Comparative Transcriptome Analysis of Celery Leaf Blades Identified an R2R3-MYB Transcription Factor that Regulates Apigenin Metabolism

Apigenin
has been proven to possess many pharmacological properties,
but the mechanism of regulation of apigenin biosynthesis in plants
remains unclear. Apigenin is the main flavonoid in celery and is mainly
accumulated in the middle stage of leaf blade development. In this
study, comparative transcriptomic analysis revealed a large number
of structural genes and transcription factor genes that may be involved
in the apigenin metabolic pathway. On the basis of the apigenin content
in different celery accessions, an R2R3-MYB transcription factor gene,
named AgMYB1, was isolated from the high apigenin
celery accession C014. Bioinformatics analysis indicated that AgMYB1
may be involved in flavonoid metabolism. AgMYB1 expression
showed a positive relation with the expression of the apigenin accumulation
marker gene FNSI and with the apigenin content in
different celery tissues. Moreover, overexpression and antisense expression
of AgMYB1 in transgenic celery plants significantly
increased and reduced the expression of apigenin biosynthetic genes
and the apigenin content, respectively. These findings suggest that AgMYB1 is involved in positive regulation of apigenin metabolism
in celery.