Transcriptomics combined with physiology and Metabolomics revealed the responses of potato tuber formation to nitrogen

Nitrogen (N) can be absorbed by plants, thereby affects plant physiological activity, interferes gene expression, alters metabolite content and influences plant growth. However, the molecular mechanism underlying the potato tuberization response to nitrogen remains unclear. The plants were cultivated in the pots using N-deficient, N-Routine and N-sufficient conditions. Physiological response analysis, transcriptomics and metabolomics were performed on potato stolon exposed to Nitrogen stress. Transcriptomics analysis revealed that 2756 differentially expressed genes (DEGs) responded to nitrogen stress. By using metabolomics analysis, a total of 600 d differentially accumulated metabolites (DAMs) were identified. Further correlation analysis of major DEGs and DAMs showed that 9 key DEGs were involved in alpha-linolenic acid metabolism, 16 key DEGs in starch and sucrose metabolism, 7 key DEGs in nitrogen metabolism, and 16 key DEGs in ABC transporters. Nitrogen deficiency significantly up-regulated the contents of sucrose, GDP-glucose and L-glutamic acid, and promoted the growth of stolon by up-regulating the expression of AMY, SBE, SS, SPS, AGPS and NR-related genes. However, High nitrogen is the opposite. In addition, high nitrogen treatment up-regulated EG, SUS and GDH related genes, accumulated a large number of 9 (S) -HpOTr E, 13 (S) -HpOTr E and L-Glutamine, ultimately affected the balance between plant growth and defense. In general, our study revealed the co-expressed genes and potential pathways related to potato tuber formation under different nitrogen conditions. These comprehensive analysis data provide a better understanding of improving potato tuber traits at the molecular and metabolic levels. To compare the RNA-seq date gene expression of potato variety Kexin 13 stolons under different nitrogen treatments (AN0, AN1, AN2)，each treatment was repeated three times. AN0 represents nitrogen deficiency treatment. AN1 represents conventional nitrogen treatment. AN2 represents excessive nitrogen treatment.