Comparative Metabolomics Revealed Differences in Alkaloids Metabolism Between Morus nigra L. and Morus. alba L. at Different Growth Stages

Mulberry (Morus spp.), a flowering plant in the Moraceae family, is known for the edible fruit, and mulberry leaves have various applications. This experiment utilized ultra-high performance liquid chromatography-quadrupole time of flight mass spectrometry (UPLC-Q-TOF-MS) and Progenesis QI software to rapidly identify secondary metabolites in the leaves of Morus nigra L. and Morus alba L.. Orthogonal partial least squares discriminant analysis (OPLS-DA), principal component analysis (PCA) and Hierarchical clustering analysis (HCA) were used to examine the dynamic changes and stage specificity of metabolites, particularly alkaloids, in M. nigra and M. alba leaves during seven primary growth stages. In results, the leaf samples from different growth stages uncovered a total of 182 metabolites from 13 distinct categories. M. nigra had significantly higher levels of metabolites than those in M. alba, according to differences in leaf metabolite accumulation patterns. Multiple statistical analyses revealed that the metabolome of M. nigra and M. alba leaves exhibited a significant interspecific and developmental specific accumulation patterns, with most DNJ alkaloids having the highest content in M. nigra leaves. In different growth stages, the metabolites of M. nigra leaves showed significant stage specificity. During the development stage of small fruit stage, obvious changes occurred in the chemical composition of M. nigra leaves, with a significant increase in DNJ alkaloid metabolites. Overall, this study provides a theoretical reference for the comprehensive development and sustainable utilization of M. nigra resources in Xinjiang.