Microcystin-LR-induced phytotoxicity in rice crown root is associated with the cross-talk between auxin and nitric oxide

Chemosphere. 2013 Sep;93(2):283-93. doi: 10.1016/j.chemosphere.2013.04.079. Epub 2013 May 29.


Irrigation with cyanobacterial-blooming water containing microcystin-LR (MC-LR) poses threat to the growth of agricultural plants. Large amounts of rice (Oryza sativa) field in the middle part of China has been irrigating with cyanobacterial-blooming water. Nevertheless, the mechanism of MC-LR-induced phytotoxicity in the root of monocot rice remains unclear. In the present study, we demonstrate that MC-LR stress significantly inhibits the growth of rice root by impacting the morphogenesis rice crown root. MC-LR treatment results in the decrease in IAA (indole-3-acetic acid) concentration as well as the expression of CRL1 and WOX11 in rice roots. The application of NAA (1-naphthylacetic acid), an IAA homologue, is able to attenuate the inhibitory effect of MC-LR on rice root development. MC-LR treatment significantly inhibits OsNia1-dependent NO generation in rice roots. The application of NO donor SNP (sodium nitroprusside) is able to partially reverse the inhibitory effects of MC-LR on the growth of rice root and the expression of CRL1 and WOX11 by enhancing endogenous NO level in rice roots. The application of NO scavenger cPTIO [2-(4-carboxy-2-phenyl)-4,4,5,5-tetramethylinidazoline-1-oxyl-3-oxide] eliminates the effects of SNP. Treatment with NAA stimulates the generation of endogenous NO in MC-LR-treated rice roots. Treatment with NO scavenger cPTIO abolishes the ameliorated effect of NAA on MC-LR-induced growth inhibition of rice root. Treatment with SNP enhanced IAA concentration in MC-LR-treated rice roots. Altogether, our data suggest that NO acts both downstream and upstream of auxin in regulating rice root morphogenesis under MC-LR stress.

Keywords: Auxin; Crown root; Microcystin-LR; Nitric oxide; Oryza sativa.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Breeding
  • Gene Expression Regulation / drug effects
  • Indoleacetic Acids / metabolism*
  • Microcystins / toxicity*
  • Naphthaleneacetic Acids / pharmacology
  • Nitric Oxide / metabolism*
  • Nitroprusside / pharmacology
  • Oryza / drug effects*
  • Oryza / genetics
  • Oryza / growth & development*
  • Oryza / metabolism
  • Plant Proteins / genetics
  • Plant Roots / drug effects*
  • Plant Roots / genetics
  • Plant Roots / growth & development*
  • Plant Roots / metabolism
  • Stress, Physiological / drug effects
  • Transcription, Genetic / drug effects


  • Indoleacetic Acids
  • Microcystins
  • Naphthaleneacetic Acids
  • Plant Proteins
  • Nitroprusside
  • Nitric Oxide
  • 1-naphthaleneacetic acid
  • cyanoginosin LR