College of Life Sciences, Ganzhou Key Laboratory of Greenhouse Vegetable, Gannan Normal University, Ganzhou, 341000, China.
Environment-Friendly Crop Germplasm Innovation and Genetic Improvement Key Laboratory of Sichuan Province, Crop Research Institute, Sichuan Academy of Agricultural Sciences, Chengdu, 610066, China.
Planta. 2023 Jun 14;258(1):19. doi: 10.1007/s00425-023-04171-7.
BraANS.A3 was the key gene controlling purple leaf color in pak choi, and two short fragments of promoter region in green pak choi might be interfering its normal expression. Pak choi (B. rapa L. ssp. chinensis) is an influential and important vegetable with green, yellow, or purple leaves that is cultivated worldwide. The purple leaves are rich in anthocyanins, but the underlying genetics and evolution have yet to be extensively studied. Free-hand sections of the purple leaves indicated that anthocyanins mainly accumulate throughout the adaxial and abaxial epidermal leaf cells. Segregation analyses of an F2 population of a B. rapa ssp. chinensis L. purple leaf mutant ZBC indicated that the purple trait is controlled by an incompletely dominant nuclear gene. Bulked segregant analysis (BSA) showed that the key genes controlling the trait were between 24.25 and 38.10 Mb on chromosome A03 of B. rapa. From the annotated genes, only BraA03g050560.3C, homologous to Arabidopsis AtANS, was related to the anthocyanin synthesis pathway. Genome annotation results and transcriptional sequencing analyses revealed that the BraANS.A3 gene was involved in the purple leaf trait. qRT-PCR analyses showed that BraANS.A3 was highly upregulated in ZBC but hardly expressed in the leaves of an inbred homozygous line of B. campestris ssp. chinensis L. green leaf mutant WTC, indicating that BraANS.A3 played a key role catalyzing anthocyanin synthesis in ZBC. Full-length sequence alignment of BraANS.A3 in WTC and ZBC showed that it was highly conserved in the gene region, with significant variation in the promoter region. In particular, the insertion of two short fragments of the promoter region in WTC may interfere with its normal expression. The promoter regions of ANS in six Brassica species all had multiple cis-elements involved in responses to abscisic acid, light, and stress, suggesting that ANS may be involved in multiple metabolic pathways or biological processes. Protein-protein interactions predicted that BraANS.A3 interacts with virtually all catalytic proteins in the anthocyanin synthesis pathway and has a strong relationship with Transparent Testa 8 (TT8). These results suggest that BraANS.A3 promotes anthocyanin accumulation in purple pak choi and provide new insights into the functional analysis of anthocyanin-related genes in Chinese cabbage and transcriptional regulatory networks.
BraANS.A3 是控制白菜紫色叶色的关键基因，而在绿色白菜中两个短的启动子区域片段可能干扰了其正常表达。白菜（B. rapa L. ssp. chinensis）是一种具有重要影响力的蔬菜，其叶片有绿色、黄色或紫色。紫色叶片富含花色素苷，但背后的遗传学和进化仍有待广泛研究。徒手切片的紫色叶片表明，花色素苷主要积累在叶表皮的上表皮和下表皮细胞中。B. rapa ssp. chinensis L. 紫色叶突变体 ZBC 的 F2 群体的分离分析表明，紫色性状由一个不完全显性核基因控制。混池分离分析（BSA）表明，控制该性状的关键基因位于 B. rapa 染色体 A03 的 24.25 到 38.10 Mb 之间。从注释基因中，只有 BraA03g050560.3C 与拟南芥 AtANS 同源，与花青素合成途径有关。基因组注释结果和转录组测序分析表明，BraANS.A3 基因参与了紫色叶性状。qRT-PCR 分析表明，BraANS.A3 在 ZBC 中高度上调，但在 B. campestris ssp. chinensis L. 绿色叶突变体 WTC 的纯合自交系叶片中几乎不表达，表明 BraANS.A3 在 ZBC 中催化花青素合成中起关键作用。WTC 和 ZBC 中 BraANS.A3 的全长序列比对表明，该基因区域高度保守，启动子区域存在显著变异。特别是，WTC 中启动子区域插入了两个短片段，可能干扰了其正常表达。六个芸薹属物种的 ANS 启动子区域都有多个参与响应脱落酸、光照和胁迫的顺式元件，表明 ANS 可能参与多个代谢途径或生物学过程。蛋白质-蛋白质相互作用预测，BraANS.A3 与花青素合成途径中的几乎所有催化蛋白相互作用，与 Transparent Testa 8（TT8）关系密切。这些结果表明，BraANS.A3 促进了紫色白菜中花青素的积累，为白菜中花青素相关基因的功能分析和转录调控网络提供了新的见解。
