# Identification of CqCYP76AD5v1, a gene involved in betaxanthin biosynthesis in Chenopodium quinoa, and its product, betaxanthin, which inhibits amyloid-β aggregation

## TL;DR

This study identifies a gene in quinoa involved in making betaxanthin, a pigment that can inhibit harmful protein clumping linked to Alzheimer's disease.

## Contribution

The study identifies CqCYP76AD5v1 as a key gene for betaxanthin biosynthesis in quinoa and shows its product inhibits amyloid-β aggregation.

## Key findings

- CqCYP76AD5v1 was found to have L-DOPA synthesis activity in Nicotiana benthamiana.
- A tobacco cell line producing betaxanthins inhibited amyloid-β aggregation.
- Vulgaxanthin I was identified as the main betaxanthin produced in the engineered cell line.

## Abstract

Betalain pigments, primarily produced by the order Caryophyllales, are categorized into betacyanins (red/purple) and betaxanthins (yellow/orange). While the biosynthetic pathways of these pigments are well-studied, the genes responsible for betaxanthin biosynthesis in quinoa were previously unknown. This study identified three candidate genes, CqCYP76AD5v1, CqCYP76AD5v2, and CqCYP76AD130, as quinoa orthologs of beet CYP76AD5 and CYP76AD6. Agroinfiltration experiments in Nicotiana benthamiana revealed that CqCYP76AD5v1 exhibited L-DOPA synthesis activity, whereas CqCYP76AD130 did not. To enable large-scale production of betaxanthins, we developed a tobacco BY-2 cell line expressing CqCYP76AD5v1 and CqDODA1-1, with vulgaxanthin I identified as the predominant product. Furthermore, the betaxanthin mixture extracted from this line inhibited amyloid-β (Aβ) aggregation, a key factor associated with Alzheimer’s disease. These findings demonstrate the potential of betaxanthins derived from quinoa betaxanthin-biosynthesis genes for applications in health supplements and pharmaceuticals.