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Elevated carbon dioxide reduces emission of herbivore‐induced volatiles in Zea mays

2017; Wiley; Volume: 40; Issue: 9 Linguagem: Inglês

10.1111/pce.12976

1365-3040

Anna K. Block, Martha Vaughan, Shawn A. Christensen, Hans T. Alborn, James H. Tumlinson,

Insect-Plant Interactions and Control

Abstract Terpene volatiles produced by sweet corn ( Zea mays ) upon infestation with pests such as beet armyworm ( Spodoptera exigua ) function as part of an indirect defence mechanism by attracting parasitoid wasps; yet little is known about the impact of climate change on this form of plant defence. To investigate how a central component of climate change affects indirect defence, we measured herbivore‐induced volatile emissions in plants grown under elevated carbon dioxide (CO 2 ). We found that S. exigua infested or elicitor‐treated Z. mays grown at elevated CO 2 had decreased emission of its major sesquiterpene, ( E )‐β‐caryophyllene and two homoterpenes, (3 E )‐4,8‐dimethyl‐1,3,7‐nonatriene and (3 E ,7 E )‐4,8,12‐trimethyl‐1,3,7,11‐tridecatetraene. In contrast, inside the leaves, elicitor‐induced ( E )‐β‐caryophyllene hyper‐accumulated at elevated CO 2 , while levels of homoterpenes were unaffected. Furthermore, gene expression analysis revealed that the induction of terpene synthase genes following treatment was lower in plants grown at elevated CO 2 . Our data indicate that elevated CO 2 leads both to a repression of volatile synthesis at the transcriptional level and to limitation of volatile release through effects of CO 2 on stomatal conductance. These findings suggest that elevated CO 2 may alter the ability of Z. mays to utilize volatile terpenes to mediate indirect defenses.