Strigolactones Are Transported through the Xylem and Play a Key Role in Shoot Architectural Response to Phosphate Deficiency in Nonarbuscular Mycorrhizal Host Arabidopsis

We demonstrate that this induction is conserved in Arabidopsis, Arabidopsis is not a host for arbuscular mycorrhizal fungi

Wouter Kohlen; Tatsiana Charnikhova; Qing Liu; Ralph Bours; Malgorzata A. Domagalska; Sebastien Beguerie; Francel Verstappen; Ottoline Leyser; Harro Bouwmeester; Carolien Ruyter-Spira

2010

Scholarcy highlights

  • For many years, strigolactones have been known as rhizosphere signaling molecules
  • To assess if the induction by Arabidopsis root exudates of germination of P. ramosa seed is increased by phosphate deficiency, 4-week-old Arabidopsis plants were subjected to phosphate starvation for 2 weeks, in parallel with fully fertilized plants
  • It was shown that strigolactone production in Arabidopsis is up-regulated by phosphate deficiency and that MAX1 and MAX4 activity is required for the biosynthesis of orobanchol and the germination stimulatory compounds eluting in HPLC fractions 11 and 17
  • The increase in P. ramosa germination induced by Arabidopsis root exudates of plants grown under phosphate starvation shows that phosphate limitation increases the secretion of germination stimulatory compounds by this non-arbuscular mycorrhizal host
  • HPLC fractionation of Arabidopsis root exudates resulted in a number of bioactive fractions, which are only partially explained by our MRM-LC-MS/MS data
  • A strong reduction in orobanchol content was found in max and max under phosphate-sufficient conditions as well as under phosphate starvation
  • MRM-LC-MS/MS analysis of HPLC-fractioned strigolactone standards showed that the strigolactones 7-hydroxyorobanchyl acetate and solanacol elute in fraction 17 and orobanchol elutes in fraction 20, with traces of these strigolactone standards present in the fractions, which probably explains the residual germination observed in these fractions
  • When concentrated Col-0 xylem sap was analyzed by MRM-LC-MS/MS, a significant 27% increase of orobanchol was detected under phosphate depletion compared with plants grown under phosphate-sufficient levels, indicating that orobanchol, likely fraction 20, is involved in the regulation of the shoot architectural response to phosphate starvation

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