Effects of magnesium application on the arbuscular mycorrhizal symbiosis in tomato

The arbuscular mycorrhizal symbiosis (AMS) is formed between arbuscular mycorrhizal fungi (AMF) and the root of approximately 80% land plants, and this mutualistic interaction significantly contributes to plants’ nutrient acquisition. However, the effect of AMS on magnesium (Mg) nutrition has received less attention. In the present study, we co-cultured tomato plants ( Solanum lycopersicum ) with Rhizophagus irregularis supplied with different concentrations of Mg. The results indicated that Mg application can promote plant growth and mycorrhizal colonization. We noticed a positive effect of AMF inoculation on Mg acquisition under medium-Mg and high-Mg conditions in tomato plants. In parallel, the phylogenetic and expression analyses of seven putative magnesium transporter (MGT) genes were also carried out. RT-qPCR revealed that the transcript levels of SlMGT1-1 , SlMGT2-1 , and SlMGT5-2 were significantly altered in response to AMS. Together, these results indicated that AMS plays a significant role in tomato Mg acquisition, and provided valuable information to further investigations on the relationships between AMS and plant Mg uptake.