Sun Jingjing, Li Qinglin, Xu Hui, Zhang Wentao
School of Agricultural Engineering, Jiangsu University, Zhenjiang 212013, China.
Metabolites. 2022 Apr 18;12(4):361. doi: 10.3390/metabo12040361.
Cucumber xylem and phloem sap is a key link in nutrient distribution, transportation and signal transduction of cucumber plants; however, the metabolic response mechanism of cucumber xylem and phloem sap under phosphorus stress has not been clearly revealed. In this study, gas chromatography-mass spectrometry (GC-MS) combined with principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were used to analyze the metabolites in cucumber xylem and phloem sap under different phosphorus stress. A total of 22 differential metabolites were screened from xylem and phloem sap, respectively. Through the analysis of metabolic pathways of differential metabolites, four and three key metabolic pathways were screened, respectively. The results showed that compared with the normal phosphorus level, the content of most amino acids in the key metabolic pathway increased in xylem but decreased in phloem both under low and high phosphorus stress levels. The contents of sucrose and glucose in phloem glycolysis pathway showed a positive correlation with the change of phosphorus nutrient levels. The tricarboxylic acid cycle was promoted in xylem and phloem of cucumber under low and high phosphorus nutrient levels, and the contents of malic acid and citric acid increased significantly. This study provided abundant biochemical information for the metabolic response and regulation strategies of cucumber xylem and phloem under phosphorus stress, and is committed to looking for more sensitive markers to evaluate the supply level of phosphorus nutrients in cucumber.
黄瓜木质部和韧皮部汁液是黄瓜植株养分分配、运输及信号转导的关键环节；然而，磷胁迫下黄瓜木质部和韧皮部汁液的代谢响应机制尚未明确揭示。本研究采用气相色谱-质谱联用（GC-MS）结合主成分分析（PCA）和偏最小二乘判别分析（PLS-DA），对不同磷胁迫下黄瓜木质部和韧皮部汁液中的代谢物进行分析。分别从木质部和韧皮部汁液中筛选出22种差异代谢物。通过对差异代谢物代谢途径的分析，分别筛选出4条和3条关键代谢途径。结果表明，与正常磷水平相比，在低磷和高磷胁迫水平下，关键代谢途径中多数氨基酸在木质部中的含量增加，而在韧皮部中的含量降低。韧皮部糖酵解途径中蔗糖和葡萄糖的含量与磷营养水平的变化呈正相关。在低磷和高磷营养水平下，黄瓜木质部和韧皮部的三羧酸循环均被促进，苹果酸和柠檬酸含量显著增加。本研究为磷胁迫下黄瓜木质部和韧皮部的代谢响应及调控策略提供了丰富的生化信息，致力于寻找更敏感的指标来评估黄瓜磷营养的供应水平。
