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: 6.34). 09/2012; 6(1). DOI: 10.1093/mp/sss110
Source: PubMed


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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Available from: Amanda Rasmussen, Oct 14, 2015
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    • "As does endogenous SL, GR24 interacts with and is cleaved by the α/β-hydrolase fold protein DAD2/D14 (Hamiaux et al., 2012; Kagiyama et al., 2013; Zhao et al., 2013). Cyano-isoindole-strigolactone-analog-1 (CISA-1) is structurally related to nijmegen-1 (Figure 4A; Nefkens et al., 1997) and has also been shown to act through a MAX2-mediated signaling pathway (Rasmussen et al., 2013). Remarkably, CISA-1 is more active and stable than GR24, and possesses interesting fluorescent properties (Rasmussen et al., 2013, see also the “Labeled molecules: compelling tools to understand the action of signaling molecules” section). "
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    ABSTRACT: Plants have acquired the capacity to grow continuously and adjust their morphology in response to endogenous and external signals, leading to a high architectural plasticity. The dynamic and differential distribution of phytohormones is an essential factor in these developmental changes. Phytohormone perception is a fast but complex process modulating specific developmental reprogramming. In recent years, chemical genomics or the use of small molecules to modulate target protein function has emerged as a powerful strategy to study complex biological processes in plants such as hormone signaling. Small molecules can be applied in a conditional, dose-dependent and reversible manner, with the advantage of circumventing the limitations of lethality and functional redundancy inherent to traditional mutant screens. High-throughput screening of diverse chemical libraries has led to the identification of bioactive molecules able to induce plant hormone-related phenotypes. Characterization of the cognate targets and pathways of those molecules has allowed the identification of novel regulatory components, providing new insights into the molecular mechanisms of plant hormone signaling. An extensive structure-activity relationship (SAR) analysis of the natural phytohormones, their designed synthetic analogs and newly identified bioactive molecules has led to the determination of the structural requirements essential for their bioactivity. In this review, we will summarize the so far identified small molecules and their structural variants targeting specific phytohormone signaling pathways. We will highlight how the SAR analyses have enabled better interrogation of the molecular mechanisms of phytohormone responses. Finally, we will discuss how labeled/tagged hormone analogs can be exploited, as compelling tools to better understand hormone signaling and transport mechanisms.
    Frontiers in Plant Science 07/2014; 5:373. DOI:10.3389/fpls.2014.00373 · 3.95 Impact Factor
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    • "Since only caulonema filaments grow in dark, caulonema length and caulonema cell sizes can be easily quantified in dark culture conditions. In addition, the use of the SL-deficient Ppccd8 mutant [6] make it possible to better characterize the effect of exogenous SL added to the growth medium, since this effect is enhanced in comparison with the wild type (WT) which contains endogenous SLs, and as observed in other SAR studies on vascular plants [32], [33], [36], [37]. Here, we show that SLs control filament extension by decreasing the caulonema cell division rate with a slight effect on cell elongation. "
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    ABSTRACT: In vascular plants, strigolactones (SLs) are known for their hormonal role and for their role as signal molecules in the rhizosphere. SLs are also produced by the moss Physcomitrella patens, in which they act as signaling factors for controlling filament extension and possibly interaction with neighboring individuals. To gain a better understanding of SL action at the cellular level, we investigated the effect of exogenously added molecules (SLs or analogs) in moss growth media. We used the previously characterized Ppccd8 mutant that is deficient in SL synthesis and showed that SLs affect moss protonema extension by reducing caulonema cell elongation and mainly cell division rate, both in light and dark conditions. Based on this effect, we set up bioassays to examine chemical structure requirements for SL activity in moss. The results suggest that compounds GR24, GR5, and 5-deoxystrigol are active in moss (as in pea), while other analogs that are highly active in the control of pea branching show little activity in moss. Interestingly, the karrikinolide KAR1, which shares molecular features with SLs, did not have any effect on filament growth, even though the moss genome contains several genes homologous to KAI2 (encoding the KAR1 receptor) and no canonical homologue to D14 (encoding the SL receptor). Further studies should investigate whether SL signaling pathways have been conserved during land plant evolution.
    PLoS ONE 06/2014; 9(6):e99206. DOI:10.1371/journal.pone.0099206 · 3.23 Impact Factor
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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; 7(4). DOI:10.1093/mp/sst163 · 6.34 Impact Factor
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