Bio-Control and Ultrastructure of Post-Harvest Pathogenic Fungi of Apple Fruits

Abstract

Post-harvest pathogenic fungi of fruits cause huge losses. Apples fruits are important for consumers. The antifungal activity of aqueous and ethanolic extracts of eleven medicinal plants at fives concentrations (0, 1, 3, 5, 10%; w/v) were tested against Alternaria alplateternata. Inhibition of fungal growth, along with the lower D50 values of the ethanolic extract of the tested plants compared to those of the aqueous extract exhibited more efficient antifungal activity. The ultrastructure of the fungal hyphae without treatment (control) showed normal hyphae enclosed by a wall composed of three layers in which the middle layer is more electron- denser than the outer and inner layers. An intact plasma membrane was also observed. In addition, an electron-dense material was observed at the tip of the hyphae. The cytoplasm contained several organelles. On the other hand, the treated hyphae with the ethanolic extracts of the mixture of E. citriodora and T. capitatus exhibited many changes as noted in both T.S and L.S such as the increase of the electron density of the outer layer of the hyphal wall more than the control, also numerous big lipid bodies were almost occupied the cytoplasm. Eucalyptus citridora and Thymus capitatus had a potential as antifungal agent for biocontrol of post-harvest pathogenic fungi of tested apple fruits.

Essential Oils Reduce Grey Mould Rot of Apples and Modify the Fruit Microbiome during Postharvest Storage

“…Many essential oils (EOs) proved their effectiveness against grey mould and brown rot ( Monilinia species) on pome and stone fruit, strawberries, and table grapes [ 8 , 9 , 10 , 11 ]. On apples, various studies have reported the efficacy of EOs against blue mould ( Penicillium expansum ) [ 12 , 13 , 14 ], grey mould [ 8 , 12 , 15 , 16 ], and bitter rot ( Colletotrichum species) [ 17 , 18 ], as well as Alternaria and Fusarium rots [ 17 , 18 , 19 ]. Different researchers described the volatile organic compounds (VOCs) present in EOs, such as thymol, eugenol, p -cymene, and carvacrol, which show strong antifungal activity and could be used for grey mould control on fruit [ 20 ].…”

Biotechnological and Biocontrol Approaches for Mitigating Postharvest Diseases Caused by Fungal Pathogens and Their Mycotoxins in Fruits: A Review

“…Essential oils derived from various plant sources possess antimicrobial properties and have been explored for postharvest disease control . Numerous essential oils are discovered for the antifungal properties of gray and brown molds in strawberries, peaches, pears, and plums. − For example, essential oils such as oregano oil, thyme oil, and cinnamon oil have exhibited antifungal activity against pathogens such as P. expansum , , B. cinerea , , Fusarium spp., and Alternaria spp …”

“…81−83 For example, essential oils such as oregano oil, thyme oil, and cinnamon oil have exhibited antifungal activity against pathogens such as P. expansum, 84,85 B. cinerea, 86,87 Fusarium spp., and Alternaria spp. 88 Another notable biochemical in fruit postharvest pathology is salicylic acid (SA). SA is a naturally occurring plant hormone known for its role in inducing plant defense responses against pathogens.…”