Rhizosphere secondary metabolites quinolones and benzoxazinoid alleviate continuous cropping obstacles of strawberry

Alterations to the rhizosphere microenvironment following the continuous cropping of strawberry can result in substantial declines in yield and quality. Plant rhizosphere produces a wide variety of secondary metabolites, which play important roles in regulating plant growth and development. According to the chemical structure and biosynthesis pathways, secondary metabolites can be devided into different groups, and some of these metabolites have been demonstrated to hold ecological significance and responsing to biotic and abiotic stresses. But how this type of feedback affects plant growth is unknown. In this research, strawberry cultivar ‘Santa’ under continuous cropping for 10 years at different cultivation media were used. We assessed the pH value and conductivity of medium solution, dry weight of roots and analyzed the secondery metabolites using ultra performance liquid chromatography (UPLC). After adding cow dung, we detected a significant lower conductivity of medium solution. In addition, after adding goat manure, we detected a significant heigher dry weight of roots. A total of 736 metabolites from 11 classes were detected across all samples. The 20 most significant differentially accumulated metabolites with variable importance in projection scores greater than 1 in each treatment included 17 terpenoids, 5 organic acids, 5 nucleotides and derivatives, 4 lipids, 2 alkaloids, 2 flavonoids, 1 phenolic acid, and 4 others. Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis revealed that these metabolites were significantly enriched in the following pathways: metabolic pathways, nucleotide metabolism, and biosynthesis of secondary metabolites. Statistical approach showed that the rhizosphere secondary metabolites quinolones and benzoxazinoid were two key compounds that alleviate continuous cropping obstacles of strawberry. If this phenomenon holds true across different soils and environments, this strategy could be a powerful and tractable application to alleviate continuous cropping obstacles.