Differential responses of Moroccan date palm cultivars to Mauginiella scaettae: in vivo and in vitro evidence for biochemical determinants of tolerance

Date palm ( Phoenix dactylifera L.) productivity is increasingly threatened by inflorescence rot caused by Mauginiella scaettae . This study assessed the response of ten Moroccan cultivars using a controlled spikelet inoculation assay, biochemical profiling, and evaluation of the effects of spikelet extracts on fungal growth. Susceptible cultivars ( Mejhoul , Boufgous and Bousthami ) showed rapid symptom development and stimulated fungal growth in vitro, whereas tolerant cultivars ( Tadment , Najda and Sair-Lyalat ) displayed delayed symptom expression and strong antifungal activity. More tolerant cultivars accumulated higher levels of phenolics, flavonoids, condensed tannins, and antioxidant activity evaluated by three complementary antioxidant assays (DPPH, ABTS, and FRAP), whereas susceptible cultivars contained lower levels of these defensive metabolites and may have contained higher amounts of readily available nutritive compounds that favored fungal proliferation. To our knowledge, this is the first study to develop and apply a controlled spikelet-based assay to assess date palm cultivar response to M. scaettae under experimental conditions. These findings indicate that the response to M. scaettae depends on the balance between antifungal secondary metabolites and pathogen-promoting nutrients, thereby providing useful insights for breeding and disease management.