Evaluation of Precursors and Analogs of Strigol as Witchweed (<i>Striga asiatica</i>) Seed Germination Stimulants

Pepperman, Armand B.; Connick, William J.; Vail, Sidney L.; Worsham, A. D.; Pavlišta, Alexander D.; Moreland, Donald E.

doi:10.1017/s0043174500041175

Cited by 36 publications

(22 citation statements)

References 15 publications

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“…To check whether this D-OH sensitivity was a specificity of the P. ramosa PrKAI2d3, we reexamined the germination-stimulating activity of D-OH on S. hermonthica . In contrast to previous results 37,38 , D-OH induced S. hermonthica germination (EC 50 = 1.2 μM). Moreover, in Arabidopsis lines expressing a GFP fused to ShHTL7, the known S. hermonthica SL receptor 30,39 , was induced by (±)-DOH (EC 50 = 3.1 μM) (Supplementary Figure 14, Supplementary Table 1).…”

Section: Resultscontrasting

confidence: 99%

“…The use of SL mimics, for which the part equivalent to the ABC moiety is in most cases xenobiotic, increases the risk of potential toxicity or pollution for the environment. In contrast to previous studies 37,38 , we found that D-OH is bioactive as a witchweed seed germination stimulant and that it could possibly be used for S. hermonthica biocontrol.…”

Section: Discussioncontrasting

confidence: 99%

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APhelipanche ramosaKAI2 Protein Perceives enzymatically Strigolactones and Isothiocyanates

Germain¹,

Jacobs²,

Brun³

et al. 2020

Preprint

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22Phelipanche ramosa is an obligate root-parasitic weed threatening major crops in central 23Europe. For its germination, it has to perceive various structurally diverging host-exuded 24 signals, including isothiocyanates (ITCs) and strigolactones (SLs). However, the receptors 25 involved are still uncharacterized. Here, we identified five putative SL receptors in P. ramosa, 26 of which PrKAI2d3 is involved in seed germination stimulation. We established the high 27 plasticity of PrKAI2d3, allowing interaction with different chemicals, including ITCs. The SL 28 perception mechanism of PrKAI2d3 is similar to that of endogenous SLs in non-parasitic 29 plants. We provide evidence that the PrKAI2d3 enzymatic activity confers hypersensitivity to 30SLs. Additionally, we demonstrated that methylbutenolide-OH binds PrKAI2d3 and 31 stimulates P. ramosa germination with a bioactivity comparable to that of ITCs. This study 32 highlights that P. ramosa has extended its signal perception system during evolution, a fact to 33 be considered in the development of specific and efficient biocontrol methods. 34Besides their involvement in germination, SLs have a strong stimulating activity on 54 arbuscular mycorrhizal fungi (Glomeromycotina) by promoting mitochondrial metabolism 55 and hyphal branching 7 , thereby mediating the establishment of the oldest mutualistic 56 interaction of land plants 8 . In addition to their role in rhizosphere signaling, SLs act as 57 hormones in planta with pervasive roles throughout the plant development ,9 and, as such, are 58 perceived in vascular plants by the α/β-hydrolase DWARF14 (D14) 10,11 . Biochemical 59 analyses with recombinant D14 proteins by means of the synthetic SL analog GR24 revealed 60 that the SL signal transduction requires GR24 cleavage 11,12 . One of the cleavage products, the 61 D ring, may remain covalently attached to the receptor 13,14 , thereby probably allowing the 62 recruitment of partners for downstream processes 15,16 . The required SL cleavage for signal 63 transduction is still under debate 15,16 . 64 In Arabidopsis thaliana, D14 belongs to a small gene family, including KARRIKIN 65 INSENSITIVE2/HYPOSENSITIVE TO LIGHT (AtKAI2/AtHTL) that shares the α/β-66 hydrolase catalytic triad. However, AtKAI2 regulates AtD14-independent processes, such as 67 seed germination, and preferentially perceives (−)-GR24 that mimics non-natural SLs, 68 karrikins 17 , and supposedly a still unknown endogenous ligand 18 . Interestingly, the KAI2 gene 69 family has expanded during the evolution of obligate parasitic-plant genomes 19 . For example, 70Phelipanche aegyptiaca and Striga hermonthica possess five and eleven KAI2/HTL genes, 71 respectively. Two KAI2 paralogs play a role in SL response in P. aegyptiaca 19 and six S. 72 hermonthica KAI2/HTL proteins are hypersensitive to SLs 19,20 , with ShHTL7 exhibiting the 73 same perception mechanism as D14 21 . The remarkable expansion of the KAI2 gene family in 74Orobanchaceae along with the capacity of P. ramosa to perceive ITCs let us...

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Section: Resultscontrasting

confidence: 99%

Section: Discussioncontrasting

confidence: 99%

APhelipanche ramosaKAI2 Protein Perceives enzymatically Strigolactones and Isothiocyanates

Germain¹,

Jacobs²,

Brun³

et al. 2020

Preprint

View full text Add to dashboard Cite

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“…2). Several A and A/B analogues of strigol lacking the D‐ring and the ABC enol ether 11 were also prepared and were biologically inactive in inducing germination 35–38. The D‐ring with an ethoxy group 12 is also inactive 32, 39.…”

Section: The Bioactiphore In Strigolactonesmentioning

confidence: 99%

Structure and function of natural and synthetic signalling molecules in parasitic weed germination

Zwanenburg

Mwakaboko

Reizelman

et al. 2009

Pest Management Science

220

192

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The structures of naturally occurring germination stimulants for seeds of the parasitic weeds Striga spp. and Orobanche spp. are described. The bioactiphore in this strigolactone family of stimulants is deduced from a structure-activity relationship and shown to reside in the CD part of the stimulant molecule. A molecular mechanism for the initial stages of seed germination is proposed. The influence of stereochemistry on the stimulant activity is significant. Combining this molecular information leads to a model for the design of synthetic strigolactones. Nijmegen-1 is a typical example of a highly active, newly designed synthetic stimulant. The occurrence of natural stimulants not belonging to the strigolactone family, such as cotylenin and parthenolide, is briefly described. The biosynthesis of natural strigolactones from beta-carotene is analysed in terms of isolated and predicted stimulants. This scheme will be helpful in the search for new strigolactones from root exudates. Protein fishing experiments to isolate and characterise the receptor protein using biotin-labelled GR 24 are described. A receptor protein of 60 kD was identified by this method. Nijmegen-1 has been tested as a suicidal germination agent in field trials on tobacco infested by Orobanche ramosa L. The preliminary results are highly rewarding. Finally, some future challenges in synthesis are described. These include synthesising new natural and synthetic stimulants and establishing the molecular connection between strigolactones as germination stimulants, as the branching factor for arbuscular mycorrhizal fungi and as an inhibitor of shoot branching.

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“…Characterization of the Striga seed's receptor site for germination signals might clarify structure-activity relationships between these molecules which are active as germination stimulants. There have been many efforts to develop synthetic germination stimulants based on simple analogs of strigol (34)(35)(36)(37)(38). The lactone rings, the linkage between them and the substituents on them, seem to be of crucial importance for germination stimulant activity.…”

Section: Host Control Of Striga Development By Means Of Chemical Signalsmentioning

confidence: 99%

Chemical Communication Between the Parasitic Weed Striga and Its Crop Host

Butler

1994

ACS Symposium Series

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Adaptation of Striga to parasitism includes not only dependence upon a host plant for metabolic inputs such as water, minerals, and energy, but also for developmental signals. In this way parasite and host development are highly integrated. The early host-derived chemical signals Striga requires, for seed germination and for initiation of the haustorium by which it attaches to host roots, are exuded from host roots into the soil. After Striga penetrates the host root, subsequent developmental signals are apparently exchanged directly, through vascular tissue. Germination stimulants for most Striga hosts have been identified as strigol-type compounds (strigolactones). Sorghum genotypes which produce extremely low amounts of stimulant are resistant to Striga. The gene for this trait has been mapped and incorporated into improved sorghums being released for production. Subsequent host-derived signals required by Striga are being characterized for possible independent mechanisms of resistance.Plants that have surrendered their independence and adopted a parasitic lifestyle generally obtain their water, minerals, and/or energy (in the form of photosynthate) from their host plant. But successful parasitism involves much more than dependence upon a host for metabolic inputs. In addition to these essentials, the parasite's growth, morphological development and even its manner of reproduction must be compatible with that of the host. In effect, the entire life cycle of the parasite must, to a significant extent, be integrated with that of the host. This integration is necessarily more intimate, more molecular, than the integration of plants which depend upon other organisms for pollination or seed dispersal with the lifestyles and characteristics of the organisms which provide these services.Because their requirements are so specific and complex, parasitic plants would seem to be more vulnerable than independent, non-parasitic plants. Successful plant parasitism involves a series of stringent conditions and interactions, all of which 0097-6156/95/0582-0158$08.00/0

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Evaluation of Precursors and Analogs of Strigol as Witchweed (Striga asiatica) Seed Germination Stimulants

Cited by 36 publications

References 15 publications

APhelipanche ramosaKAI2 Protein Perceives enzymatically Strigolactones and Isothiocyanates

APhelipanche ramosaKAI2 Protein Perceives enzymatically Strigolactones and Isothiocyanates

Structure and function of natural and synthetic signalling molecules in parasitic weed germination

Chemical Communication Between the Parasitic Weed Striga and Its Crop Host

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