Yamaji Naoki, Mitani-Ueno Namiki, Fujii Toshiki, Shinya Tomonori, Shao Ji Feng, Watanuki Shota, Saitoh Yasunori, Ma Jian Feng
Institute of Plant Science and Resources, Okayama University, Chuo 2-20-1, Kurashiki, 710-0046, Japan.
State Key Laboratory of Subtropical Silviculture, Zhejiang Agriculture & Forestry University, Lin'an, 311300, China.
Nat Commun. 2024 Dec 27;15(1):10712. doi: 10.1038/s41467-024-55322-7.
Plants accumulate silicon to protect them from biotic and abiotic stresses. Especially in rice (Oryza sativa), a typical Si-accumulator, tremendous Si accumulation is indispensable for healthy growth and productivity. Here, we report a shoot-expressed signaling protein, Shoot-Silicon-Signal (SSS), an exceptional homolog of the flowering hormone "florigen" differentiated in Poaceae. SSS transcript is only detected in the shoot, whereas the SSS protein is also detected in the root and phloem sap. When Si is supplied from the root, the SSS transcript rapidly decreases, and then the SSS protein disappears. In sss mutants, root Si uptake and expression of Si transporters are decreased to a basal level regardless of the Si supply. The grain yield of the mutants is decreased to 1/3 due to insufficient Si accumulation. Thus, SSS is a key phloem-mobile protein for integrating root Si uptake and shoot Si accumulation underlying the terrestrial adaptation strategy of grasses.
植物积累硅以保护自身免受生物和非生物胁迫。特别是在典型的硅积累植物水稻（Oryza sativa）中，大量的硅积累对于其健康生长和生产力是不可或缺的。在此，我们报道了一种在地上部表达的信号蛋白，即地上部硅信号（SSS），它是禾本科中与开花激素“成花素”不同的一种特殊同源物。SSS转录本仅在地上部检测到，而SSS蛋白在根和韧皮部汁液中也能检测到。当从根部供应硅时，SSS转录本迅速减少，随后SSS蛋白消失。在sss突变体中，无论硅供应情况如何，根对硅的吸收以及硅转运蛋白的表达均降至基础水平。由于硅积累不足，突变体的谷物产量降至三分之一。因此，SSS是一种关键的韧皮部移动蛋白，对于整合根对硅的吸收和地上部硅积累，是禾本科植物陆地适应策略的基础。
