Graduate student Purdue University West Lafayette, Indiana
Body of Abstract: Volatile organic compounds (VOCs), produced and released from plants, play essential roles in plant defense, reproduction, and plant-plant interactions. For VOCs to be emitted from their sites of biosynthesis into the atmosphere, they must move across the plasma membrane, the cell wall, and the cuticle. However, little is known about how VOCs traverse cytosol to reach the plasma membrane. As VOCs are lipophilic low-molecular-weight molecules (100-200 Da), they are likely to partition into the hydrophobic environment, such as subcellular membranes, and get to the plasma membrane via vesicle-mediated trafficking. From the RNA-seq datasets generated from Petunia hybrida flowers, which produce high levels of benzenoid and phenylpropanoid volatiles, vesicle trafficking-related genes with expression profiles matching VOC biosynthesis and emission patterns were searched. Three PhSV2s, homologs of mouse synaptic vesicle protein 2A (MmSV2A) which is important for the fusion of vesicles to target membranes in mice, were identified in petunia. PhSV2s expression pattern shows a rhythmic manner, with an increase during the night and a decrease during the day, corresponding to the VOC emission profile of petunia. Therefore, we hypothesize that PhSV2 is involved in VOC emission through vesicle-mediated trafficking. To examine the role of PhSV2 in VOC emission, the expressions of PhSV2s were downregulated. To further identify if PhSV2s localize to the secretory pathway, PhSV2s fused to a green fluorescent protein (GFP) and syntaxin-32 (SYP32), Golgi-localized Qa-soluble N-ethylmaleimide sensitive factor attachment protein receptors (SNAREs), from Arabidopsis fused to a red fluorescent protein (RFP) were transiently co-expressed in petunia petals. Here we show that the downregulation of PhSV2s results in reduced VOC emission, and GFP-PhSV2s are co-localized with RFP-SYP32, indicating Golgi localization of PhSV2s.