Making sense of petunia scents
Researchers have identified a key protein that helps release the flowery essence of petunias. While the compounds that flowers release often smell wonderful to us, for the plants from which they emanate, they are responsible for much more than a pleasant scent; volatile organic compounds (VOCs) play essential roles in pollinator and seed-disperser attraction, above- and below-ground defense against herbivores and pathogens, and plant-to-plant signaling, for example, in some cases even interfering with the growth and success of competing plants. However, whether VOCs are actively transported across the plant cell membrane, or simply diffused, remains unknown. Here, Funmilayo Adebesin used RNA sequencing data of the flower Petunia hybrida to identify shifts in gene expression between petunia developmental stages with the lowest and highest VOC emissions, respectively — the plant's budding stage on one day and its opening stage the next. As the flowers transitioned to a high VOC emitting state, the researchers identified the protein PhABCG1, which is predicted to help transport compounds across cell membranes and is expressed almost exclusively in petals of open flowers. The researchers found that when they reduced expression levels of PhABCG1 by 70 to 80%, it resulted in a 52 to 62% decreases in total VOC emission. This finding suggests that PhABCG1 acts as a key transporter of VOCs across the cell membrane, although other transporters have yet to be identified. Franziska Eberl and Jonathan Gershenzon discuss this finding in greater detail in a related Perspective.
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