| The aroma of horticultural plants is produced by volatile organic compounds (VOCs) in their cells, mainly composed of esters, alcohols, aldehydes, ketones, ethers, terpenoids, alkanes and other substances, which is an important quality index. Horticultural plants are mainly divided into fruit trees, vegetables, flowers and tea. VOCs in different types of horticultural plants vary. This is an important factor leading to the diversity of flavors of horticultural products. The main factors affecting VOCs in horticultural plants include gene expression, cultivation conditions and postharvest treatment. The expression of different genes is an important reason for the VOCs differences between different horticultural plants. Cultivation conditions such as light intensity, cultivation environment, fertilizer application and varieties of grafted stocks directly or indirectly affect the synthesis of VOCs in horticultural plants. Storage temperature and ethylene content after harvest are important factors affecting VOCs. The VOCs synthesis pathways mainly include fatty acid pathway, amino acid pathway, shikimate/ phenylpropanoid pathway, terpenoid pathway, lipoxygenase (LOX) pathway and etc. Straight chain aldehydes, alcohols and esters are mainly produced by the lipoxygenase (LOX) pathway and β-oxidation pathway, branched chain aldehydes, alcohols and esters are produced by the amino acid pathway, terpenoids are produced by the terpenoid pathway, and polyphenolic compounds are produced by the shikimic acid/phenylpropanoid pathway. This review summarizes the components
of aroma substances, the factors affecting aroma volatilization and the biosynthesis regulation of volatile aroma compounds in horticultural plants. The problems of less studies on physiological function of aroma-related enzymes, genetic control of aroma and its influencing factors, aroma substances and metabolic mechanism of horticultural plants are proposed, and the future research directions are put farward. |
