Å NO production in Arabidopsis thaliana in response to Pseudomonas syringae pv maculicola. NOS activity increased substantially in leaves inoculated with P. syringae. However, electron paramagnetic resonance experiments showed a much higher Å NO formation that was dependent on nitrite and mitochondrial electron transport rather than on arginine or nitrate. Overall, these results indicate that NOS, NR and a mitochondrial-dependent nitrite-reducing activity cooperate to produce Å NO during A. thaliana-P. syringae interaction.

No abstract

No abstract

Characterization of resistance response to pathogens is a fundamental strategy in plant breeding programmes. Thus, in this study, we developed an effective inoculation method for resistance tests of bacterial halo blight (BHB), caused by Pseudomonas syringae pv. garcae on coffee. Firstly, aggressiveness of eight selected bacterial strains as well as seven mixed strains was assessed on coffee seedlings of Mundo Novo IAC 376‐4 cultivar. Two experiments were conducted comparing three inoculation techniques: initially, we compare the methods of sprinkling and multiple needles on four cultivars of Coffea arabica; later, four cultivars and seven genotypes were compared for the multiple needles method and the abrasion technique. Severity was evaluated according a disease rating scale (DRS), considering either leaf surface area affected for sprinkling, or affected inoculated area for inoculation by multiple needles and abrasion. The area under the disease progress curve of disease (AUDPC) was calculated considering weekly evaluations of disease from seven until 42 days postinoculation (DPI). The standard deviation (SD), coefficient of variation (CV) and confidence interval (CI) variables were used to denote the effectiveness of the methods. According to the results, strain IBSBF 1197 was the most aggressive, and three other strains showed high aggressiveness. All inoculation methods were able to discriminate the resistance response to BHB, wherein the sprinkling method was less efficient than multiple needles and abrasion technique was more efficient than multiple needles. In addition, disease evaluations at 14 DPI showed a high correlation coefficient with area under AUDPC at 42 DPI, validating the early selection to BHB. Results of inoculation methods indicated the abrasion on first pair of leaves, together with evaluations on fourteenth DPI, as the most promising technique for early selection on coffee breeding to BHB.

This study was carried out to evaluate the potential of acibenzolar‐S‐methyl (ASM), combined or not combined with fungicides and antibiotics for the control of brown eye spot (Cercospora coffeicola) and bacterial blight (Pseudomonas syringae pv. garcae) in coffee seedlings, and ASM combined with conventional fungicide application schedules for the control of coffee rust (Hemileia vastatrix) and brown leaf spot (Phoma costarricencis) under field conditions in two coffee crops in the State of São Paulo, Brazil. ASM protected coffee seedlings against C. coffeicola when applied at the rates of 2.5 and 5 g of active ingredient per hectolitre of water (g a.i. hL−1), providing 34–55% of disease control, and against bacterial blight, when applied at the rates of 2.5, 10 and 20 g a.i. hL−1, with 38–57% of disease control. Tebuconazole (100 g a.i. hL−1) and azoxystrobin (10 g a.i. hL−1) showed the best results for brown eye spot control. Oxytetracycline + streptomycin, kasugamycin hydrochloride, oxytetracycline + metallic copper, copper oxychloride and mancozeb + copper oxychloride also controlled bacterial blight in levels similar to those shown by ASM. In the field experiments, all fungicide application schedules tested, cyproconazole (December, February, April), epoxiconazole (December, March), tetraconazole (December, February, April), cyproconazole (December, February) and azoxystrobin (January, March) were effective for coffee rust control and provided partial control of brown leaf spot. The results also showed that for all experiments, there was no synergistic effect of the combination of ASM with azoxystrobin, cyproconazole or cupric fungicides.

No abstract

of P. syringae. Through biochemical, serological and pathogenicity tests, the pathogens were identified as P. syringae pv. garcae and P. syringae pv. tabaci, with prevalence of isolates belonging to pathovar tabaci and, as well as in certain samples, it was identified simultaneous infection by both etiological agents. Then, this is the first report of associated occurrence of garcae and tabaci pathovars of P. syringae and of the incidence of "bacterial-leaf-spot" under field conditions and in the State of Paraná.KEy wORdS: Coffea arabica L., bacterial-halo-blight, bacterial-leaf-spot.

No abstract