Relationships Between Mycorrhizal Attributes and Stable Carbon and Azote Isotopes in a Semi-arid Environment as Influenced by Durum Wheat Cultivars and Salinity Level

The effect of plant species on their root-associated arbuscular mycorrhizal fungi (AMF) under salt stress is well studied, but how cultivars modulate this association remains largely unexplored. To fill in such a gap in knowledge, this study investigates how durum wheat cultivars shape their AMF communities in relation with plant physiological traits. Six durum wheat cultivars were grown in semi-arid areas and irrigated with three salinity levels (6, 12, and 18 dS m(-1)). The interaction between cultivar and salinity had a considerable impact on AMF status, plant physiological traits, and grain yield (GY). In particular, Maali (modern variety) exhibited the highest belowground inputs (mycorrhizal root colonization, spore density, and spore morphotype number) at 6 and 12 dS m(-1), while a clear prevalence was obtained for Agili Glabre (landrace) at 18 dS m(-1). Furthermore, these two cultivars were distinguished by a low yield stress susceptibility index and a high GY. Some AMF genera (e.g., Glomus, Funneliformis, and Paraglomus) seem to interact with most cultivars, while some others including Acaulospora and Septoglomus preferred to colonize Agili Glabre cultivar. This study indicates the contribution of durum wheat cultivar in operating the AMF diversity. Under both conditions (6 and 12 dS m(-1)), the partial least square structural equation modelling (PLS-SEM) showed that AMF colonization had an indirect effect on GY through C metabolism, expressed mainly by delta C-13(flag leaf) and delta C-13(grain). These findings highlight that durum wheat cultivar is a determinant factor in AMF symbiosis performance, therefore of salt-tolerance.