Metabolomic combined with transcriptome analysis revealed the improvement of strawberry fruit quality after potassium sulfate treatment.

Potash fertilizer is important for improving fruit quality, but its specific moderating roles must be further explored. To accomplish this objective, we utilized metabolomics and transcriptomics analyses to reveal the changes in metabolites and differential genes after potassium sulfate treatment, and we determined that the treatment substantially enhanced the intrinsic and external quality of 'Yanli' (Fragaria ×ananassa Duch.). The results showed that 345 metabolites were found in wide metabolomics, with 115 up-regulated and 230 down-regulated, in which the primary metabolites were more sugars, and the secondary metabolites were more flavonoids, accounting for 20.26% of the metabolites. Sugar metabolomics revealed a substantial increase in fructose content of 34.2 mg g after potassium sulfate treatment. 2335 differentially expressed genes were found in the transcriptome. The KEGG enrichment scatter plot revealed that the more enriched pathways were metabolic pathways, starch and sucrose metabolism pathways, and flavonoid biosynthesis pathways. Combined transcriptome and metabolomics analyses showed that three genes, FaGal, FaINV and FaFK were highly influential in the sugar metabolic pathway, five candidate genes were identified in the anthocyanin metabolic pathway. This study revealed the regulatory mechanism of potassium sulfate treatment for improving strawberry fruit quality. Our findings provide an important basis for in-depth research on the mechanism of differentially expressed genes as well as substantial theoretical and practical guidance for the scientific and rational application of potash fertilizers in strawberry production.