Table_5_Transcriptomic and metabolomic reveals silicon enhances adaptation of rice under dry cultivation by improving flavonoid biosynthesis, osmoregulation, and photosynthesis.XLSX

Dry cultivation is a new rice crop mode used to alleviate water shortage and develop water-saving agriculture. There is obvious genetic difference compared with drought-tolerant rice. Silicon (Si) plays an important role in plant adaptation to adverse environmental conditions and can significantly improve the drought tolerance and yield of rice. However, the regulatory mechanism via which Si provides plant tolerance or adaptation under dry cultivation is not well understood. The present study investigated the changes in plant growth, photosynthetic gas exchange, and oxidative stress of the rice cultivar “Suijing 18” under dry cultivation. Si improved photosynthetic performance and antioxidant enzyme activity and subsequently reduced lipid peroxidation of rice seedlings, promoted LAI and promoted leaf growth under dry cultivation. Further, transcriptomics combined with quasi-targeted metabolomics detected 1416 and 520 differentially expressed genes (DEGs), 38 and 41 differentially accumulated metabolites (DAMs) in the rice leaves and roots, respectively. Among them, 13 DEGs were involved in flavonoid biosynthesis, promoting the accumulation of flavonoids, anthocyanins, and flavonols in the roots and leaves of rice under dry cultivation. Meanwhile, 14 DEGs were involved in photosynthesis, promoting photosystem I and photosystem II responses, increasing the abundance of metabolites in leaves. On the other hand, 24 DAMs were identified involved in osmoregulatory processes, significantly increasing amino acids and carbohydrates and their derivatives in roots. These results provide new insight into the role of Si in alleviating to adverse environmental, Si enhanced the accumulation of flavonoids and osmoregulatory metabolites, thereby alleviating drought effect on the roots. On the other hand, improving dehydration resistance of leaves, guaranteeing normal photosynthesis and downward transport of organic matter. In conclusion, Si promoted the coordinated action between the above-ground and below-ground plant parts, improved the root/shoot ratio (R/S) of rice and increased the sugar content and enhancing rice adaptability under dry cultivation conditions. The establishment of the system for increasing the yield of rice under dry cultivation provides theoretical and technical support thereby promoting the rapid development of rice in Northeast China, and ensuring national food security.

旱作栽培（Dry cultivation）是一种用于缓解水资源短缺、发展节水农业的新型水稻种植模式。与耐旱水稻相比，其遗传差异显著。硅（Silicon, Si）在植物适应逆境环境过程中发挥关键作用，可显著提升水稻的耐旱性与籽粒产量。但硅在旱作栽培条件下介导植物产生耐受性或适应能力的调控机制仍未完全明晰。
本研究以水稻品种‘绥粳18（Suijing 18）’为试材，探究了旱作栽培条件下其植株生长、光合气体交换及氧化应激水平的变化。结果表明，硅可提升水稻幼苗的光合性能与抗氧化酶活性，进而降低脂质过氧化程度，同时促进叶面积指数（Leaf Area Index, LAI）提升与叶片生长。
进一步结合转录组学与准靶向代谢组学联合分析，在水稻叶片与根系中分别检测到1416个、520个差异表达基因（Differentially Expressed Genes, DEGs），以及38个、41个差异积累代谢物（Differentially Accumulated Metabolites, DAMs）。其中，13个差异表达基因参与类黄酮生物合成途径，可促进旱作栽培下水稻根系与叶片中类黄酮、花青素（anthocyanins）及黄酮醇（flavonols）的积累；另有14个差异表达基因参与光合作用过程，可介导光系统I（Photosystem I）与光系统II（Photosystem II）的响应，提升叶片内代谢物丰度。
另一方面，研究鉴定出24个参与渗透调节过程的差异积累代谢物，可显著提升根系内氨基酸、碳水化合物及其衍生物的含量。
上述研究结果为解析硅在缓解植物逆境胁迫中的作用提供了新视角：硅可促进类黄酮与渗透调节代谢物的积累，从而缓解干旱对根系的损伤；同时提升叶片的脱水抗性，保障光合作用正常进行与光合产物的向下运输。
综上，硅可促进植物地上与地下部分的协同作用，提升水稻根冠比（Root/Shoot Ratio, R/S）与糖分含量，增强水稻在旱作栽培条件下的适应能力。本研究构建的旱作水稻增产技术体系，可为我国东北地区水稻产业的快速发展提供理论与技术支撑，同时保障国家粮食安全。