title: Induced maize salt tolerance by rhizosphere inoculation of Bacillus amyloliquefaciens SQR9.
abstract: Salt stress reduces plant growth and is now becoming one of the most important factors restricting agricultural productivity. Inoculation of plant growth-promoting rhizobacteria (PGPR) has been shown to confer plant tolerance against abiotic stress, but the detailed mechanisms of how this occurs remain unclear. In this study, hydroponic experiments indicated that the PGPR strain Bacillus amyloliquefaciens SQR9 could help maize plants tolerate salt stress. After exposure to salt stress for 20 days, SQR9 significantly promoted the growth of maize seedlings and enhanced the chlorophyll content compared with the control. Additional analysis showed that the involved mechanisms could be the enhanced total soluble sugar content for decreasing cell destruction, improved peroxidase/catalase activity and glutathione content for scavenging reactive oxygen species, and reduced Na(+) levels in the plant to decrease Na(+) toxicity. These physiological appearances were further confirmed by the upregulation of RBCS, RBCL, H(+) -PPase, HKT1, NHX1, NHX2 and NHX3, as well as downregulation of NCED expression, as determined by quantitative reverse transcription-polymerase chain reaction. However, SQR9 counteracted the increase of abscisic acid in response to salt stress. In summary, these results show that SQR9 confers plant salt tolerance by protecting the plant cells and managing Na(+) homeostasis. Hence, it can be used in salt stress prone areas, thereby promoting agricultural production.
authors.affiliation: Jiangsu Key Lab and Engineering Center for Solid Organic Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Nanjing Agricultural University, Nanjing 210095, P.R. China.
authors.forename: Lin
authors.initials: L
authors.lastname: Chen
authors.affiliation: Key Laboratory of Microbial Resources Collection and Preservation, Ministry of Agriculture, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, P.R. China.
authors.forename: Yunpeng
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Jiangsu Key Lab and Engineering Center for Solid Organic Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Nanjing Agricultural University, Nanjing 210095, P.R. China.
authors.forename: Gengwei
authors.initials: G
authors.lastname: Wu
authors.affiliation: Jiangsu Key Lab and Engineering Center for Solid Organic Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Nanjing Agricultural University, Nanjing 210095, P.R. China.
authors.forename: Kimani
authors.initials: K
authors.lastname: Veronican Njeri
authors.affiliation: Jiangsu Key Lab and Engineering Center for Solid Organic Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Nanjing Agricultural University, Nanjing 210095, P.R. China.
authors.forename: Qirong
authors.initials: Q
authors.lastname: Shen
authors.affiliation: Jiangsu Key Lab and Engineering Center for Solid Organic Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Nanjing Agricultural University, Nanjing 210095, P.R. China.
authors.forename: Nan
authors.initials: N
authors.lastname: Zhang
authors.affiliation: Jiangsu Key Lab and Engineering Center for Solid Organic Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Nanjing Agricultural University, Nanjing 210095, P.R. China.|Key Laboratory of Microbial Resources Collection and Preservation, Ministry of Agriculture, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, P.R. China.
authors.forename: Ruifu
authors.initials: R
authors.lastname: Zhang
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D000069977:Bacillus amyloliquefaciens / Q000502:physiology*; D006706:Homeostasis; D010937:Plant Growth Regulators / Q000378:metabolism; D018515:Plant Leaves / Q000187:drug effects / Q000382:microbiology / Q000502:physiology; D018517:Plant Roots / Q000187:drug effects / Q000382:microbiology / Q000502:physiology; D058441:Rhizosphere; D055049:Salt Tolerance; D036226:Seedlings / Q000187:drug effects / Q000382:microbiology / Q000502:physiology; D012964:Sodium / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology*; D013312:Stress, Physiological; D003313:Zea mays / Q000187:drug effects / Q000382:microbiology* / Q000502:physiology
chemical_list: D010937:Plant Growth Regulators; D012965:Sodium Chloride; D000040:Abscisic Acid; D012964:Sodium