Efficient Role of Endophytic Aspergillus terreus in Biocontrol of Rhizoctonia solani Causing Damping-off Disease of Phaseolus vulgaris and Vicia faba.

The wide spread of plant pathogens affects the whole world, threatening national food security. Various fungi including Rhizoctonia solani induce the fungal disease damping-off that negatively affects plant seedlings' growth. Recently, endophytic fungi are used as safe alternatives to chemical pesticides that harm plant and human health. Here, an endophytic Aspergillus terreus was isolated from Phaseolus vulgaris seeds to control damping-off diseases by improving the defense system in Phaseolus vulgaris and Vicia faba seedlings. Endophytic fungus was morphologically and genetically identified Aspergillus terreus, and it is deposited in GeneBank under accession OQ338187. A. terreus demonstrated antifungal efficacy against R. solani with an inhibition zone at 22.0 mm. Moreover, the minimum inhibitory concentrations (MIC) of ethyl acetate extract (EAE) of A. terreus were between 0.3125 and 0.625 mg/mL to inhibit R. solani growth. Precisely 58.34% of the Vicia faba plants survived when A. terreus was added compared with the untreated infected (16.67%). Similarly, Phaseolus vulgaris achieved 41.67% compared to the infected (8.33%). Both groups of treated infected plants showed reduced oxidative damage (reduced Malondialdehyde and hydrogen peroxide levels) as compared to untreated infected plants. Reduced oxidative damage was correlated with the increase in photosynthetic pigments and the antioxidant defense system including polyphenol oxidase, peroxidase, catalase, and superoxide dismutase enzyme activities. Overall, the endophytic A. terreus can be considered an effective tool to control the suppression of Rhizoctonia solani in legumes, especially Phaseolus vulgaris and Vicia faba, as an alternative to synthetic chemical pesticides that harm the environment and human health.

Antagonistic Effect of Plant Growth-Promoting Fungi Against Fusarium Wilt Disease in Tomato: In vitro and In vivo Study.

Fusarium wilt is considered one of the most destructive diseases for tomato plants. The novelty of this work was to investigate the antifungal and plant growth-promoting capabilities of some plant growth-promoting fungi (PGPF). Plant growth-promoting fungi (PGPF) improved the plant health and control plant infections. In this study, two fungal strains as PGPF were isolated and identified as Aspergillus fumigatus and Rhizopus oryzae using molecular method. The extracts of A. fumigatus and R. oryzae exhibited promising antifungal activity against F. oxysporum in vitro. Moreover, antagonistic effect of A. fumigatus and R. oryzae against F. oxysporum causing tomato wilt disease was evaluated in vivo. Disease severity and growth markers were recorded and in vitro antagonistic activity assay of the isolated A. fumigatus and R. oryzae against Fusarium oxysporum was measured. Physiological markers of defense in plant as response to stimulate systemic resistance (SR) were recorded. Our results indicated that A. fumigatus and R. oryzae decreased the percentage of disease severity by 12.5 and 37.5%, respectively. In addition, they exhibited relatively high protection percentage of 86.35 and 59.06% respectively. Fusarium wilt was declined the growth parameters, photosynthetic pigments, total soluble carbohydrate, and total soluble protein, whereas content of free proline, total phenols, and the activity of antioxidant enzymes activity increased under infection. Moreover, application of A. fumigatus and R. oryzae on infected plants successfully recovered the loss of morphological traits, photosynthetic pigment total carbohydrates, and total soluble proteins in comparison to infected control plants. PGPF strains in both non-infected and infected plants showed several responses in number and density of peroxidase (POD) and polyphenol oxidase (PPO) isozymes.

Inhibition of Aspergillus flavus Growth and Aflatoxin Production in Zea mays L. Using Endophytic Aspergillus fumigatus.

Aspergillus flavus infection of vegetative tissues can affect the development and integrity of the plant and poses dangerous risks on human and animal health. Thus, safe and easily applied approaches are employed to inhibit A. flavus growth. To this end, the fungal endophyte, i.e., Aspergillus fumigatus, was used as a safe biocontrol agent to reduce the growth of A. flavus and its infection in maize seedlings. Interestingly, the safe endophytic A. fumigatus exhibited antifungal activity (e.g., 77% of growth inhibition) against A. flavus. It also reduced the creation of aflatoxins, particularly aflatoxin B1 (AFB1, 90.9%). At plant level, maize seedling growth, leaves and root anatomy and the changes in redox status were estimated. Infected seeds treated with A. fumigatus significantly improved the germination rate by 88.53%. The ultrastructure of the infected leaves showed severe disturbances in the internal structures, such as lack of differentiation in cells, cracking, and lysis in the cell wall and destruction in the nucleus semi-lysis of chloroplasts. Ultrastructure observations indicated that A. fumigatus treatment increased maize (leaf and root) cell wall thickness that consequentially reduced the invasion of the pathogenic A. flavus. It was also interesting that the infected seedlings recovered after being treated with A. fumigatus, as it was observed in growth characteristics and photosynthetic pigments. Moreover, infected maize plants showed increased oxidative stress (lipid peroxidation and H2O2), which was significantly mitigated by A. fumigatus treatment. This mitigation was at least partially explained by inducing the antioxidant defense system, i.e., increased phenols and proline levels (23.3 and 31.17%, respectively) and POD, PPO, SOD and CAT enzymes activity (29.50, 57.58, 32.14 and 29.52%, respectively). Overall, our study suggests that endophytic A. fumigatus treatment could be commercially used for the safe control of aflatoxins production and for inducing biotic stress tolerance of A. flavus-infected maize plants.

Potential of biosynthesized zinc oxide nanoparticles to control Fusarium wilt disease in eggplant (Solanum melongena) and promote plant growth.

In this study, a novel, non-toxic, eco-friendly zinc oxide nanoparticles (ZnO-NPs) was used instead of the synthetic fungicides widely used to control the destructive phytopathogenic fungus Fusarium oxysporum, the causative agent of wilt disease in Solanum melongena L. Herein, the biosynthesized ZnO-NPs was carried out by Penicillium expansum ATCC 7861. In vitro, mycosynthesized ZnO-NPs exhibited antifungal activity against Fusarium oxysporum. In vivo, ZnO-NPs suppressed Fusarium wilt disease in cultivated Solanum melongena L. by decreasing the disease severity with 75% of plant protection. Moreover, ZnO-NPs stimulated the recovery of eggplant as an indicated by improving of morphological and metabolic indicators including plant height(152.5%), root length(106.6%), plant fresh biomass (146%), chlorophyll a (102.8%), chlorophyll b (67.86%), total soluble carbohydrates (48.5%), total soluble protein (81.8%), phenol (10.5%), antioxidant activity and isozymes compared with infected control. Therefore, this study suggests using mycosynthesized ZnO-NPs as an alternative to synthetic fungicides not only to eradicate the Fusarium wilt disease in cultivated eggplant (Solanum melongena) but also to promote the growth parameters and metabolic aspects.

Bioactive Compounds and Antifungal Activity of Leaves and Fruits Methanolic Extracts of Ziziphus spina-christi L.

Zizyphus spina-christi L. has antimicrobial properties because of the presence of biologically active compounds. Alternaria is an opportunistic pathogen that causes leaf spots, rots, and blights on a variety of plant parts. This study aimed to reduce the usage of synthetically derived fungicides. Identification of the bioactive components present in leaves and fruits methanolic extracts of Z. spina-christi was performed using high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS). The efficacy of the two methanol extracts was tested against (a) in vitro fungal growth and (b) pathogenicity control on non-wounded and wounded tomato fruits. The results revealed that gallic acid and ellagic acid were the major components in leaves extract while quercetin was the major component in fruits extract. In addition, Phenol, 2,5-bis(1,1-dimethylethyl) (40.24%) and Decane, 2-methyl-(18.53%) were the most abundant components in the leaf extract, and the presence of D-mannonic acid, 2,3,5,6-tetrakis-o-(trimethylsilyl), and γ-lactone (22.72%) were major components in fruits extract. The methanolic extracts of Z. spina-christi leaves and fruits demonstrated significant antifungal activity against the growth of Alternaria alternata, A. citri, and A. radicina with variable inhibition percentages at different concentrations. Pathogenicity was increased when the skin was injured, as expected. Both extracts reduced the percentage of infected fruits.

Interaction between Growth Regulators Controls In Vitro Shoot Multiplication in Paulownia and Selection of NaCl-Tolerant Variants.

The interaction between cytokinin, auxin and GA controlled in vitro shoot multiplication in paulownia was influenced by a medium water potential (Ψ) modulation, where it was modulated using different textures or strengths of MS medium, media of different types (MS, WPM, SH and B5) or NaCl incorporation. The interaction between 2 mg/L BAP and 0.1 mg/L NAA expressed the highest shoot number on each media type, but it was better with media of lower water potential (MS and WPM), and MS medium was the best. Ψ of full-strength semisolid MS medium expressed the highest shoot multiplication. The opposite was detected when Ψ of MS medium was changed using half- or double-strength MS. Ψ of full-strength MS medium in semisolid form resulted in a valuable interaction between 2 mg/L BAP, 0.1 mg/L NAA and 0.1 mg/L GA, leading to efficient shoot formation, and it was associated with an increase in internode length and decrease in stem diameter, which facilitated obtaining synseeds with a high ability to convert. High genetic variation was recorded under long-term culture (14 subcultures). Polymorphism using the ISSR technique was higher than that of RAPD. A further increase in polymorphism was detected when NaCl was used, where five salt-tolerant lines were selected. Some salt-tolerant-selected lines showed one or more amplification products of a specific molecular weight that did not appear in the control. For example, with OPA-07 and OPG-02 RAPD primers, all the salt-tolerant-selected lines showed the appearance of amplification fragments (610 bp and 300 bp, respectively) that were not detected in control.

Potency of plant extracts against Penicillium species isolated from different seeds and fruits in Saudi Arabia.

Antifungal activity of extracts of cinnamon (Cinnamomum zeylanicum), Cloves (Syzygium aromaticum), ginger (Zingiber officinale) and turmeric (Curcuma longa) were evaluated in vitro against 17 Penicillium spp. Seed disease and rotten fruit caused by these species cause considerable loss of quality for different agricultural products. Isolates of Penicillium spp. were screened for production of patulin an important serious mycotoxin. About 70.59% of Penicillium spp. produced this toxin in concentrations ranging from 4 to 31 ppb. The response of Penicillium spp. to plant extracts differed according to the plant extract and concentration. Cinnamon extract showed the greatest effect on P. asperosporum, P. aurintogriseum and P. brevicompactum, and cloves extract produced the greatest effect on P. chermesinum and P. duclauxii. Turmeric extract had less effect on P. duclauxii. Cloves extract was the most effective in reducing the growth of Penicillium spp. On the other hand, ginger extract with all concentrations used had less effect against most Penicillium spp in the laboratory. Plant extracts are promising as natural sources of environmentally friendly compounds in laboratory studies.