title: Endophytic bacteria improve seedling growth of sunflower under water stress, produce salicylic acid, and inhibit growth of pathogenic fungi.
abstract: Endophytic bacterial strains SF2 (99.9% homology with Achromobacter xylosoxidans), and SF3 and SF4 (99.9% homology with Bacillus pumilus) isolated from sunflower grown under irrigation or drought were selected on the basis of plant growth-promoting bacteria (PGPB) characteristics. Aims of the study were to examine effects of inoculation with SF2, SF3, and SF4 on sunflower cultivated under water stress, to evaluate salicylic acid (SA) production by these strains in control medium or at Ψa = -2.03 MPa, and to analyze effects of exogenously applied SA, jasmonic acid (JA), bacterial pellets, and bacterial supernatants on growth of pathogenic fungi Alternaria sp., Sclerotinia sp., and Verticillum sp. Growth response to bacterial inoculation was studied in two inbred lines (water stress-sensitive B59 and water stress-tolerant B71) and commercial hybrid Paraiso 24. Under both water stress and normal conditions, plant growth following inoculation was more strongly enhanced for Paraiso 24 and B71 than for B59. All three strains produced SA in control medium; levels for SF3 and SF4 were higher than for SF2. SA production was dramatically higher at Ψa = -2.03 MPa. Exogenously applied SA or JA caused a significant reduction of growth for Sclerotinia and a lesser reduction for Alternaria and Verticillum. Fungal growth was more strongly inhibited by bacterial pellets than by bacterial supernatants. Our findings indicate that these endophytic bacteria enhance growth of sunflower seedlings under water stress, produce SA, and inhibit growth of pathogenic fungi. These characteristics are useful for formulation of inoculants to improve growth and yield of sunflower crops.
authors.affiliation: Departamento de Ciencias Naturales, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, 5800, Río Cuarto, Argentina.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Forchetti
authors.forename: Oscar
authors.initials: O
authors.lastname: Masciarelli
authors.forename: María J
authors.initials: MJ
authors.lastname: Izaguirre
authors.forename: Sergio
authors.initials: S
authors.lastname: Alemano
authors.forename: Daniel
authors.initials: D
authors.lastname: Alvarez
authors.forename: Guillermina
authors.initials: G
authors.lastname: Abdala
mesh_terms: D042441:Achromobacter denitrificans / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D000898:Antibiosis; D001407:Bacillus / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D003681:Dehydration; D005658:Fungi / Q000254:growth & development*; D006368:Helianthus / Q000254:growth & development / Q000382:microbiology*; D010935:Plant Diseases / Q000382:microbiology / Q000517:prevention & control; D020156:Salicylic Acid / Q000378:metabolism*; D036226:Seedlings / Q000254:growth & development / Q000382:microbiology; D013559:Symbiosis
chemical_list: D020156:Salicylic Acid
references.citation: J Antibiot (Tokyo). 1995 Oct;48(10):1095-103
references.pmid: 7490214
references.citation: FEMS Microbiol Lett. 2003 Jun 6;223(1):47-51
references.pmid: 12798999
references.citation: Appl Environ Microbiol. 1996 Mar;62(3):865-71
references.pmid: 16535275
references.citation: Plant Physiol. 1993 Jun;102(2):503-511
references.pmid: 12231839
references.citation: Phytopathology. 1997 Jun;87(6):588-93
references.pmid: 18945074
references.citation: Biotechnol Lett. 2004 Mar;26(6):487-91
references.pmid: 15127789
references.citation: Antonie Van Leeuwenhoek. 2002 Aug;81(1-4):373-83
references.pmid: 12448736
references.citation: J Microbiol. 2005 Dec;43(6):510-5
references.pmid: 16410767
references.citation: Colloids Surf B Biointerfaces. 2007 Oct 15;60(1):7-11
references.pmid: 17681765
references.citation: Appl Microbiol Biotechnol. 2007 Oct;76(5):1145-52
references.pmid: 17657487
references.citation: Biochemistry. 1970 Sep 29;9(20):3984-7
references.pmid: 5501654
references.citation: J Appl Microbiol. 2003;94(2):159-66
references.pmid: 12534806
references.citation: J Appl Microbiol. 2004;97(6):1247-56
references.pmid: 15546416
references.citation: Phytopathology. 1998 Jul;88(7):678-84
references.pmid: 18944940
references.citation: Chemosphere. 2008 Dec;74(1):45-50
references.pmid: 18952255
references.citation: J Bacteriol. 1988 Nov;170(11):5364-7
references.pmid: 3141387
references.citation: Plant Biol (Stuttg). 2004 Sep;6(5):643-50
references.pmid: 15375736