| Title: | A flavin-dependent monooxygenase produces nitrogenous tomato aroma volatiles using cysteine as a nitrogen source |
| Author(s): | Liscombe DK; Kamiyoshihara Y; Ghironzi J; Kempthorne CJ; Hooton K; Bulot B; Kanellis V; McNulty J; Lam NB; Nadeau LF; Pautler M; Tieman DM; Klee HJ; Goulet C; |
| Address: | "Biochemistry Group, Vineland Research and Innovation Centre, Vineland Station, ON LOR 2E0, Canada. Department of Biological Sciences, Brock University, St. Catharines, ON L2S 3A1, Canada. Horticultural Sciences, University of Florida, Gainesville, FL 32611. Departement de Phytologie, Universite Laval, Quebec City, QC G1V 0A6, Canada. Chemical Biotechnology Graduate Program, Brock University, St. Catharines, ON L2S 3A1, Canada. Department of Chemistry and Chemical Biology, McMaster University, Hamilton, ON L8S 4M1, Canada. Genomics Services, Platform Genetics Inc., Vineland Station, ON L0R 2E0, Canada. Horticultural Sciences, University of Florida, Gainesville, FL 32611; charles.goulet@fsaa.ulaval.ca hjklee@ufl.edu. Departement de Phytologie, Universite Laval, Quebec City, QC G1V 0A6, Canada; charles.goulet@fsaa.ulaval.ca hjklee@ufl.edu" |
| ISSN/ISBN: | 1091-6490 (Electronic) 0027-8424 (Print) 0027-8424 (Linking) |
| Abstract: | "Tomato (Solanum lycopersicum) produces a wide range of volatile chemicals during fruit ripening, generating a distinct aroma and contributing to the overall flavor. Among these volatiles are several aromatic and aliphatic nitrogen-containing compounds for which the biosynthetic pathways are not known. While nitrogenous volatiles are abundant in tomato fruit, their content in fruits of the closely related species of the tomato clade is highly variable. For example, the green-fruited species Solanum pennellii are nearly devoid, while the red-fruited species S. lycopersicum and Solanum pimpinellifolium accumulate high amounts. Using an introgression population derived from S. pennellii, we identified a locus essential for the production of all the detectable nitrogenous volatiles in tomato fruit. Silencing of the underlying gene (SlTNH1;Solyc12g013690) in transgenic plants abolished production of aliphatic and aromatic nitrogenous volatiles in ripe fruit, and metabolomic analysis of these fruit revealed the accumulation of 2-isobutyl-tetrahydrothiazolidine-4-carboxylic acid, a known conjugate of cysteine and 3-methylbutanal. Biosynthetic incorporation of stable isotope-labeled precursors into 2-isobutylthiazole and 2-phenylacetonitrile confirmed that cysteine provides the nitrogen atom for all nitrogenous volatiles in tomato fruit. Nicotiana benthamiana plants expressing SlTNH1 readily transformed synthetic 2-substituted tetrahydrothiazolidine-4-carboxylic acid substrates into a mixture of the corresponding 2-substituted oxime, nitro, and nitrile volatiles. Distinct from other known flavin-dependent monooxygenase enzymes in plants, this tetrahydrothiazolidine-4-carboxylic acid N-hydroxylase catalyzes sequential hydroxylations. Elucidation of this pathway is a major step forward in understanding and ultimately improving tomato flavor quality" |
| Keywords: | Fruit/*chemistry/metabolism Solanum lycopersicum/*metabolism Mixed Function Oxygenases/genetics/*metabolism Nitrogen/chemistry/*metabolism Odorants/*analysis Sitosterols/*metabolism Volatile Organic Compounds N-hydroxylation aroma volatile biosynthesis fl; |
| Notes: | "MedlineLiscombe, David K Kamiyoshihara, Yusuke Ghironzi, Jeremie Kempthorne, Christine J Hooton, Kevin Bulot, Blandine Kanellis, Vassili McNulty, James Lam, Nghi B Nadeau, Louis Felix Pautler, Michael Tieman, Denise M Klee, Harry J Goulet, Charles eng 2022/02/09 Proc Natl Acad Sci U S A. 2022 Feb 15; 119(7):e2118676119. doi: 10.1073/pnas.2118676119" |
