Characterization of strigolactones exuded by Asteraceae plants

Abstract

Strigolactones (SLs), originally characterized as germination stimulants for root parasitic weeds, are now recognized as hyphal branching factors for symbiotic arbuscular mycorrhizal fungi and as a novel class of plant hormones inhibiting shoot branching. In the present study, SLs in root exudates of 13 Asteraceae plants including crops, a weed, and ornamental plants were characterized. High performance liquid chromatography/tandem mass spectrometry (LC-MS/MS) analyses revealed that all the Asteraceae plants examined exuded known SLs and, except for sunflower (Helianthus annuus), high germination stimulant activities at retention times corresponding to these SLs were confirmed. The two major SLs exuded by these Asteraceae plants were orobanchyl acetate and orobanchol. 5-Deoxystrigol and 7-hydroxyorobanchyl acetate were detected in root exudates from several Asteraceae species examined in this study.

Tomato strigolactones

“…24 The configuration of these two compounds does, however, not match the proposed stereochemistry of 7-oxoorobanchol 21 and 7-hydroxyorobanchol. 13,16 However, in these reports the stereochemistry of the latter compound was not unambiguously determined. Technical advancements, in combination with an increasing interest in the stereochemistry of strigolactones have resulted in debate on the structural reliability of authentic standards (personal communication Prof. Dr. Binne Zwanenburg) and led identified as 7β-hydroxyorobanchol.…”

“…1A). It has been reported that this enol ether bridge is not only essential for parasitic seed germination, 12,13 but is also required for the induction of AM branching 14 and their hormonal activity in planta. 15 Although the main structure of strigolactones is rather similar, their A-and B-ring decoration and stereochemistry can vary substantially (Fig.…”

Structural diversity of strigolactones and their distribution in the plant kingdom

“…29,30) 5DS was originally isolated as a branching factor for AM fungi and was then shown to be produced by several plant species. 31) However, the retention of 5DS is very similar to that of its isomer 4-deoxyorobanchol (4DO, 7) in both reversed phase and normal phase high performance liquid chromatography, and some plant species reported to produce 5DS may produce 4DO. Sorgomol (8) is an isomer of strigol and orobanchol and was isolated from sorghum root exudates.…”

Photomodulation of strigolactone biosynthesis and accumulation during sunflower seedling growth

“…These include GR5, GR7 and GR24. 9,10 Natural SLs can be divided into 2 groups on the basis of their orientation: 1. strigol-type (b-oriented), 2. orobanchol-type (a-oriented). 11 Major SLs identified in the root exudates of sunflower (Helianthus annuus) plants are orobanchyl acetate, 5-deoxystrigol and certain related secondary metabolites, such as sesquiterpene lactones.…”