Competition mediates costs of jasmonate-induced defences, nitrogen acquisition and transgenerational plasticity in Nicotiana attenuata

1. Plants adjust their phenotype in response to environmental signals, but little is known about the interaction of plastic responses to simultaneousl y occurring environmental stresses. 2. To examine the costs of induced resistance on reproductive performance i n plants subjected to other important environmental variables, resistance w as elicited with a jasmonate treatment (MeJA) to one, both or neither of tw o Nicotiana attenuata plants growing competitively in either high- or low-N soils. Half the plants were subjected to leaf removal (LR). (KNO3)-N-15 wa s used to quantify differences in N acquisition and allocation. Transgenera tional effects were measured with seed germination and seedling performance tests. 3. An induced plant competing with an uninduced plant produced significantl y fewer seeds, acquired less N-15 and allocated less N-15 to seed productio n. Uninduced plants competing with induced plants realized a comparable fit ness benefit. 4. The costs of induction were greater under high N. Plants grown under low N minimized costs by allocating significantly more N to seeds. LR decrease d seed production independently of any other effect. Low N and LR both redu ced germination rates. 5. The effects of MeJA on seed germination depended on competition and N su pply. The differences in germination rates resulted in dramatic fitness dif ferences among offspring. 6. N. attenuata plants appear to use N availability and their induced statu s to alter their current phenotype and their offspring's phenotype to adjus t to environmental changes that occur predictably over time in their natura l environment.