Mycorrhization of three cultivars of Colocasia esculenta L. Schott and evaluation of their resistance to mildew caused by Phytophthora colocasiae

Abstract

The objective of this work was to evaluate the effect of arbuscular mycorrhizal fungi on the development of taro leaf blight during the interaction of Colocasia esculenta - Phytophthora colocasiae. Three cultivars of C. esculenta were used with local names, Ekwanfre, Macoumba, and Banlah. The experimental device was a complete randomized block with two repetitions. Four treatments were applied (Control, Mycorrhizal, Infected, and Mycorrhizal+infected). After one month of growth, an artificial infection was carried out with a solution of spores of P. colocasiae of 5x104 sporangia/ml. Disease severity was assessed every 5 days for 20 days. On D20, cytological analysis, mycorrhizal status, metabolite content, and leaf antioxidant enzyme activity were determined. The results showed that the incidence of the disease is 100% from D10 for the treatment infected with the Macoumba cultivar. Mycorrhization inhibited the action of the pathogen. The incidence and severity of the disease are low and less than 50%, in the Mycorrhizal+infected treatment plants compared to the Infected treatment. Cytological analysis revealed fungal, and mycorrhizal structures in the leaves and roots. The maximum frequency and intensity of mycorrhization were 73.33±02.51 and 12.83±04.75% in the mycorrhizal plants of the Macoumba treatment. The total chlorophyll content is less than 1 mg.g-1 of WF, in the three cultivars in infection condition. The contents of total soluble proteins, amino acids, and proline are higher in the plants of the infected treatment compared to mycorrhizal and Mycorrhizal+infected. The H2O2 produced was scavenged by APX and G-POD compared to CAT. These results make it possible to note that the AMFs used contribute to the protection of the C. esculenta plants against the harmful effects linked to the presence of P. colocasiae