Perception of extracellular damage
Plants are often exposed to injury and serve as hosts for a variety of pests and pathogens. Therefore, they require mechanisms to detect damage, inform the plant about tissue disruption, and initiate processes aimed at restoring homeostasis. A variety of damage signals can inform the plant about the occurrence of lesions, including chemical and physical ones. The jasmonate pathway is a key regulator of plant defense responses. In spite of its importance, it is still unknown what molecular mechanisms trigger JA production. We have recently isolated novel mutants, which are now being characterized to identify those sensing mechanisms. In addition, we are quantifying the stimulus needed to activate intracellular JA signalling with a mechanistic approach.
Cellular specificity of JA responses
The activation of JA-mediated defense is costly and often accompanied by signiﬁcant growth inhibition. To therefore effectively coordinate growth-defense trade-offs in both space and time, JA-Ile signalling mediated by MYC transcription factors (chiefly MYC2, MYC3 and MYC4) is normally inhibited by a modular repressor complex of JAZ, NINJA and TPL proteins. The presence of several MYCs and 13 JAZ genes in Arabidopsis, some of which are subjected to alternative splicing, suggests that there is large diversity in small molecule recognition and signalling in different tissues and cell-types. We are currently investigating those cellular specificities in JA-regulated responses.