Effectiveness of Bacillus thuringiensis in alleviating oxidative and drought stress in Lavandula plants colonized by single or mixed autochthonous AMF inoculum

Abstract

This study determined the different responses in Lavandula plants when inoculated with single autochthonous arbuscular mycorrhizal (AM) fungi (S strains)or their mixture under natural drought conditions. The dual interactions of these fungal inocula with an autochthonous strain of Bacillus thuringiensis highly increased the mycorrhizal development (tested as AM intensity and arbuscular production) and reduced oxidative damage as index of drought tolerance. The interaction of AM consortium and B. thuringiensis caused the greatest AM colonization, shoot biomass and N, C, K, Ca, Mg, Cu, S and Zn content and concomitantly the lowest oxidative damage of lipids (MOA) and shoot/root ratio in these plants helping them to cope with drought. The minimized MOA production and the enhancement of antioxidants (SOO, APX, CAT and GR) enzymes reflected the highest stress tolerance in these dually inoculated plants. These abilities of inoculants in Lavandula under drought conditions can be used as powerful strategy to improve drought tolerance. Autochthonous AM fungi, particularly their mixture and B. thuringiensis help the plants to resist and tolerate drought in semiarid ecosystems in Mediterranean areas.