In Vitro and In Vivo Biocontrol of Tomato Fusarium Wilt by Extracts from Brown, Red, and Green Macroalgae

Yasser S Mostafa,Sulaiman A Alrumman,Saad A Alamri,Mostafa A Taher,Mohamed Hashem,Zakaria A Baka

doi:10.3390/agriculture12030345

Yasser S Mostafa, Sulaiman A Alrumman + Show 4 more

Open Access

https://doi.org/10.3390/agriculture12030345

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Abstract

Fusarium wilt caused by Fusarium oxysporum f. sp. lycopersici (FOL) in tomatoes is globally recognized as one of the most significant tomato diseases, both in fields and in greenhouses. Macroalgae contain a diversity of bioactive complexes. This research was carried out to assess the value of the extracts from three macroalgae (Sargassum dentifolium belongs to Phaeophyta, Gracilaria compressa belongs to Rhodophyta, and Ulva lactuca belongs to Chlorophyta) against wilt disease in tomato plants. The fungal pathogen was isolated from diseased tomato plants growing in several parts of Saudi Arabia. Isolates of the pathogen were identified by morphological and molecular methods. Three organic solvents, in addition to water, were used for extraction to assess the effect of reducing FOL hyphal growth on potato dextrose agar (PDA). Radial reductions in pathogen hyphal growth were seen with all of the solvent and water extracts, but the three macroalgae methanol extracts that were tested showed the greatest reduction in pathogen hyphal growth. The total phenol content of the S. dentifolium extract was higher than that of the other two macroalgae. The phenolic compounds showed variability in all of the extracts that were identified and calculated by high-performance liquid chromatography (HPLC). Phloroglucinol (7.34 mg/g dry weight), vanillic acid (7.28 mg/g dry weight), and gallic acid (6.89 mg/g dry weight) were the phenolic compounds with the highest concentrations in the S. dentifolium, G. compressa, and U. lactuca extracts, respectively. The mycelium of FOL treated with a crude macroalgae extract of tested at 100 µg/mL was examined with a scanning electron microscope. The results showed an obvious difference between the extract-treated and untreated hyphae. The extract-treated hyphae collapsed and bruised, as well as; empty and dead. In the greenhouse experiment, S. dentifolium powder was used to evaluate its effect on disease decline. It led to a decrease in disease severity of 40.8%. The highest total yield (560.8 g) was obtained from the plants treated with S. dentifolium powder. We recommend the use of macroalgae extracts to combat fungal phytopathogens. Because chemical fungicides are extremely toxic to humans and the environment, macroalgae extracts are a good alternative that can be widely and safely used in the field.

Highlights

Tomatoes (Lycopersicon esculentum Mill.) are significant organic plants in Saudi Arabia, with a production per year of about 306,000 tones [1,2]
This study screened crude extracts of three marine macroalgae related to Phaeophyta (S. dentifolium), Rhodophyta (G. compressa), and Chlorophyta (U. lactuca) for an antifungal activity for controlling the Fusarium wilt of tomatoes caused by FOL
This study indicated that S. dentifolium extract completely inhibited the growth of FOL

Summary

Introduction

Tomatoes (Lycopersicon esculentum Mill.) are significant organic plants in Saudi Arabia, with a production per year of about 306,000 tones [1,2]. A catastrophic disorder caused by Fusarium oxysporum f. Lycopersici (FOL) drastically decreases tomato yield in both greenhouse and field conditions [3]. Yield losses can reach up to 90% [4]. Fighting tomato wilting with standard chemical methods is a challenge. This type of management is limited in organic farming [5]. The control of this disease depends on the application of some chemical fungicides in the late stages of tomato production [6]

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