A whiff of the future: functions of phenylalanine‐derived aroma compounds and advances in their industrial production

Abstract

Summary Plants produce myriad aroma compounds—odorous molecules that are key factors in countless aspects of the plant's life cycle, including pollinator attraction and communication within and between plants. For humans, aroma compounds convey accurate information on food type, and are vital for assessing the environment. The phenylpropanoid pathway is the origin of notable aroma compounds, such as raspberry ketone and vanillin. In the last decade, great strides have been made in elucidating this pathway with the identification of numerous aroma‐related biosynthetic enzymes and factors regulating metabolic shunts. These scientific achievements, together with public acknowledgment of aroma compounds' medicinal benefits and growing consumer demand for natural products, are driving the development of novel biological sources for wide‐scale, eco‐friendly, and inexpensive production. Microbes and plants that are readily amenable to metabolic engineering are garnering attention as suitable platforms for achieving this goal. In this review, we discuss the importance of aroma compounds from the perspectives of humans, pollinators and plant–plant interactions. Focusing on vanillin and raspberry ketone, which are of high interest to the industry, we present key knowledge on the biosynthesis and regulation of phenylalanine‐derived aroma compounds, describe advances in the adoption of microbes and plants as platforms for their production, and propose routes for improvement.

Coordination among flower pigments, scents and pollinators in ornamental plants

“…Global environmental changes are causing a decline in pollinator diversity worldwide, threatening the mutualistic relationship between plants and their pollinators (Byers and Chang 2017;Glenny et al 2018;Cordeiro and Dӧtterl 2023). To address this issue, modifying flower color and scent characteristics to enhance their appeal to pollinators is a potential approach to maintaining or improving pollination efficiency (Skaliter et al 2022). This review explores the roles of color and scent in attracting pollinators.…”

“…Approximately 87.5% of flowering plants rely on animals for pollination (Skaliter et al 2022). The distinctive characteristics of flowers, known as pollination syndromes, including color, scent, morphology, nectar, and pollen, allow plants to attract specific pollinators.…”

A BAHD acyltransferase contributes to the biosynthesis of both ethyl benzoate and methyl benzoate in the flowers of Lilium oriental hybrid ‘Siberia’

“…Benzenoid biosynthesis in plants originates from phenylalanine, which is first deaminated to form cinnamic acid by phenylalanine ammonia-lyase (PAL) (Skaliter et al, 2022). Subsequent conversion of cinnamic acid to the precursor for volatile benzenoids, benzoyl-CoA/benzoic acid is achieved through the b-oxidation pathway and/or the non-b-oxidation pathway (Widhalm and Dudareva, 2015).…”

Developmental and temporal changes in petunia petal transcriptome reveal scent-repressing plant-specific RING–kinase–WD40 protein

“…A number of studies on the mechanisms of biosynthesis, metabolism and emission of floral scent compounds have been conducted on Petunia x hybrida ( Muhlemann et al., 2014 ; Lynch and Dudareva, 2020 ; Skaliter et al., 2022 ). The diversity of floral volatiles found in petunia petals is represented mainly by benzenoids (benzyl alcohol, benzaldehyde, benzyl benzoate, methyl benzoate), phenylpropenes (eugenol, isoeugenol) and phenylpropanoid-related scent compounds (phenylacetaldehyde, phenylethyl alcohol, phenylethyl acetate, phenylethyl benzoate) synthesized from phenylalanine.…”

“…The diversity of floral volatiles found in petunia petals is represented mainly by benzenoids (benzyl alcohol, benzaldehyde, benzyl benzoate, methyl benzoate), phenylpropenes (eugenol, isoeugenol) and phenylpropanoid-related scent compounds (phenylacetaldehyde, phenylethyl alcohol, phenylethyl acetate, phenylethyl benzoate) synthesized from phenylalanine. Most enzymes and biochemical steps in this pathway leading to the production of volatile organic compounds (VOCs) have been characterized ( Muhlemann et al., 2014 ; Huang et al., 2022 ; Skaliter et al., 2022 ).…”