A hydroponic cultivation platform for analyzing nodal root development, cell wall thickening, and hormone responses in grasses

Abstract

Nodal roots are central to water and nutrient uptake, anchorage, and resistance to lodging in grasses. These functions are especially important under variable and severe weather conditions that impact plant performance and crop stability. However, controlled induction and quantitative analysis of nodal roots under controlled conditions remain a major technical challenge. To address this limitation, we developed a hydroponic growth and analytical platform that enables reproducible induction and quantitative analysis of shoot-borne nodal roots beyond early seedling stages. The hydroponic system supported stable nodal root development and enabled controlled chemical perturbations. When combined with histological and quantitative imaging approaches, the platform resolved tissue-specific cell wall properties across defined cell types. Using Brachypodium distachyon and Triticum aestivum (wheat), we found that phytohormone perturbations produced distinct effects on leaf nodal root development and anatomy. Treatment with GA 3 or trans-zeatin increased secondary wall thickening in both cortical and vascular tissues. Perturbation of auxin application primarily affected root initiation and elongation with limited effects on wall deposition. Jasmonate signaling altered cell wall properties primarily in outer cortical tissues, revealing an uncoupling of lignin accumulation and wall thickness, while vascular wall thickness remained largely unchanged. The platform was successfully applied to wheat, where GA 3 treatment induced cortical secondary wall thickening similar to that observed in B. distachyon . This platform provides a scalable and accessible method for studying nodal root development and secondary cell wall deposition in grasses. The results highlight strong cell type-specific regulation of wall thickening and demonstrate the utility of the platform for comparative studies of root anatomy in grasses. By linking controlled perturbations with quantitative anatomical measurements, this approach enables comparative analysis of root traits relevant to plant stability and performance and provides a foundation for future studies of root development in grasses.