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Abstracts - Luiz Rezende

Type of the Presentation: Oral presentation

LEAF DAMAGE AFFECTS VOLATILE EMISSION AND FLORAL VISITATION OF TRICHOGONIOPSIS ADENANTHA (ASTERACEAE)

Luiz Rezende1*, Gustavo Romero2 and Martín Pareja2

1 Programa de Pós-Graduação em Ecologia, Unicamp; hgrluiz@gmail.com

2 Instituto de Biologia, Unicamp; gqromero@gmail.com, martinpareja@unicamp.br

* Correspondence: hgrluiz@gmail.com

Floral visitors commonly use chemical signals, particularly volatile organic compounds (VOCs) that make up the floral scent, to find the flowers they visit. Leaf damage can affect these signals and then floral attractiveness through induction of plant defensive compounds whose biosynthesis compromises the synthesis of floral attractive compounds. Additionally, vegetative VOCs emitted right after damage may change the chemical background upon which flowers are presented. We tested these hypotheses by asking whether different levels of mechanical leaf damage in the reproductive branches of the tropical shrub Trichogoniopsis adenantha (Asteraceae) affect floral VOC profile. We also tested whether damage affects the interaction of the inflorescences with floral visitors and whether this effect depends on time after damage. In the field, we selected 24 plants. One reproductive branch of each plant was randomly submitted to damage in all of its leaves (0%, 25%, 50% or 75% of leaf area removed) and floral visitation was assessed 2 min and 24 h subsequently. To assess changes in VOC profile, we randomly submitted reproductive branches of greenhouse grown plants to mechanical damage with 50% of leaf area removed. The volatiles on floral headspace was collected 2 min and 24 h after manipulation using Dynamic Headspace and Solid-Phase Microextraction techniques. Moderate leaf damage (25-50%) led to a rapid reduction in floral visitation (landings), which was still detected 24 h later. For branches with 25% leaf damage, there was an increase in the mean number of approaches to the inflorescences 24 h later. Regarding volatiles, we detected 48 ​​terpenes, one benzenoid, and one aliphatic compound, none of which were specific to flowers. There was no change in total amount of VOCs emitted after damage, but the emission of certain compounds changed 2 min and 24 h later. The emission of α-phelandrene decreased, and that of β-myrcene and γ-terpinene increased 24 h after damage. Likewise, the emission of (E, E)-4,8,12-Trimethyltrideca-1,3,7,11-Tetraene (TMTT) fell 2 min after damage, and increased 24 h latter. We argue that there is likely to be a cause-effect relationship between changes in VOC profile and floral visitor’s behavior if compounds with reduced emission are attractive, and those with increased emission are repellent or new for them (chemical neophobia). Our results show that vegetative volatiles may be important in plant–floral visitor interactions, and leaf damage can potentially affect these interaction by rapidly and persistently changing its chemical context.