The Effect of Bacillus Cereus on the Ion Homeostasis, Growth Parameters, and the Expression of Some Genes of Artemisinin Biosynthesis Pathway in Artemisia Absinthium Under Salinity Stress.

Background: Soil salinity is a major problem in the world that affects the growth and yield of plants. Application of new and up-to-date techniques can help plants in dealing with salinity stress. One of the approaches for reducing environmental stress is the use of rhizosphere bacteria.

Objective: The aim of present study was to investigate the effect of the inoculation of Bacillus cereus on physiological and biochemical indicators and the expression of some key genes involved in the Artemisinin biosynthesis pathway in Artemisia absinthium under salinity stress.

Materials and methods: The study was conducted using three different salinity levels (0, 75, 150 mM/NaCl) and two different bacterial treatments (i. e, without bacterial inoculation and co-inoculation with B. cereus isolates). The data from the experiments were analyzed using factorial analysis, and the resulting interaction effects were subsequently examined and discussed.

Results: The results showed that with increasing salinity, root and stem length, root and stem weight, root and stem dry weight, and potassium content were decreased, although the content of sodium was increased. Rhizosphere bacteria increased the contents of Artemisinin, potassium, calcium, magnesium, and iron and the expression of Amorpha-4,11-diene synthase and Cytochrome P450 monooxygenase1 genes as well as the growth indicators; although decreased the sodium content. The highest ADS expression was related to co-inoculation with B. cereus isolates E and B in 150 mM salinity. The highest CYP71AV1 expression was related to co-inoculation with B. cereus isolates E and B in 150 mM salinity.

Conclusion: These findings showed that the increase in growth indices under salinity stress was probably due to the improvement of nutrient absorption conditions as a result of ion homeostasis, sodium ion reduction and Artemisinin production conditions by rhizosphere B. cereus isolates E and B.