Microelement Research Center, Huazhong Agricultural University, Wuhan, 430070, China; Key Laboratory of Potato Biology and Biotechnology, Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan, 430070, Wuhan, Hubei, 430070, China.
Key Laboratory of Potato Biology and Biotechnology, Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan, 430070, Wuhan, Hubei, 430070, China.
Plant Physiol Biochem. 2020 Dec;157:38-46. doi: 10.1016/j.plaphy.2020.09.040. Epub 2020 Oct 7.
Nitrogen (N) is an important nutrient for increased potato tuber yield. However, excessive N can decrease tuber quality. Furthermore, the impact of optimal and higher N levels of potato tuber metabolic profile at harvest and cold storage remains unclear. This study aimed to investigate the metabolic profiling of free amino acids and sugars in potato tubers affected by different nitrogen levels (optimal, ON; and excessive, EN) at harvest (AH) and cold storage (CS) (~4 °C, 4 weeks) through untargeted GC-TOF-MS, and targeted UHPLC-QqQ-MS. Carbohydrate content and vacuolar invertase activity (IV) were determined. Principal component analysis of metabolite data indicated a distinct separation between ON and EN treatments at harvest and cold storage. Multivariate data analysis revealed that sucrose, reducing sugars, and free asparagine were the most altered metabolites (VIP > 1 and P < 0.05), which were involved in starch and sucrose metabolism, and alanine, aspartate and glutamate metabolism. At harvest, the absolute contents of various free amino acids including asparagine were higher (by 1.3-1.5 fold) in the EN treatment than ON treatment, and this difference was maintained at 4-week cold storage. Under the EN treatment, tuber maturity was reduced, and sucrose accumulation was increased at harvest, while IV was increased after cold storage, reducing sugar also accumulated. These results highlighted the negative effects of EN on free amino acid and sugars metabolism in the post-harvest tubers and provided useful information for understanding the underpinning physiological mechanisms.
氮（N）是提高马铃薯块茎产量的重要营养物质。然而，过量的氮会降低块茎的品质。此外，收获和冷藏时，最佳和更高氮水平对马铃薯块茎代谢谱的影响尚不清楚。本研究旨在通过非靶向 GC-TOF-MS 和靶向 UHPLC-QqQ-MS 研究不同氮水平（最佳，ON；和过量，EN）对收获（AH）和冷藏（CS）（约 4°C，4 周）时马铃薯块茎游离氨基酸和糖代谢谱的影响。测定了碳水化合物含量和液泡转化酶活性（IV）。代谢物数据的主成分分析表明，收获和冷藏时 ON 和 EN 处理之间存在明显分离。多元数据分析表明，蔗糖、还原糖和游离天冬酰胺是变化最大的代谢物（VIP>1 和 P<0.05），它们参与淀粉和蔗糖代谢以及丙氨酸、天冬氨酸和谷氨酸代谢。在收获时，EN 处理中各种游离氨基酸（包括天冬酰胺）的绝对含量（增加 1.3-1.5 倍）高于 ON 处理，这种差异在 4 周冷藏时仍保持。在 EN 处理下，块茎成熟度降低，收获时蔗糖积累增加，而 IV 在冷藏后增加，还原糖也积累。这些结果突出了 EN 对收获后块茎中游离氨基酸和糖代谢的负面影响，并为理解潜在的生理机制提供了有用信息。
