Effect of Enterobacter sp. FYP1101 on wheat seedling growth under salt stress

Abstract:

[Background] Saline-alkali land area in China is big, wide distributed and diversified, which is mainly distributed in northeast, northwest, north and coastal areas in China. The research in recent years has shown that the bioremediation by inoculation of PGPR can improve resistance of plants to salt stress, increasing the saline-alkali land management. [Objective] To preliminarily discover the growth promoting effect and mechanism of Enterobacter sp. FYP1101 on wheat seedling under salt stress, and to provide the theoretical basis for the field application of the strain. [Methods] On medium of phytate-phosphorus, using spread and streak plating technique to isolate; on Ashby medium and inorganic-phosphorus medium, the bacteria of nitrogen-fixation and inorganic-phosphorus-solubilizing were screened preliminarily, then analyzed their abilities for nitrogen-fixation, phytate-phosphorus-solubilizing, inorganic-phosphorus-solubilizing, siderophore- producing, 1-aminocyclopropane-1-carboxylate (ACC)-deaminase-producing and indole acetic acid (IAA)-producing; 16S rRNA gene was applied to preliminarily and taxonomically classify the strain FYP1101; plotted wheat under salt stress and conducted 3 treatments (treatment FP, adding particle microbial fertilizer containing FYP1101; treatment NK, adding null particle carrier containing no bacterial inoculant; treatment CK, neither particle microbial fertilizer nor null particle carrier added), then compared the shifts of the growth traits and physiochemical properties of rhizosphere soil of wheat seedlings under salt stress between different treatments. [Results] A total of 96 rhizospheric strains were isolated; one isolate designated by FYP1101 has salt tolerance up to 8%, and showed strong abilities of nitrogen-fixation (nitrogenase activity of 2.59 nmol C2H4/(h?mg protein)), phytate-phosphorus-solubilizing (2.70 μg/mL), inorganic-phosphorus-solubilizing (4.29 μg/mL), siderophore-producing (D/d ratio of 2.88), ACC-deaminase-activity (7.32 μmol α-butanone/(h·mg protein)) and IAA-producing (24.93 mg/L); based on 16S rRNA gene sequence, strain FYP1101 was classified into the genus of Enterobacter; Compared with NK and CK, the wheat inoculated by FP under salt stress showed chlorophyll content and biomass of overground and underground increased markedly (with increments of 19%?54%) and root length also increased markedly (with increments of 46%); the concentration of rhizospheric organic matter and available nitrogen were improved by about 52%?98%, whereas pH slightly decreased (0.12 and 0.17 units) and salinity increased about 40%. [Conclusion] Enterobacter sp. FYP1101 has many kinds of plant growth promoting traits. The strain can significantly affect the root establishment of wheat seedling under salt stress, improve the content of nutrition in rhizosphere soil, reduce the absorption of wheat for salt and promote the growth of wheat seedling. This suggests that Enterobacter sp. FYP1101 has a great potential in improving the adaptation of plant to stress.