Increasing Temperature Changes Flux into Multiple Biosynthetic Pathways for 2-Phenylethanol in Model Systems of Tea (Camellia sinensis) and Other Plants

Abstract

2-Phenylethanol (2PE) is a representative aromatic aroma compound in tea (Camellia sinensis) leaves. However, its formation in tea remains unexplored. In our study, feeding experiments of [ 2 H 8 ]L-phenylalanine (Phe), [ 2 H 5 ]phenylpyruvic acid (PPA), or (E/Z)-phenylacetaldoxime (PAOx) showed that three biosynthesis pathways for 2PE derived from L-Phe occurred in tea leaves, namely, pathway I (via phenylacetaldehyde (PAld)), pathway II (via PPA and PAld), and pathway III (via (E/Z)-PAOx and PAld). Furthermore, increasing temperature resulted in increased flux into the pathway for 2PE from L-Phe via PPA and PAld. In addition, tomato fruits and petunia flowers also contained the 2PE biosynthetic pathway from L-Phe via PPA and PAld and increasing temperatures led to increased flux into this pathway, suggesting that such a phenomenon might be common among most plants containing 2PE. This represents a characteristic example of changes in flux into the biosynthesis pathways of volatile compounds in plants in response to stresses.

Alternative Pathway to the Formation of trans-Cinnamic Acid Derived from l-Phenylalanine in Tea (Camellia sinensis) Plants and Other Plants

“…Using l -[ 2 H 8 ]­Phe tracing in plants, multiple pathways from l -Phe to its downstream volatile products, such as 2-phenylethanol, have been proposed in tea leaves, rose flowers, petunia flowers, and tomato fruits. ,,− Three biosynthetic pathways have been discovered to 2-phenylethanol from l -Phe in plants . Furthermore, using l -[ 2 H 8 ]­Phe tracing in flowers of tea plants, two potential pathways from l -Phe to its downstream volatile products, such as acetophenone and 1-phenylethanol, have been proposed .…”

“…Plant treatments with l -[ 2 H 8 ]­Phe were performed as reported in previous studies. , C. sinensis ‘Jinxuan’ branches with one bud and three leaves collected in March 2019 were cultivated in two different solutions (Figure S1A of the Supporting Information), namely, H 2 O and 12 mM l -[ 2 H 8 ]­Phe.…”

“…sinensis ‘Jinxuan’ branches with one bud and three leaves collected in March 2019 were cultivated in two different solutions (Figure S1A of the Supporting Information), namely, H 2 O and 12 mM l -[ 2 H 8 ]­Phe. In the previous study, the times for feeding l -[ 2 H 8 ]­Phe into ‘Jinxuan’ branches were set on 3 and 7 days, and the labeled l -Phe-derived metabolites could be detected on 3 days. Therefore, in the study, the feeding time was only set on 3 days for C.…”

“…esculentum Mill. fruit . After 1 day of feeding, the tomato fruit was in a good state and could be kept for longer periods.…”

Brewing rich 2‐phenylethanol beer from cassava and its producing metabolisms in yeast

“…Among them, alcohols, including ethanol and higher alcohols, are the main components of beer and play a crucial role in the taste. In particular, 2‐phenylethanol is an important aromatic compound, which gives beer an elegant and delicate rose fragrance 26–31 . In recent years, with the swift growth of the beer industry, barley raw materials are more and more scarce, which requires the development and selection of new beer adjuncts to reduce and replace the existing beer adjuncts.…”