State Key Laboratory of Crop Stress Adaptation and Improvement, Henan Joint International Laboratory for Crop Multi-Omics Research, School of Life Sciences, Henan University, Kaifeng, 475004, China.
National Key Laboratory of Wheat and Maize Crop Science, College of Agronomy, Henan Agricultural University, Zhengzhou, 450002, China.
Adv Sci (Weinh). 2024 May;11(20):e2400916. doi: 10.1002/advs.202400916. Epub 2024 Mar 23.
The rigid hull encasing Tartary buckwheat seeds necessitates a laborious dehulling process before flour milling, resulting in considerable nutrient loss. Investigation of lignin composition is pivotal in understanding the structural properties of tartary buckwheat seeds hulls, as lignin is key determinant of rigidity in plant cell walls, thus directly impacting the dehulling process. Here, the lignin composition of seed hulls from 274 Tartary buckwheat accessions is analyzed, unveiling a unique lignin chemotype primarily consisting of G lignin, a common feature in gymnosperms. Furthermore, the hardness of the seed hull showed a strong negative correlation with the S lignin content. Genome-wide detection of selective sweeps uncovered that genes governing the biosynthesis of S lignin, specifically two caffeic acid O-methyltransferases (COMTs) and one ferulate 5-hydroxylases, are selected during domestication. This likely contributed to the increased S lignin content and decreased hardness of seed hulls from more domesticated varieties. Genome-wide association studies identified robust associations between FtCOMT1 and the accumulation of S lignin in seed hull. Transgenic Arabidopsis comt1 plants expressing FtCOMT1 successfully reinstated S lignin content, confirming its conserved function across plant species. These findings provide valuable metabolic and genetic insights for the potential redesign of Tartary buckwheat seed hulls.
鞑靼荞麦种子的坚硬外壳在面粉加工前需要进行艰苦的脱壳过程，这导致了大量营养物质的损失。研究木质素的组成对于了解鞑靼荞麦种皮的结构特性至关重要，因为木质素是植物细胞壁刚性的关键决定因素，因此直接影响脱壳过程。在这里，分析了 274 个鞑靼荞麦品种种子外壳的木质素组成，揭示了一种主要由 G 木质素组成的独特木质素化学型，这是裸子植物的共同特征。此外，种子外壳的硬度与 S 木质素含量呈强烈负相关。全基因组选择性扫描发现，参与 S 木质素生物合成的基因，特别是两个咖啡酸-O-甲基转移酶（COMTs）和一个阿魏酸 5-羟化酶，在驯化过程中受到选择。这可能导致驯化程度较高的品种的 S 木质素含量增加和种子外壳硬度降低。全基因组关联研究鉴定出 FtCOMT1 与种子外壳中 S 木质素积累之间存在稳健的关联。表达 FtCOMT1 的拟南芥 comt1 转基因植物成功地恢复了 S 木质素的含量，证实了其在植物物种间的保守功能。这些发现为鞑靼荞麦种子外壳的潜在重新设计提供了有价值的代谢和遗传见解。
