Effects of Plant Growth Regulators on Metabolites in Flue-cured Tobacco Leaves under Adverse Climatic Conditions

To investigate the effects of the novel plant growth regulators polyglutamic acid（PGA） and algal oligosaccharides（AOS） on metabolites in flue-cured tobacco leaves, particularly their mechanisms in enhancing stress resistance under adverse climatic conditions, we designed field experiments and employed untargeted metabolomics technology（LC-MS/MS） to detect and analyze differential metabolites between treated and control tobacco leaves. The results showed that the application of AOS and PGA significantly enhanced the stress resistance of flue-cured tobacco, resulting in superior field growth compared to the conventional control. A total of 885 metabolites were identified across all samples in both groups, with lipids and lipid-like molecules accounting for the highest proportion（312, 35.25%）. There were 215 differentially expressed metabolites between the two groups（P＜0.05）, and 62 significantly differential metabolites were identified through further screening by the OPLSDA model（VIP＞1）, most of which showed significant upregulation in the treated group L（54 metabolites）. Functional analysis revealed that 8 metabolites related to tobacco stress resistance. KEGG pathway enrichment analysis indicated that the differential metabolites were mainly involved in 5 pathways. These pathways comprehensively regulate the growth and development of treated tobacco leaves through secondary metabolite synthesis, energy metabolism, and basic metabolism, thereby improving the stress resistance of flue-cured tobacco under adverse climatic conditions.