title: Seed-vectored endophytic bacteria modulate development of rice seedlings.
abstract: OBJECTIVE
  The aim of the present study was to evaluate the effects of the removal of indigenous bacteria from rice seeds on seedling growth and development. Here we report the presence of three indigenous endophytic bacteria in rice seeds that play important roles in modulating seedling development (shoot and root lengths, and formation of root hairs and secondary roots) and defence against pathogens.
  
  
  RESULTS
  Seed-associated bacteria were removed using surface sterilization with NaOCl (bleach) followed by antibiotic treatment. When bacteria were absent, growth of seedlings in terms of root hair development and overall seedling size was less than that of seedlings that contained bacteria. Reactive oxygen staining of seedlings showed that endophytic bacteria became intracellular in root parenchyma cells and root hairs. Roots containing endophytic bacteria were seen to stain densely for reactive oxygen, while roots free of bacteria stained lightly for reactive oxygen. Bacteria were isolated and identified as Enterobacter asburiae (VWB1), Pantoea dispersa (VWB2) and Pseudomonas putida (VWB3) by 16S rDNA sequencing. Bacteria were found to produce indole acetic acid (auxins), inhibited the pathogen Fusarium oxysporum and solubilized phosphate. Reinoculation of bacteria onto seedlings derived from surface-disinfected rice and Bermuda grass seeds significantly restored seedling growth and development.
  
  
  CONCLUSIONS
  Rice seeds harbour indigenous bacterial endophytes that greatly influence seedling growth and development, including root and shoot lengths, root hair formation and disease susceptibility of rice seedlings.
  
  
  CONCLUSIONS
  This study shows that seeds of rice naturally harbour bacterial endophytes that play key roles in modulation of seedling development.
authors.affiliation: Department of Plant Biology, Rutgers University, New Brunswick, NJ, USA.|Centre of Advanced Study in Botany, Banaras Hindu University, Varanasi, UP, India.
authors.forename: S K
authors.initials: SK
authors.lastname: Verma
authors.affiliation: Department of Plant Biology, Rutgers University, New Brunswick, NJ, USA.
authors.forename: K
authors.initials: K
authors.lastname: Kingsley
authors.affiliation: Department of Plant Biology, Rutgers University, New Brunswick, NJ, USA.
authors.forename: I
authors.initials: I
authors.lastname: Irizarry
authors.affiliation: Department of Plant Biology, Rutgers University, New Brunswick, NJ, USA.
authors.forename: M
authors.initials: M
authors.lastname: Bergen
authors.affiliation: Centre of Advanced Study in Botany, Banaras Hindu University, Varanasi, UP, India.
authors.forename: R N
authors.initials: RN
authors.lastname: Kharwar
authors.affiliation: Department of Plant Biology, Rutgers University, New Brunswick, NJ, USA.
authors.forename: J F
authors.initials: JF
authors.lastname: White
mesh_terms: D001419:Bacteria / Q000235:genetics / Q000302:isolation & purification; D018407:Bacterial Physiological Phenomena; D060026:Endophytes / Q000502:physiology*; D004754:Enterobacter / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology; D007210:Indoleacetic Acids / Q000378:metabolism; D012275:Oryza / Q000254:growth & development / Q000382:microbiology*; D020636:Pantoea / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology; D018517:Plant Roots / Q000254:growth & development / Q000382:microbiology; D016958:Pseudomonas putida / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology; D036226:Seedlings / Q000254:growth & development / Q000382:microbiology; D012639:Seeds / Q000254:growth & development / Q000382:microbiology
chemical_list: D007210:Indoleacetic Acids; C030737:indoleacetic acid
keywords: ROS; antifungal; auxins; development; root hairs; seed-borne endophytes; seedlings