Moderate Nitrogen with Medium Planting Density Enhances Sweet Potato Storage Root Growth via Hormone Signaling and Carbon Metabolism: A Multi-Omics Perspective

Optimizing nitrogen (N) application and planting density is essential for sustainable sweet potato productivity, yet the molecular mechanisms underlying their synergistic effects remain poorly understood. In this study, field and pot experiments were integrated with transcriptomic and metabolomic analyses to compare low-density, high‑nitrogen (LDHN) and medium‑density, medium‑nitrogen (MDMN) cultivation regimes. Over two growing seasons, MDMN increased yield by 15–25%, primarily by elevating the number of storage roots per plant and per unit area, while individual root weight remained unchanged. Anatomical examinations revealed that MDMN accelerated cambial ring formation and increased xylem vessel density at 15–30 days after planting, thereby enhancing assimilate transport to developing storage roots. Transcriptome profiling at 30 days identified 9,856 differentially expressed genes, with upregulation of genes involved in starch and sucrose metabolism ( SUS, glgC, WAXY, GBE1 ) and MAPK /hormone signaling pathways, alongside downregulation of phenylpropanoid and flavonoid biosynthesis genes, indicating a metabolic shift from nitrogen‑intensive defense toward carbon storage. Metabolomic analysis detected 1,240 differentially accumulated metabolites, including elevated levels of glucose, trehalose, D‑fructose, and key hormone conjugates (auxin, cytokinin, jasmonate), which collectively support root initiation, vascular development, and stress tolerance. Weighted gene co‑expression network analysis further identified WRKY, NAC, bHLH, and TCP transcription factors as central regulators linking nitrogen and density signaling. qRT‑PCR validation confirmed that hub genes ( XTH15, XTH16, POD31, HSP70 ) were positively correlated with storage‑root biomass. These multi‑omics results demonstrate that MDMN promotes a sink‑optimized phenotype through coordinated hormonal signaling, carbon allocation, and modulation of secondary metabolism. This study provides key regulatory targets for future breeding and biotechnology strategies aimed at enhancing nitrogen‑use efficiency and yield in sweet potato and related root crops under high‑density, low‑input cultivation systems. Information & Authors Information Version history Peer review timeline Published Industrial Crops and Products Version of Record1 May 2026Published Copyright This work is licensed under a Non Exclusive No Reuse License.

Authors Metrics & Citations Metrics Article Usage 178views 89downloads Citations Download citation Jinyang Zhao, Muhammad Shahid, Yujie Li, et al. Moderate Nitrogen with Medium Planting Density Enhances Sweet Potato Storage Root Growth via Hormone Signaling and Carbon Metabolism: A Multi-Omics Perspective. Authorea. 04 February 2026. DOI: https://doi.org/10.22541/au.177021773.36771208/v1 DOI: https://doi.org/10.22541/au.177021773.36771208/v1 If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download. For more information or tips please see 'Downloading to a citation manager' in the Help menu.