Marlin, Danica, Nicolson, Susan W., Yusuf, Abdullahi A., Stevenson, Philip C. ORCID: https://orcid.org/0000-0002-0736-3619, Heyman, Heino M. and Kruger, Kerstin (2014) The only African wild tobacco, Nicotiana africana: Alkaloid content and the effect of herbivory. PLOS ONE, 9 (7):e10266. ISSN 1932-6203 (doi:10.1371/journal.pone.0102661)

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Abstract

Herbivory in some Nicotiana species is known to induce alkaloid production. This study examined herbivore-induced defenses in the nornicotine-rich African tobacco N. africana, the only Nicotiana species indigenous to Africa. We tested the predictions that: 1) N. africana will have high constitutive levels of leaf, flower and nectar alkaloids; 2) leaf herbivory by the African bollworm Helicoverpa armigera will induce increased alkaloid levels in leaves, flowers and nectar; and 3) increased alkaloid concentrations in herbivore-damaged plants will negatively affect larval growth. We grew N. africana in large pots in a greenhouse and exposed flowering plants to densities of one, three and six fourth-instar larvae of H. armigera, for four days. Leaves, flowers and nectar were analyzed for nicotine, nornicotine and anabasine. The principal leaf alkaloid was nornicotine (mean: 28 µg/g dry mass) followed by anabasine (4.9 µg/g) and nicotine (0.6 µg/g). Nornicotine was found in low quantities in the flowers, but no nicotine or anabasine were recorded. The nectar contained none of the alkaloids measured. Larval growth was reduced when leaves of flowering plants were exposed to six larvae. As predicted by the optimal defense theory, herbivory had a localized effect and caused an increase in nornicotine concentrations in both undamaged top leaves of herbivore damaged plants and herbivore damaged leaves exposed to one and three larvae. The nicotine concentration increased in damaged compared to undamaged middle leaves. The nornicotine concentration was lower in damaged leaves of plants exposed to six compared to three larvae, suggesting that N. africana rather invests in new growth as opposed to protecting older leaves under severe attack. The results indicate that the nornicotine-rich N. africana will be unattractive to herbivores and more so when damaged, but that potential pollinators will be unaffected because the nectar remains alkaloid-free even after herbivory.

Item Type:	Article
Additional Information:	[1] Citation: Marlin D, Nicolson SW, Yusuf AA, Stevenson PC, Heyman HM, et al. (2014) The Only African Wild Tobacco, Nicotiana africana: Alkaloid Content and the Effect of Herbivory. PLoS ONE 9(7): e102661. doi:10.1371/journal.pone.0102661. [2] Copyright: � 2014 Marlin et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Uncontrolled Keywords:	African wild yobacco, Nicotiana africana, alkaloid content Herbivory
Subjects:	S Agriculture > SB Plant culture
Faculty / School / Research Centre / Research Group:	Faculty of Engineering & Science > Natural Resources Institute Faculty of Engineering & Science > Natural Resources Institute > Agriculture, Health & Environment Department Faculty of Engineering & Science > Natural Resources Institute > Chemical Ecology Research Group
Related URLs:	Publisher
Last Modified:	05 Nov 2016 16:36
URI:	http://gala.gre.ac.uk/id/eprint/12117

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