Interfacial mechanisms involved in the interaction between Fusarium oxysporum f. sp. albedinis and date palm root

Our study aims to evaluate the physicochemical mechanism involved in the adhesion of Fusarium oxysporum f. sp. albedinis (Foa) on date palm root of resistant (Aziza M) and susceptible (Boufegouss) varieties by determining their surface properties. Hydrophobicity of Date palm root and Foa was evaluated by contact angle measurement (θw) and free energy of interaction determination (ΔGiwi). Our results showed that Foa surface is hydrophilic (θw = 30.57° and ΔGiwi = 15.51 mj/m2) and has an important electron donor character (γ- = 53,99mj/m2), whereas its electron acceptor property is low (γ+ = 8.95 mj/m2). Regarding date palm, the surface of sensitive variety’s root is hydrophilic (θw = 62.97°), while that of resistant variety is hydrophobic (θw = 69.50°). This character was confirmed by quantitative approach (ΔGiwi = 6.84 mj/m2 for sensitive variety and ΔGiwi = -20.61 mj/m2 for resistant variety). Also, it was noted that both resistant and sensitive varieties are weak electron acceptors (γ + = 0.15 mj/m2 and γ + = 0.08 mj/m2 for resistant and sensitive varieties respectively). The two varieties are relatively important electron donors, but the sensitive variety is more donor (γ- = 30.5 mj/m2) than the resistant one (γ- = 16.57 mj/m2). These results suggest that hydrophilic character and electron donor/acceptor character may be responsible for the adhesion of Foa on sensitive date palm root and therefore causes its susceptibility to bayoud disease. In contrast, the hydrophobic character of the resistant variety could explain its resistance.