Identification of endophytic Pseudomonas sp. YDX26 in Glycine soja and its growth-promoting and stress-resistant characteristics

Abstract:

[Background] Glycine soja has some excellent characteristics over the cultivated soybean, which is related to its unique endophytic bacteria and has become a research hotspot. [Objective] The endophytic bacteria of G. soja were isolated and identified. The strains with growth-promoting activity and stress-resistant potential were screened out. [Methods] The endophytic bacteria were isolated by tissue culture and streaking method. The strains were identified based on morphological, physiological, and biochemical characteristics and the 16S rRNA gene sequence-based phylogenetic analysis. The growth-promoting characteristics of the strains were analyzed by selective media or colorimetric method. Hydroponic experiment was carried out to analyze the effect of strain on the growth of rice seedlings. Salt stress and PEG-6000 simulated drought stress were used to explore the stress resistance of the strain. [Results] A strain YDX26 was isolated. According to the morphological, physiological and biochemical characteristics, and the results of phylogenetic analysis based on 16S rRNA gene sequence, the strain YDX26 was primarily identified as Pseudomonas sp. This strain had the phosphorus solubilization of 46.12 mg/L, the IAA activity of 19.97 μg/mL, and the ACC deaminase activity of 3.95 μmol/(mg·h). Moreover, it significantly increased the height, root length, aboveground dry weight, and underground dry weight of rice seedlings by 17.34%, 12.19%, 5.32%, and 10.70%, respectively. Compared with the control strain DX22, strain YDX26 showed improved salt and drought tolerance. [Conclusion] The endophytic bacterial strain YDX26 has better growth-promoting ability and salt and drought tolerance, and thus can be used as a new strain resource for agricultural production.