Competition mediates costs of jasmonate-induced defences, nitrogen acquisition and transgenerational plasticity in Nicotiana attenuata
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*Present address: Netherlands Institute of Ecology, Centre for Terrestrial Ecology, Multitrophic Interactions Department, PO Box 40, 6666 ZG Heteren, The Netherlands.
- 1 Plants adjust their phenotype in response to environmental signals, but little is known about the interaction of plastic responses to simultaneously occurring environmental stresses.
- 2 To examine the costs of induced resistance on reproductive performance in plants subjected to other important environmental variables, resistance was elicited with a jasmonate treatment (MeJA) to one, both or neither of two Nicotiana attenuata plants growing competitively in either high- or low-N soils. Half the plants were subjected to leaf removal (LR). K15NO3 was used to quantify differences in N acquisition and allocation. Transgenerational effects were measured with seed germination and seedling performance tests.
- 3 An induced plant competing with an uninduced plant produced significantly fewer seeds, acquired less 15N and allocated less 15N to seed production. Uninduced plants competing with induced plants realized a comparable fitness 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 decreased seed production independently of any other effect. Low N and LR both reduced germination rates.
- 5 The effects of MeJA on seed germination depended on competition and N supply. The differences in germination rates resulted in dramatic fitness differences among offspring.
- 6 N. attenuata plants appear to use N availability and their induced status to alter their current phenotype and their offspring’s phenotype to adjust to environmental changes that occur predictably over time in their natural environment.