INITIAL STAGES OF INFECTIOUS PROCESS OF Pseudomonas syringae pv. garcae IN COFFEE LEAVES

Abstract

<p>Bacterial blight of coffee (<em>Pseudomonas</em> <em>syringae</em> pv. <em>garcae</em>) (PSG) has been causing damage and losses to coffee growing. However, initial stages of the infectious process<em> </em>should be described in order to understand the relationship cycle and to propose efficient management strategies. This study described the initial stages of<strong> </strong>infectious process of the PSG in coffee leaves over time. The bacterial penetration sites studied were stomata, leaf margins, and wounds. Coffee seedlings received 50μL inoculum suspension at marked points on the abaxial face and leaf margins, and around wounds. By 30 minutes, 1, 3, 6, and 12 hours after inoculation, leaf disks collected at inoculated points were analyzed with scanning electron microscopy. One hour after inoculation, bacterial groups could be seen as result of cell multiplication. Subsequently, the number of grouped bacteria increased proportionally over time. A growing population concentration was found near stomata, wounds, epidermal appendages, and wax layer on leaf margins and leaf tip. Bacteria were positioned in their long axis starting from structures, thus creating a population gradient and displacement flow toward penetration pathways. Initial stages of infectious process occurred in all penetration sites, thus it was not possible to determine a preferred pathway.</p>

Resistance of genotypes and defence compounds against bacterial halo blight of coffee

“…As the infection process of P. syringae pv. garcae in coffee leaves has exponential increase in colonization after inoculation (Souza et al., 2019), UFV 7158 genotype possibly was more effective in the increase expression this genes of plant defence. Studies carried out with tobacco modified for PAL gene overexpression indicated that these plants were more resistant to infection by Cercospora nicotianae than wild plants (Shadle et al., 2003).…”

Molecular Characterization and Genome Mechanical Features of Two Newly Isolated Polyvalent Bacteriophages Infecting Pseudomonas syringae pv. garcae

“…The phytopathogenic bacterium Pseudomonas syringae pv. garcae (Psg) is responsible for the coffee halo blight disease of coffee plants [12][13][14][15][16][17][18].…”