Arbuscular symbiosis affects transcriptomic regulation of primary metabolism in leaves of soilless cultivated lettuces

Lettuce (Lactuca sativa) is an annual autogamous diploid plant belonging to Asteraceae and amongst the top ten most profitable crops worldwide. Nevertheless, one of the major problems for extensive lettuce cultivation is represented by fertiliser exploitation in soil and extra soil system. In this context, arbuscular mycorrhizal (AM) fungi could help reduce the impact of fertilisers, particularly phosphorus (P), improving plant nutrition and contributing to growing healthier plants. In our work, we collected lettuces (cv. Salinas) inoculated with the AM fungus Funneliformis mossae and grown in soilless culture with a P-deficient nutrient solution. Gene expression profile of leaves was analysed. Overall, 1,458 genes were differentially regulated by mycorrhizal symbiosis. Interestingly, the pattern of differentially expressed genes showed regulation of photosynthesis and starch sucrose metabolism. These data are coherent with biochemical and physiological results recently reported in the literature and suggest the possible exploitation of AM symbionts for lettuce soilless cultivation with beneficial effects on plant growth.