Inoculation with selenobacteria and arbuscular mycorrhizal fungi to enhance selenium content in lettuce plants and improve tolerance against drought stress

This study evaluated the co-inoculation effect of the endophytic selenobacteria Bacillus sp., Klebsiella sp. or Acinetobacter sp. and the arbuscular mycorrhizal (AM) fungus Rhizophagus intraradices on lettuce plants grown under drought conditions. Plants inoculated with both microorganisms were able to enhance the Se content in their shoots (1 to 6 mu g plant(-1)) and promote macro-and micronutrient uptake. Moreover, the inoculated plants showed significant tolerance to drought stress, as determined by their adaptation to physiological parameters (relative water content and stomatal conductance), increase in photosynthetic pigments (chlorophyll and carotenoids) and improvement inantioxidant enzyme levels (catalase, ascorbate peroxidase and glutathione reductase). The selenobacteria increased the Se content in lettuce plants and enhanced the effect of AM fungus in controlling the antioxidant systems that play a role as elicitors of plant drought responses and improving the nutritional quality and physiological and biochemical processes involved in plant drought tolerance.