Descrição
Sania Ejaz1, Mário Lucio Vilela de Resende1, Júlia Marques Oliveira1 Deila Magna Dos Santos Botelho2.
1Departamento de Fitopatologia, Universidade Federal de Lavras, Lavras, Minas Gerais, Brazil; 2Epamig Sul, Campus Universidade Federal de Lavras (UFLA), Lavras, MG, Brazil.
Rationale: Bacterial halo blight (BHB) of coffee, caused by Pseudomonas syringae pv. garcae presents a significant challenge to coffee cultivation, particularly in high-altitude regions with moderate climates. The increasing global demand for sustainable coffee production emphasizes the necessity to reduce the use of chemical fungicides and promotes the adoption of environmentally friendly disease management practices. Among these practices, plant resistance inducers emerge as a promising and cost-effective strategy [1].
Methods: This study evaluated the defense mechanisms in coffee plants activated by acibenzolar-S-methyl (ASM), a systemic acquired resistance activator, and copper silicate. A randomized complete block design with 4 replications was employed. Six treatments were assessed based on disease severity at three-day intervals: copper silicate at 5 mL/L, 7.5 mL/L, and 10 mL/L; ASM; kasugamycin; and an untreated control. The most effective copper silicate concentration and ASM were selected for further biochemical analyses. The enzymatic activity of phenylalanine ammonia-lyase (PAL) and peroxidase (POX) was measured at 0, 24, and 48 hours before and after inoculation.
Results: Enzymatic analyses indicated a significant increase in POX activity following treatment application at 0, 24, and 48 h. After pathogen inoculation, however, a significant elevation in POX activity was observed only at 0 h, with no statistically significant changes detected at 24 and 48 h. For PAL, the application of ASM significantly enhanced activity at 0 and 24 h post-inoculation, outperforming other treatments. Nonetheless, no significant differences in PAL activity were observed among treatments at any of the assessed time points post-application. All treatments significantly reduced severity compared to the control, which exhibited 100% disease incidence. Copper silicate (10 mL/L) and ASM were the most effective, reducing disease severity by 86% and 87%, respectively.
Conclusion and Perspective: The results demonstrate that copper silicate and ASM are capable of inducing defense-related enzymatic responses in coffee plants, particularly through the activation of POX and PAL. These elicitors also contributed to a reduction in disease severity, outperforming other treatment options. From a management perspective, the use of copper silicate and ASM represents a promising strategy for enhancing the innate resistance of coffee plants and mitigating the impact of BHB.
References
1. Badel, J. L., & Zambolim, L. (2019). Coffee bacterial diseases: a plethora of scientific opportunities. Plant Path., 68, 1–17.
Acknowledgements: INCT–Café, CNPQ, CAPES, and FAPEMIG
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