In vitro rhizobia response and symbiosis process under Aluminum stress

Aluminium (Al) toxicity is a major problem affecting soil fertility, microbial diversity, and nutrients uptake of plants. Rhizobia response and legume-interaction under Al conditions are still unknown and it is important to understand how to develop and improve legume cultivation under Al-stress. In this study, rhizobia-response was recorded under different Al-concentrations. Al-effect on rhizobial cells was characterized by combination with different two pH conditions. Symbiosis process was compared between α- and β-rhizobia inoculated onto soybean varieties. Rhizobial cell numbers was decreased as Al concentration increased. However, induced Al-tolerance considerably depended on rhizobia types and their origins. Accordingly, organic acid results were in correlation with growth rate and cell density which suggested that citric acid might be a positive selective force for Al-tolerance and plant-interaction on rhizobia. Al-toxicity delayed and interrupted the plant-rhizobia interaction and the effect was m...