Benzaldehyde Synthases Are Encoded by Cinnamoyl-CoA Reductase Genes in Cucumber (Cucumis sativusL.)

Abstract

Benzaldedyde, commonly detected in plant VOC (volatile organic compounds) profiling, is derived from phenylalanine. However, the last enzymatic step for benzaldedyde formation, designated as benzaldehyde synthase, remains elusive for long time. Here, we demonstrated that cinnamoyl-CoA reductases are responsible for benzaldedyde production in cucumber (Cucumis sativus L.). Comprehensive tissue specificity of VOC profiling revealed that benzaldehyde was specifically accumulated in root and flower of cucumber plants. VOC-gene correlation analysis suggested that several CCRs are candidate genes for benzaldehyde production: CsaCCR7 had a root-specific expression pattern while CsaCCR9 and CsaCCR18 showed a flower-specific expression pattern. Enzymatic assay demonstrated that CsaCCR7, CsaCCR9 and CsaCCR18 convert benzoyl-CoA to benzaldehyde. Subcellular localization experiments revealed that CsaCCR7 and CsaCCR18 are localized in cytosol, while CsaCCR9 was localized in peroxisome. In contrast to the long-standing view that CCR enzymes are involved in lignin biosynthesis in plants, it is the first time here to add a new biochemical role of CCR as benzaldehyde synthase in plants.HighlightsBenzaldehyde is mainly produced in flower and root of cucumber plants.14 genes encoding CCR enzyme from cucumber are comprehensively analyzed.Three CsaCCRs, function as benzaldehyde synthases, utilize benzoyl-CoA as substrate to produce benzaldehyde in vitro.

Characteristic flavor metabolic network of fish sauce microbiota with different fermentation processes based on metagenomics

“…Moreover, under the action of numerous microorganisms and complex enzyme systems in Aspergillus oryzae koji, the nutrients in raw fish were decomposed and converted into a wide variety of metabolites, and the volatile esters were often more diverse. Liu et al used GC–MS to compare the volatile components of traditional fish sauce and koji fermented fish sauce, and found that the content of ester compounds in the koji fermentation fish sauce was significantly higher than the commercial fish sauce ( 27 ). Therefore, the ester flavor of fish sauce produced by koji fermentation was generally superior to heat preservation and enzyme adding process.…”

“…Benzaldehyde could also be generated from Phe as a precursor. Briefly, Phe was transferred into cinnamic acid through Phe ammonia-lyase, followed by generating benzaldehyde under the action of benzaldehyde synthase ( 27 ). Nevertheless, this was only a theoretical method and required to be verified experimentally.…”

A multi‐omics framework reveals strawberry flavor genes and their regulatory elements

“…High correlations (mean r = 0.42) were detected between expression of FxaC_21g33200 and abundances of: acetic acid, butyl ester; acetic acid, hexyl ester; acetic acid, octyl ester; hexanoic acid, octyl ester; and hexanoic acid, decyl ester. This highly expressed CCR in fruit potentially could catalyze substrates including precursor CoAs of medium‐chain esters, because a homolog of CCR was validated to convert benzoyl‐CoA to benzaldehyde (Liu et al ., 2019 ). A putative anthranilate phosphoribosyltransferase (FxaC_19g06300) catalyzing the reaction of free anthranilate to N‐(5‐phospho‐ d ‐ribosyl)‐anthranilate was associated with the Chr 5C methyl anthranilate (MA) GWAS peak.…”

Plant Volatiles of Lettuce and Chicory Cultivated in Aquaponics Are Associated to Their Microbial Community

“…In the literature, it is known that benzaldehyde, commonly detected in plant VOC profiling, plays a key role in plant fitness. In plants, benzaldehyde biosynthesis is a product from trans-cinnamic acid, which is produced by the breakdown of phenylalanine [ 27 ]. Benzaldehyde and benzyl alcohol (probably derived from benalzaldehyde by an oxidoreductase) are found to be accumulated in cucumber roots and flowers [ 27 ].…”

“…In plants, benzaldehyde biosynthesis is a product from trans-cinnamic acid, which is produced by the breakdown of phenylalanine [ 27 ]. Benzaldehyde and benzyl alcohol (probably derived from benalzaldehyde by an oxidoreductase) are found to be accumulated in cucumber roots and flowers [ 27 ]. The VOCs describing CI leaves were in common with LS leaves, notably benzeneacetaldehyde and 3-hexen-1-ol, (Z)-, but the CI leaves were characterized by a higher number of VOCs, including also butanal, 3-methyl-, 2-hexenal and 2,4-hexadienal, (E, E)-.…”