# Co-Analysis of Transcriptome and Metabolome Reveals Flavonoid Biosynthesis in Macadamia Pericarp Across Developmental Stages

## TL;DR

This study explores how flavonoids are produced in macadamia pericarp during different growth stages using gene and metabolite analysis.

## Contribution

The study is the first to reveal the temporal shift in flavonoid biosynthesis in macadamia pericarp through integrated transcriptomic and metabolomic profiling.

## Key findings

- Early developmental stages show high expression of genes like PAL, 4CL, CHS, and FLS with abundant flavonols and anthocyanins.
- Late stages exhibit upregulation of CHI and F3’5’H, leading to increased flavanones and isoflavones.
- Flavonoid biosynthesis is linked to jasmonate and gibberellin signaling and regulated by MYB, NAC, and bHLH transcription factors.

## Abstract

The pericarp of Macadamia integrifolia represents a promising but underexplored source of functional flavonoids. To systematically elucidate their biosynthesis and enhance the industrial potential of this by-product, we conducted integrated transcriptomic and metabolomic profiling of pericarps across five developmental stages (50, 80, 110, 140, and 170 days after flowering). Our analysis reveals, for the first time, a distinct temporal shift in both gene expression and metabolite accumulation. Early stages were characterized by high expression of PAL, 4CL, CHS, and FLS, coupled with abundant flavonols and anthocyanins. In contrast, late stages exhibited upregulation of CHI and F3’5’H, redirecting the metabolic flux toward flavanones and isoflavones. This dynamic profile was closely associated with jasmonate and gibberellin signaling pathways and was likely regulated by key transcription factors (MYB, NAC, bHLH). These findings provide a multi-omics framework that elucidates the temporal flavonoid biosynthesis in macadamia pericarp, thereby laying the groundwork for its future industrial valorization.