How nitrogen reshapes root system architecture in plants?

In soil, nitrogen (N), an essential macronutrient for plant growth, exhibits significant spatial heterogeneity. This necessitates plants to grapple with a complex array of environmental conditions in their quest for N sustenance. Roots, as the pivotal organs in N acquisition, manifest a remarkable morphological plasticity, including variations in the length and density of primary roots, lateral roots, and root hairs, in response to the form and content of available N, which is termed N-dependent root system architecture (RSA). For cultivated crops, the cultivation of an ideotype RSA, characterized by sensitive plasticity under diverse N conditions, is paramount for efficient N utilization, curtailment of N fertilizer inputs, and the realization of a green and sustainable agricultural development trajectory. What is the genetic basis of N-dependent RSA? The answers to this question will not only enrich the current understanding of the plants N utilization process, but also provide a treasure trove of genetic resources for targeted genetic modification, aimed at cultivating crops with ideotype RSA.

Prof. Chengcai Chu and his team from South China Agricultural University have systematically summarized the process of genetic basis of N-dependent RSA in Arabidopsis and major crops. Firstly, N sensing and signaling in plants is the fundamental to N-dependent RSA. The extracellular nitrate signal is primarily sensed and transduced into nucleus through the conserved NRT1-NLPs cascade across diverse plant taxa. Furthermore, long-distance N signal transduction between roots and shoots is mainly mediated by cytokinins and polypeptides, ensuring a harmonious interplay between different plant parts. Upon reception, these N signals intricately interact with phytohormones, such as auxin and brassinosteroid, either directly or indirectly influencing their synthesis, sensing, signaling, and distribution within the root system. This intricate hormonal crosstalk ultimately orchestrates the root developmental process in an N-dependent manner, reshaping the root architecture to suit varying N availabilities. While the majority of studies elucidating the genetic basis of N-dependent RSA have been conducted in the model plant Arabidopsis, our understanding of this process in crop plants remains nascent, let alone the implementation of genetic modification for cultivating ideotype RSA in these economically vital species. Fortunately, integration of advanced techniques like X-ray computed tomography and single cell analysis into plants research promises to unravel the genetic mysteries governing N-dependent RSA in crops. With these innovative tools at our disposal, the realization of ideotype RSA in future crop cultivars may soon transition from a distant aspiration to a tangible reality, heralding a new era in precision agriculture and sustainable food production.

This review has been published on the Journal of Frontiers of Agricultural Science and Engineering in 2025, 12(1): 3–15. DOI: 10.15302/J-FASE-2024587.

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