Zi Hailing, Ding Yaxin, Fang Ruiyuan, Li Xinxin, Song Zhiyuan, Huang Huailing, Li Nana, Fan Shoujin, Zhao Chuanzhi, Wang Xingjun, Xia Han
Institute of Crop Germplasm Resources (Institute of Biotechnology), Shandong International Joint Laboratory of Agricultural Germplasm Resources Innovation, Shandong Academy of Agricultural Sciences, Jinan, 250100, People's Republic of China.
College of Life Sciences, Shandong Normal University, Jinan, 250014, People's Republic of China.
Theor Appl Genet. 2025 Jul 11;138(8):182. doi: 10.1007/s00122-025-04966-0.
Anthocyanins and proanthocyanidins (PAs), which determine the color of peanut seed coats, not only offer protection to plants under biotic and abiotic stress but also contribute to human health. The white testa peanut contains lower levels of anthocyanins and PAs, yet the mechanisms underlying the white testa phenotype in peanuts remain largely unknown. In the current study, two homologous peanut AhTT8 genes, namely AhTT8_AA and AhTT8_BB, were identified as the key genes controlling the seed coat color of peanuts through BSA-seq analysis and fine mapping. Null mutations or long sequence insertions were observed in two AhTT8 genes across six cultivated peanut varieties with white seed coat, and expression of AhTT8 genes was downregulated significantly in the white seed coat of peanuts. Overexpression of AhTT8 successfully restored PA and anthocyanin productions in Arabidopsis thaliana tt8 mutant. Furthermore, transcriptomic profiling of the seed coats of pink testa peanuts and white testa peanuts showed that expression of genes encoded transcription factors like AhMYB5, AhTTG1, AhMYB1, AhCPC, AhTTG2 and AhGL2 was downregulated in the white seed coats, while a subset of genes involved in PA and anthocyanin biosynthesis were also downregulated in the white seed coats. These results indicated that AhTT8 plays a central role in the regulation of peanut PA and anthocyanin biosynthesis, and resolving the molecular mechanisms of AhTT8 in peanuts is of great significance for peanut molecular breeding.
花青素和原花青素（PAs）决定了花生种皮的颜色，它们不仅能在生物和非生物胁迫下保护植物，还对人类健康有益。白色种皮花生的花青素和PAs含量较低，但花生白色种皮表型的潜在机制在很大程度上仍不清楚。在本研究中，通过BSA-seq分析和精细定位，鉴定出两个同源花生AhTT8基因，即AhTT8_AA和AhTT8_BB，它们是控制花生种皮颜色的关键基因。在六个具有白色种皮的栽培花生品种中，两个AhTT8基因均存在无效突变或长序列插入，并且花生白色种皮中AhTT8基因的表达显著下调。在拟南芥tt8突变体中过表达AhTT8成功恢复了PA和花青素的合成。此外，对粉色种皮花生和白色种皮花生种皮的转录组分析表明，在白色种皮中，AhMYB5、AhTTG1、AhMYB1、AhCPC、AhTTG2和AhGL2等转录因子编码基因的表达下调，而参与PA和花青素生物合成的一部分基因在白色种皮中也下调。这些结果表明，AhTT8在花生PA和花青素生物合成调控中起核心作用，解析花生中AhTT8的分子机制对花生分子育种具有重要意义。
