Strigolactone deficiency confers resistance in tomato line SL-ORT1 to the parasitic weeds Phelipanche and Orobanche spp

Phytopathology. 2011 Feb;101(2):213-22. doi: 10.1094/PHYTO-07-10-0184.

Abstract

The parasitic flowering plants of the genera Orobanche and Phelipanche (broomrape species) are obligatory chlorophyll-lacking root-parasitic weeds that infect dicotyledonous plants and cause heavy economic losses in a wide variety of plant species in warm-temperate and subtropical regions. One of the most effective strategies for broomrape control is crop breeding for broomrape resistance. Previous efforts to find natural broomrape-resistant tomato (Solanum lycopersicon) genotypes were unsuccessful, and no broomrape resistance was found in any wild tomato species. Recently, however, the fast-neutron-mutagenized tomato mutant SL-ORT1 was found to be highly resistant to various Phelipanche and Orobanche spp. Nevertheless, SL-ORT1 plants were parasitized by Phelipanche aegyptiaca if grown in pots together with the susceptible tomato cv. M-82. In the present study, no toxic activity or inhibition of Phelipanche seed germination could be detected in the SL-ORT1 root extracts. SL-ORT1 roots did not induce Phelipanche seed germination in pots but they were parasitized, at the same level as M-82, after application of the synthetic germination stimulant GR24 to the rhizosphere. Whereas liquid chromatography coupled to tandem mass spectrometry analysis of root exudates of M-82 revealed the presence of the strigolactones orobanchol, solanacol, and didehydro-orobanchol isomer, these compounds were not found in the exudates of SL-ORT1. It can be concluded that SL-ORT1 resistance results from its inability to produce and secrete natural germination stimulants to the rhizosphere.

MeSH terms

  • Chromatography, Liquid / methods
  • Germination / drug effects*
  • Germination / physiology
  • Immunity, Innate / genetics*
  • Lactones / metabolism*
  • Orobanche / drug effects
  • Orobanche / growth & development*
  • Orobanche / physiology
  • Plant Diseases / parasitology
  • Plant Exudates / pharmacology*
  • Plant Roots / chemistry
  • Plant Roots / parasitology*
  • Plant Weeds / drug effects
  • Plant Weeds / growth & development*
  • Plant Weeds / physiology
  • Plants / drug effects
  • Rhizosphere
  • Seeds / drug effects
  • Solanum lycopersicum / chemistry
  • Solanum lycopersicum / genetics*
  • Solanum lycopersicum / parasitology*
  • Species Specificity
  • Tandem Mass Spectrometry / methods

Substances

  • Lactones
  • Plant Exudates
  • orobanchol
  • strigol