Salicylic Acid And Acibenzolar-s-methyl Induced Resistance Against Toxic Effect Of Juglone, A Toxin Of Mycosphaerella Fijiensis Causal Agent Of Banana Black Leaf Streak Disease

Abstract

Salicylic acid and its analogues are considered the most important compounds which can be activated a systemic acquired resistance (SAR) in plants. The disadvantages and limits related to the usual methods in particular fungicide spray to the control of black leaf streak disease (BLSD) require research of approaches more respectful of the environment for this disease management such as the use of SAR inducers. The effects of Salicylic acid (SA) and Acibenzolar-S-methyl (ASM) on the interaction of two susceptible cultivars of banana (Orishele and Corne 1) with the hemibiotrophic fungal Mycosphaerella fijiensis and his toxin (juglone) were investigated. The results showed that SA and ASM at low concentrations (25 and 50 µg/ml) did not affect M. fijiensis development but have the capacity to induce protection into sensitive banana against juglone toxic effect. These SAR inducers reduced the intensity of the necrosis due to the juglone and lengthened the incubation period of M. fijiensis after inoculation of banana leaves. The expression of the resistance induced was related to the variety of banana. More significant effectiveness of protection was obtained with ASM in particular on Corne 1. A total protection against the induction of necrosis was kept up to 100 µg/ml of juglone 2 to 3 weeks after application of ASM on the soil and on the leaves of banana. ASM constitutes a viable and noncontaminant option in the fight against to BLSD because of his non-inhibiting action on M. fijiensis and excellent protection into banana when roots and leaves were treated.