Potatoes (Solanum tuberosum L.) are the third largest food crop globally and are pivotal for global food security. Widespread N fertilizer waste in potato cultivation has caused diverse environmental issues. This study employed microbial metagenomic sequencing to analyze the causes behind the declining N use efficiency (NUE) and escalating greenhouse gas emissions resulting from excessive N fertilizer application. Addressing N fertilizer inefficiency through breeding has emerged as a viable solution for mitigating overuse in potato cultivation. In this study, transcriptome and metabolome analyses were applied to identify N fertilizer-responsive genes. Metagenomic sequencing revealed that excessive N fertilizer application triggered alterations in the population dynamics of 11 major bacterial phyla, consequently affecting soil microbial functions, particularly N metabolism pathways and bacterial secretion systems. Notably, the enzyme levels associated with NO₃^- increased, and those associated with NO and N₂O increased. Furthermore, excessive N fertilizer application enhanced soil virulence factors and increased potato susceptibility to diseases. Transcriptome and metabolome sequencing revealed significant impacts of excessive N fertilizer use on lipid and amino acid metabolism pathways. Weighted gene co‑expression network analysis (WGCNA) was adopted to identify two genes associated with N fertilizer response: PGSC0003DMG400021157 and PGSC0003DMG400009544.

The potato is the third largest food crop, and nitrogen fertilizer is important for increasing potato yields; however, the shallow root system of potatoes causes the nitrogen fertilizer utilization rate to be low, which results in waste and environmental pollution, meaning that high nitrogen efficiency breeding is highly significant for potatoes. In the high nitrogen efficiency breeding of potatoes, genes with a nitrogen-deficient response should first be identified, and RNA-seq is an efficient method for identifying nitrogen-deficiency-response genes. In this study, two potato cultivars, Dongnong 322 (DN322) and Dongnong 314 (DN314), were utilized, and two nitrogen fertilizer application rates (N0 and N1) were set for both cultivars. Through the determination of physiological indicators, we identified that DN314 is more sensitive to nitrogen fertilizer, while DN322 is relatively insensitive to nitrogen fertilizer. Samples were taken at the seedling and tuber formation stage. At the seedling stage, DN322 and DN314 had 573 and 150 differentially expressed genes (DEGs), while at the tuber formation stage, they had 59 and 1905 DEGs, respectively. A total of three genes related to a low-nitrogen response were obtained via the combined analysis of differentially expressed genes (DEGs) and weighted correlation network analysis (WGCNA), of which two genes were obtained at the tuber formation stage and one gene in the seedling stage, providing theoretical guidance for the high nitrogen efficiency breeding of potatoes.

Potato (Solanum tuberosum L.) has high nutritional value and strong adaptability and plays an extremely important role in global food security. Excessive use of nitrogen (N) fertilizer in potato production has increased costs and environmental pollution. In this study, the N use efficiency (NUE) of two potato varieties (DXY and DN310) was determined under high nitrogen conditions. The N use efficiency of DXY was relatively high. The differences between the rhizosphere microbial population groups of the two varieties were determined using the metagenomic sequencing method. The genes related to N efficiency were jointly identified using transcriptome and metabolome analyses. Significant difference was observed between the two varieties of microorganisms, leading to different rhizosphere microorganisms. Compared with DN310, the roots of DXY retained more available N and generated less NO. Additionally, DXY exhibited relatively low disease susceptibility. Combined transcriptome and metabolome analyses indicated that the differentially expressed metabolites in the two different varieties under high N conditions were mainly enriched in amino acid metabolism and sugar metabolism pathways. Using weighted gene co-expression network analysis, two genes associated with N fertilizer response were identified: PGSC0003DMG400025888 and PGSC0003DMG400017276. This study provided valuable insights into breeding potato varieties with high N efficiency.