Post anthesis, loquat flowers emit volatile benzenoids, including phenylacetaldehyde, phenylethyl alcohol, and 2-phenethyl benzoate. Previous studies have shown that pyridoxal phosphate-dependent aromatic L-amino acid decarboxylase (AADC) produces phenylacetaldehyde from L-phenylalanine. Here, two
AADC genes (
EjAADC1 and
EjAADC2) were isolated from loquat (
Eriobotrya japonica) flowers. The EjAADC1 and EjAADC2 proteins showed approximately 72% and 55% identity, respectively, to a rose AADC homolog that has phenylacetaldehyde synthase activity. Transcript analyses indicated that
EjAADC1 was specifically expressed in petals, with the highest level of expression in fully opened flowers; the petals showed high levels of volatile benzenoids, including phenylacetaldehyde. In contrast,
EjAADC2 was expressed at a lower level than
EjAADC1 in all tested tissues, including leaves and developing flowers. Functional characterization of a recombinant EjAADC1 protein expressed in
Escherichia coli showed that it catalyzes the formation of phenylacetaldehyde from L-phenylalanine in a pyridoxal phosphate-dependent manner. Our results suggest that
EjAADC1 is mainly responsible for the biosynthesis of volatile benzenoids in loquat flowers.
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