Isolation and Identification of Plant Growth-Promoting Endophytes Bacteria Highly Effective in Suppressing Damping-off in Sugar Beet

Sugar beet is an important sugar producing cash crop in the world with high economic value, but the crop faces a great economic loss every year due to damping-off. The concept of interactions produced between plant endophytic bacteria and host plants as an important biological control are gaining importance. In the present study, a strain of sugar beet standoff antagonist was obtained through plate standoff isolation and purification. Morphological observation, comparison of physiological and biochemical characteristics, and 16S rRNA gene sequences analysis were conducted for the classification and identification of the bacterial strain. The strain sb-13 was identified as Bacillus altitudinis. Through potting experiments, the growth of sugar beet inoculated with and without sb-13 was compared to analyze the effect of the endophytic bacteria on the growth of sugar beet, and it was found that the bacterium has the properties of promoting plant growth such as solubilizing phosphorus and dissolving potassium and enhancing the ability of soil enzyme activity. The experimental results showed that the growth of sugar beet inoculated with sb-13 was significantly better than that of the control group, and its physiological and biochemical indicators were significantly improved. In the anti-blight experiment, it was found that the bacterium antagonist had the ability to possess cellulose degradation and pectinase, and the incidence rate of sugar beet damping-off inoculated with sb-13 was significantly lower than that of the control group. This study provides a new idea for the biological control of sugar beet damping-off.