Mycorrhizal inoculation affected growth, mineral composition, proteins and sugars in lettuces biofortified with organic or inorganic selenocompounds

• New synthesized organic selenocompounds were applied for biofortification of lettuces.
• Effect of mycorrhizal inoculation on biofortification of Se in lettuces was tested.
• Mycorrhizal inoculation reduced the accumulation of Se in shoots of lettuces.
• Imidoselenocarbamate enhanced growth of red-leaf mycorrhizal lettuces.
• Imidoselenocarbamate increased proteins and sugars in red-leaf mycorrhizal lettuces.

Mycorrhizal inoculation can enhance the nutritional value of lettuces. However, the role of arbuscular mycorrhizal fungi (AMF) in biofortification of selenium (Se) in lettuce is unknown. We tested the capacity of two cultivars of lettuces, inoculated or not with AMF, for accumulating Se in shoots after applying sodium selenite or new synthesized organic selenocompounds. Sodium selenite was the most effective for increasing Se in shoots, but it decreased levels of macronutrients, micronutrients and proteins in one cultivar. Mycorrhizal inoculation reduced the accumulation of Se in leaves, but inoculated plants had higher contents of minerals, proteins and/or sugars than the non-inoculated controls supplied with Se. Mycorrhizal inoculation may impair the biofortification of lettuces with Se, but could be adequate for cultivating lettuces on soils rich in Se. The organic imidoselenocarbamate improved the effectiveness of AMF for enhancing growth, and proteins and sugars in leaves of one greenhouse-grown cultivar of lettuce.