Effect of salicylic acid on phenolic compounds related to date palm resistance to Fusarium oxysporum f.sp. albedinis

Salicylic acid (SA) plays a key role in establishing resistance to pathogens in many plants. To study the possible involvement of SA in the resistance of date palm (Phoenix dactylifera L.) to Fusarium oxysporum f. sp. albedinis (FOA), we investigated levels of phenolic compounds, known as indicators of resistance in the date palm/ Fusarium pathosystem. After treatment with SA the content of root soluble phenolics in F. oxysporum inoculated date palm seedlings was about 4 times higher in cv. Bousthami noir and 6 times higher in cv. Jihel than that in untreated plants showing disease symptoms. The largest increase was at a SA concentration of 50 µM. SA treatment also enhanced the content of cell wall phenolics. In addition, inoculation of SA-treated roots of date palm with FOA (strain ZAG) resulted in a greater number of plants showing only limited hypersensitive reaction-like necrotic lesions. In contrast, SA-untreated plants normally showed spreading necrosis in response to fungus inoculation

Chitosan, Antifungal Product against Fusarium oxysporum f. sp. albedinis and Elicitor of Defence Reactions in Date Palm Roots

The effect of chitosan on the growth and morphology of Fusarium oxysporum f. sp. albedinis (Foa), the causal agent of Bayoud disease, and its ability to elicit a defence reaction against this fungus in date palm roots were investigated. Chitosan at 1 mg ml-1 reduced the growth of Foa on potato dextrose agar medium by an average of 75%, while mycelial growth was totally inhibited in a liquid medium. When added to a solid medium, chitosan caused morphological changes in Foa mycelium. In addition, when injected into roots at three concentrations (0.1, 0.5 and 1 mg ml-1), chitosan elicited peroxidase (PO) and polyphenoloxidase (PPO) activity and, particularly at the concentration of 1 mg ml-1, increased the level of phenolic compounds. Concerning phenolics, chitosan led to an accumulation of non-constitutive hydroxycinnamic acid derivatives, known to be of great importance in date palm resistance to Bayoud. The accumulation of hydroxycinnamic acid derivatives was greater in cv. BSTN than in cv. JHL. Chitosan could be used to protect date palm against this vascular disease

Effect of Exogenous Application of Jasmonic Acid on Date Palm Defense Reaction against <em>Fusarium oxysporum</em> f.sp. <em>albedinis</em>

The effect of jasmonic acid in the date palm defence reaction against Fusarium oxysporum f. sp. albedinis was investigated taking into account changes in H2O2 and malonyldialdehyde (MDA) levels and peroxidase activity. Treatment of seedlings of two cultivars with jasmonic acid increased levels of H2O2 and enhanced lipid peroxidation as indicated by MDA accumulation and an increase in peroxidase activity. Similar changes occurred with date palm seedlings infected with Foa and showing necrotic hypersensitive-reaction like lesions. In general, both Foa and jasmonic acid increased H2O2 to a level 2 to 7 times that of the control, depending on the treatment and the time of analysis. Peroxidase activity was 2 to 3 times greater and MDA levels were increased 2 to 8 times. In contrast, seedlings presenting disease symptoms did not show any such reactions. It is suggested that oxidative burst (H2O2 generation) and its consequences (lipid peroxidation) and the change in peroxidase activity are used by date palm to resist Foa and that jasmonic acid is a signal for the expression of these defence reactions

Prevention of fungal spoilage in food products using natural compounds: A review

[EN] The kingdom Fungi is the most important group of microorganism contaminating food commodities, and chemical additives are commonly used in the food industry to prevent fungal spoilage. However, the increasing consumer concern about synthetic additives has led to their substitution by natural compounds in foods. The current review provides an overview of using natural agents isolated from different sources (plants, animals, and microorganisms) as promising antifungal compounds, including information about their mechanism of action and their use in foods to preserve and prolong shelf life. Compounds derived from plants, chitosan, lactoferrin, and biocontrol agents (lactic acid bacteria, antagonistic yeast, and their metabolites) are able to control the decay caused by fungi in a wide variety of foods. Several strategies are employed to reduce the drawbacks of some antifungal agents, like their incorporation into oil-in-water emulsions and nanoemulsions, edible films and active packaging, and their combination with other natural preservatives. These strategies facilitate the addition of volatile agents into food products and, improve their antifungal effectiveness. Moreover, biological agents have been investigated as one of the most promising options in the control of postharvest decay. Numerous mechanisms of action have been elucidated and different approaches have been studied to enhance their antifungal effectiveness.Ribes-Llop, S.; Fuentes López, A.; Talens Oliag, P.; Barat Baviera, JM. (2017). Prevention of fungal spoilage in food products using natural compounds: A review. Critical Reviews in Food Science and Nutrition. 1-11. doi:10.1080/10408398.2017.1295017S11