Drought and herbicide are two major abiotic stress factors that often occur simultaneously in nature, affecting negatively wheat performance and yield. Combined herbicide and drought stresses (HDS) induce oxidative damages in plants due to increase production of reactive oxygen species (ROS). Plant growth-promoting (PGP) endophytic bacteria Bacillus subtilis exerts protective effect on the growth of stressed plants, but underlying mechanisms are still not clear. In this work, a relationship between an increased antioxidant activity and HDS tolerance in soft spring wheat plants (Triticum aestivum L., cv. Ekada70) upon endophytes B. subtilis (strains 10-4 and 26D) application was revealed. The results showed that endophytes-inoculated wheat plants efficiently coordinate superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase activities involved in ROS detoxification under HDS. Moreover, the regulation of γ-aminobutyric acid (GABA) endogenous levels in stressed cv. Ekada70 plants by endophytes B. subtilis 10-4 and 26D was discovered. The results suggest the involvement of GABA as a signal molecule in these endophytes-mediated wheat tolerance under HDS via regulating stomatal opening, increased chlorophyll and osmolyte proline along with enhanced antioxidant capacity. As a result, the endophytes-inoculated plants had less oxidative damages and higher grain yield in comparison with non-inoculated control.

This research was funded by Russian Science Foundation, grant number 22-26-00076, https://rscf.ru/en/project/22-26-00076/.

Keywords: Triticum aestivum L., stress tolerance, herbicide+drought, endophytic bacteria, Bacillus subtilis, GABA, antioxidants, plant-microbe interactions

Dr. Oksana Lastochkina works at the Institute of Biochemistry and Genetics UFRC RAS (Ufa, Russia) as Head of Laboratory of Molecular Mechanisms of Plant Stress Resistance. Her research areas include Plants Stress Physiology/Biochemistry, Biostimulants-Induced Plant Stress Resistance/Tolerance, Plant-Microbe Interactions.

In 2007, she graduated from the Agronomy Faculty of the Bashkir State Agrarian University (Ufa, Russia) with honors. In 2011, she earned her Ph.D. in Biology from the Institute of Biochemistry and Genetics RAS (Ufa, Russia) working with Prof. Farida Shakirova. In dissertation work, she has investigated the role of hormonal intermediates in the implementation of the protective effect of salicylic acid and methyl jasmonate on wheat plants under salinity. From 2011 to 2020 she worked as a Research Associate and then as a Senior Scientist at the Laboratory of Plant-Microbe Interactions of the Bashkir Research Institute of Agriculture UFRC RAS, where she has investigated the mechanisms of Bacillus subtilis-induced plant stress resistance/tolerance under biotic (phytopathogens) and abiotic (drought, salinity) stresses. From 2018 to 2020, she worked as a Senior Researcher at the Laboratory of Bioinjeneering of Plants and Microorganisms IBG UFRC RAS. Since 2020 to present she is Head of the Laboratory of Molecular Mechanisms of Plant Stress Resistance IBG UFRC RAS. The results of her research work were presented in many international conferences, supported by RSF, RFBR, Council of the President of RF, FESPB, AGRISERA, and Society of PSB, and awarded by other diplomas. She has over 125 publications and 4 Invited Book Chapter in Springer International Publishing. From 2013 to 2016, she has also had experience as a Senior Lecturer at the Bashkir State Agrarian University (Ufa, Russia). Since 2017, she supervises diploma works of students, bachelors, and masters of Bashkir State University (Ufa, Russia); since 2019, co-supervising of MS students of the Tehran University (Tehran, Iran). She is a member of the Russian Society of Plant Physiologists and FESPB; reviewer in international journals indexing in WoS, Scopus. Her current work is focused on physio-biochemical and molecular mechanisms underlying effective interactions of endophytic B. subtilis and crop plants under combined abiotic stresses.