Due to their simplicity of synthesis, stability, and functionalization, low toxicity, and ease of detection, gold nanoparticles (AuNPs) are a natural choice for biomedical applications. AuNPs’ unique optoelectronic features have subsequently been investigated and used in high-tech applications such as organic photovoltaics, sensory probes, therapeutic agents, the administration of drugs in biological and medical applications, electronic devices, catalysis, etc. Researchers have demonstrated the biosynthesis of AuNPs using plants. The present study evaluates 109 plant species used in the traditional medicine of Middle East countries as new sources of AuNPs in a wide variety of laboratory environments. In this study, dried samples of bark, bulb, flower, fruit, gum, leaf, petiole, rhizome, root, seed, stamen, and above-ground parts were evaluated in water extracts. About 117 plant parts were screened from 109 species in 54 plant families, with 102 extracts demonstrating a bioreduction of Au³⁺ to Au⁰, revealing 37 new plant species in this regard. The color change of biosynthesized AuNPs to gray, violet, or red was confirmed by UV-Visible spectroscopy, TEM, FSEM, DLS, and EDAX of six plants. In this study, AuNPs of various sizes were measured from 27 to 107 nm. This study also includes an evaluation of the potency of traditional East Asian medicinal plants used in this biosynthesis of AuNPs. An environmentally safe procedure such as this could act as a foundation for cosmetic industries whose quality assessment systems give a high priority to non-chemically synthesized products. It is crucial that future optimizations are adequately documented to scale up the described process.

Damping-off caused by Pythium aphanidermatum, as one of the most infamous plant diseases, is considered as a significant disease that causes severe damages in greenhouse and field crops in a vast range of hosts especially vegetables. The application of chemical fungicides as a common method to control this disease poses negative side effects on humans and the environmental components. Actinobacteria, especially members of the genus Streptomyces, are fascinating biocontrol agents and plant growth-promoting rhizobacteria, which exhibit safer alternative managements to control this disease. The present study aims to explore for bioactives soil Streptomyces isolates that are able to control P. aphanidermatum, which is the causal agent of damping-off in tomato. Out of a total of 116 actinobacteria isolates collected from the soil, 53 have showed an antagonistic activity against P. aphanidermatum, as deduced through in vitro dual cultures. Based on in vitro Petri plate seedling-bioassays (IPSB), from the 53 tested isolates in dual cultures, two isolates coded as H2 and H3, considered as the most bioactive agents, were selected to assess their biocontrol performances against P. aphanidermatum in the Sandwich bed-mix technique in greenhouse experiments. In vivo greenhouse statistical studies were performed to compare seven treatments using completely randomized design experiments. Metalaxyl fungicide was applied as the chemical-control treatment. To evaluate biocontrol efficiencies of the two Streptomyces symbionts, disease incidence recorded throughout the course of experiment and criteria of number of leaves, length of the plants, plant fresh and dry weights, were measured at the end of experiment and analyzed statistically. The resulted disease incidences for all treatments indicated that the two Streptomyces strains had PGPR activity, and they were effective in decreasing disease incidence and improving plant performances regarding number of leaves, height, and plant fresh and dry weights. Based on the phylogenetic analysis of the partial sequences of the 16S rRNA gene, the strain H2 revealed a close relation to six Streptomyces species, namely S. badius, S. caviscabies, S. globisporus, S. parvus, S. sindenensis, and S. griseoplanus, with 99.9% similarity. The strain H3 also indicated a close relation of the same similarity to two species, namely S. flavogriseus and S. pratensis. In overall, collected data dictated that the two bioactive root symbiont Streptomyces strains effectively controlled the damping-off disease caused by P. aphanidermatum.

Greenhouse-grown cucurbit crops in several Iranian regions were surveyed for the incidence of Cucumber mosaic virus (CMV), Squash mosaic virus (SqMV), Papaya ring spot virus-type W (PRSV-W), Watermelon mosaic virus-2 (WMV-2), Zucchini yellow mosaic virus (ZYMV), Cucumber necrosis virus (CuNV) and Tomato spotted wilt virus (TSWV) from September 2002 to June 2004. In all, 1,304 random and 1,085 symptomatic leaf or fruit samples were collected. Samples were analyzed for virus infection by enzyme-linked immunosorbent assay. CMV and ZYMV were the viruses most frequently detected, accounting for 21.2 and 18% of the infected plants, respectively. WMV-2 was detected with 4.3% incidence in 15 regions and TSWV with 1.25% incidence only in 2 regions. CuNV, SqMV, and PRSV-W were not detected in any samples. Double and triple infections involving different combinations of CMV, ZYMV, WMV-2, and TSWV were noted in 117 and 4 samples, respectively. Natural infection of cucumber with TSWV and ZYMV is reported for the first time from Iran. Of 16 plant species from 14 genera, growing in or around greenhouse facilities, 6 were found infected with ZYMV, TSWV, WMV-2, and CMV and may act as reservoirs of the viruses. Four species are reported as new hosts of these viruses.

A survey was conducted to determine the incidence of Cucumber mosaic virus (CMV), Beet curly top virus (BCTV), Tomato yellow leaf curl virus (TYLCV), Tomato chlorotic spot virus (TcSV), Potato virus Y (PVY), Potato virus S (PVS), Tomato spotted wilt virus (TSWV), Tomato ringspot virus (TRSV), Tomato aspermy virus (TAV), Arabis mosaic virus (ArMV), Tobacco streak virus (TSV), Tomato bushy stunt virus (TBSV), Tobacco mosaic virus (TMV), and Tomato mosaic virus (ToMV) on tomato (Solanum lycopersicum) in the major horticultural crop growing areas in the southeast and central regions of Iran. A total of 1,307 symptomatic leaf samples from fields and 603 samples from greenhouses were collected from January 2003 to July 2005 in five southeastern and central provinces of Iran. Samples of symptomatic plants were analyzed for virus infection by enzyme-linked immunosorbent assay (ELISA) using specific polyclonal antibodies. ArMV and CMV were the most frequently found viruses, accounting for 25.6 and 23.4%, respectively, of the collected samples. BCTV, TSWV, TMV, PVY, ToMV, and TYLCV were detected in 6.1, 5.8, 5.6, 5, 4.8, and 1.6% of the samples, respectively. TBSV, TAV, TSV, PVS, and TRSV were not detected in any of the samples tested. Double and triple infections involving different combination of viruses were found in 13.9 and 1.7% of samples, respectively. This is the first report of PVY and ArMV as viruses naturally infecting tomato in Iran. Infection of tomato plants with PVY and ArMV was confirmed. Six out of 20 plant species belonging to six genera, growing in tomato fields or in the nearby areas, were found infected with TSWV, TMV, PVY, and CMV.