SlCCD1A Enhances the Aroma Quality of Tomato Fruits by Promoting the Synthesis of Carotenoid-Derived Volatiles

Abstract

The loss of volatiles results in the deterioration of flavor in tomatoes. Volatiles are mainly derived from fatty acid, carotenoid, phenylpropane, and branched chain amino acids. In this study, the tomato accession CI1005 with a strong odor and accession TI4001 with a weak odor were analyzed. The volatile contents were measured in tomato fruits using gas chromatography-mass spectrometry. The scores of tomato taste and odor characteristics were evaluated according to hedonistic taste and olfaction. It was found that the content of fatty acid-derived volatiles accounted for more than half of the total volatiles that had grassy and fatty aromas. Phenylpropane-derived volatiles had irritation and floral aromas. Branched-chain amino acid-derived volatiles had a caramel aroma. Carotenoid-derived volatiles had floral, fruity, fatty, and sweet-like aromas, preferred by consumers. A lack of carotenoid-derived volatiles affected the flavor quality of tomato fruits. The accumulation of carotenoid-derived volatiles is regulated by carotenoid cleavage oxygenases (CCDs). A tissue-specific expression analysis of the SlCCD genes revealed that the expression levels of SlCCD1A and SlCCD1B were higher in tomato fruits than in other tissues. The expression levels of SlCCD1A and SlCCD1B were consistent with the trend of the carotenoid-derived volatile contents. The expression of SlCCD1A was higher than that for SlCCD1B. A bioinformatics analysis revealed that SlCCD1A was more closely linked to carotenoid metabolism than SlCCD1B. The overexpression of SlCCD1A indicated that it could cleave lycopene, α-carotene, and β-carotene to produce 6-methyl-5-hepten-2-one, geranylacetone, α-ionone, and β-ionone, increasing the floral, fruity, fatty, and sweet-like aromas of tomato fruits. The flavor quality of tomato fruits could be improved by overexpressing SlCCD1A.

Determination of astaxanthins contribution to the aroma characteristics and aroma‐active compounds of hot‐air‐dried shrimp products using sensory evaluation, E‐nose and GC–MS

“…Free astaxanthin lacks fatty acids and therefore cannot be degraded to aldehydes and alcohols. 6‐Methyl‐5‐hepten‐2‐one was detected in FA and DA, following thermal degradation of astaxanthin (Cheng et al ., 2021).…”

New process of goji fermented wine: effect of goji residue degradation to generate norisoprenoid aroma compounds

“…It imparted a fresh floral and sweet aroma to goji wine. Limonene had a slightly citrus aroma and was the modifier compound for GW3 (Cheng et al, 2021). Thus, these compounds imparted goji wine a fresh floral and fruity aroma in general, accompanied by woody aromas and had the typical characteristics of wine.…”

“…All carotenoids degraded under the combined influence of photolysis and OH scavenging and the major degradation products were apo-aldehydes and apo-ketones (Semitsoglou-Tsiapou et al, 2022). Cheng et al (2021) reported that the accumulation of norisoprenoid volatiles is regulated by carotenoid cleavage oxygenases (CCDs). In addition, these carotenoid-derived volatile compounds have floral, fruity, fatty, and sweet-like flavors, which greatly enhance the quality of the aroma of goji wine (Simkin, 2021).…”

“…In view of these shortcomings of chemical and thermal degradation, the advantages of biodegradation include high yield, mild catalytic conditions, high specificity, and high efficiency of degradation (Nagai et al, 2015). Cheng et al (2021) reported the overexpression of SlCCD1A indicated that it could cleave lycopene, α-carotene, and β-carotene to produce 6-methyl-5hepten-2-one, geranylacetone, α-ionone, and β-ionone, increasing the floral, fruity, fatty, and sweet-like aromas of tomato fruits. Long et al (2021) suggested that biological enzymes function like free oxygen on the C-C double bonds in carotenoids and cleave them to produce fragrance.…”

The dissection of tomato flavor: biochemistry, genetics, and omics

“… Simkin et al. (2004) observed that the downregulation of the LeCCD1A and LeCCD1B genes using an antisense construct in tomato resulted in a significant reduction in the rates of emission of geranylacetone and β-ionone in cut tomato fruits, but did not affect the overall carotenoid content ( Simkin et al., 2004 ; Cheng et al., 2021 ; Simkin, 2021 ). This suggests that additional enzymes may be involved in carotenoid cleavage.…”