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A Fluorescent Alternative to the Synthetic Strigolactone GR24

Plant Production, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, Ghent 9000, Belgium.
Molecular Plant (Impact Factor: 6.61). 09/2012; 6(1). 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.

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    • "Induction and measurement of adventitious roots in intact Arabidopsis plants were performed as previously described (Rasmussen et al., 2012, 2013), with minor modifications. Arabidopsis seeds (wild-type Columbia (Col-0) and mutant homozygous seed lines: max2-1, max4-1 were gas sterilized for 4 h and sown on square agar plates containing "
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    ABSTRACT: Strigolactones (SLs) are not only known as plant hormones but also as rhizosphere signals for establishing symbiotic and parasitic interactions. The design of new specific SL analogues is a challenging goal in understanding the basic plant biology and is also useful to control plant architectures without favoring the development of parasitic plants. Two different molecules (23 (3(')-methyl-GR24), 31 (thia-3(')-methyl-debranone-like molecule)) already described and a new one (AR36), for which the synthesis is presented, are biologically compared with the well-known GR24 and the recently identified CISA-1. These different structures emphasize the wide range of parts attached to the D ring for the bioactivity as a plant hormone. These new compounds possess a common dimethylbutenolide motif but their structure varies in the ABC part of the molecules: 23 has the same ABC part as GR24 while 31 and AR36 carry respectively an aromatic ring and an acyclic carbon chain. Detailed information is given for the bioactivity of such derivatives in strigolactone synthesis or in perception mutant plants (pea rms1 and rms4, Arabidopsis max1, max2, max4) for different hormonal functions along with their action in the rhizosphere on arbuscular mycorrhizal hyphal growth and parasitic weed germination.
    Molecular Plant 11/2013; DOI:10.1093/mp/sst163
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    • "n all genotypes , includ - ing in the max2 mutants compared with NAA treatment alone . These data might at first sight appear to be contradic - tory , but such observations may result from the operation of negative feedback loops . For example , GR24 can reduce MAX4 gene expression and possibly also endogenous SL levels ( Mashiguchi et al . 2009 ; Rasmussen et al . 2013 ) . GR24 has been reported to reduce the effects of auxins on root hair growth ( Koltai et al . 2010 ) and on the adventitious roots in tomato ( Kohlen et al . 2012 ) and Arabidopsis ( Rasmussen et al . 2012 ) . Further work on the spatio - temporal expression patterns of SL , auxin and LR markers in different genetic backgrounds is nee"
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    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.
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    ABSTRACT: Strigolactones (SLs) are a group of plant-exuded terpenoid lactones, initially known as the triggering signals for seed germination of parasitic weeds, and more recently for hyphal branching of arbuscular mycorrhizal fungi. In 2008 they were defined as a new class of plant hormones controlling plant architecture. Since then, great advances have been made on the biochemistry of SL biosynthesis and signal transduction, with several key genetic determinants now characterized. However, the complete pathway of de novo SL biosynthesis and transduction has not been firmly established yet. Recent findings have determined that besides shoot and root branching, SL-related components play essential roles in diverse processes including seed germination (for nonparasitic plants), hypocotyl elongation, reproductive development, leaf senescence, and nodulation. In this update, we present an overview of the current knowledge on the SL biosynthetic pathway and perception/transduction mechanism. Then we highlight recent studies, which have delineated the functions of SLs in the interaction of plants with beneficial and parasitic (micro)organisms, and in the adaptive responses to a number of environmental stimuli.
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