Metabolomic and proteomic changes in leaves of rubber seedlings infected by <i>Phytophthora palmivora</i>

Phytophthora palmivora, an oomycete pathogen, induces leaf fall disease in rubber trees (Hevea brasiliensis), causing significant economic losses. Effective disease management requires an understanding metabolic dynamics during infection. This study employed untargeted metabolomic and proteomic analyses to investigate the response of rubber seedling leaves to P. palmivora infection. Metabolomic profiling revealed 1702 and 979 metabolite peaks in positive and negative ionization modes, respectively, with 212 metabolites identified after duplicate removal. Principal component analysis demonstrated distinct metabolic profiles between infected and non-infected leaves. Volcano plots indicated significant changes in 90 metabolites (P < 0.05, fold-change ≥ 2), with 20 showing increased levels and 70 showing decreased levels in infected leaves. Pathway analysis highlighted nine metabolic pathways, with alanine, aspartate, and glutamate metabolism being the most impacted. Proteomic analysis identified 391 proteins, with 283 in infected leaves and 253 in control leaves. Among these, 145 were common to both conditions, suggesting their roles in maintaining homeostasis and responding to stress. Unique proteins in infected leaves were linked to oxidative phosphorylation, ATP synthesis and metabolic adjustments, reflecting the increased energy demands. Control samples showed proteins related to growth and photosynthesis. Integrating metabolomic and proteomic data revealed significant alterations in energy metabolism pathways in response to infection. These findings enhance our understanding of rubber seedlings' defense strategies against P. palmivora, with implications for improving plant resistance and disease management strategies.