Si Jia, Zhou Xiaoqing, Chen Xinyu, Ming Huilin, Liu Hanqiang, Hui Maixia
Vegetables Engineering and Technology Research Center of Shaanxi Province, College of Horticulture, Northwest A&F University, Yangling, 712100, Shaanxi, China.
Department of Vegetable Science, College of Horticulture, Northwest A&F University, No. 3 Taicheng Road, Yangling Demonstration Zone, Xianyang, Shaanxi, China.
Planta. 2025 Mar 6;261(4):80. doi: 10.1007/s00425-025-04630-3.
Chalcone isomerase (BraCHI, BraA03g059660.3C) is the candidate gene controlling purple leaf coloration in non-heading Chinese cabbage. A 10-bp deletion in its promoter enhances gene expression in purple plants, likely by disrupting MYB transcription factor binding, leading to anthocyanin accumulation. Leaf color is a critical trait influencing the commercial and nutritional value of leafy vegetables, with purple-leafed varieties prized for their high anthocyanin content. In this study, we investigated the genetic basis of purple leaf coloration in non-heading Chinese cabbage (Brassica rapa). Using a recombinant inbred line (RIL) population derived from a cross between purple-leafed S45P and green-leafed S45G lines, bulked segregant analysis sequencing (BSA-seq) and fine mapping were performed. The analysis identified BraP2, a locus on chromosome A03 associated with purple leaf coloration. Within the 65.31 kb candidate region, BraA03g059660.3C, encoding chalcone isomerase (CHI), was identified as the strongest candidate gene. Quantitative real-time PCR (qRT-PCR) revealed significantly higher expression of BraA03g059660.3C in purple-leafed S45P plants compared to green-leafed S45G plants. Further sequence analysis uncovered a 10-bp deletion in the promoter region of BraA03g059660.3C in S45P plants. This deletion likely disrupts a MYB transcription factor binding site, enhancing gene expression and promoting anthocyanin accumulation. Our findings demonstrate that BraA03g059660.3C plays a pivotal role in controlling purple leaf coloration in non-heading Chinese cabbage. This discovery advances the understanding of anthocyanin biosynthesis regulation and provides valuable genetic resources for breeding Brassica crops with improved esthetic and nutritional qualities.
查尔酮异构酶（BraCHI，BraA03g059660.3C）是控制不结球白菜紫叶着色的候选基因。其启动子中的一个10bp缺失增强了该基因在紫色植株中的表达，可能是通过破坏MYB转录因子结合，导致花青素积累。叶色是影响叶菜类蔬菜商业价值和营养价值的关键性状，紫叶品种因其高花青素含量而备受青睐。在本研究中，我们调查了不结球白菜（Brassica rapa）紫叶着色的遗传基础。利用从紫叶S45P和绿叶S45G品系杂交获得的重组自交系（RIL）群体，进行了混合分组分析法测序（BSA-seq）和精细定位。分析确定了A03染色体上与紫叶着色相关的位点BraP2。在65.31 kb的候选区域内，编码查尔酮异构酶（CHI）的BraA03g059660.3C被确定为最有可能的候选基因。定量实时PCR（qRT-PCR）显示，与绿叶S45G植株相比，BraA03g059660.3C在紫叶S45P植株中的表达显著更高。进一步的序列分析发现，S45P植株中BraA03g059660.3C启动子区域存在一个10bp的缺失。这种缺失可能破坏了一个MYB转录因子结合位点，增强了基因表达并促进了花青素积累。我们的研究结果表明，BraA03g059660.3C在控制不结球白菜紫叶着色中起关键作用。这一发现增进了对花青素生物合成调控的理解，并为培育具有更好外观和营养品质的芸苔属作物提供了宝贵的遗传资源。
