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- Root-mediated signal transmission of systemic acquired resistance against above-ground and below-ground pathogens
- Geun Cheol Song; H J Sim; S G Kim; Choong-Min Ryu
- Bibliographic Citation
- Annals of Botany, vol. 118, pp. 821-831
- Publication Year
- Background and Aims Plants modulate defence signalling networks in response to various biotic stresses via
inter-organ communications. The root-mediated transmission of systemic acquired resistance (SAR) against soilborne
and air-borne plant pathogens from SAR-induced plants to neighbouring plants subjected to local chemical
and pathogen treatments was evaluated.
Methods The first two plants out of ten Nicotiana benthamiana seedlings were pre-treated with the SARtriggering
chemical benzothiadiazole (BTH). All ten seedlings were then challenged with two pathogenic bacteria,
i.e. the root (bacterial wilt) pathogen Ralstonia solanacearum and the leaf (wildfire) pathogen Pseudomonas syringae
pv. tabaci, at 7 d after SAR induction.
Key Results Disease severity was noticeably lower in BTH-pre-treated plants than in the control. Surprisingly,
two plants located next to BTH-treated plants exhibited reduced disease symptoms indicating that SAR signal transmission
occurred through the root system. Determinant(s) secreted from the root system were search for and it was
found that salicylic acid (SA) is a major molecule involved in SAR transmission through the root. Analysis of the
expression of the defence-related genes N. benthamiana pathogenesis-related gene 1a (NbPR1a) and NbPR2 confirmed
that BTH treatment elicited SAR via root？root transmission between plants. Plants with knock-down of the
multiple resistance component SGT1 and SA biosynthesis-related gene ICS1 by Tobacco rattle virus-mediated
virus-induced gene silencing exhibited a lack of root-mediated SAR transmission. The biological relevance of this
finding was validated by challenge with the SAR-inducing avirulent pathogen P. syringae pv. syringae instead of
BTH, which produced similar results.
Conclusions Our findings demonstrated that SAR is transmissible through the root system from SAR-triggered
plants to neighbouring plants.
- Systemic acquired resistance; root-to-root transmission; signal transduction; benzothiadiazole; salicylic acid; Nicotiana benthamiana.
- Oxford Univ Press
- Appears in Collections:
- Division of Research on National Challenges > Infectious Disease Research Center > 1. Journal Articles
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