Jasmonate
[1] Some JAs can also be released as volatile organic compounds (VOCs) to permit communication between plants in anticipation of mutual dangers.
[5] However Van Poecke & Dicke 2003 finds Arabidopsis's emission of volatiles to not require JA-Ile, nor VanDoorn et al 2011 for Solanum nigrum's herbivore resistance.
For example, in the tomato, wounding produces defense molecules that inhibit leaf digestion in guts of insects.
MeJA on leaves can travel airborne to nearby plants and elevate levels of transcripts related to wound response.
[1] In general, this emission can further upregulate JA biosynthesis and cell signaling, thereby inducing nearby plants to prime their defenses in case of herbivory.
JAs' roles in these processes are suggestive of methods by which the plant defends itself against biotic challenges and limits the spread of infections.
Pseudomonas syringae causes bacterial speck disease in tomatoes by hijacking the plant's jasmonate (JA) signaling pathway.
This bacteria utilizes a type III secretion system to inject a cocktail of viral effector proteins into host cells.
By activating the JA wound response pathway, P. syringae could divert resources from its host's immune system and infect more effectively.
[16] Plants produce N-acylamides that confer resistance to necrotrophic pathogens by activating JA biosynthesis and signalling.
AA is an evolutionarily conserved signalling molecule that acts in plants in response to stress similar to that in animal systems.
For example, silencing phenylalanine ammonia lyase (PAL), an enzyme synthesizing precursors to SA, reduces SAR but enhances herbivory resistance against insects.
[19] Cross talk also occurs between JA and other plant hormone pathways, such as those of abscisic acid (ABA) and ethylene (ET).
However, in the presence of JA or its bioactive derivatives, JAZ proteins are degraded, freeing transcription factors for expression of genes needed in stress responses.
Specifically, JA-Ile binds both to a ligand-binding pocket in COI1 and to a 20 amino-acid stretch of the conserved Jas motif in JAZ.
A plant that has lost all three will be as susceptible to damage as coi1 mutants, which are completely unresponsive to JA and cannot mount a defense against herbivory.
