Chloroplast-mediated activation of plant immune signalling in Arabidopsis.
Chloroplasts have a critical role in plant immunity as a site for the production for salicylic acid and jasmonic acid, important mediators of plant immunity. However, the molecular link between chloroplasts and the cytoplasmic-nuclear immune system remains largely unknown. Here we show that pathogen-associated molecular pattern (PAMP) signals are quickly relayed to chloroplasts and evoke specific Ca(2+) signatures in the stroma. We further demonstrate that a chloroplast-localized protein, named calcium-sensing receptor (CAS), is involved in stromal Ca(2+) transients and responsible for both PAMP-induced basal resistance and R gene-mediated hypersensitive cell death. CAS acts upstream of salicylic acid accumulation. Transcriptome analysis demonstrates that CAS is involved in PAMP-induced expression of defence genes and suppression of chloroplast gene expression possibly through (1)O(2)-mediated retrograde signalling, allowing chloroplast-mediated transcriptional reprogramming during plant immune responses. The present study reveals a previously unknown chloroplast-mediated signalling pathway linking chloroplasts to cytoplasmic-nuclear immune responses.
Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Sakyo-ku, Kyoto 606-8522, Japan.
Hironari
H
Nomura
Teiko
T
Komori
Shuhei
S
Uemura
Yui
Y
Kanda
Koji
K
Shimotani
Kana
K
Nakai
Takuya
T
Furuichi
Kohsuke
K
Takebayashi
Takanori
T
Sugimoto
Satoshi
S
Sano
I Nengah
IN
Suwastika
Eiichiro
E
Fukusaki
Hirofumi
H
Yoshioka
Yoichi
Y
Nakahira
Takashi
T
Shiina
D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D002736:Chloroplasts / Q000378:metabolism*; D057865:Plant Immunity / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology
D029681:Arabidopsis Proteins