Detection of biosynthetic gene and phytohormone production by endophytic actinobacteria associated with Solanum lycopersicum and their plant-growth-promoting effect

Res Microbiol. 2016 Oct;167(8):692-705. doi: 10.1016/j.resmic.2016.07.001. Epub 2016 Jul 12.

Abstract

In the present study, fifteen endophytic actinobacterial isolates recovered from Solanum lycopersicum were studied for their antagonistic potential and plant-growth-promoting (PGP) traits. Among them, eight isolates showed significant antagonistic and PGP traits, identified by amplification of the 16S rRNA gene. Isolate number DBT204, identified as Streptomyces sp., showed multiple PGP traits tested in planta and improved a range of growth parameters in seedlings of chili (Capsicum annuum L.) and tomato (S. lycopersicum L.). Further, genes of indole acetic acid (iaaM) and 1-aminocyclopropane-1-carboxylate (ACC) deaminase (acdS) were successively amplified from five strains. Six antibiotics (trimethoprim, fluconazole, chloramphenicol, nalidixic acid, rifampicin and streptomycin) and two phytohormones [indole acetic acid (IAA) and kinetin (KI)] were detected and quantified in Streptomyces sp. strain DBT204 using UPLC-ESI-MS/MS. The study indicates the potential of these PGP strains for production of phytohormones and shows the presence of biosynthetic genes responsible for production of secondary metabolites. It is the first report showing production of phytohormones (IAA and KI) by endophytic actinobacteria having PGP and biosynthetic potential. We propose Streptomyces sp. strain DBT204 for inoculums production and development of biofertilizers for enhancing growth of chili and tomato seedlings.

Keywords: 1-Aminocyclopropane-1-carboxylate (ACC) deaminase; Antagonistic traits, PGP; Endophytic actinobacteria; Solanum lycopersicum; UPLC-ESI-MS/MS; iaaM.

MeSH terms

  • Actinobacteria / classification
  • Actinobacteria / genetics
  • Actinobacteria / metabolism*
  • Anti-Bacterial Agents / metabolism
  • Capsicum / growth & development
  • Capsicum / microbiology
  • Cluster Analysis
  • DNA, Bacterial / chemistry
  • DNA, Bacterial / genetics
  • DNA, Ribosomal / chemistry
  • DNA, Ribosomal / genetics
  • Endophytes / classification
  • Endophytes / genetics
  • Endophytes / metabolism*
  • Metabolic Networks and Pathways / genetics*
  • Phylogeny
  • Plant Growth Regulators / metabolism*
  • RNA, Ribosomal, 16S / genetics
  • Sequence Analysis, DNA
  • Solanum lycopersicum / growth & development*
  • Solanum lycopersicum / microbiology*

Substances

  • Anti-Bacterial Agents
  • DNA, Bacterial
  • DNA, Ribosomal
  • Plant Growth Regulators
  • RNA, Ribosomal, 16S