Reliable detection of the fungal pathogenfusarium oxysporum f.sp.albedinis, causal agent of bayoud disease of date palm, using molecular techniques

Bayoud, caused by the soilborne fungusFusarium oxysporum f.sp.albedinis (FOA), is the most serious disease of date palm. Since the disease is located in the North African countries of Morocco and Algeria, and advancing steadily eastwards, the ultimate goal is to prevent spread of the pathogen to other date-growing areas in the region and farther afield. Molecular diagnostic techniques have been developed for detection of FOA. In view of the fact that the fungus does not exist in Israel, DNA of FOA was obtained to determine the reliability of these methods for diagnostic purposes. Random amplified polymorphic DNA was not reliable enough for differentiation between FOA and various pathogenic and saprophyticFusarium isolates. However, the polymerase chain reaction utilizing FOA-specific primers was accurate and enabled amplification of a unique band specific to FOA DNA alone, and not that of the other tested pathogenic and saprophyticFusaria. The availability of a rapid and reliable diagnostic tool for detection of FOA will enable the Plant Protection and Inspection Services of the Israel Ministry of Agriculture to test date palm tissue for the presence of the pathogen. Contribution no. 513/00 from the Inst. of Plant Protection, ARO, The Volcani Center, Bet Dagan, Israel.     

Effectiveness of arbuscular mycorrhizal fungi in the protection of date palm (Phoenix dactylifera L.) against bayoud disease

In the present study, arbuscular mycorrhizal fungi (AMF) (Glomus monosporus, Glomus deserticola, Glomus clarum and a complex of native AMF coming from the Aoufous date palm grove in the south of Morocco) have been shown to protect date palm seedlings against bayoud disease. Treatment with AMF reduced disease severity by 8–77% depending on the AMF isolate used. In addition, all mycorrhizal fungi stimulate significantly shoot height and biomass and increase the number of leaves per plant. The plants associated with Aoufous complex present the best improvement of plant growth and great effectiveness in reducing bayoud disease incidence. Moreover, the AMF induce change in activities of two defence-related enzymes (peroxidases and polyphenoloxidases). The potential involvement of this induced biochemical defence reaction in protecting date palm against bayoud is discussed.