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Article|14 Mar 2022|OPEN
Characterization and functional validation of β-carotene hydroxylase AcBCH genes in Actinidia chinensis
Hui Xia1,2 ,† , Yuanjie Zhou1 ,† , Zhiyi Lin1 , Yuqi Guo1 , Xinling Liu1 , Tong Wang1 , Jin Wang1,2 , Honghong Deng1,2 , Lijin Lin1,2 , Qunxian Deng1 , Xiulan Lv1,2 , Kunfu Xu1,2 , Dong Liang,1,2 ,
1College of Horticulture, Sichuan Agricultural University, Chengdu 611130, China
2Institute of Pomology and Olericulture, Sichuan Agricultural University, Chengdu 611130, China
*Corresponding author. E-mail: liangeast@sicau.edu.cn
Both authors contributed equally to the study.

Horticulture Research 9,
Article number: uhac063 (2022)
doi: https://doi.org/10.1093/hr/uhac063
Views: 177

Received: 27 Dec 2021
Accepted: 28 Feb 2022
Published online: 14 Mar 2022

Abstract

Carotenoids are the pigment substances of yellow-fleshed kiwifruit, and among them β-cryptoxanthin has only been detected in the brighter yellow-fleshed variety ‘Jinshi 1’. β-Carotene hydroxylase (BCH) catalyzes the formation of β-cryptoxanthin and zeaxanthin, but its molecular characteristics and functions have not been fully explained. Here we isolated two β-carotene hydroxylase genes, AcBCH1 and AcBCH2 from kiwifruit (Actinidia chinensis), and their relative expression levels exhibited a close correlation with the content of β-cryptoxanthin. AcBCH1 catalyzed the formation of β-cryptoxanthin when transformed into β-carotene-accumulating yeast cells. Moreover, silenced expression of AcBCH1 in kiwifruit caused decreases in the contents of zeaxanthin, lutein, and β-cryptoxanthin, and an increase in β-carotene content. The content of β-carotene decreased significantly after the AcBCH1/2 genes were overexpressed in tomato. The content of zeaxanthin increased and β-carotene decreased in transgenic kiwifruit seedlings. The results will enrich our knowledge of the molecular mechanisms of carotenoid biosynthesis in kiwifruit.