Abstract
Oligogalacturonides (OGs) are fragments of pectin released from the
plant cell wall during insect or pathogen attack. They can be perceived
by the plant as damage signals, triggering local and systemic defence
responses. Here, we analyse the dynamics of local and systemic responses
to OG perception in tomato roots or shoots, exploring their impact
across the plant and their relevance in pathogen resistance. Targeted
and untargeted metabolomics and gene expression analysis in plants
treated with purified OGs revealed that local responses were transient,
while distal responses were stronger and more sustained. Remarkably,
changes were more conspicuous in roots, even upon foliar application of
the OGs. The treatments differentially activated the synthesis of
defence-related hormones and secondary metabolites including flavonoids,
alkaloids and lignans, some of them exclusively synthetized in roots.
Finally, the biological relevance of the systemic defence responses
activated upon OG perception was confirmed, as the treatment induced
systemic resistance to Botrytis cinerea. Overall, this study shows the
differential regulation of tomato defences upon OGs perception in roots
and shoots and reveal the key role of roots in the coordination of the
plant responses to damage sensing.