Bacillus aryabhattai SRB02 tolerates oxidative and nitrosative stress and promotes the growth of soybean by modulating the production of phytohormones

PLoS One. 2017 Mar 10;12(3):e0173203. doi: 10.1371/journal.pone.0173203. eCollection 2017.

Abstract

Plant growth promoting rhizobacteria (PGPR) are diverse, naturally occurring bacteria that establish a close association with plant roots and promote the growth and immunity of plants. Established mechanisms involved in PGPR-mediated plant growth promotion include regulation of phytohormones, improved nutrient availability, and antagonistic effects on plant pathogens. In this study, we isolated a bacterium from the rhizospheric soil of a soybean field in Chungcheong buk-do, South Korea. Using 16S rRNA sequencing, the bacterium was identified as Bacillus aryabhattai strain SRB02. Here we show that this strain significantly promotes the growth of soybean. Gas chromatography-mass spectrometry analysis showed that SRB02 produced significant amounts of abscisic acid, indole acetic acid, cytokinin and different gibberellic acids in culture. SRB02-treated soybean plants showed significantly better heat stress tolerance than did untreated plants. These plants also produced consistent levels of ABA under heat stress and exhibited ABA-mediated stomatal closure. High levels of IAA, JA, GA12, GA4, and GA7, were recorded in SRB02-treated plants. These plants produced longer roots and shoots than those of control plants. B. aryabhattai SRB02 was found to be highly tolerant to oxidative stress induced by H2O2 and MV potentiated by high catalase (CAT) and superoxide dismutase (SOD) activities. SRB02 also tolerated high nitrosative stress induced by the nitric oxide donors GSNO and CysNO. Because of these attributes, B. aryabhattai SRB02 may prove to be a valuable resource for incorporation in biofertilizers and other soil amendments that seek to improve crop productivity.

MeSH terms

  • Abscisic Acid / analysis
  • Abscisic Acid / metabolism
  • Bacillus / genetics
  • Bacillus / isolation & purification
  • Bacillus / metabolism*
  • Catalase / metabolism
  • Gas Chromatography-Mass Spectrometry
  • Gibberellins / analysis
  • Gibberellins / metabolism
  • Glycine max / growth & development
  • Glycine max / metabolism
  • Glycine max / microbiology*
  • Hydrogen Peroxide / toxicity
  • Indoleacetic Acids / analysis
  • Indoleacetic Acids / metabolism
  • Microscopy, Electron, Scanning
  • Nitric Oxide Donors / toxicity
  • Oxidative Stress / drug effects
  • Plant Growth Regulators / analysis
  • Plant Growth Regulators / metabolism*
  • Plant Roots / growth & development
  • Plant Roots / metabolism
  • Plant Roots / microbiology
  • RNA, Ribosomal, 16S / chemistry
  • RNA, Ribosomal, 16S / genetics
  • RNA, Ribosomal, 16S / metabolism
  • Rhizosphere
  • Sequence Analysis, DNA
  • Soil Microbiology*
  • Superoxide Dismutase / metabolism
  • Symbiosis
  • Temperature

Substances

  • Gibberellins
  • Indoleacetic Acids
  • Nitric Oxide Donors
  • Plant Growth Regulators
  • RNA, Ribosomal, 16S
  • indoleacetic acid
  • Abscisic Acid
  • Hydrogen Peroxide
  • gibberellic acid
  • Catalase
  • Superoxide Dismutase

Grants and funding

This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2014R1A1A2A10058022) to In-Jung Lee and by a grant from the Next-Generation BioGreen 21 Program (SSAC, Grant No. PJ01110201), Rural Development Administration, Republic of Korea to Byung-Wook Yun.