Cytochrome P450 CitCYP97B modulates carotenoid accumulation diversity by hydroxylating β-cryptoxanthin in Citrus

作者：Yingzi Zhang, Jiajing Jin, Nan Wang, Quan Sun, Di Feng, Shenchao Zhu, Zexin Wang, Shunxin Li, Junli Ye, Lijun Chai, Zongzhou Xie, Xiuxin Deng · 发表于：Plant Communications · 年份：2024 · DOI：10.1016/j.xplc.2024.100847 · 被引用次数：19 · 研究领域：Antioxidant Activity and Oxidative Stress、Plant biochemistry and biosynthesis、Plant Reproductive Biology

Carotenoids in plant foods provide health benefits by functioning as provitamin A. One of the vital provitamin A carotenoids, β-cryptoxanthin, is typically plentiful in citrus fruit. However, little is known about the genetic basis of β-cryptoxanthin accumulation in citrus. Here, we performed a widely targeted metabolomic analysis of 65 major carotenoids and carotenoid derivatives to characterize carotenoid accumulation in Citrus and determine the taxonomic profile of β-cryptoxanthin. We used data from 81 newly sequenced representative accessions and 69 previously sequenced Citrus cultivars to reveal the genetic basis of β-cryptoxanthin accumulation through a genome-wide association study. We identified a causal gene, CitCYP97B, which encodes a cytochrome P450 protein whose substrate and metabolic pathways in land plants were undetermined. We subsequently demonstrated that CitCYP97B functions as a novel monooxygenase that specifically hydroxylates the β-ring of β-cryptoxanthin in a heterologous expression system. In planta experiments provided further evidence that CitCYP97B negatively regulates β-cryptoxanthin content. Using the sequenced Citrus accessions, we found that two critical structural cis-element variations contribute to increased expression of CitCYP97B, thereby altering β-cryptoxanthin accumulation in fruit. Hybridization/introgression appear to have contributed to the prevalence of two cis-element variations in different Citrus types during citrus evolution. Ove...