, WIPK, and NTF6, are involved in defense induction in response to PAMPs, INF1 and HWC [11,12]. Both WIPK and SIPK are sufficient to induce N-gene mediated resistance to the tobacco mosaic virus [13]. ET/JA pathways are required for necrotrophic resistance against Alternaria brassicicola [18]

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