# Cloning and Characterization of IbHQT1: A BAHD Acyltransferase Gene That Positively Regulates Chlorogenic Acid Biosynthesis in Sweet Potato

## TL;DR

This paper identifies and characterizes a gene in sweet potato that increases the production of chlorogenic acid, an important plant compound.

## Contribution

The study experimentally confirms the role of IbHQT1 in chlorogenic acid biosynthesis in sweet potato.

## Key findings

- IbHQT1 encodes a protein with conserved motifs of the BAHD acyltransferase family.
- Overexpression of IbHQT1 increases chlorogenic acid levels in sweet potato leaves and roots.
- RNAi suppression of IbHQT1 reduces chlorogenic acid content in sweet potato.

## Abstract

Background: Hydroxycinnamoyl-CoA quinate hydroxycinnamoyl-transferase (HQT) is an essential enzyme for chlorogenic acid (CGA) biosynthesis in plants. Multiple HQT-encoding genes potentially involved in CGA synthesis in sweet potato (Ipomoea batatas) have been predicted. However, the functions of these genes have not been verified. Methods: In this study, the gene IbHQT1 was isolated from the sweet potato cultivar ‘Nanshu-88’ and functionally characterized using transgenic technology. Results: IbHQT1 encodes a protein comprising 431 amino acids, with conserved HXXXD and DFGWG motifs characteristic of BAHD acyltransferase family members. A phylogenetic analysis indicated that IbHQT1 has a close evolutionary relationship with StHQT in Solanum tuberosum. According to qPCR data, IbHQT1 is highly expressed in young leaves, and its expression is affected by exogenous MeJA (100 µM), ABA (100 µM), GA3 (50 µM), and SA (100 µM). Analyses of cis-acting regulatory elements indicated that the IbHQT1 promoter contains multiple elements responsive to MeJA, ABA, SA, GA3, and light. In plants overexpressing IbHQT1, CGA contents in mature leaves and storage roots increased 1.30- to 1.44-fold and 1.28- to 1.43-fold, respectively. Conversely, in IbHQT1-RNAi lines, CGA contents in mature leaves and storage roots decreased by 16–38% and 18–40%, respectively. Conclusions: These findings indicate that IbHQT1 positively regulates CGA biosynthesis in sweet potato plants.