Strigolactones (SL) are butenolide plant hormones with tricyclic lactone, that influence root branching leaf shape and senescence. Karrikins (KAR) are different butenolide molecules produced during wildfires in smoke and deposited on soil surface. They are absorbed by seeds and activate germination. KAI2 and D14 are paralogous alpha/beta hydrolase receptors respectively for KARs and SLs they belong to the RsbQ-like family. KAI2 (KARRIKIN-INSENSITVE-2) and D14 (DWARF14) are both receptors and enzymes. Strigol induces germination of the facultative parasitic plant Phtheirospermum japonicum in the absence of nitrate ions
3 moreTitle: Strigol induces germination of the facultative parasitic plant Phtheirospermum japonicum in the absence of nitrate ions Ogawa S, Shirasu K Ref: Plant Signal Behav, 17:2114647, 2022 : PubMed
Root parasitic plants in the family Orobanchaceae, such as Striga and Orobanche spp., infest major crops worldwide, leading to a multibillion-dollar loss annually. Host-derived strigolactones (SLs), recognized by a group of alpha/beta hydrolase receptors (KAI2d) in these parasites, are important determinants for germinating root parasitic plants near the roots of host plants. Phtheirospermum japonicum, a facultative hemiparasitic Orobanchaceae plant, can germinate and grow in the presence or absence of the host and can also exhibit root chemotropism to host-derived SLs that are perceived via KAI2d. However, the importance of SLs in P. japonicum germination remains unclear. In this study, we found that germination of P. japonicum was suppressed in the absence of nitrate ions and that germination of P. japonicum was promoted by exogenous strigol, an SL, under such conditions. We propose a model in which P. japonicum may select either independent living or parasitism in response to ambient nitrogen conditions and host presence.
INTRODUCTION: Strigolactones (SLs) are the most representative germination stimulants for seeds of root parasitic plants, and they show activity even at concentrations below 10(-10) M. The low amounts of stimulants produced by the host and their rapid degradability make it crucial to develop analytical methods with very low limits of quantification. OBJECTIVE: To develop a sensitive and validated analytical method for the simultaneous quantification of seven SLs [7-oxoorobanchyl acetate (1), solanacol (2), orobanchol (4), strigol (5), fabacyl acetate (6), orobanchyl acetate (7), and 5-deoxystrigol (8)]. METHODS: SLs were analysed using ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS), with (+/-)-GR24 (3) employed as internal standard (IS). Validation was based on selectivity, linearity, precision of the peak areas (repeatability and intermediate precision), detection and quantification limits, and stability. RESULTS: A simple, rapid and reliable UHPLC-MS/MS method has been validated for the routine analysis of seven SLs and has been successfully applied to quantify them in exudates and extracts from tomato roots (Solanum lycopersicum). The limits of quantifications range from 0.05 microg/L for 5-deoxystrigol to 0.96 microg/L for solanacol. CONCLUSION: The method provides a useful tool for research in all the fields related to SLs, both for studies related to their function as hormones, and signalling molecules in the rhizosphere, without sample preparation required for extracts and root exudates in less than 11 minutes.
A range of analogues of the natural germination stimulant, strigol, for parasitic weeds of the genera Striga and Orobanche, has been prepared. Most of the products contain an a-formyl-7-lactone (or a-formyl-7-lactam) grouping attached through an enol-ether linkage to the 5-position of a but-2-enolide. Some have shown sufficiently high activities as to warrant large-scale field trials
3 lessTitle: Strigol induces germination of the facultative parasitic plant Phtheirospermum japonicum in the absence of nitrate ions Ogawa S, Shirasu K Ref: Plant Signal Behav, 17:2114647, 2022 : PubMed
Root parasitic plants in the family Orobanchaceae, such as Striga and Orobanche spp., infest major crops worldwide, leading to a multibillion-dollar loss annually. Host-derived strigolactones (SLs), recognized by a group of alpha/beta hydrolase receptors (KAI2d) in these parasites, are important determinants for germinating root parasitic plants near the roots of host plants. Phtheirospermum japonicum, a facultative hemiparasitic Orobanchaceae plant, can germinate and grow in the presence or absence of the host and can also exhibit root chemotropism to host-derived SLs that are perceived via KAI2d. However, the importance of SLs in P. japonicum germination remains unclear. In this study, we found that germination of P. japonicum was suppressed in the absence of nitrate ions and that germination of P. japonicum was promoted by exogenous strigol, an SL, under such conditions. We propose a model in which P. japonicum may select either independent living or parasitism in response to ambient nitrogen conditions and host presence.
Parasitic plants are worldwide threats that damage major agricultural crops. To initiate infection, parasitic plants have developed the ability to locate hosts and grow towards them. This ability, called host tropism, is critical for parasite survival, but its underlying mechanism remains mostly unresolved. To characterise host tropism, we used the model facultative root parasite Phtheirospermum japonicum, a member of the Orobanchaceae. Here, we show that strigolactones (SLs) function as host-derived chemoattractants. Chemotropism to SLs is also found in Striga hermonthica, a parasitic member of the Orobanchaceae, but not in non-parasites. Intriguingly, chemotropism to SLs in P. japonicum is attenuated in ammonium ion-rich conditions, where SLs are perceived, but the resulting asymmetrical accumulation of the auxin transporter PIN2 is diminished. P. japonicum encodes putative receptors that sense exogenous SLs, whereas expression of a dominant-negative form reduces its chemotropic ability. We propose a function for SLs as navigators for parasite roots.
INTRODUCTION: Strigolactones (SLs) are the most representative germination stimulants for seeds of root parasitic plants, and they show activity even at concentrations below 10(-10) M. The low amounts of stimulants produced by the host and their rapid degradability make it crucial to develop analytical methods with very low limits of quantification. OBJECTIVE: To develop a sensitive and validated analytical method for the simultaneous quantification of seven SLs [7-oxoorobanchyl acetate (1), solanacol (2), orobanchol (4), strigol (5), fabacyl acetate (6), orobanchyl acetate (7), and 5-deoxystrigol (8)]. METHODS: SLs were analysed using ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS), with (+/-)-GR24 (3) employed as internal standard (IS). Validation was based on selectivity, linearity, precision of the peak areas (repeatability and intermediate precision), detection and quantification limits, and stability. RESULTS: A simple, rapid and reliable UHPLC-MS/MS method has been validated for the routine analysis of seven SLs and has been successfully applied to quantify them in exudates and extracts from tomato roots (Solanum lycopersicum). The limits of quantifications range from 0.05 microg/L for 5-deoxystrigol to 0.96 microg/L for solanacol. CONCLUSION: The method provides a useful tool for research in all the fields related to SLs, both for studies related to their function as hormones, and signalling molecules in the rhizosphere, without sample preparation required for extracts and root exudates in less than 11 minutes.
A range of analogues of the natural germination stimulant, strigol, for parasitic weeds of the genera Striga and Orobanche, has been prepared. Most of the products contain an a-formyl-7-lactone (or a-formyl-7-lactam) grouping attached through an enol-ether linkage to the 5-position of a but-2-enolide. Some have shown sufficiently high activities as to warrant large-scale field trials
Title: Germination stimulants .2. Structure of strigol - potent seed-germination stimulant for witchweed (Striga-Lutea lour) Cook CE, Coggon P, Mcphail AT, Wall ME, Whichard LP, Egley GH, Luhan PA Ref: Journal of the American Chemical Society, 94:6198, 1972 : PubMed
We wish to report the structure of strigol (la), a novel, highly potent seed germination stimulant isolated from the root exudates of cotton (Gossypium hirsutum L.).2 In the absence of exogenous stimulant the seeds of the parasite witchweed (Striga lutea Lour.)do not germinate, but application of 10-11 M solutions of strigol results in over 50% germination.
Title: Germination of Witchweed (Striga lutea Lour.): Isolation and Properties of a Potent Stimulant Cook CE, Whichard LP, Turner B, Wall ME, Egley GH Ref: Science, 154:1189, 1966 : PubMed
A crystalline germination stimulant (trivial name strigol) for the rootparasite, witchweed (Striga lutea Lour.), has been isolated from cotton rootexudates and characterized as a C(19)H(22)O(6) compound. Although apparently different from known plant hormones, the stimulant is active at hormonal levels, causing germination at concentrations less than 1O(-5) part per million.
