Editorial: New Avenues of Silicon's Role in Plant Biology: Trends and Controversies

Mohammad Mukarram^1*Francisco J Corpas²Alexander Lux^3,4

• ¹Jilin Agricultural University, Changchun, China
• ²Estacion Experimental del Zaidin, Granada, Spain
• ³Univerzita Komenskeho v Bratislave, Bratislava, Slovakia
• ⁴Chemicky ustav Slovenskej akademie vied, Bratislava, Slovakia

Silicon (Si) is a paradoxical element in plant biology: abundant in soils yet historically omitted from essential nutrient lists (Epstein, 1999). Over the past few decades, evidence has established Si as a quasi-essential element that can enhance plant growth, yield, and resilience under stress (Manivannan et al., 2023). Several Si-accumulating plants, such as Oryza sativa, uptake astonishing amounts of Si (up to ~10% of their dry weight, exceeding even macronutrients like N or K) (Hodson et al., 2006). Yet how Si confers these advantages remains an active area of debate. Is Si primarily fortifying cell walls and acting as a mechanical barrier, or is it integral to plant stress physiology? This core controversy of anatomical vs physiological modes of Si action is a rapidly evolving frontier. Researchers are probing Si's modus operandi, crosstalk with signalling molecules (e.g., reactive oxygen species (ROS) and phytohormones), and its stress-mitigating potential. The present Research Topic aims to advance our understanding of these phenomena. Articles in this collection tackle Si from diverse angles, ranging from stress mitigation and nutrient dynamics to molecular mechanisms and innovative Si delivery methods, reflecting the breadth of current Si research. embedded rice husk silica nanoparticles (SiNPs) in an alginate seed film to create a slow-release Si source. SiNPs-coated Vigna radiata seeds exhibited more vigorous early growth than controls under high salt conditions, owing to enhanced metabolic activity, proton pump function, and ROS scavenging in the seedlings. This seed priming strategy with Si opens new avenues for protecting crops against stress right from the outset. He et al. present field evidence that moderate (750-1500 kg/ha) Si fertilisation can enhance both the yield and quality of a high-value crop (Nicotiana tabacum). Si increased the N and K use efficiency by up to ~40%, having clear agronomic significance for reducing fertiliser waste and environmental runoff. Si-treated leaves had higher sugar-to-alkaloid ratios and mineral balance (higher desirable K, lower Cl). These modulations resulted in the increased high-grade Nicotiana tabacum leaves (~95%), yield (15.7%), and economic output (30.8%) over no Si application.However, the highest dose (3000 kg/ha) slightly depressed leaf quality by elevating nicotine and upsetting the sugar-alkali balance. This dose-dependent response underscores the need to optimise Si nutrition, as more is not always better. He et al.'s findings align with a broader recognition that Si can improve plant nutrient status, better resource use, and product quality What mechanistic magic underlies silicon's broad benefits? Zexer et al. revealed that silica aggregates alongside the short-chain, less-polymerised lignin monomers in root endodermal cell walls. Alternatively, the lignin at these sites polymerises into more extensive, highly cross-linked doughnut-shaped structures in Si-absence. The authors suggested that silicic acid interrupts the typical polymerisation of lignin and nucleates silica gel. This finding reinforces the hypothesised "Si-C trade-off" in plant defence strategies (de Tombeur et al. ). These remarkable effects underscore that size matters. While Si effects are well reported, we still seek to understand several key phenomena. For example, (1) how are Si effects realised at the molecular level (e.g., signalling networks for As the plant science community addresses the open questions and refines methodologies, we anticipate rapid progress in demystifying how Si works and how best to harness it. We hope this collection will inspire cross-disciplinary collaboration and many other interesting Si studies.