Natural variation in responsiveness of Arabidopsis thaliana to methyl jasmonate is developmentally regulated

A number of Arabidopsis thaliana (L.) Heynh ecotypes were assayed for their responses to methyl jasmonate in order to determine any natural variation in response to this volatile signal. We observed that the regulation of methyl jasmonate-induced expression of the vegetative storage proteins VSP1 and VSP2 is linked to the developmental stage of the plants. In two ecotypes investigated further, Gr-3 and Col-0, it was observed that the VSP1/2 genes became non-responsive to methyl jasmonate stimulation as the plants progressed to bolt formation and flowering. However, the onset of when this transcriptional inactivation occurred differed between the two ecotypes, with Col-0 displaying still high levels of transcript at the onset of flowering whereas Gr-3 showed no induction of VSP1/2 transcription at the same developmental stage. To our knowledge, this is the first time that such a pattern of regulation has been described for a methyl jasmonate-regulated gene. Moreover, in an F(2) population of a cross between these two ecotypes, the trait for VSP1/2 methyl jasmonate non-responsiveness' segregated among individuals, indicating the feasibility of mapping the genetic components of this response.