Cowpea severe mosaic virus (CPSMV) represents a major constraint for cowpea (Vigna unguiculata (L.) Walp.) cultivation. However, the metabolic basis underlying CPSMV resistance remains poorly understood. Given the importance of metabolism for plant defence against pathogens, we hypothesized that cowpea resistance to CPSMV is associated to the activation of defence-related pathways from both primary and secondary metabolisms. We investigated the metabolic dynamics associated with CPSMV infection in the resistant cowpea genotype Macaibo using a time-resolved, network-based metabolomics approach. Conventional RT-PCR suggests that the intensity of the CPSMV coat protein band increased in the first eight Hours After CPSMV Inoculation (HAI) but appeared reduced in the following 72 HAI. Metabolomic analyses revealed that CPSMV infection had little impact on secondary metabolism, whereas several primary metabolites were significantly altered over time. Transient increases in fumarate, pyruvate, and several amino acids, including alanine, asparagine, glutamine, glutamate, isoleucine, leucine, proline, serine, threonine, and valine, were observed at 48 HAI compared with mock-treated leaves. Network analysis indicated that overall metabolic network density and heterogeneity remained relatively stable during infection. However, a highly connected metabolic module composed of the branched-chain amino acids (BCAAs) isoleucine, leucine, and valine emerged in infected leaves. Our results indicate that CPSMV infection reshapes primary metabolic dynamics without extensive alterations in secondary metabolism during early infection in cowpea leaves. Despite these metabolic adjustments, the overall metabolic network structure remained stable, suggesting that a robust metabolic reprograming, including the activation of BCAA-associated pathways, may help buffer viral perturbation in cowpea leaves.
