Alcohol Acyltransferase Is Involved in the Biosynthesis of C6 Esters in Apricot (Prunus armeniaca L.) Fruit

Abstract

Short-chain esters derived from fatty acid contribute to the characteristic flavor of apricot fruit, and the biosynthesis of these compounds in fruit is catalyzed by alcohol acyltransferase (AAT). In this work, we investigated the AAT gene family via genome-wide scanning, and three AAT loci were identified in different linkage groups (LGs), with PaAAT1 (PARG22907m01) in LG7, PaAAT2 (PARG15279m01) in LG4, and PaAAT3 (PARG22697m01) in LG6. Phylogenetic analysis showed that PaAAT1 belongs to clade 3, while PaAAT2 and PaAAT3 belong to clade 1 and clade 2, respectively. In contrast, the three AAT genes present different expression patterns. Only PaAAT1 exhibited distinct patterns of fruit-specific expression, and the expression of PaAAT1 sharply increased during fruit ripening, which is consistent with the abundance of C4–C6 esters such as (E)-2-hexenyl acetate and (Z)-3-hexenyl acetate. The transient overexpression of PaAAT1 in Katy (KT) apricot fruit resulted in a remarkable decrease in hexenol, (E)-2-hexenol, and (Z)-3-hexenol levels while significantly increasing the corresponding acetate production (p < 0.01). A substrate assay revealed that the PaAAT1 protein enzyme can produce hexenyl acetate, (E)-2-hexenyl acetate, and (Z)-3-hexenyl acetate when C6 alcohols are used as substrates for the reaction. Taken together, these results indicate that PaAAT1 plays a crucial role in the production of C6 esters in apricot fruit during ripening.

Free and Glycosidically Bound Volatile Compounds in Okinawan Pineapple (Ananas comosus)

“…For instance, ethyl acetate might emit solvent-like notes, whilst ethyl hexanoate could also produce a wine-like scent. In general, short-chain esters are derived from fatty acids, and the biosynthesis of these compounds is catalyzed by the alcohol acyltransferase reaction in acyl-CoA and alcohol precursors [21,22]. For instance, methyl hexanoate might be derived from methanol and hexanoyl-CoA substrates.…”

Advances in Discoveries of Plant Phytochemicals

“…Since alcohol acyltransferases mediate the synthesis of specific esters in different plants, which could be an important reason that causes different fruits to exude unique smells. For example, short-chain esters derived from fatty acids contribute to the characteristic flavor of pear, while its alcohol acyltransferase, PaAAT1, is thought to be closely associated with the production of C6 esters (Zhou et al, 2021). The odor in peaches is mainly determined by g-decalactone, whose synthesis is mainly catalyzed by Prunus persica alcohol acyltransferase (PpAAT) .…”

“…Bioactive lignans and their corresponding derivatives have been identified as the major active ingredients of I. indigotica. In our previous study, notable progress has been made in understanding the biosynthetic pathway and regulatory mechanism of lignans in I. indigotica (Feng et al, 2021). Here, four SIRD genes were first identified in the I. indigotica genome.…”

Family characteristics, phylogenetic reconstruction, and potential applications of the plant BAHD acyltransferase family

“…Since alcohol acyltransferases mediate the synthesis of specific esters in different plants, which could be an important reason that causes different fruits to exude unique smells. For example, short-chain esters derived from fatty acids contribute to the characteristic flavor of pear, while its alcohol acyltransferase, Pa AAT1, is thought to be closely associated with the production of C6 esters ( Zhou et al., 2021 ). The odor in peaches is mainly determined by γ-decalactone, whose synthesis is mainly catalyzed by Prunus persica alcohol acyltransferase ( Pp AAT) ( Song et al., 2021 ).…”