Dynamics of organic acid exudation and rhizobacteria in maize rhizosphere respond to N-CDs

Le Yue; Liya Jiao; Mengna Tao; Lanqing Xu; Xuesong Cao; Feiran Chen; Chuanxi Wang; Bingxu Cheng; Zhenyu Wang

doi:10.1016/j.scitotenv.2023.166500

Dynamics of organic acid exudation and rhizobacteria in maize rhizosphere respond to N-CDs

Sci Total Environ. 2023 Nov 25:901:166500. doi: 10.1016/j.scitotenv.2023.166500. Epub 2023 Aug 22.

Authors

Le Yue¹, Liya Jiao¹, Mengna Tao¹, Lanqing Xu¹, Xuesong Cao¹, Feiran Chen¹, Chuanxi Wang¹, Bingxu Cheng¹, Zhenyu Wang²

Affiliations

¹ Institute of Environmental Processes and Pollution Control, and School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, China; Jiangsu Engineering Laboratory for Biomass Energy and Carbon Reduction Technology, Wuxi 214122, China.
² Institute of Environmental Processes and Pollution Control, and School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, China; Jiangsu Engineering Laboratory for Biomass Energy and Carbon Reduction Technology, Wuxi 214122, China. Electronic address: wang0628@jiangnan.edu.cn.

PMID: 37619720
DOI: 10.1016/j.scitotenv.2023.166500

Abstract

To sustainably feed the growing global population, it is essential to increase crop yields on limited land while reducing the use of fertilizers and agrochemicals. The rhizosphere regulation shows significant potential to address this challenge. Here, foliar applied doping of nitrogen in carbon dots (N-CDs) entered maize leaves, and were transported to the stems and roots. The internalized N-CDs significantly increased the biomass (26.4-93.8%) and photosynthesis (17.0-20.3 %) of maize seedling during the three-week application of N-CDs, providing the substrate for tricarboxylic acid cycle (TCA) in shoots and roots. Correspondingly, more organic acids involved in TCA cycle, such as citric acid (14.0-fold), succinic acid (4.4-fold) and malic acid (3.4-fold), were synthesized and then secreted into rhizosphere after exposed to N-CDs for one day. As the exposure time increased, greater secretion of above organic acids by the roots was induced. However, no significant change was observed in the relative abundance of rhizobacteria after foliar application with N-CDs for one day. After one week, the relative abundances of Azotobacter, Bacillus, Lysobacter, Mucilaginibacter, and Sphingomonas increased by 0.8-3.8 folds. The relative abundance of more beneficial rhizobacteria (Sphingomonas, Lysobacter, Rhizobium, Azotobacter, Pseudomonas, Mucilaginibacter and Bacillus) enriched by 0.3-6.0 folds after two weeks, and Sphingomonas, Flavisolibacter and Bacillus improved by 0.6-3.2 folds after three weeks. These dynamic changes suggested that N-CDs initiate the synthesis and secretion of organic acids and then recruited beneficial rhizobacteria. The hierarchical partitioning analysis further indicated that N-CDs-induced secretion of organic acids from the roots was the main drivers of rhizobacteria community dynamics. The differential microbes altered by N-CDs were mainly involved in nitrogen (N) and phosphorus (P) cycles, which are beneficial for N and P uptake, and maize growth. These results provide insights into understanding the rhizosphere regulation of nanomaterials to improve plant productivity and nutrient-use efficiency.

Keywords: Doping of nitrogen in carbon dots; Maize growth promotion; Rhizobacteria; Root exudates; TCA cycle.