World Pathology Week

Biography

Abstract

Mauginiella scaettae is a fungal pathogen causing inflorescence rot date palm: one of the most divesting diseases in date palm growing regions worldwide. This disease was first reported by Cavara (1925) in Libya but the infection mechanisms remain obscure. To characterise the infection mechanism it was attempted to develop the model plant  Arabidopsis thaliana as an alternative host for strains of Mauginiella scaettae were isolated from different oases of East-south of Algeria: Ouargla1 (OU1) ,Ouargla2 (OU2), Ouargla3 (OU3), Hadjira (Ha),Touggour1(T1), Touggourt2 (T2), Oued1 (OE1), Oued2 (OE2), Ghardaïa (G) and Biskra (Bis). Sequencing the internal spacer (ITS) regions of indicated the phylogenetic position of M. scaettae. Upon drop-inoculation with conidia of M. scaettae, Arabidopsis exhibited white necrotic lesions with marginal yellowing appeared on leaves at 6 days post inoculation and subsequently expanded throughout the entire leaves. It was noted that strain G was the most and T2 is the least virulent. Microscopic investigations demonstrated that a preference for fungal penetration via stomata, accompanied by hyphal tip swelling which may represent a primitive haustorium. Both of these features were also observed on M. scaettae infected date palm spathes. On Arabidopsis initial biotrophic growth was followed by a necrotrophic lifestyle, similar to what happens on date palms. To investigate how host resistance mechanisms could modify the interaction were examined M. scaettae interactions with Arabidopsis mutants cpr1 and sid2 respectively increased and compromised in biotrophic resistance mechanisms, and eto2 which displays elevated resistance against necrotrophic pathogens. Interactions with eto2 appeared to be particularly affected, suggesting that anti-necrotrophic mechanisms - here linked to ethylene - could be effective in conferring resistance to M. scaettae. This study demonstrated the value of using model species in providing novel insights into previously cryptic interactions.