Salicylic Acid, Phosphorous Acid and Fungicide Sumi 8 Effects on Polyphenol Oxidases Activities and Cassava Resistance to Anthracnose

In Cote d’Ivoire, cassava contributes enormously to improve food security of population by increasing national production and financial resources of vulnerable households. But, plant is attacked by several diseases including anthracnose. This study was done to improve its resistance to anthracnose by stimulating its natural defense following treatment plants with salicylic acid, phosphorous acid and fungicide Sumi 8 as elicitors. Polyphenol oxidases were chosen as resistance marker. Results showed that in the three cultivars (yace, TMS30572 and I88/00158), yace was more susceptible to anthracnose (p<0.05; F = 6.83). After treatments, cassava resistance against anthracnose has been improved. Polyphenol oxidases activities were more stimulated in presence of elicitor’s phosphorous acid and salicylic acid. Native-PAGE of polyphenol oxidases revealed 11 isoenzymes including 7 new isoenzymes detected in elicited plants, treated plants contaminated or uncontaminated by Colletotrichum gloeosporioides, pathogen of anthracnose. Recent isoenzymes were specific for each cultivar. Their appearance was correlated with plant resistance to C. gloeosporioides. In these plants, in particular those germinated directly in elicitation medium, anthracnose symptoms were lessened. These elicitors were thus induced and/or stimulated cassava defense especially polyphenol oxidases activities.