Nicotine's Defensive Function in Nature

• DOI: 10.1371/journal.pbio.0020217
• Publication Date: 2004-08-09T15:19:13Z
• Authors: Anke Steppuhn; Klaus Gase; Bernd Krock; Rayko Halitschke; Ian T Baldwin
• Keywords: Beet armyworm; Exigua; Cabbage looper

Plants produce metabolites that directly decrease herbivore performance, and as a consequence, herbivores are selected for resistance to these metabolites. To determine whether actually function defenses requires measuring the performance of plants altered only in production certain metabolite. date, defensive value most plant traits has not been demonstrated nature. We transformed native tobacco(Nicotiana attenuata) with consensus fragment its two putrescine N-methyl transferase (pmt) genes either antisense or inverted-repeat (IRpmt) orientations. Only latter reduced (by greater than 95%) constitutive inducible nicotine. With D4-nicotinic acid (NA), we demonstrate silencing pmt inhibits nicotine production, while excess NA dimerizes form anatabine. Larvae nicotine-adapted Manduca sexta (tobacco hornworm) grew faster and, like beetle Diabrotica undecimpunctata, preferred IRpmt choice tests. When planted their habitat, were attacked more frequently compared wild-type plants, lost 3-fold leaf area from variety herbivores, which beet armyworm, Spodoptera exigua, Trimerotropis spp. grasshoppers caused damage. These results provide strong evidence functions an efficient defense nature highlights transgenic techniques ecological research.