College of Life Science, Sichuan Agricultural University, No. 46, Xinkang Road, Ya'an, 625014, China.
Xichang University, 615013 Xichang, Sichuan, China.
Int J Biol Macromol. 2024 Nov;279(Pt 2):135275. doi: 10.1016/j.ijbiomac.2024.135275. Epub 2024 Sep 2.
Starch serves as a crucial energy source for both plants and humans, predominantly synthesized and stored in endosperms, tubers, rhizomes, and cotyledons. Given the significant role of amylose in determining the quality of starchy crops, optimizing its content has become a key objective in current crop breeding efforts. Tartary buckwheat, a dicotyledonous plant, notably accumulates high levels of amylose in its endosperm, surpassing common cereals like rice and maize. However, the mechanisms underlying amylose accumulation, distribution, and regulation in Tartary buckwheat remain unclear. Here, amylose content was determined across various tissues and organs of Tartary buckwheat, identifying with the endosperm as the primary site for its biosynthesis and accumulation. RNA sequencing analysis of endosperms from different developmental stages identified 35 genes potentially involved in starch biosynthesis, with 13 genes showing high endosperm-specific expression, suggesting crucial roles in starch biosynthesis. Additionally, the transcription factor FtNF-YB2, which was specifically highly expressed in the endosperm, was discovered to enhance amylose synthesis. Moreover, promoters with potential endosperm-specific activity were identified, advancing our understanding of amylose regulation. Additionally, this study also demonstrates that brassinosteroids (BR) positively influence amylose biosynthesis in Tartary buckwheat endosperm. These findings provide essential insights into the mechanisms of understanding amylose biosynthesis, accumulation and regulation in Tartary buckwheat, offering significant implications for future breeding strategies.
淀粉是植物和人类的重要能量来源，主要在胚乳、块茎、根茎和子叶中合成和储存。鉴于直链淀粉在决定淀粉作物品质方面的重要作用，优化其含量已成为当前作物育种工作的主要目标。鞑靼荞麦是一种双子叶植物，其胚乳中直链淀粉含量显著升高，超过了水稻和玉米等常见谷物。然而，鞑靼荞麦中直链淀粉积累、分布和调节的机制尚不清楚。本研究在不同的组织和器官中测定了鞑靼荞麦的直链淀粉含量，发现胚乳是其生物合成和积累的主要部位。对不同发育阶段胚乳的 RNA 测序分析鉴定了 35 个可能参与淀粉生物合成的基因，其中 13 个基因在胚乳中特异性高表达，表明它们在淀粉生物合成中起着关键作用。此外，还发现了特异性高表达于胚乳的转录因子 FtNF-YB2，它可以增强直链淀粉的合成。此外，还鉴定了具有潜在胚乳特异性活性的启动子，这有助于我们深入了解直链淀粉的调控机制。此外，本研究还表明，油菜素内酯（BR）可正向影响鞑靼荞麦胚乳中直链淀粉的生物合成。这些发现为深入了解鞑靼荞麦直链淀粉生物合成、积累和调控机制提供了重要线索，对未来的育种策略具有重要意义。
