Plant defences mediate interactions between herbivory and the direct foliar uptake of atmospheric reactive nitrogen

• Published in: Nature communications 2018-11, Vol.9 (1), p.4743-7, Article 4743
• Main Authors: Campbell, Stuart A., Vallano, Dena M.
• Format: Article
• Language: English
• Subjects: 631/158/2455; 631/449/2668; 704/158; 704/158/670; 704/172/4081; 82/16; 82/58; Air pollution; Consumers; Herbivory; Humanities and Social Sciences; Insects; Leaves; Metabolites; multidisciplinary; Nitrogen balance; Nitrogen dioxide; Plant metabolism; Plant roots; Pollutants; Science; Science (multidisciplinary); Smog
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-018-07134-9

Reactive nitrogen from human sources (e.g., nitrogen dioxide, NO 2 ) is taken up by plant roots following deposition to soils, but can also be assimilated by leaves directly from the atmosphere. Leaf uptake should alter plant metabolism and overall nitrogen balance and indirectly influence plant consumers; however, these consequences remain poorly understood. Here we show that direct foliar assimilation of NO 2 increases levels of nitrogen-based defensive metabolites in leaves and reduces herbivore consumption and growth. These results suggest that atmospheric reactive nitrogen could have cascading negative effects on communities of herbivorous insects. We further show that herbivory induces a decrease in foliar uptake, indicating that consumers could limit the ability of vegetation to act as a sink for nitrogen pollutants (e.g., smog from mobile emissions). Our study suggests that the interactions of foliar uptake, plant defence and herbivory could have significant implications for understanding the environmental consequences of reactive nitrogen. Reactive nitrogen oxides can be assimilated by leaves, though the trophic and nitrogen cycling impacts of this are unclear. Here Campbell and Vallano show foliar uptake of NO 2 increases defensive metabolites, reduces herbivore consumption and growth, and herbivory reduces foliar NO 2 uptake.