Effects of potassium-solubulizing and photosynthetic bacteria on tolerance to salt stress in maize.

AIMS: The purpose of this study was to determine the positive effects of potassium-solubilizing bacteria and photosynthetic bacteria on the salt tolerance of maize.

METHODS AND RESULTS: We selected the maize inbred lines USTB-265 (salt-sensitive), USTB-109 (moderately salt-tolerant) and USTB-297 (salt-tolerant) to investigate their growth characteristics, enzyme activity and gene expression in response to inoculation with photosynthetic bacteria and potassium-solubilizing bacteria under salt-stress conditions.

CONCLUSIONS: Photosynthetic bacteria and potassium-solubilizing bacteria inoculation significantly enhanced the expression of antioxidant enzyme-related genes and increased the activities of the antioxidant enzymes superoxide dismutase, catalase and ascorbate peroxidase. In addition, inoculation with photosynthetic bacteria more efficiently improved maize salt tolerance than inoculation with potassium-solubilizing bacteria. While the effects of these bacteria differed among the three maize lines, both photosynthetic bacteria and potassium-solubilizing bacteria can enhance salt tolerance in maize.

SIGNIFICANCE AND IMPACT OF THE STUDY: Soil salinization is one of the most critical factors affecting maize growth. These two types of bacteria (e.g. Bacillus mojavensis JK07 and Rhodopseudomonas palustris) have proven useful in salinized agricultural lands as bio-inoculants to increase crop productivity.