Zhu Meiling, Zang Yu, Zhang Xuelei, Shang Shuai, Xue Song, Chen Jun, Tang Xuexi
College of Marine Life Sciences, Ocean University of China, Qingdao, Shandong, China.
Key Laboratory of Marine Eco-Environmental Science and Technology, First Institute of Oceanography, Ministry of Natural Resources, Qingdao, Shandong, China.
Front Plant Sci. 2023 Mar 10;14:1130292. doi: 10.3389/fpls.2023.1130292. eCollection 2023.
Seed development is a crucial phase in the life cycle of seed-propagated plants. As the only group of angiosperms that evolved from terrestrial plants to complete their life cycle submerged in marine environments, the mechanisms underlying seed development in seagrasses are still largely unknown. In the present study, we attempted to combine transcriptomic, metabolomic, and physiological data to comprehensively analyze the molecular mechanism that regulates energy metabolism in seeds at the four major developmental stages. Our results demonstrated that seed metabolism was reprogrammed with significant alteration of starch and sucrose metabolism, glycolysis, the tricarboxylic acid cycle (TCA cycle), and the pentose phosphate pathway during the transition from seed formation to seedling establishment. The interconversion of starch and sugar provided energy storage substances in mature seeds and further acted as energy sources to support seed germination and seedling growth. The glycolysis pathway was active during germination and seedling establishment, which provided pyruvate for TCA cycle by decomposing soluble sugar. Notably, the biological processes of glycolysis were severely inhibited during . seed maturation may have a positive effect on seed germination, maintaining a low level of metabolic activity during seed maturation to preserve seed viability. Increased acetyl-CoA and ATP contents were accompanied with the higher TCA cycle activity during seed germination and seedling establishment, indicating that the accumulations of precursor and intermediates metabolite that can strengthen the TCA cycle and facilitate energy supply for . seed germination and seedling growth. The large amount of oxidatively generated sugar phosphate promotes fructose 1,6-bisphosphate synthesis to feed back to glycolysis during seed germination, indicating that the pentose phosphate pathway not only provides energy for germination, but also complements the glycolytic pathway. Collectively, our findings suggest these energy metabolism pathways cooperate with each other in the process of seed transformation from maturity to seedling establishment, transforming seed from storage tissue to highly active metabolic tissue to meet the energy requirement seed development. These findings provide insights into the roles of the energy metabolism pathway in the complete developmental process of . seeds from different perspectives, which could facilitate habitat restoration of . meadows seeds.
种子发育是种子繁殖植物生命周期中的一个关键阶段。作为唯一一类从陆生植物进化而来，在海洋环境中完成其生命周期的被子植物，海草种子发育的潜在机制仍 largely 未知。在本研究中，我们试图结合转录组学、代谢组学和生理数据，全面分析在四个主要发育阶段调节种子能量代谢的分子机制。我们的结果表明，在从种子形成到幼苗建立的转变过程中，种子代谢被重新编程，淀粉和蔗糖代谢、糖酵解、三羧酸循环（TCA 循环）和磷酸戊糖途径发生了显著变化。淀粉和糖的相互转化在成熟种子中提供能量储存物质，并进一步作为能量来源支持种子萌发和幼苗生长。糖酵解途径在萌发和幼苗建立过程中活跃，通过分解可溶性糖为 TCA 循环提供丙酮酸。值得注意的是，在种子成熟过程中糖酵解的生物学过程受到严重抑制，这可能对种子萌发有积极影响，在种子成熟期间保持低水平的代谢活性以维持种子活力。在种子萌发和幼苗建立期间，乙酰辅酶 A 和 ATP 含量的增加伴随着较高的 TCA 循环活性，表明前体和中间代谢物的积累可以加强 TCA 循环并促进为种子萌发和幼苗生长提供能量。大量氧化生成的磷酸糖在种子萌发期间促进果糖 1,6 - 二磷酸的合成以反馈到糖酵解，表明磷酸戊糖途径不仅为萌发提供能量，还补充糖酵解途径。总体而言，我们的研究结果表明，这些能量代谢途径在种子从成熟到幼苗建立的转化过程中相互协作，将种子从储存组织转变为高活性代谢组织，以满足种子发育的能量需求。这些发现从不同角度深入了解了能量代谢途径在种子完整发育过程中的作用，这可能有助于海草草甸种子的栖息地恢复。
