# The Snapdragon LATE Elongated Hypocotyl
## 3 Results
### AmLHY Controls the Timing of Scent Emission  
We detected 15 volatile organic compounds (Table S5; Figures 3 and 4). In wild-type flowers, most selected volatiles showed a diurnal pattern. The release of VOCs started in the early morning, reaching their maximum emission at midday or before dusk. We classified the emitted VOCs in three groups based on their time of maximum emission. The first group comprises myrce, ocimee, linalool,  
Figure 4: Daily scent emission of minor compounds in wild type (**a**), and transgenic lines _RNAi:AmLHY14_ (**b**), _RNAi:AmLHY26_ (**c**), _RNAi:AmLHY27_ (**d**). An average of RNAi lines is represented in (**e**). ZT indicates _zeifigger_ time. decanal, nonanal, 3,5-dimethoxyytoluene, 2-hydroxiacetophenone, and methyl cinnamate, that reached their maximum emission at early day and midday. A second group included cinnamyl alcohol and farnesene that peaked at the end of the light period. Finally, the third group covered acetophenone, methyl benzoate, and methyl salicylate, which increased their emission at midnight (Table S6). In contrast, we found that the maximum emission of some VOCs shifted in RNAi lines, and we divided the volatiles into three groups. First, the monoterpene linalool, the aldehydes nonanal and decanal and the benzenoids/phenylpropanoids cinnamyl alcohol, 3,5-dimethoxyytoluene, and 2-hydroxyacetophenone did not present any differences with wild-type flowers, showing its maximum emission at the same time. The second group comprised the derivatives of benzoic acid methyl benzoate and methyl salicylate, and the monoterenes myrcene and ocimene, which delayed their maximum emission. Finally, acetophenone, benzaldehyde, methyl cinnamate (except in line _RNAi:AmLHY26_, which did not show any difference) and the sesquiterpene famesene peaked early in transgenic lines (Table S6). We could not determine the phase of the ethyl benzoate, due to their irregular emission (Table S6). Based on the known phenylpropanol/benzenoid pathway we divided it into two principal branches, which have a common precursor, L-phenylalanine. The first branch included those compounds that derived from trans-cinnamic acid, as methyl cinnamate. The second branch covered benzoic acid derivatives, methyl salicylate, and methyl benzoate (Figure 5). Our results showed that the down-regulation of _AmLHY_ advanced the maximum emission of acetophenone, benzaldehyde, and methyl cinnamate, while it caused a delayed peak of methyl salicate and methyl benzoate. We found a similar pattern in terpene emission. Geranyl pyrophosphate (GPP) is the precursor of the monoterenes linalool, myrcene, and ocimene [61], whose reactions are catalyzed by linalool synthase (LS), myrcene synthase (MYS) and ocimene synthase (OCS), respectively. RNAi flowers displayed a delayed emission of myrcene and ocimene, peaking at midday (ZT6). In contrast, linalool  
Figure 5: Schematic view of some phenylpropanoids/benzenoids (**a**), monoterenes (**b**) and sesquiterpenes (**c**) pathway. Non-volatile compounds are represented in a dashed and blue rectangle and volatile compounds with a solid line and a rounded rectangle, the green color indicates a volatile that displays a delayed emission and the red color, an advanced emission. Enzymes and the C\({}_{5}\) unit IPP (isopentyl diphosphate) are shown over the arrows. Enzyme abbreviations: BA2H (benzoic acid 2-hydroxylase), BALDH (benzaldehyde dehydrogenase), BAMT (benzoic acid carboxyl methyl transferase), CCMT (cinnamic acid carboxyl methyl transferase), FS (farnesene synthase), LS (linalool synthase), MYS (myrcene synthase), OCS (ocimene synthase), PAL (phenylalanine ammonia lyase) and SAMT (salicylic acid carboxyl methyl transferase). was not affected. The emission of farnesene, a sesquiterpene that derives from farnesyl pyrophosphate (FPP) by addition of isopentyl diphosphate (IPP) to GPP [62], was advanced in transgenic snapdragons (Figure 5, Table S6). Altogether, our results suggest that _AmLHY_ regulates the synthesis and/or emission of volatile compounds at different levels.