Effects of Bacillus cereus on physiological and biochemical characteristics of wheat under arsenic and cadmium stress: A biological agent to reduce heavy metal stress

B. cereus is an important plant growth promoting bacteria. It provides sustainable ways to increase plant yield as well as protection from environmental stress such as heavy metals. B. cereus can both increase plant nutrition and act as an osmoprotection agent. This study investigated seed priming of B. cereus into T. aestivum seeds under arsenic and cadmium stress. Growth parameters, gas exchange, photosynthesis efficiency, and antioxidant capacity were measured. As and/or Cd application caused 32 %, 18 % and 24 % decrease in the relative growth rate (RGR) in the As, Cd, and combined stress (As+Cd) groups, respectively. High amounts of reduction of photosynthetic parameters detected on T. aestivum under stress. B. cereus applications caused recovery in these parameters as well as increased proline accumulation. The increases in Fv/Fm and Fv/Fo indicated that photosynthesis system efficiency in PSII reaction center recovered. As and/or Cd stress caused ROS accumulation in T. aestivum. By B. cereus priming indicated ROS stress recovered with increased activity of SOD by 42.8 % in As+B group and 11.80 % in Cd+B group. With application of bacteria other antioxidant enzymes also showed boosted activity therefore reducing H2O2 content and preventing peroxidation. Bacteria application is also boosted AsA-GSH cycle in under both stresses. Therefore, seed priming with B. cereus is highly effective against heavy metal stress by reducing the availability of heavy metals and, ROS accumulation and increasing photosynthetic efficiency and antioxidant system for plants.