Bouwmeester HJ

References (17)

Title : Maize resistance to witchweed through changes in strigolactone biosynthesis - Li_2023_Science_379_94
Author(s) : Li C , Dong L , Durairaj J , Guan JC , Yoshimura M , Quinodoz P , Horber R , Gaus K , Li J , Setotaw YB , Qi J , De Groote H , Wang Y , Thiombiano B , Flokova K , Walmsley A , Charnikhova TV , Chojnacka A , Correia de Lemos S , Ding Y , Skibbe D , Hermann K , Screpanti C , De Mesmaeker A , Schmelz EA , Menkir A , Medema M , van Dijk ADJ , Wu J , Koch KE , Bouwmeester HJ
Ref : Science , 379 :94 , 2023
Abstract : Maize (Zea mays) is a major staple crop in Africa, where its yield and the livelihood of millions are compromised by the parasitic witchweed Striga. Germination of Striga is induced by strigolactones exuded from maize roots into the rhizosphere. In a maize germplasm collection, we identified two strigolactones, zealactol and zealactonoic acid, which stimulate less Striga germination than the major maize strigolactone, zealactone. We then showed that a single cytochrome P450, ZmCYP706C37, catalyzes a series of oxidative steps in the maize-strigolactone biosynthetic pathway. Reduction in activity of this enzyme and two others involved in the pathway, ZmMAX1b and ZmCLAMT1, can change strigolactone composition and reduce Striga germination and infection. These results offer prospects for breeding Striga-resistant maize.
ESTHER : Li_2023_Science_379_94
PubMedSearch : Li_2023_Science_379_94
PubMedID: 36603079

Title : The tomato cytochrome P450 CYP712G1 catalyses the double oxidation of orobanchol en route to the rhizosphere signalling strigolactone, solanacol - Wang_2022_New.Phytol__
Author(s) : Wang Y , Durairaj J , Suarez Duran HG , van Velzen R , Flokova K , Liao CY , Chojnacka A , MacFarlane S , Schranz ME , Medema MH , van Dijk ADJ , Dong L , Bouwmeester HJ
Ref : New Phytol , : , 2022
Abstract : Strigolactones (SLs) are rhizosphere signalling molecules and phytohormones. The biosynthetic pathway of SLs in tomato has been partially elucidated, but the structural diversity in tomato SLs predicts that additional biosynthetic steps are required. Here, root RNA-seq data and co-expression analysis were used for SL biosynthetic gene discovery. This strategy resulted in a candidate gene list containing several cytochrome P450s. Heterologous expression in Nicotiana benthamiana and yeast showed that one of these, CYP712G1, can catalyse the double oxidation of orobanchol, resulting in the formation of three didehydro-orobanchol (DDH) isomers. Virus-induced gene silencing and heterologous expression in yeast showed that one of these DDH isomers is converted to solanacol, one of the most abundant SLs in tomato root exudate. Protein modelling and substrate docking analysis suggest that hydroxy-orbanchol is the likely intermediate in the conversion from orobanchol to the DDH isomers. Phylogenetic analysis demonstrated the occurrence of CYP712G1 homologues in the Eudicots only, which fits with the reports on DDH isomers in that clade. Protein modelling and orobanchol docking of the putative tobacco CYP712G1 homologue suggest that it can convert orobanchol to similar DDH isomers as tomato.
ESTHER : Wang_2022_New.Phytol__
PubMedSearch : Wang_2022_New.Phytol__
PubMedID: 35612785

Title : Maize domestication phenotypes reveal strigolactone networks coordinating grain size evolution with kernel-bearing cupule architecture - Guan_2022_Plant.Cell__
Author(s) : Guan JC , Li C , Flint-Garcia S , Suzuki M , Wu S , Saunders JW , Dong L , Bouwmeester HJ , McCarty DR , Koch KE
Ref : Plant Cell , : , 2022
Abstract : The maize (Zea mays) ear represents one of the most striking domestication phenotypes in any crop species, with the cob conferring an exceptional yield advantage over the ancestral form of teosinte. Remodeling of the grain-bearing surface required profound developmental changes. However, the underlying mechanisms remain unclear and can only be partly attributed to the known domestication gene Teosinte glume architecture 1 (Tga1). Here we show that a more complete conversion involves strigolactones (SLs), and that these are prominent players not only in the Tga1 phenotype, but also other domestication features of the ear and kernel. Genetic combinations of a teosinte tga1 allele with three SL-related mutants progressively enhanced ancestral morphologies. The SL mutants, in addition to modulating the tga1 phenotype, also reshaped kernel-bearing pedicels and cupules in a teosinte-like manner. Genetic and molecular evidence are consistent with SL regulation of TGA1, including direct interaction of TGA1 with components of the SL-signaling system shown here to mediate TGA1 availability by sequestration. Roles of the SL network extend to enhancing maize seed size and, importantly, coordinating increased kernel growth with remodeling of protective maternal tissues. Collectively, our data show that SLs have central roles in releasing kernels from restrictive maternal encasement and coordinating other factors that increase kernel size, physical support, and their exposure on the grain-bearing surface.
ESTHER : Guan_2022_Plant.Cell__
PubMedSearch : Guan_2022_Plant.Cell__
PubMedID: 36573016

Title : Probing strigolactone perception mechanisms with rationally designed small-molecule agonists stimulating germination of root parasitic weeds - Wang_2022_Nat.Commun_13_3987
Author(s) : Wang D , Pang Z , Yu H , Thiombiano B , Walmsley A , Yu S , Zhang Y , Wei T , Liang L , Wang J , Wen X , Bouwmeester HJ , Yao R , Xi Z
Ref : Nat Commun , 13 :3987 , 2022
Abstract : The development of potent strigolactone (SL) agonists as suicidal germination inducers could be a useful strategy for controlling root parasitic weeds, but uncertainty about the SL perception mechanism impedes real progress. Here we describe small-molecule agonists that efficiently stimulate Phelipanchce aegyptiaca, and Striga hermonthica, germination in concentrations as low as 10(-8) to 10(-17) M. We show that full efficiency of synthetic SL agonists in triggering signaling through the Striga SL receptor, ShHTL7, depends on the receptor-catalyzed hydrolytic reaction of the agonists. Additionally, we reveal that the stereochemistry of synthetic SL analogs affects the hydrolytic ability of ShHTL7 by influencing the probability of the privileged conformations of ShHTL7. Importantly, an alternative ShHTL7-mediated hydrolysis mechanism, proceeding via nucleophilic attack of the NE2 atom of H246 to the 2'C of the D-ring, is reported. Together, our findings provide insight into SL hydrolysis and structure-perception mechanisms, and potent suicide germination stimulants, which would contribute to the elimination of the noxious parasitic weeds.
ESTHER : Wang_2022_Nat.Commun_13_3987
PubMedSearch : Wang_2022_Nat.Commun_13_3987
PubMedID: 35810153

Title : Effect of strigolactones on recruitment of the rice root-associated microbiome - Kim_2022_FEMS.Microbiol.Ecol__
Author(s) : Kim B , Westerhuis JA , Smilde AK , Flokova K , Suleiman AKA , Kuramae EE , Bouwmeester HJ , Zancarini A
Ref : FEMS Microbiol Ecol , : , 2022
Abstract : Strigolactones are endogenous plant hormones regulating plant development and are exuded into the rhizosphere when plants experience nutrient deficiency. There, they promote the mutualistic association of plants with arbuscular mycorrhizal fungi that help the plant with the uptake of nutrients from the soil. This shows that plants actively establish-through the exudation of strigolactones-mutualistic interactions with microbes to overcome inadequate nutrition. The signaling function of strigolactones could possibly extend to other microbial partners, but the effect of strigolactones on the global root and rhizosphere microbiome remains poorly understood. Therefore, we analyzed the bacterial and fungal microbial communities of 16 rice genotypes differing in their root strigolactone exudation. Using multivariate analyses, distinctive differences in the microbiome composition were uncovered depending on strigolactone exudation. Moreover, the results of regression modeling showed that structural differences in the exuded strigolactones affected different sets of microbes. In particular, orobanchol was linked to the relative abundance of Burkholderia-Caballeronia-Paraburkholderia and Acidobacteria that potentially solubilize phosphate, while 4-deoxyorobanchol was associated with the genera Dyella and Umbelopsis. With this research, we provide new insight into the role of strigolactones in the interplay between plants and microbes in the rhizosphere.
ESTHER : Kim_2022_FEMS.Microbiol.Ecol__
PubMedSearch : Kim_2022_FEMS.Microbiol.Ecol__
PubMedID: 35137050

Title : Strigolactones regulate sepal senescence in Arabidopsis - Xu_2021_J.Exp.Bot__
Author(s) : Xu X , Jibran R , Wang Y , Dong L , Flokova K , Esfandiari A , McLachlan ARG , Heiser A , Sutherland-Smith AJ , Brummell DA , Bouwmeester HJ , Dijkwel PP , Hunter DA
Ref : J Exp Bot , : , 2021
Abstract : Flower sepals are critical for flower development and vary greatly in lifespan depending on their function post-pollination. Very little is known about what controls sepal longevity. Using a sepal senescence mutant screen, we identified two Arabidopsis mutants with delayed senescence directly connecting strigolactones (SL) with senescence regulation in a novel floral context that hitherto has not been explored. The mutations were in the SL biosynthetic gene MORE AXILLARY GROWTH1 (MAX1) and in the SL receptor DWARF14 (AtD14). The mutation in AtD14 changed the catalytic Ser97 to Phe in the enzyme active site, which is the first mutation of its kind in planta. The lesion in MAX1 was in the haem-iron ligand signature of the cytochrome P450 protein, converting the highly conserved Gly469 to Arg, which was shown in a transient expression assay to substantially inhibit activity of MAX1. The two mutations highlighted the importance of SL activity for driving to completion senescence initiated both developmentally and in response to carbon-limiting stress, as has been found for the more well-known senescence-associated regulators ethylene and abscisic acid. Analysis of transcript abundances in excised inflorescences during an extended night suggested an intricate relationship among sugar starvation, senescence and SL biosynthesis and signalling.
ESTHER : Xu_2021_J.Exp.Bot__
PubMedSearch : Xu_2021_J.Exp.Bot__
PubMedID: 33970249

Title : The negative regulator SMAX1 controls mycorrhizal symbiosis and strigolactone biosynthesis in rice - Choi_2020_Nat.Commun_11_2114
Author(s) : Choi J , Lee T , Cho J , Servante EK , Pucker B , Summers W , Bowden S , Rahimi M , An K , An G , Bouwmeester HJ , Wallington EJ , Oldroyd G , Paszkowski U
Ref : Nat Commun , 11 :2114 , 2020
Abstract : Most plants associate with beneficial arbuscular mycorrhizal (AM) fungi that facilitate soil nutrient acquisition. Prior to contact, partner recognition triggers reciprocal genetic remodelling to enable colonisation. The plant Dwarf14-Like (D14L) receptor conditions pre-symbiotic perception of AM fungi, and also detects the smoke constituent karrikin. D14L-dependent signalling mechanisms, underpinning AM symbiosis are unknown. Here, we present the identification of a negative regulator from rice, which operates downstream of the D14L receptor, corresponding to the homologue of the Arabidopsis thaliana Suppressor of MAX2-1 (AtSMAX1) that functions in karrikin signalling. We demonstrate that rice SMAX1 is a suppressor of AM symbiosis, negatively regulating fungal colonisation and transcription of crucial signalling components and conserved symbiosis genes. Similarly, rice SMAX1 negatively controls strigolactone biosynthesis, demonstrating an unexpected crosstalk between the strigolactone and karrikin signalling pathways. We conclude that removal of SMAX1, resulting from D14L signalling activation, de-represses essential symbiotic programmes and increases strigolactone hormone production.
ESTHER : Choi_2020_Nat.Commun_11_2114
PubMedSearch : Choi_2020_Nat.Commun_11_2114
PubMedID: 32355217

Title : Science and application of strigolactones - Aliche_2020_New.Phytol_227_1001
Author(s) : Aliche EB , Screpanti C , De Mesmaeker A , Munnik T , Bouwmeester HJ
Ref : New Phytol , 227 :1001 , 2020
Abstract : Strigolactones (SLs) represent a class of plant hormones that regulate developmental processes and play a role in the response of plants to various biotic and abiotic stresses. Both in planta hormonal roles and ex planta signalling effects of SLs are potentially interesting agricultural targets. In this review, we explore various aspects of SL function and highlight distinct areas of agriculture that may benefit from the use of synthetic SL analogues, and we identify possible bottlenecks. Our objective is to identify where the contributions of science and stakeholders are still needed to achieve harnessing the benefits of SLs for a sustainable agriculture of the near future.
ESTHER : Aliche_2020_New.Phytol_227_1001
PubMedSearch : Aliche_2020_New.Phytol_227_1001
PubMedID: 32067235

Title : An improved strategy to analyse strigolactones in complex sample matrices using UHPLC-MS\/MS - Flokova_2020_Plant.Methods_16_125
Author(s) : Flokova K , Shimels M , Andreo Jimenez B , Bardaro N , Strnad M , Novak O , Bouwmeester HJ
Ref : Plant Methods , 16 :125 , 2020
Abstract : BACKGROUND: Strigolactones represent the most recently described group of plant hormones involved in many aspects of plant growth regulation. Simultaneously, root exuded strigolactones mediate rhizosphere signaling towards beneficial arbuscular mycorrhizal fungi, but also attract parasitic plants. The seed germination of parasitic plants induced by host strigolactones leads to serious agricultural problems worldwide. More insight in these signaling molecules is hampered by their extremely low concentrations in complex soil and plant tissue matrices, as well as their instability. So far, the combination of tailored isolation-that would replace current unspecific, time-consuming and labour-intensive processing of large samples-and a highly sensitive method for the simultaneous profiling of a broad spectrum of strigolactones has not been reported. RESULTS: Depending on the sample matrix, two different strategies for the rapid extraction of the seven structurally similar strigolactones and highly efficient single-step pre-concentration on polymeric RP SPE sorbent were developed and validated. Compared to conventional methods, controlled temperature during the extraction and the addition of an organic modifier (acetonitrile, acetone) to the extraction solvent helped to tailor strigolactone isolation from low initial amounts of root tissue (150 mg fresh weight, FW) and root exudate (20 ml), which improved both strigolactone stability and sample purity. We have designed an efficient UHPLC separation with sensitive MS/MS detection for simultaneous analysis of seven natural strigolactones including their biosynthetic precursors-carlactone and carlactonoic acid. In combination with the optimized UHPLC-MS/MS method, attomolar detection limits were achieved. The new method allowed successful profiling of seven strigolactones in small exudate and root tissue samples of four different agriculturally important plant species-sorghum, rice, pea and tomato. CONCLUSION: The established method provides efficient strigolactone extraction with aqueous mixtures of less nucleophilic organic solvents from small root tissue and root exudate samples, in combination with rapid single-step pre-concentration. This method improves strigolactone stability and eliminates the co-extraction and signal of matrix-associated contaminants during the final UHPLC-MS/MS analysis with an electrospray interface, which dramatically increases the overall sensitivity of the analysis. We show that the method can be applied to a variety of plant species.
ESTHER : Flokova_2020_Plant.Methods_16_125
PubMedSearch : Flokova_2020_Plant.Methods_16_125
PubMedID: 32963580

Title : The tomato MAX1 homolog, SlMAX1, is involved in the biosynthesis of tomato strigolactones from carlactone - Zhang_2018_New.Phytol_219_297
Author(s) : Zhang Y , Cheng X , Wang Y , Diez-Simon C , Flokova K , Bimbo A , Bouwmeester HJ , Ruyter-Spira C
Ref : New Phytol , 219 :297 , 2018
Abstract : Strigolactones (SLs) are rhizosphere signalling molecules exuded by plants that induce seed germination of root parasitic weeds and hyphal branching of arbuscular mycorrhiza. They are also phytohormones regulating plant architecture. MORE AXILLARY GROWTH 1 (MAX1) and its homologs encode cytochrome P450 (CYP) enzymes that catalyse the conversion of the strigolactone precursor carlactone to canonical strigolactones in rice (Oryza sativa), and to an SL-like compound in Arabidopsis. Here, we characterized the tomato (Solanum lycopersicum) MAX1 homolog, SlMAX1. The targeting induced local lesions in genomes method was used to obtain Slmax1 mutants that exhibit strongly reduced production of orobanchol, solanacol and didehydro-orobanchol (DDH) isomers. This results in a severe strigolactone mutant phenotype in vegetative and reproductive development. Transient expression of SlMAX1 - together with SlD27, SlCCD7 and SlCCD8 - in Nicotiana benthamiana showed that SlMAX1 catalyses the formation of carlactonoic acid from carlactone. Plant feeding assays showed that carlactone, but not 4-deoxy-orobanchol, is the precursor of orobanchol, which in turn is the precursor of solanacol and two of the three DDH isomers. Inhibitor studies suggest that a 2-oxoglutarate-dependent dioxygenase is involved in orobanchol biosynthesis from carlactone and that the formation of solanacol and DDH isomers from orobanchol is catalysed by CYPs.
ESTHER : Zhang_2018_New.Phytol_219_297
PubMedSearch : Zhang_2018_New.Phytol_219_297
PubMedID: 29655242

Title : Zealactones. Novel natural strigolactones from maize - Charnikhova_2017_Phytochemistry_137_123
Author(s) : Charnikhova TV , Gaus K , Lumbroso A , Sanders M , Vincken JP , De Mesmaeker A , Ruyter-Spira CP , Screpanti C , Bouwmeester HJ
Ref : Phytochemistry , 137 :123 , 2017
Abstract : In the root exudate and root extracts of maize hybrid cv NK Falkone seven putative strigolactones were detected using UPLC-TQ-MS-MS. All seven compounds displayed MS-MS-fragmentation common for strigolactones and particularly the presence of a fragment of m/z 97 Da, which may indicate the presence of the so-called D-ring, suggests they are strigolactones. The levels of all these putative strigolactones increased upon phosphate starvation and decreased upon fluridone (carotenoid biosynthesis inhibitor) treatment, both of which are a common response for strigolactones. All seven compounds were subsequently isolated with prep-HPLC-MS. They all exhibited Striga hermonthica seed germination inducing activity just as the synthetic strigolactone analog GR24. The structure of two of the seven compounds was elucidated by NMR spectroscopy as: methyl (2E,3E)-4-(3,3-dimethyl-5-oxo-2-(prop-1-en-2-yl)tetrahydrofuran-2-yl)-2-(((4-methyl-5-oxo-2,5-dihydrofuran-2-yl)oxy)methylene)but-3-enoate (two diastereomers 1a and 1b). Strigolactones (1a/b) are closely related to the methyl ester of carlactonoic acid (MeCLA) and heliolactone. However, they contain a unique 4,4-dimethyltetrahydrofuran-2-one motif as the "A-ring" instead of the classical (di)methylcyclohexene. Because these compounds were isolated from maize (Zea mays) we called them "zealactone 1a and 1b". The implications of this discovery for our view on strigolactones and their biosynthesis are discussed.
ESTHER : Charnikhova_2017_Phytochemistry_137_123
PubMedSearch : Charnikhova_2017_Phytochemistry_137_123
PubMedID: 28215609

Title : Evaluation of field resistance to Striga hermonthica (Del.) Benth. in Sorghum bicolor (L.) Moench. The relationship with strigolactones - Mohemed_2016_Pest.Manag.Sci_72_2082
Author(s) : Mohemed N , Charnikhova T , Bakker EJ , van Ast A , Babiker AG , Bouwmeester HJ
Ref : Pest Manag Sci , 72 :2082 , 2016
Abstract : BACKGROUND: Significant losses in sorghum biomass and grain yield occur in sub-Saharan Africa owing to infection by the root-parasitic weed Striga hermonthica (Del.) Benth. One strategy to avoid these losses is to adopt resistant crop varieties. For further delineation of the role of germination stimulants in resistance, we conducted a field experiment employing six sorghum genotypes, in eastern Sudan, and in parallel analysed the strigolactone levels in the root exudates of these genotypes under controlled conditions in Wageningen. RESULTS: The root exudates of these genotypes displayed large differences in strigolactone composition and Striga-germination-inducing activity. Korokollow, Fakimustahi and Wadfahel exuded the highest amounts of 5-deoxystrigol. Fakimustahi was by far the highest sorgomol producer, and Wadbaco and SRN39 produced the highest amount of orobanchol. The concentration of 5-deoxystrigol in the root exudate showed a significant positive correlation with in vitro Striga germination and was positively associated with Striga infection in the field experiments, whereas orobanchol was negatively associated with Striga infection in the field experiments. CONCLUSION: For the first time a close association is reported between strigolactone levels analysed under laboratory conditions and Striga infection in the field in sorghum genotypes. These genotypes may be used for further study of this resistance mechanism and for the introgression of the low germination trait in other sorghum varieties to breed for a strigolactone composition with low stimulant activity. The use of such improved varieties in combination with other Striga management tools could possibly alleviate the current Striga problem on the African continent. 2016 Society of Chemical Industry.
ESTHER : Mohemed_2016_Pest.Manag.Sci_72_2082
PubMedSearch : Mohemed_2016_Pest.Manag.Sci_72_2082
PubMedID: 27611187

Title : Strigolactones, a novel carotenoid-derived plant hormone - Al-Babili_2015_Annu.Rev.Plant.Biol_66_161
Author(s) : Al-Babili S , Bouwmeester HJ
Ref : Annu Rev Plant Biol , 66 :161 , 2015
Abstract : Strigolactones (SLs) are carotenoid-derived plant hormones and signaling molecules. When released into the soil, SLs indicate the presence of a host to symbiotic fungi and root parasitic plants. In planta, they regulate several developmental processes that adapt plant architecture to nutrient availability. Highly branched/tillered mutants in Arabidopsis, pea, and rice have enabled the identification of four SL biosynthetic enzymes: a cis/trans-carotene isomerase, two carotenoid cleavage dioxygenases, and a cytochrome P450 (MAX1). In vitro and in vivo enzyme assays and analysis of mutants have shown that the pathway involves a combination of new reactions leading to carlactone, which is converted by a rice MAX1 homolog into an SL parent molecule with a tricyclic lactone moiety. In this review, we focus on SL biosynthesis, describe the hormonal and environmental factors that determine this process, and discuss SL transport and downstream signaling as well as the role of SLs in regulating plant development.
ESTHER : Al-Babili_2015_Annu.Rev.Plant.Biol_66_161
PubMedSearch : Al-Babili_2015_Annu.Rev.Plant.Biol_66_161
PubMedID: 25621512

Title : Rice cytochrome P450 MAX1 homologs catalyze distinct steps in strigolactone biosynthesis - Zhang_2014_Nat.Chem.Biol_10_1028
Author(s) : Zhang Y , van Dijk AD , Scaffidi A , Flematti GR , Hofmann M , Charnikhova T , Verstappen F , Hepworth J , van der Krol S , Leyser O , Smith SM , Zwanenburg B , Al-Babili S , Ruyter-Spira C , Bouwmeester HJ
Ref : Nat Chemical Biology , 10 :1028 , 2014
Abstract : Strigolactones (SLs) are a class of phytohormones and rhizosphere signaling compounds with high structural diversity. Three enzymes, carotenoid isomerase DWARF27 and carotenoid cleavage dioxygenases CCD7 and CCD8, were previously shown to convert all-trans-beta-carotene to carlactone (CL), the SL precursor. However, how CL is metabolized to SLs has remained elusive. Here, by reconstituting the SL biosynthetic pathway in Nicotiana benthamiana, we show that a rice homolog of Arabidopsis More Axillary Growth 1 (MAX1), encodes a cytochrome P450 CYP711 subfamily member that acts as a CL oxidase to stereoselectively convert CL into ent-2'-epi-5-deoxystrigol (B-C lactone ring formation), the presumed precursor of rice SLs. A protein encoded by a second rice MAX1 homolog then catalyzes the conversion of ent-2'-epi-5-deoxystrigol to orobanchol. We therefore report that two members of CYP711 enzymes can catalyze two distinct steps in SL biosynthesis, identifying the first enzymes involved in B-C ring closure and a subsequent structural diversification step of SLs.
ESTHER : Zhang_2014_Nat.Chem.Biol_10_1028
PubMedSearch : Zhang_2014_Nat.Chem.Biol_10_1028
PubMedID: 25344813

Title : A petunia ABC protein controls strigolactone-dependent symbiotic signalling and branching - Kretzschmar_2012_Nature_483_341
Author(s) : Kretzschmar T , Kohlen W , Sasse J , Borghi L , Schlegel M , Bachelier JB , Reinhardt D , Bours R , Bouwmeester HJ , Martinoia E
Ref : Nature , 483 :341 , 2012
Abstract : Strigolactones were originally identified as stimulators of the germination of root-parasitic weeds that pose a serious threat to resource-limited agriculture. They are mostly exuded from roots and function as signalling compounds in the initiation of arbuscular mycorrhizae, which are plant-fungus symbionts with a global effect on carbon and phosphate cycling. Recently, strigolactones were established to be phytohormones that regulate plant shoot architecture by inhibiting the outgrowth of axillary buds. Despite their importance, it is not known how strigolactones are transported. ATP-binding cassette (ABC) transporters, however, are known to have functions in phytohormone translocation. Here we show that the Petunia hybrida ABC transporter PDR1 has a key role in regulating the development of arbuscular mycorrhizae and axillary branches, by functioning as a cellular strigolactone exporter. P. hybrida pdr1 mutants are defective in strigolactone exudation from their roots, resulting in reduced symbiotic interactions. Above ground, pdr1 mutants have an enhanced branching phenotype, which is indicative of impaired strigolactone allocation. Overexpression of Petunia axillaris PDR1 in Arabidopsis thaliana results in increased tolerance to high concentrations of a synthetic strigolactone, consistent with increased export of strigolactones from the roots. PDR1 is the first known component in strigolactone transport, providing new opportunities for investigating and manipulating strigolactone-dependent processes.
ESTHER : Kretzschmar_2012_Nature_483_341
PubMedSearch : Kretzschmar_2012_Nature_483_341
PubMedID: 22398443

Title : The effects of auxin and strigolactones on tuber initiation and stolon architecture in potato - Roumeliotis_2012_J.Exp.Bot_63_4539
Author(s) : Roumeliotis E , Kloosterman B , Oortwijn M , Kohlen W , Bouwmeester HJ , Visser RG , Bachem CW
Ref : J Exp Bot , 63 :4539 , 2012
Abstract : Various transcriptional networks and plant hormones have been implicated in controlling different aspects of potato tuber formation. Due to its broad impact on many plant developmental processes, a role for auxin in tuber initiation has been suggested but never fully resolved. Here, auxin concentrations were measured throughout the plant prior to and during the process of tuber formation. Auxin levels increase dramatically in the stolon prior to tuberization and remain relatively high during subsequent tuber growth, suggesting a promoting role for auxin in tuber formation. Furthermore, in vitro tuberization experiments showed higher levels of tuber formation from axillary buds of explants where the auxin source (stolon tip) had been removed. This phenotype could be rescued by application of auxin on the ablated stolon tips. In addition, a synthetic strigolactone analogue applied on the basal part of the stolon resulted in fewer tubers. The experiments indicate that a system for the production and directional transport of auxin exists in stolons and acts synergistically with strigolactones to control the outgrowth of the axillary stolon buds, similar to the control of above-ground shoot branching.
ESTHER : Roumeliotis_2012_J.Exp.Bot_63_4539
PubMedSearch : Roumeliotis_2012_J.Exp.Bot_63_4539
PubMedID: 22689826

Title : Pre-attachment Striga hermonthica resistance of New Rice for Africa (NERICA) cultivars based on low strigolactone production - Jamil_2011_New.Phytol_192_964
Author(s) : Jamil M , Rodenburg J , Charnikhova T , Bouwmeester HJ
Ref : New Phytol , 192 :964 , 2011
Abstract : Striga hermonthica (Striga) is an obligate hemiparasitic weed, causing severe yield losses in cereals, including rice, throughout sub-Saharan Africa. Striga germination depends on strigolactones (germination stimulants) exuded by the host roots. The interspecific New Rice for Africa (NERICA) cultivars offer a potentially interesting gene pool for a screen for low germination-inducing rice cultivars. Exudates were collected from all NERICA cultivars and their parents (Oryza sativa and Oryza glaberrima) for the analysis of strigolactones. In vitro and in situ Striga germination, attachment and emergence rates were recorded for each cultivar. NERICA 1 and CG14 produced significantly less strigolactones and showed less Striga infection than the other cultivars. NERICAs 7, 8, 11 and 14 produced the largest amounts of strigolactones and showed the most severe Striga infection. Across all the cultivars and parents, there was a positive relationship between the amount of strigolactones in the exudate and Striga germination, attachment and emergence rates. This study shows that there is genetic variation in Striga pre-attachment resistance in NERICA rice. Cultivars combining this pre-attachment resistance with post-attachment resistance (already identified) can provide a key component for durable integrated management of this noxious weed in cereal production systems in sub-Saharan Africa.
ESTHER : Jamil_2011_New.Phytol_192_964
PubMedSearch : Jamil_2011_New.Phytol_192_964
PubMedID: 21883233