Pinolidoxin Production by Ascochyta pinodes During Pea Infection: Insights from In Planta Metabolomics

Ascochyta pinodes , the leading cause of Ascochyta blight in pea, poses a significant threat to crop yield and quality; nevertheless, limited investigations have utilized metabolomics to study the Pisum sativum - A . pinodes pathosystem. This study presents the first in planta metabolomics-based study focused on the detection of phytotoxic metabolites produced by A. pinodes . Among the fungal metabolites screened, only pinolidoxin was detected in infected tissues, peaking at 48 hours post-inoculation. This temporal association suggests a possible effector-like role for pinolidoxin in promoting early infection through interference with host signaling pathways. Furthermore, non-targeted metabolomics-based analysis of A. pinodes infection in susceptible and resistant pea cultivars, Messire and Radley, was also carried out, revealing cultivar-specific metabolic responses in the susceptible cultivar. Messire showed strong activation of phenylpropanoid metabolism, especially flavonoids and hydroxycinnamic acids, while the resistant cv. Radley upregulated amino acids and derivatives, suggesting differences in the defense strategy based on adjustments to primary metabolism, which could be related to Radley resistance. This work highlights the complexity of host-pathogen interactions. It underscores the importance of multi-omics approaches in identifying molecular targets for gaining deeper systems-level insight into pea defense strategies, thereby supporting the development of improved disease-resistant legume varieties. • 24 known fungal metabolites were dereplicated in Ascochyta pinodes in vitro culture. • DIA offers improved precision and MS 2 spectral coverage compared to DDA. • Pinolidoxin was the only fungal metabolite produced in planta. • cv. Messire upregulated flavonoids/isoflavonoids, while cv. Radley upregulated amino acids.