Constitutive Expression of Methyl jasmonate-inducible Responses Delays Reproduction and Constrains Fitness Responses to Nutrients in Arabidopsis thaliana

The analysis of a suite of traits under a range of environmental conditions is necessary to fully examine costs of resistance. I compared phenological, morphological and reproductive traits of several independent lines of a transgenic methyl jasmonate-overproducing Arabidopsis thaliana plant (JMT plants) to that of vector controls in high and low soil nutrient environments. JMT plants constitutively express a suite of responses normally inducible by wounding or jasmonate. JMT plants showed a marked delay in flowering time, and were larger with more leaves at bolting than vector controls. These traits also responded more positively to increased nutrients in JMT plants than in vector controls. At the end of the season, total seed mass and seed number was lower in JMT plants than in vector controls overall, and these traits responded much less positively to nutrient addition in JMT plants than in vector controls. This study revealed delayed phenology as a novel cost of resistance in Arabidopsis and that overproduction of methyl jasmonate and associate responses can substantially constrain fitness responses to nutrients. These results establish a mechanism whereby costs of resistance can be more apparent under high resource conditions, rather than under low resource conditions, as is widely assumed