Estimation of Phenylalanine Ammonia-Lyase Activity for Assessing Resistance of Muskmelon Against Fusarium oxysporum f. sp. melonis Infection.

Phenylalanine ammonia-lyase is a key enzyme in the phenylpropanoid pathway, responsible for the conversion of L-phenylalanine into trans-cinnamic acid. This step is crucial for the biosynthesis of lignin, phytoalexins, and other phenolic compounds that play a significant role in plant defense responses. This chapter describes a detailed protocol for the extraction and quantitative estimation of phenylalanine ammonia-lyase activity in muskmelon (Cucumis melo L.) tissues in response to Fusarium oxysporum f. sp. melonis (FOM) infection. The method enables researchers to compare phenylalanine ammonia-lyase activity in resistant and susceptible cultivars and to evaluate the temporal dynamics of the enzyme's induction during host-pathogen interaction.