Differential hydroxylation efficiency of the two non-heme carotene hydroxylases: DcBCH1, rather than DcBCH2, plays a major role in carrot taproot

文献类型： 外文期刊

第一作者： Li, Tong

作者： Li, Tong;Liu, Jie-Xia;Deng, Yuan-Jie;Duan, Ao-Qi;Liu, Hui;Xiong, Ai-Sheng;Zhuang, Fei-Yun

作者机构：

期刊名称：HORTICULTURE RESEARCH （ 影响因子：8.7； 五年影响因子：9.0 ）

ISSN： 2662-6810

年卷期： 2022 年 9 卷

页码：

收录情况： SCI

摘要： Carotene hydroxylase plays an important role in catalyzing the hydroxylation of carotene to xanthopylls, including two types: non-heme carotene hydroxylase (BCH type) and heme-containing cytochrome P450 hydroxylase (P450 type). Two BCH-encoding genes were annotated in the carrot genome. However, the role of BCHs and whether there are functional interactions between the duplicated BCHs in carrot remains unclear. In this study, two BCH encoding genes, DcBCH1 and DcBCH2, were cloned from carrot. The relative expression level of DcBCH1 was much higher than that of DcBCH2 in carrot taproots with different carotene accumulation levels. Overexpression of DcBCH1 in 'KRD' (high carotene accumulated) carrot changed the taproot color from orange to yellow, accompanied by substantial reductions in alpha-carotene and beta-carotene. There was no obvious change in taproot color between transgenic 'KRD' carrot overexpressing DcBCH2 and control carrot. Simultaneously, the content of alpha-carotene in the taproot of DcBCH2-overexpressing carrot decreased, but the content of beta-carotene did not change significantly in comparison with control carrot. Using the CRISPR/Cas9 system to knock out DcBCH1 in 'KRD' carrot lightened the taproot color from orange to pink-orange; the content of alpha-carotene in the taproot increased slightly, while the beta-carotene content was still significantly decreased, compared with control carrot. In DcBCH1-knockout carrot, the transcript level of DcBCH2 was significantly increased. These results indicated that in carrot taproot, DcBCH1 played the main function of BCH enzyme, which could hydroxylate alpha-carotene and beta-carotene; DcBCH1 and DcBCH2 had functional redundancy, and these two DcBCHs could partially compensate for each other.

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