Arbuscular Mycorrhizal Fungi and Strigolactones: Modulating Molecular Defense Mechanisms in Wheat Against Fusarium Culmorum

Abstract

Aims: The role of strigolactones (SL) in molecular signalling with arbuscular mycorrhizal fungi (AMF) has been intensively investigated, but the impact of this interaction on defence mechanisms in soil microbiota and plant-pathogen systems is not fully understood. The aim of this study was to investigate the effects of SL and AMF treatments on molecular defence strategies and growth of wheat through soil-plant interactions during Fusarium culmorum (FC) infection.MethodsWheat varieties grown with and without AMF were inoculated with SL (rac-GR24; 15 mu M) and FC (1 x 10(6) spores ml-1) at the early stage of symbiosis. To evaluate symbiotic activity and infection effects in soil, expression levels of defence genes (PAL, PR2, PR3, PR4) and growth genes (TEF, Rubisco) were analysed by qRT-PCR before and after FC inoculation.ResultsSL was found to increase AMF activity in soil media and enhance symbiosis. This interaction improved both plant growth and defence responses. Increased expression of TEF and Rubisco genes favoured plant growth, while decreased expression of PR2 facilitated the entry of AMF hyphae into root tissues. Increased expression of PR3 enhanced the production of antifungal enzymes, while down-regulation of PR4 optimised energy utilisation through a 'priming' effect. Expression of the PAL gene showed cultivar-specific changes.ConclusionsSL and AMF treatments significantly reduced disease severity during FC infection by optimising wheat defence and growth responses at the molecular level through the plant-soil system. These findings highlight the potential of SL and AMF for sustainable agricultural practices.