| Title: | Natural variations in the Sl-AKR9 aldo/keto reductase gene impact fruit flavor volatile and sugar contents |
| Author(s): | Li X; Tieman D; Alseekh S; Fernie AR; Klee HJ; |
| Address: | "Horticultural Sciences, Genetics Institute, University of Florida, Gainesville, Florida, 32611, USA. Max-Planck-Institute of Molecular Plant Physiology, 14476, Potsdam-Golm, Germany. Center of Plant Systems Biology and Biotechnology, Plovdiv, 4000, Bulgaria" |
| ISSN/ISBN: | 1365-313X (Electronic) 0960-7412 (Linking) |
| Abstract: | "The unique flavors of different fruits depend upon complex blends of soluble sugars, organic acids, and volatile organic compounds. 2-Phenylethanol and phenylacetaldehyde are major contributors to flavor in many foods, including tomato. In the tomato fruit, glucose, and fructose are the chemicals that most positively contribute to human flavor preferences. We identified a gene encoding a tomato aldo/keto reductase, Sl-AKR9, that is associated with phenylacetaldehyde and 2-phenylethanol contents in fruits. Two distinct haplotypes were identified; one encodes a chloroplast-targeted protein while the other encodes a transit peptide-less protein that accumulates in the cytoplasm. Sl-AKR9 effectively catalyzes reduction of phenylacetaldehyde to 2-phenylethanol. The enzyme can also metabolize sugar-derived reactive carbonyls, including glyceraldehyde and methylglyoxal. CRISPR-Cas9-induced loss-of-function mutations in Sl-AKR9 significantly increased phenylacetaldehyde and lowered 2-phenylethanol content in ripe fruit. Reduced fruit weight and increased soluble solids, glucose, and fructose contents were observed in the loss-of-function fruits. These results reveal a previously unidentified mechanism affecting two flavor-associated phenylalanine-derived volatile organic compounds, sugar content, and fruit weight. Modern varieties of tomato almost universally contain the haplotype associated with larger fruit, lower sugar content, and lower phenylacetaldehyde and 2-phenylethanol, likely leading to flavor deterioration in modern varieties" |
| Keywords: | Humans Sugars/metabolism Fruit/metabolism *Volatile Organic Compounds/metabolism *Phenylethyl Alcohol/analysis/metabolism Glucose/metabolism Fructose/metabolism *Solanum lycopersicum/genetics Oxidoreductases/metabolism; |
| Notes: | "MedlineLi, Xiang Tieman, Denise Alseekh, Saleh Fernie, Alisdair R Klee, Harry J eng Research Support, Non-U.S. Gov't England 2023/05/27 Plant J. 2023 Aug; 115(4):1134-1150. doi: 10.1111/tpj.16310. Epub 2023 Jun 26" |
