title: Beneficial soil bacterium Bacillus subtilis (GB03) augments salt tolerance of white clover.
abstract: Soil salinity is an increasingly serious problem worldwide that reduces agricultural output potential. Selected beneficial soil bacteria can promote plant growth and augment tolerance to biotic and abiotic stresses. Bacillus subtilis strain GB03 has been shown to confer growth promotion and abiotic stress tolerance in the model plant Arabidopsis thaliana. Here we examined the effect of this beneficial soil bacterium on salt tolerance in the legume forage crop, white clover. Plants of white clover (Trifolium repens L. cultivar Huia) were grown from seeds with or without soil inoculation of the beneficial soil bacterium Bacillus subtilis GB03 supplemented with 0, 50, 100, or 150 mM NaCl water into soil. Growth parameters, chlorophyll content, malondialdehyde (MDA) content and osmotic potential were monitored during the growth cycle. Endogenous Na(+) and K(+) contents were determined at the time of harvest. White clover plants grown in GB03-inoculated soil were significantly larger than non-inoculated controls with respect to shoot height, root length, plant biomass, leaf area and chlorophyll content; leaf MDA content under saline condition and leaf osmotic potential under severe salinity condition (150 mM NaCl) were significantly decreased. Furthermore, GB03 significantly decreased shoot and root Na(+) accumulation and thereby improved K(+)/Na(+) ratio when GB03-inoculated plants were grown under elevated salt conditions. The results indicate that soil inoculation with GB03 promotes white clover growth under both non-saline and saline conditions by directly or indirectly regulating plant chlorophyll content, leaf osmotic potential, cell membrane integrity and ion accumulation.
authors.affiliation: State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University Lanzhou, China.
authors.forename: Qing-Qing
authors.initials: QQ
authors.lastname: Han
authors.affiliation: State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University Lanzhou, China.
authors.forename: Xin-Pei
authors.initials: XP
authors.lastname: Lü
authors.affiliation: Gansu Key Laboratory of Crop Genetic and Germplasm Enhancement, Gansu Provincial Key Laboratory of Arid Land Crop Science, College of Agronomy, Gansu Agricultural University Lanzhou, China.
authors.forename: Jiang-Ping
authors.initials: JP
authors.lastname: Bai
authors.affiliation: Gansu Key Laboratory of Crop Genetic and Germplasm Enhancement, Gansu Provincial Key Laboratory of Arid Land Crop Science, College of Agronomy, Gansu Agricultural University Lanzhou, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Qiao
authors.affiliation: Department of Chemistry and Biochemistry, Texas Tech University Lubbock, TX, USA.
authors.forename: Paul W
authors.initials: PW
authors.lastname: Paré
authors.affiliation: State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University Lanzhou, China.
authors.forename: Suo-Min
authors.initials: SM
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University Lanzhou, China.
authors.forename: Jin-Lin
authors.initials: JL
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University Lanzhou, China.
authors.forename: Yong-Na
authors.initials: YN
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University Lanzhou, China.
authors.forename: Xiao-Pan
authors.initials: XP
authors.lastname: Pang
authors.affiliation: State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University Lanzhou, China.
authors.forename: Wen-Bo
authors.initials: WB
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University Lanzhou, China.
authors.forename: Zhi-Liang
authors.initials: ZL
authors.lastname: Wang
keywords: Bacillus subtilis; MDA; Na+ accumulation; osmotic potential; salt tolerance; white clover