Effects of Salicylic Acid and Acibenzolar-S-methyl on Phenols Content and Antioxidant Activity against Toxicity of Juglone in the Development of Black Leaf Streak Disease of Banana

Abstract

Aims: To evaluate the effect of salicylic acid (SA) and acibenzolar-S-methyl (ASM) on the minimal concentration of juglone (Cmin) inducing foliar necrosis- and to determine the total phenol content and antioxidant activity of extracts of banana leaves after SA and ASM applications and toxin injection. Methodology: Banana cultivars Orishele and Corne 1 were subjected to root and foliar applications of elicitors, then leaves were injected with juglone a toxin of M. fijiensis to the determination of Cmin. The determination of total phenols extracted from leaves was carried out using Folin Reagent. The antioxidant activity of phenolic crude extracts (PCE) was determined through the DPPH radical scavenging ability. Results: In banana without elicitor applications, the minimum concentration inducing necrosis varied between 12.5 and 25 ppm of juglone but reached 250 ppm of juglone into banana treated with elicitors, particularly with ASM at 50 ppm. The phenol contents were highest 14 days after elicitors application. After this incubation time, with ASM at 50 ppm and AS at 25 ppm, the levels were 16.25 mg GAE/g DW in Orishele and 17.20 mg GAE/g DW in Corne 1, respectively. But the levels were lower 28 days after banana elicitation with 50 ppm of SA into Orishele and Corne 1 respectively 5.60 and 6.79 mg GAE/g DW. Treatments with 50 ppm of ASM showed the highest antioxidant activity between 7 and 28 days after elicitors application on banana leaves. With this treatment, the lowest concentration of phenolic crude extract scavenging 50% of DPPH was 13.09 μg/mL at 21 days after foliar elicitation. Conclusion: The applications of elicitors SA and ASM affect phenol content and antioxidant activity for the detoxification of foliar tissues of banana cultivars Orishele and Corne 1 infiltrated with toxin.