Chen Jiayi, Xie Fangfang, Shah Kamran, Chen Canbin, Zeng Jianmei, Chen Jiaxuan, Zhang Zhike, Zhao Jietang, Hu Guibing, Qin Yonghua
Guangdong Provincial Key Laboratory of Postharvest Science of Fruits and Vegetables/Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (South China), Ministry of Agriculture and Rural Affairs, College of Horticulture, South China Agricultural University, Guangzhou, Guangdong 510642, China.
Guangdong Provincial Key Laboratory of Postharvest Science of Fruits and Vegetables/Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (South China), Ministry of Agriculture and Rural Affairs, College of Horticulture, South China Agricultural University, Guangzhou, Guangdong 510642, China; College of Agriculture, Guangxi University, Nanning 530004, China.
Plant Sci. 2023 Mar;328:111595. doi: 10.1016/j.plantsci.2023.111595. Epub 2023 Jan 13.
Basic helix-loop-helix (bHLH) proteins are dimeric transcription factors (TFs) involved in various plant physiological and biological processes. Despite this, little is known about the molecular properties and roles of bHLH TFs in pitaya betalain biosynthesis. Here we report the identification of 165 HubHLH genes in H. undantus genome, their chromosomal distribution, physiochemical characteristics, conserved motifs, gene structure, phylogeny and synteny of HubHLH genes. Based on phylogenetic relationship analysis, the 165 HubHLHs were divided into 26 subfamilies and unequally distributed on the 11 chromosomes of pitaya. Based on the pitaya transcriptome data, a candidate gene HubHLH159 was obtained, and the real-time quantitative PCR analysis confirmed that HubHLH159 showed a high expression level in 'Guanhuahong' pitaya (red-pulp) at mature stage, indicating its role in betalain biosynthesis. HubHLH159 is a Group II protein and contains a bHLH domain. It is a nuclear protein with transcriptional activation activity. Dual luciferase reporter assays and virus-induced gene silencing (VIGS) experiments showed that HubHLH159 promotes betalain biosynthesis by activating the expression of HuADH1, HuCYP76AD1-1, and HuDODA1. The results of the present study lay a new theoretical reference for the regulation of pitaya betalain biosynthesis and also provides as essential basis for the future analysis of the functions of HubHLH gene family.
碱性螺旋-环-螺旋（bHLH）蛋白是参与各种植物生理和生物学过程的二聚体转录因子（TFs）。尽管如此，关于bHLH转录因子在火龙果甜菜素生物合成中的分子特性和作用却知之甚少。在此，我们报告了在红肉火龙果基因组中鉴定出165个HubHLH基因，以及它们的染色体分布、理化特性、保守基序、基因结构、系统发育和HubHLH基因的共线性。基于系统发育关系分析，165个HubHLHs被分为26个亚家族，并且不均衡地分布在火龙果的11条染色体上。基于火龙果转录组数据，获得了一个候选基因HubHLH159，实时定量PCR分析证实HubHLH159在‘观音红’火龙果（红肉）成熟阶段表现出高表达水平，表明其在甜菜素生物合成中的作用。HubHLH159是一种II类蛋白，包含一个bHLH结构域。它是一种具有转录激活活性的核蛋白。双荧光素酶报告基因检测和病毒诱导基因沉默（VIGS）实验表明，HubHLH159通过激活HuADH1、HuCYP76AD1-1和HuDODA1的表达来促进甜菜素生物合成。本研究结果为火龙果甜菜素生物合成的调控提供了新的理论参考，也为未来HubHLH基因家族功能分析提供了重要依据。
