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Journal of Integrative Agriculture  2026, Vol. 25 Issue (10): 4175-4191    DOI: 10.1016/j.jia.2025.12.009
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Up-regulation of PsbHLH3 promotes cold-triggered anthocyanin biosynthesis in the amber flesh of black plums

Yubei Wang1, Ranran Xu2, Yanyan Ma1, Zhilei Zhao3, Yuhong Gu4#, Jiankang Cao1#

1 College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China

2 Institute of Agri-Food Processing and Nutrition, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100093, China

3 College of Quality and Technical Supervision, Hebei University, Baoding 071002, China

4 College of Life Sciences, Hebei Agricultural University, Baoding 071000, China

 Highlights 

• Cold storage induced flesh reddening in the amber-fleshed plum cultivar.

• Ten candidate PsbHLH genes with differential expression in reddened flesh were screened.

• PsbHLH3 was validated to be crucial in cold-induced plum anthocyanin biosynthesis.

• PsbHLH3 interacted with PsMYB10.1 to strengthen transactivation of the PsUFGT promoter.

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摘要  

黑皮琥珀色李果肉冷藏会诱导果肉中花色苷的合成与积累,引起低温后果肉的颜色变化。bHLH转录因子在响应冷诱导和花色苷生物合成中具有潜在功能。为探究bHLH基因的作用,本研究选取两个琥珀色果肉、黑色果皮的李品种(Prunus salicina Lindl. cv.‘Friar’和‘Angeleno’)作为果实材料,进行转录组学和生物信息学分析。通过 RNA 测序鉴定差异表达的bHLH基因,并利用qRT-PCR验证。在冷诱导果肉变红过程中,鉴定出10个表达变化最显著的bHLH 基因,包括5个上调和5个下调基因。对这10个bHLH蛋白的结构进行了鉴定,并构建了系统发育树。其中,evm.TU.Chr8.2504基因被鉴定为PsbHLH3,含有低温响应因子和MYB 结合位点。通过瞬时过表达实验进一步验证了PsbHLH3促进花色苷合成的功能。酵母双杂交和双分子荧光互补实验表明,PsbHLH3与PsMYB10.1互作,双荧光素酶试验证实了PsbHLH3通过促进 PsMYB10.1对PsUFGT启动子的激活,进而增强花色苷合成相关结构基因的转录。本研究表明,低温诱导PsbHLH3上调表达,推动李果实果肉变红的分子开关 “开启”,阐明了PsbHLH3在采后冷藏诱导李果肉花色苷合成调控中的作用。



Abstract  

Cold storage of amber-fleshed black plums triggers anthocyanin biosynthesis and accumulation in fruit flesh, resulting in flesh reddening under low-temperature conditions. bHLH transcription factors have potential functions in response to cold induction and anthocyanin biosynthesis. To investigate the role of bHLH genes, two amber-fleshed and blackskinned cultivars (Prunus salicina Lindl. ‘Friar’ and ‘Angeleno’) were selected as fruit materials to conduct transcriptomic and bioinformatics analyses. Differentially expressed bHLH genes were identified by RNA-seq and validated using qRTPCR. Ten bHLH genes (five upregulated, five downregulated) showed the most significant expression changes during cold- triggered flesh reddening. We characterized the protein structures of these 10 bHLH members and constructed a phylogenetic tree. Among them, the gene evm.TU.Chr8.2504 (the corresponding protein ID is evm.model.Chr8.2504), named PsbHLH3, was cold-responsive and contains MYB-binding sites. Further experiments involving transient
overexpression were performed to validate the function of PsbHLH3 in facilitating anthocyanin biosynthesis. Yeast twohybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays demonstrated that PsbHLH3 interacts with PsMYB10.1. Dual-luciferase assay showed that PsbHLH3 promoted the activation of PsMYB10.1 on the promoter of PsUFGT, and consequently augmented the transcription of structural genes related to anthocyanin biosynthesis. The study reveals that cold storage upregulates PsbHLH3, which acts as a molecular switch governing cold-triggered flesh reddening in plum fruit. These findings clarify the regulatory function of PsbHLH3 in cold-triggered anthocyanin biosynthesis in postharvest plums.

Keywords:  plum       bHLH        flesh reddening        anthocyanin biosynthesis        cold storage  
Received: 03 June 2025   Accepted: 23 June 2025 Online: 08 December 2025  
Fund: This work was supported by the Beijing Municipal Natural Science Foundation, China (6254032), the National Natural Science Foundation of China (31872907) and S&T Program of Hebei, China (C2021201011).

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Yubei Wang, Ranran Xu, Yanyan Ma, Zhilei Zhao, Yuhong Gu, Jiankang Cao. 2026. Up-regulation of PsbHLH3 promotes cold-triggered anthocyanin biosynthesis in the amber flesh of black plums. Journal of Integrative Agriculture, 25(10): 4175-4191.

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