Chemical products induce resistance to Xanthomonas perforans in tomato

The bacterial spot of tomato, caused by Xanthomonas spp., is a very important disease, especially in the hot and humid periods of the year. The chemical control of the disease has not been very effective for a number of reasons. This study aimed to evaluate, under greenhouse conditions, the efficacy of leaf-spraying chemicals (acibenzolar-S-methyl (ASM) (0.025 g.L⁻¹), fluazinam (0.25 g.L⁻¹), pyraclostrobin (0.08 g.L⁻¹), pyraclostrobin + methiran (0.02 g.L⁻¹ + 2.2 g.L⁻¹), copper oxychloride (1.50 g.L⁻¹), mancozeb + copper oxychloride (0.88 g.L⁻¹ + 0.60 g.L⁻¹), and oxytetracycline (0.40 g.L⁻¹)) on control of bacterial spot. Tomatoes Santa Clara and Gisele cultivars were pulverized 3 days before inoculation with Xanthomonas perforans. The production of enzymes associated with resistance induction (peroxidase, polyphenol oxidase, phenylalanine ammonia-lyase, β-1,3-glucanase, and protease) was quantified from leaf samples collected 24 hours before and 24 hours after chemical spraying and at 1, 2, 4, 6, and 8 days after bacterial inoculation. All products tested controlled bacterial spot, but only ASM, pyraclostrobin, and pyraclostrobin + metiram increased the production of peroxidase in the leaves of the two tomato cultivars, and increased the production of polyphenol oxidase and β-1,3-glucanase in the Santa Clara cultivar.

Effect of phenol on lipid and fatty acid profile of Xanthomonas oryzae pv. oryzae.

Effect of phenol on total lipid and fatty acid composition of Xanthomonas oryzae pv. oryzae, the causal agent of bacterial blight of rice (Oryzae sativa) was studied. Lipid level was low in phenol treated cells. Number of fatty acids detected from phenol treated cells was more than those found in untreated cells as revealed by Gas chromatography. Pentadecanoic acid (C15:0), linolenic acid (C18:3) and behenic acid (C22:0) were present only in the treated cells. Palmitic acid which is usually found in bacteria was not detected both in control and treated cells.

Effect of phenol on protein and amino acid content of Xanthomonas oryzae pv. oryzae.

Leaf blight disease of rice (Oryza sativa) is caused by the bacterium Xanthomonas oryzae pv. oryzae. Phenol (1 to 4 mM) induced changes in protein profiles of X. o. pv. oryzae and a stress protein with a molecular mass of 69,000 appeared. HPLC analysis indicated occurrence of amino acids such as asparagine, alanine, methionine and cystine in phenol treated cells. Proton NMR analysis also revealed variation on the presence of amino acids in the cells treated with phenol.

Meningitis due to Xanthomonas maltophilia.

During 1st week of post-operative period, a 28 year old female patient operated for left cerebellopontine angle tumor, continued to get fever. Lumbar puncture did not reveal any organisms. She responded to ciprofloxacin. Two months later, she was readmitted with signs and symptoms of meningitis. The CSF tapped on lumbar puncture grew Xanthomonas maltophilia, Gram negative bacilli, sensitive to various antibiotics, ciprofloxacin being one of them. The patient was given ciprofloxacin for 3 weeks. On follow up, a year later she was found to be asymptomatic.