Protective Activity of Rhizobium leguminosarum bv. viciae Strain 33504-Mat209 against Alfalfa Mosaic Virus Infection in Faba Bean Plants.

The application of Rhizobium spp., nitrogen-fixing plant growth-promoting rhizobacteria, as biocontrol agents to enhance systemic disease resistance against plant viral infections is a promising approach towards achieving sustainable and eco-friendly agriculture. However, their potential as antivirals and biocontrol agents is less studied. Herein, the capability of Rhizobium leguminosarum bv. viciae strain 33504-Mat209 was evaluated to promote plant growth and enhance faba bean systemic resistance against alfalfa mosaic virus (AMV) infection. Under greenhouse conditions, the soil inoculation with 3504-Mat209 resulted in notable improvements in growth and an increase in chlorophyll content. This led to a marked decrease in the disease incidence, severity, and viral accumulation level by 48, 74, and 87%, respectively. The protective effect of 33504-Mat209 was linked to significant decreases in non-enzymatic oxidative stress indicators, specifically H2O2 and MDA. Additionally, there were significant increases in the activity of reactive oxygen species scavenging enzymes, such as peroxidase (POX) and polyphenol oxidase (PPO), compared to the virus treatment. The elevated transcript levels of polyphenolic pathway genes (C4H, HCT, C3H, and CHS) and pathogenesis-related protein-1 were also observed. Out of 18 detected compounds, HPLC analysis revealed that 33504-Mat209-treated plants increased the accumulation of several compounds, such as gallic acid, chlorogenic acid, catechin, pyrocatechol, daidzein, quercetin, and cinnamic acid. Therefore, the ability of 33504-Mat209 to promote plant growth and induce systemic resistance against AMV infection has implications for utilizing 33504-Mat209 as a fertilizer and biocontrol agent. This could potentially introduce a new strategy for safeguarding crops, promoting sustainability, and ensuring environmental safety in the agricultural sector. As far as we know, this is the first study of biological control of AMV mediated by Rhizobium spp. in faba bean plants.

Genotoxicity studies on the removal of a direct textile dye by a fungal strain, in vivo, using micronucleus and RAPD-PCR techniques on male rats.

The genotoxicity of the azo dye 'Direct Violet' and the removal of this dye by Aspergillus niger strain at different conditions have been investigated in male rats. Two genotoxicity techniques, namely bone marrow micronucleus assay and RAPD fingerprinting pattern, were used in this study for the direct dye and its removal by the fungal strain. Sixty male rats were divided into six treatment groups including a control group and other groups which were exposed for 2 or 8 weeks to Direct Violet dye, Direct Violet dye treated with A. niger at pH 2 or pH 9 or without agitation and acrylamide (30 mg/kg b.w.). A potent dose-dependent response was observed following oral gavage of the dye up to 1000 mg kg(-1), after which significant toxicity to the erythroid compartment was observed. Acrylamide and Direct Violet treatments increased the number of micronucleated polychromatic erythrocytes (MnPCEs) with respect to the controls. This increase was statistically significant in the two time intervals (2 and 8 weeks treatment, P < 0.0001). Fungi treatments at pH 2 and without agitation were able to reduce the number of MnPCEs induced by Direct Violet administration in all duration groups. Fungi treatment at pH 9 was only able to inhibit the genotoxicity of Direct Violet after 8 weeks treatment. The RAPD fingerprinting pattern indicated that most DNA of the samples treated with dye alone or acrylamide revealed polymorphic bands including the appearance and disappearance of the bands, which did not appear in the DNA samples of normal or fungi protected rats. The implications of these findings for the health and safety of occupationally exposed workers are discussed.

Evaluation of biotoxicity of textile dyes using two bioassays.

The toxicity of eight textile dyes was evaluated using two bioassays namely: Ames test and seed germination test. The Ames test is widely used for the evaluation of hazardous mutagenic effect of different chemicals, as a short-term screening test for environmental impact assessment. The eight-textile dyes and Eithidium bromide dye (as positive control) were tested with five "his" Salmonella typhimurium strains: TA 100; TA 98; TA 1535; TA 1537; TA 1538. Using six concentrations of each dye (2.5 microg/ml, 4.5 microg/ml, 9 microg/ml, 13.5 microg/ml, 18 microg/ml, and 22.5 microg/ml) revealed that, most of the dyes were mutagenic for the test strains used in this study. The high concentrations of dye eliminated microbial colonies due to the high frequency of mutation causing lethal effect on the cells. In this work the phytotoxicity of different soluble textile dyes was estimated by measuring the relative changes in seed germination of four plants: clover, wheat, tomato and lettuce. The changes in shooting percentages and root length as affected by dye were also measured. Seed germination percent and shoot growth as well as root length were recorded after 6 days of exposure to different concentrations of textile dyes in irrigation water. The results show that high concentrations of dyes were more toxic to seed germination as compared with the lower concentrations. However, the low concentrations of the tested dyes adversely affected the shooting percent significantly.