RESUMEN
To elucidate the role of the phenylpropanoid pathway in the expression of resistance during compatible and incompatible interactions between pigeon pea and wilt-causing vascular pathogen Fusarium udum, we estimated the total phenol content, lignin, phenolic acids and activity of enzymes involved in lignin polymerization of monolignols and examined the expression pattern of lignin biosynthesis genes. Our results demonstrated a higher accumulation of free and cell wall-bound phenolics and total lignin content in the highly resistant pigeon pea genotype ICP 14623 as compared to susceptible genotype ICP 14166. An increased activity of phenylpropanoid pathway-associated defense enzymes such as Phenylalanine ammonia-lyase, polyphenol oxidase, ascorbate and guaiacol- dependent peroxidases in resistant pigeon pea genotypes suggests their role in resistance. Moreover, analysis of lignin biosynthesis genes revealed their differential expression during resistant and susceptible interactions, revealed their crucial role in imparting resistance against wilt. Overall, our results indicated the role of physical and biochemical components of the phenylpropanoid pathway in the expression of resistance in pigeon pea against Fusarium wilt.