Effect of Pruning on Cassava (Manihot esculenta) Post-harvest Physiological Deterioration

Cassava is a cyanogenic crop and one of the most important source of carbohydrates in many countries. Despite this importance, cassava has a low storage potential due to Post-harvest Physiological Deterioration (PPD). PPD is considered to be a wound stress response where reactive oxygen species (ROS) are involved. Interestingly, cyanogenesis in cassava causes ROS to accumulate and an oxidative burst follows which leads to PPD. This deterioration in cassava causes economic losses and restricts the capacity of the plant to become a commercial crop. A low cost method that has been associated with the reduction of PPD is pruning, but its cellular mechanisms are not completely known. In order to uncover and assess cellular mechanisms linking pruning to PPD, we analyzed cassava roots of unpruned and pruned plants grown at the Isabela Agricultural Experiment Station (PR). Qualitative measurements of PPD percentage for the roots were evaluated visually 0, 5 and 10 days after harvest. Chemical assays were performed for linamarin and beta-cyanoalanine, which are involved in the cyanogenesis and cyanogen detoxification pathways, respectively. Also scopoletin, a hydroxycoumarin that has been previously shown to accumulate due to PPD, was analyzed. Gene expression analysis using Real-time PCR is on-going to identify transcripts up- or down-regulated as a result of PPD of cassava roots from unpruned and pruned plants.