Green synthesis of nanoparticles using botanicals and their application in management of fungal phytopathogens: a review

Green synthesis of nanoparticles is an emerging aspect in plant disease management that blends nanotechnology and plant-derived ingredients to produce a biocontrol formulation. Different physical and chemical processes employed in the synthesis of nanoparticles are polluting, expensive, and also release hazardous by- products. The range of secondary metabolites present in plants makes them efficient reducing and stabilizing agent during the synthesis process. These metabolites serve a vital role in plant defense against the invasion of phytopathogens including fungi, bacteria, viruses, insect pests, etc. The plant metabolites, such as sugars, terpenoids, polyphenols, alkaloids, phenolic acids, and proteins, have been shown to be crucial in the reduction of metal ions into nanoparticles. In green synthesis of nanoparticles, the plant extracts are used as potential reducing and capping. This also restricts the formation of clusters or aggregates and improves the colloidal stability. The nanoparticles exhibit excellent antimycotic against a variety of phytopathogens and are very efficient in managing plant diseases. The aim of this review is to highlight plants, phytochemicals exhibiting antifungal properties, green synthesis of nanoparticles using plant material and their antimycotic activity.

Identification, pathogenicity and effects of plant extracts on Neopestalotiopsis and Pseudopestalotiopsis causing fruit diseases

Pestalotiopsis and related genera, including Neopestalotiopsis and Pseudopestalotiopsis have damaged many plants for many decades; however, there is little available information about the fungi on tropical fruit in Thailand. This study isolated and characterized pestalotioid fungi on tropical fruit, investigated host specificity, and screened whether plant extracts could control the fungi. In total, 53 diseased fruit samples were sampled from eight types of fruit trees (jackfruit, rose apple, mangosteen, plum, snake fruit, rambutan, strawberry, and avocado). Based on morphological characteristics, 44 isolates were classified as belonging to pestalotioid taxa. Of these isolates, seven with distinct characteristics were selected for identification using molecular analysis, and six isolates were identified as Neopestalotiopsis and one as Pseudopestalotiopsis. In the cross-inoculation experiment, the isolates exhibited nonhost specificity and could infect at least two host plants. The isolates were used to screen for a potential biocontrol resource using six crude plant extracts (clove, ginger, lemongrass, mangosteen, roselle, and turmeric). All crude extracts except mangosteen could inhibit the growth of Neopestalotiopsis and Pseudopestalotiopsis. Application of crude plant extracts could be a potential treatment to control these diseases on tropical fruit.

The Phytochemical, Antifungal, and First Report of the Antiviral Properties of Egyptian Haplophyllum tuberculatum Extract

In this study, ethanol whole plant extract (WPE) of Haplophyllum tuberculatum was characterized and tested for its antifungal and antiviral activities against Fusarium culmorum, Rhizoctonia solani and tobacco mosaic virus (TMV). High Performance Liquid Chromatography (HPLC) analysis showed that the main phytochemical constituents of H. tuberculatum WPE were resveratrol (5178.58 mg/kg), kaempferol (1735.23 mg/kg), myricetin (561.18 mg/kg), rutin (487.04 mg/kg), quercetin (401.04 mg/kg), and rosmarinic acid (387.33 mg/kg). By increasing H. tuberculatum WPE at concentrations of 1%, 2%, and 3%, all of the fungal isolates were suppressed compared to the two positive and negative controls. Under greenhouse conditions, WPE-treated Chenopodium amaranticolor plants strongly inhibited TMV infection and significantly reduced TMV accumulation levels when compared to non-treated plants. Moreover, the induction of systemic resistance with significant increases in the transcriptional levels of the pathogenesis-related protein-1 (PR-1), chalcone synthase (CHS), and hydroxycinnamoyl-CoA quinate transferase (HQT) genes for treated plants were noticed at 3 and 5 days post-inoculation (dpi) for both assays. To the best of our knowledge, this is the first reported observation of the antiviral activity of H. tuberculatum extract against plant viral infections. Finally, the results obtained suggest that H. tuberculatum WPE can be considered a promising source of both antifungal and antiviral substances for practical use and for developing plant-derived compounds for the effective management of plant diseases.

Study on Fungi Inhabiting Indoor Woods and their Eco-Friendly Management

Biodeterioration of indoor wood and microbial pollution inside buildings is one of important problem in humid areas. Number of fungi are associated with indoor wood and many of them are responsible for its deterioration by causing decay and stain. Some of them may release mycotoxins, which have hazardous impact on human health. In present study, fifteen fungi associated with wood surface were isolated and out of which genus Aspergillus dominate with four species. A. flavus was recorded from all locations. The potential of leaf extracts of nine tree species on the growth of A. flavus was evaluated by amending culture media. Considerable growth inhibition of A. flavus in the range of 1.14-45.45% was recorded on solid media and 9.37-86.66% in liquid media. Amendment of culture media @ 30% concentration of the leaf extract of Corymbia torelliana have recorded maximum growth inhibition irrespective of the media used.

Study on Fungi Inhabiting Indoor Woods and their Eco-Friendly Management

Biodeterioration of indoor wood and microbial pollution inside buildings is one of important problem in humid areas. Number of fungi are associated with indoor wood and many of them are responsible for its deterioration by causing decay and stain. Some of them may release mycotoxins, which have hazardous impact on human health. In present study, fifteen fungi associated with wood surface were isolated and out of which genus Aspergillus dominate with four species. A. flavus was recorded from all locations. The potential of leaf extracts of nine tree species on the growth of A. flavus was evaluated by amending culture media. Considerable growth inhibition of A. flavus in the range of 1.14-45.45% was recorded on solid media and 9.37-86.66% in liquid media. Amendment of culture media @ 30% concentration of the leaf extract of Corymbia torelliana have recorded maximum growth inhibition irrespective of the media used.