Plant Soil Environ., X:X | DOI: 10.17221/229/2025-PSE

Variation in the capacity for organic nitrogen acquisition along the root length of rice and wheatOriginal Paper

Baozhen Li ORCID...^1,2, Paul W. Hill³, Emily C. Cooledge³, Davey L. Jones³, Zhifan Zhang^2,5, Yue Xie⁵, Tida Ge⁴, Jianlin Shen²

¹ School of Soil and Water Conservation, Central South University of Forestry and Technology, Changsha, P.R. China

² Changsha Research Station for Agricultural & Environmental Monitoring, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, P.R. China

³ School of Environmental and Natural Sciences, Bangor University, Bangor, Gwynedd, UK

⁴ State Key Laboratory for Quality and Safety of Agro-Products, International Science and Technology Cooperation Base for the Regulation of Soil Biological Functions and One Health of Zhejiang Province, Ningbo University, Ningbo, P.R. China

⁵ College of Resource and Environment, Anhui Science and Technology University, Bengbu, P.R. China

Oligopeptides constitute an important yet understudied component of soil’s dissolved organic nitrogen (DON) pool, representing a primary breakdown product of proteins. However, the mechanisms of oligopeptide uptake and utilisation by crop roots remain poorly understood in a plant nutrition context. We investigated the rate and spatial uptake pattern of ¹⁴C-labelled alanine and di- to pentapeptides of alanine in wheat and rice under sterile hydroponic conditions. Both species demonstrated the capacity to absorb N through amino acids and oligopeptides, with rice roots showing higher peptide uptake than wheat. Specifically, alanine absorption exceeded peptide uptake by 3–7-fold in rice and 6–9-fold in wheat. Using phosphor imaging, we demonstrated that alanine and oligopeptide uptake occurred throughout the root system, with the highest accumulation in the root tip and root hair regions. Further, spatial analysis revealed that peptide absorption rates in rice were 2–5 times higher in the 0–1 cm root section and 1.5–4 times higher in the 1–2 cm section compared to corresponding wheat root segments. We conclude that plants can directly take up amino acids and oligopeptides to acquire exogenous N, with marked differences occurring among species in both uptake efficiency and spatial uptake patterns.

Keywords: amino acid uptake; crop nutrition; dissolved organic carbon; peptide transport

Received: May 27, 2025; Revised: August 22, 2025; Accepted: August 26, 2025; Prepublished online: September 3, 2025