Transcriptional activation of AaAGPase by AaGLK transcription factor determines ascorbic acid levels in kiwifruit
- 1National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Zhengzhou Fruit Research Institute, Chinese Academy of Agricultural Sciences, Zhengzhou 450009, Henan, China.
- 2College of Horticulture and Plant Protection, Henan University of Science and Technology,, Luoyang 471003, Henan, China.
Abstract
Humans cannot synthesize ascorbic acid (AsA), making dietary intake from fruits and vegetables crucial. Kiwifruit is a rich source of AsA; however, the genetic and regulatory basis for its accumulation is not fully elucidated. This study integrates quantitative trait locus (QTL) mapping, transcriptomics, and functional characterization to uncover a novel regulatory role of AaAGPase, encoding an ADP-glucose pyrophosphorylase, in determining AsA levels in kiwifruit. A significant QTL was mapped on chr10 in a tetraploid Actinidia arguta biparental population, explaining 11.46% of the variation in AsA levels. Based on gene annotation and expression differences between high- and low-AsA genotypes, ADP-glucose pyrophosphorylase (AGPase) was identified as a negative regulator. Our results indicated that a promoter variation in AGPase affects both AsA and starch levels. Overexpression of AaAGPase in transiently transformed fruit and transgenic kiwifruit plants led to reduced AsA levels via downregulation of key genes in the L-galactose pathway while increasing starch levels. Conversely, virus-induced gene silencing of AaAGPase resulted in increased AsA but decreased starch levels. Additionally, we identified the Golden 2-like transcription factor, AaGLK, which binds to and activates the AaAGPase promoter. Manipulating AaGLK expression resulted in variations in AsA levels by regulating AaAGPase expression. These findings reveal that the AaGLK-AaAGPase module negatively regulates AsA biosynthesis in kiwifruit. Additionally, we developed a molecular marker based on the sequence variation of AGPase promoter for marker assisted selection. In summary, our study revealed that AaAGPase, which is transcriptionally activated by AaGLK, plays a novel role in determining AsA levels through carbohydrates substrates competition.
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BibTeX
@article{li2026transcriptional,
title = {{Transcriptional activation of AaAGPase by AaGLK transcription factor determines ascorbic acid levels in kiwifruit}},
author = {Sikai Li and Ran Wang and Miaomiao Lin and Leiming Sun and Yukuo Li and Li Liu and Ziqi Zhang and Xiujuan Qi},
journal = {Horticulture research},
year = {2026},
month = jun,
doi = {10.1093/hr/uhag212},
url = {https://europepmc.org/article/PMC/PMC13718306},
note = {CC BY},
}
RIS
TY - JOUR
TI - Transcriptional activation of AaAGPase by AaGLK transcription factor determines ascorbic acid levels in kiwifruit
AU - Sikai Li
AU - Ran Wang
AU - Miaomiao Lin
AU - Leiming Sun
AU - Yukuo Li
AU - Li Liu
AU - Ziqi Zhang
AU - Xiujuan Qi
PY - 2026
DA - 2026/06/01
JO - Horticulture research
DO - 10.1093/hr/uhag212
UR - https://europepmc.org/article/PMC/PMC13718306
AB - Humans cannot synthesize ascorbic acid (AsA), making dietary intake from fruits and vegetables crucial. Kiwifruit is a rich source of AsA; however, the genetic and regulatory basis for its accumulation is not fully elucidated. This study integrates quantitative trait locus (QTL) mapping, transcriptomics, and functional characterization to uncover a novel regulatory role of AaAGPase, encoding an ADP-glucose pyrophosphorylase, in determining AsA levels in kiwifruit. A significant QTL was mapped on chr10 in a tetraploid Actinidia arguta biparental population, explaining 11.46% of the variation in AsA levels. Based on gene annotation and expression differences between high- and low-AsA genotypes, ADP-glucose pyrophosphorylase (AGPase) was identified as a negative regulator. Our results indicated that a promoter variation in AGPase affects both AsA and starch levels. Overexpression of AaAGPase in transiently transformed fruit and transgenic kiwifruit plants led to reduced AsA levels via downregulation of key genes in the L-galactose pathway while increasing starch levels. Conversely, virus-induced gene silencing of AaAGPase resulted in increased AsA but decreased starch levels. Additionally, we identified the Golden 2-like transcription factor, AaGLK, which binds to and activates the AaAGPase promoter. Manipulating AaGLK expression resulted in variations in AsA levels by regulating AaAGPase expression. These findings reveal that the AaGLK-AaAGPase module negatively regulates AsA biosynthesis in kiwifruit. Additionally, we developed a molecular marker based on the sequence variation of AGPase promoter for marker assisted selection. In summary, our study revealed that AaAGPase, which is transcriptionally activated by AaGLK, plays a novel role in determining AsA levels through carbohydrates substrates competition.
SN - 2662-6810
SN - 2052-7276
ER -