Changes in Carbohydrate, Amino Acid and Phenol Contents in Cocoa Pods from Three Clones after Infection with Phytophthora megakaryaBra. and Grif.

Abstract

Mature pods from three clones of Theobroma cacaoL., differing in their susceptibility to Phytophthora megakaryaBra. and Grif., were infected with the fungal mycelium. Variations of the contents in carbohydrates, ketohexoses, amino acids, phenols and flavonol, and hydroxycinnamic derivatives were followed in the cortex for 4d. After pod infection, the amount of carbohydrates decreased more rapidly in the clone SNK10 (highly susceptible) than in the clones SNK413 (low susceptibility) and ICS95 (mildly susceptible), suggesting their utilization by the fungus. At the same time, the amount of ketohexoses decreased by 22% in the clone SNK10, remained almost constant in the clone SNK413, and increased by 53% in the clone ICS95. The content of amino acids increased with time in the pods of the three clones. The results suggest that the amino acid variation is related to pod aging and to the infection. Four days after treatment, an increase in phenolics was measured in all cases. The increase in flavonol and hydroxycinnamic derivatives was related to the wounding and to the infection of the pods. During Phytophthorablack pod development, variations of the contents in the biochemicals studied herein were genotype-dependent, and the patterns of the changes could be related, at least in part, to the susceptibility of the genotype to P. megakarya.