Application of root exudates derived from peanut/maize intercropping system promotes peanut growth and yield via modulating nitrogen turnover processes.

BACKGROUND

Legume-based intercropping systems function in boosting crop productivity. However, the precise physiological mechanisms by which root exudates derived from these systems on crop growth have not been characterized. Here, the rhizosphere soil from a peanut/maize intercropping system was analyzed for metabolome profiles. Sucrose (SUC) and myo-inositol (MI) were significantly declined while oxalic acid (OA) was dramatically enriched compared with peanut monoculture. After concentration screening, the optimal concentrations of OA, SUC, and MI have been determined as 1.0 g/pot, 0.1 g/pot, and 0.1 g/pot, respectively. Armed with the optimal concentrations, OA, SUC, MI, and their combinations were applied to peanut soil, respectively.

RESULTS

Agronomical and physiological assesses indicated that single application of SUC and the combination application of "OA + SUC" showed better performance on peanut growth, pod yield, and soil nitrogen (N) turnover processes including total N and NO-N contents as well as activities of N turnover enzymes. Consequently, the transcriptome and metabolome profiles of SUC were further determined. A total of 1036/24 up-regulated and 797/35 down-regulated differential expressed genes (DEGs)/differential accumulated metabolites (DAMs) were detected in SUC-treated peanut roots, respectively. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis advocated that DEGs were mostly enriched in crucial pathways like Glycolysis/Gluconeogenesis-tricarboxylic acid cycle (TCA cycle) and N uptake and assimilation. Moreover, DAMs like D-Aspartic acid, L-Glutamic acid, and L-Threonine were identified in "Sucrose vs. Control".

CONCLUSION

Application of root exudates like sucrose and oxalic acid derived from root exudates of peanut/maize intercropping system fulfil pivotal roles in enhancing peanut growth and productivity via modulating N turnover processes.