Biological control of ornamental plant diseases caused by Fusarium oxysporum: A review

In this study, nanostructured edible coatings based on chitosan nanoparticles (CSNPs) and chitosan-thyme essential oil nanoparticles (CSTEO-NPs) were characterized and evaluated on in vitro growth of Colletotrichum gloeosporioides and on inoculated avocado fruit cv. Hass, to evaluate their fungicidal activity and the effect on fruit quality. From TEM and particle size distribution characterization, the size of nanoparticles increased after thyme essential oil incorporation. Overall a synergistic effect between the chitosan and thyme essential oil (TEO) was observed. For in vitro evaluation, incorporation of this essential oil to CSNPs improved the control of C. gloeosporioides as there was a complete growth inhibition. CSNPs with concentrations of TEO at 3 and 5% had a fungicidal effect. The coating formulation with 55% CSTEO-NPs notably reduced the incidence of C. gloeosporioides on avocado cv. Hass by up to 60%. Also, at the end of the 8-day storage period, CSTEO-NPs incorporation into the coating did not affect the quality of avocado; moreover, fruit firmness was better maintained than untreated fruit.

The Effect of Nanostructured Chitosan and Chitosan‐thyme Essential Oil Coatings on Colletotrichum gloeosporioides Growth in vitro and on cv Hass Avocado and Fruit Quality

This paper reports on the use of Ruta chalepensis L. extracts as a potential nematicide against root knot nematodes Meloidogyne incognita and Meloidogyne javanica. The essential oil (REO) and methanol extract (RME) of R. chalepensis were tested against second-stage juveniles, with REO inducing paralysis in both species (EC50/1d = 77.5 and 107.3 mg/L) and RME being selective for M. incognita (EC50/1d = 1001 mg/L). Chemical characterization of extracts was done by means of GC-MS and LC-MS, revealing mainly aliphatic ketones and coumarins, respectively. The first-ranking volatile nematicidal component in terms of individual activity against both species was 2-undecanone (EC50 = 20.6 and 22.5 mg/L for M. incognita and M. javanica, respectively). This fact together with its high concentration in the most active extract found in this study, namely, REO (2926 mg/kg), categorizes 2-undecanone among the nematicidal principles of R. chalepensis. On the contrary, coumarins rutin and 8-methoxypsoralen were not found ...

Aliphatic ketones from Ruta chalepensis (Rutaceae) induce paralysis on root knot nematodes.

The antifungal properties of 12 Eos, that is, Syzygium aromaticum, Pelargonium graveolens, Lavandula angustifolia, Cupresus sempervirens, Mentha piperita, Santolina chamaecyparissus, Citrus sinensis, Pogostemon patchouli, Thymus mastichina, Thymus vulgaris, Eucalyptus globulus and Rosmarinus officinalis, were screened. The influence of five doses of each EOs was tested against Botrytis cinerea, Sclerotinia sclerotiorum, Fusarium oxysporum, Phytophthora parasitica, Pythium aphanidermatum, Alternaria brassicae, Cladobotryum mycophilum and Trichoderma aggressivum f.sp. europaeum using disc-diffusion method. The mycelial growth inhibition and ED50 were calculated. The chemical analysis of the EOs was analysed using gas chromatography-mass spectroscopy. A total of 58 compounds were identified in the 12 EOs. All essential oils (EOs) analysed showed antifungal activity against the test pathogens in the range of 5·32-100%. The inhibitory effect of oils showed dose-dependent activity on the tested fungus. Based on the ED50 values, clove, rose geranium, peppermint and patchouli were the most effective. This study warrants further research into the practical use of EOs for the control of important myco- and phytopathogens in intensive horticulture. Significance and impact of the study Due to the serious damage caused by fungal pathogens of vegetables and mushrooms, it is necessary to search for integrated strategies of disease control. This study provides relevant information about the effects of 12 essential oils (EOs) against eight pathogens of agricultural interest, included mycopathogens with emphasis on the possible future application of the EOs as alternative antifungal agents.

Screening of antifungal activity of 12 essential oils against eight pathogenic fungi of vegetables and mushroom

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Effects of Organic Acids and Salts on the Development of Penicillium italicum: The Causal Agent of Citrus Blue Mold

In vitro antifungal activity of essential oils and their compounds on mycelial growth of Fusarium oxysporum f. sp. gladioli (Massey) Snyder and Hansen.

Cell-surface-localized pattern recognition receptors (PRRs) and intracellular nucleotide-binding domain and leucine-rich repeat receptors (NLRs) are plant immune proteins that trigger an orchestrated downstream signaling in response to molecules of microbial origin or host plant origin. Historically, PRRs have been associated with pattern-triggered immunity (PTI), whereas NLRs have been involved with effector-triggered immunity (ETI). However, recent studies reveal that such binary distinction is far from being applicable to the real world. Although the perception of plant pathogens and the final mounting response are achieved by different means, central hubs involved in signaling are shared between PTI and ETI, blurring the zig-zag model of plant immunity. In this review, we not only summarize our current understanding of PRR- and NLR-mediated immunities in plants, but also highlight those signaling components that are evolutionarily conserved across the plant kingdom. Altogether, we attempt to offer an overview of how plants mediate and integrate the induction of the defense responses that comprise PTI and ETI, emphasizing the need for more evolutionary molecular plant–microbe interactions (EvoMPMI) studies that will pave the way to a better understanding of the emergence of the core molecular machinery involved in the so-called evolutionary arms race between plants and microbes.

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L. J. Garcia-Barrera

Papers

In vitro antifungal activity of essential oils and their compounds on mycelial growth of Fusarium oxysporum f. sp. gladioli (Massey) Snyder and Hansen.

An Overview of PRR- and NLR-Mediated Immunities: Conserved Signaling Components across the Plant Kingdom That Communicate Both Pathways