Effect of inoculation with a strain of Pseudomonas pseudoalcaligenes isolated from the endorhizosphere of Salicornia europea on salt tolerance of the glasswort

Abstract

Salicornia europea, a glasswort, is one of the halophytes belonging to the Chenopodiaceae growing in the seashore of temperate and subtropic areas. We investigated the effect of inoculation with nitrogen-fixing rhizobacteria of S. europea on the salt tolerance of the plant. Under sterile conditions, the glasswort grew optimally in Murashige–Skoog agar medium supplemented with NaCl at a concentration ranging from 0.2 to 0.3 mol L⁻¹. Inoculation of the plant seedlings with a strain Sal35 out of five strains isolated from the surface-sterilized roots of the glasswort growing wild in a previous salt field resulted in higher concentrations of total nitrogen, chlorophylls, Na⁺ and K⁺ in the shoot than the un-inoculated plants at 47 days after sowing, while the fresh weight and dry weight of the shoot were not affected. Glasswort plants inoculated with the strain Sal35 showed no acetylene-reducing activity during 7 weeks of cultivation, indicating no supply of fixed nitrogen by the inoculum strain. Physiological characters and 16S rRNA gene similarity suggested that the strain Sal35 belonged to Pseudomonas pseudoalcaligenes.