Arbuscular mycorrhizal fungi cause divergence in carbon investment strategies and the regulation of nitrogen transformation efficiency in the cotton-soil system.

Authors

Mengjuan Liu, Xiaoxiao Liu, Yunzhu He, Zihui Shen, Hushan Wang, Wangfeng Zhang, Xiaozhen Pu

Published in

Planta. Volume 264. Issue 1. Jun 22, 2026. Epub Jun 22, 2026.

Abstract

Different AMF species regulate soil nitrogen transformation by guiding divergent cotton carbon investment strategies. Moderate inoculation with Acaulospora scrobiculata achieves optimal nitrogen benefits at minimal carbon cost. Arbuscular mycorrhizal fungi (AMF) form symbioses with most terrestrial plants, enhancing phosphorus and nitrogen uptake. However, the mechanisms by which different AMF species and inoculation dosages synergistically regulate host nitrogen uptake efficiency remain insufficiently elucidated. This study investigated three AMF species-Glomus heterosporum (Gh), Acaulospora scrobiculata (As), and Paraglomus occultum (Po)-at different inoculation dosages (440, 880, and 1320 spores g^-1) on cotton growth, nitrogen uptake, plant carbon-to-nitrogen ratio, soil organic carbon input via hyphae, and soil enzyme activities. AMF significantly reduced soil organic carbon content and plant carbon-to-nitrogen ratio, altered soil enzyme activities, alleviated soil microbial nitrogen limitation, and promoted cotton growth and nitrogen uptake. At the moderate inoculation dosage (880 spores g^-1), As exhibited the strongest promoting effect, increasing soil nitrogen acquisition-related enzyme activities by 103.7%, and enhancing shoot and root nitrogen accumulation by 3.46-fold and 2.40-fold, respectively. It effectively drives soil nitrogen transformation processes by guiding a moderate allocation of plant carbon. Gh exhibited the highest mycorrhizal nitrogen response at the high inoculation dosage (1320 spores g^-1), but its carbon flow had limited stimulatory effects on nitrogen transformation. In contrast, the growth-promoting effect of Po and its ability to regulate soil nitrogen transformation were weaker. Furthermore, the AMF colonization rate was positively correlated with the mycorrhizal nitrogen and growth response, but negatively correlated with the input of soil organic carbon via the hyphal pathway. This study elucidates how carbon investment strategies directed by different AMF species regulate soil nitrogen transformation, supporting sustainable, AMF-based fertilization strategies in cotton cultivation.

PMID:
42329303
Bibliographic data and abstract were imported from PubMed on 12 Jul 2026.

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