Article

A fluorescent alternative to the strigolactone GR24.

Plant Production, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, Ghent 9000, Belgium.
Molecular Plant (Impact Factor: 6.13). 09/2012; DOI:10.1093/mp/sss110
Source: PubMed

ABSTRACT Strigolactones have recently been implicated in both above and below ground developmental pathways in higher plants. To facilitate the molecular and chemical properties of strigolactones in vitro and in vivo, we have developed a fluorescent strigolactone molecule, CISA-1, synthesised via a novel method which was robust, high-yielding and used simple starting materials. We demonstrate that CISA-1 has a broad range of known strigolactone activities and further report on an adventitious rooting assay in Arabidopsis which is a highly sensitive and rapid method for testing biological activity of strigolactone analogues. In this rooting assay and the widely used Orobanche germination assay CISA-1 showed stronger biological activity than the commonly tested GR24. CISA-1 and GR24 were equally effective at inhibiting branching in Arabidopsis inflorescence stems. In both the branching and adventitious rooting assay we also demonstrated that CISA-1 activity is dependent on the max strigolactone signalling pathway. In water methanol solutions, CISA-1 was about 3 fold more stable than GR24, which may contribute to the increased activity observed in the various biological tests.

0 0
 · 
0 Bookmarks
 · 
110 Views
  • Source
    [show abstract] [hide abstract]
    ABSTRACT: The signaling molecules strigolactone (SL) and karrikin are involved in seed germination, development of axillary meristems, senescence of leaves, and interactions with arbuscular mycorrhizal fungi. The signal transduction pathways for both SLs and karrikins require the same F-box protein (MAX2) and closely related α/β hydrolase fold proteins (DAD2 and KAI2). The crystal structure of DAD2 has been solved revealing an α/β hydrolase fold protein with an internal cavity capable of accommodating SLs. DAD2 responds to the SL analog GR24 by changing conformation and binding to MAX2 in a GR24 concentration-dependent manner. DAD2 can also catalyze hydrolysis of GR24. Structure activity relationships of analogs indicate that the butenolide ring common to both SLs and karrikins is essential for biological activity, but the remainder of the molecules can be significantly modified without loss of activity. The combination of data from the study of DAD2, KAI2, and chemical analogs of SLs and karrikins suggests a model for binding that requires nucleophilic attack by the active site serine of the hydrolase at the carbonyl atom of the butenolide ring. A conformational change occurs in the hydrolase that results in interaction with the F-box protein MAX2. Downstream signal transduction is then likely to occur via SCF (Skp-Cullin-F-box) complex-mediated ubiquitination of target proteins and their subsequent degradation. The role of the catalytic activity of the hydrolase is unclear but it may be integral in binding as well as possibly allowing the signal to be cleared from the receptor. The α/β hydrolase fold family consists mostly of active enzymes, with a few notable exceptions. We suggest that DAD2 and KAI2 represent an intermediate stage where some catalytic activity is retained at the same time as a receptor role has evolved.
    Frontiers in Plant Science 01/2012; 3:296.
  • [show abstract] [hide abstract]
    ABSTRACT: Reduced glutathione (GSH) is required for root development but its functions are not characterised. The effects of GSH depletion on root development were therefore studied in relation to auxin and strigolactone (SL) signalling using a combination of molecular genetic approaches and pharmacological techniques. Lateral root density was significantly decreased in GSH synthesis mutants (cad2-1, pad2-1, rax1-1) but not by the GSH synthesis inhibitor, buthionine sulfoximine (BSO). BSO-induced GSH depletion did therefore not influence root architecture in the same way as genetic impairment. Root glutathione contents were similar in the wild type seedlings and max3-9 and max4-1 mutants that are deficient in SL synthesis and in the SL signalling mutant, max2-1. BSO-dependent inhibition of GSH synthesis depleted the tissue GSH pool to a similar extent in the wild type and SL synthesis mutants, with no effect on LR density. The application of the SL analogue GR24 increased root glutathione in the wild type, max3-9 and max4-1 seedlings but this increase was absent from max2-1. Taken together, these data establish a link between SLs and the GSH pool that occurs in a MAX2-dependent manner.
    Plant Cell and Environment 07/2013; · 5.14 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: Strigolactones (SLs), a group of small carotenoid-derived molecules, were first known for their function in the rhizosphere in both symbiotic and parasitic interactions. Most of the progress for deciphering SL biosynthesis and signalling pathways comes from the use of high branching mutants identified in several species demonstrating that SLs also play a hormonal role in plant development. How SLs are perceived by the different organisms on which they show bioactivity is a current major challenge for the growing SL research community. These molecules very likely predate the colonization of land by plants and represent a fascinating example of signalling molecules involved in key innovations during plant evolution.
    Current opinion in plant biology 07/2013; · 10.33 Impact Factor

Full-text (2 Sources)

View
43 Downloads
Available from
Sep 27, 2013