@article{chowdhury_fluorogenic_2023,
	title = {Fluorogenic properties of 4-dimethylaminocinnamaldehyde ({DMACA}) enable high resolution imaging of cell-wall-bound proanthocyanidins in plant root tissues},
	volume = {13},
	issn = {1664-462X},
	url = {https://www.frontiersin.org/articles/10.3389/fpls.2022.1060804},
	doi = {10.3389/fpls.2022.1060804},
	abstract = {Proanthocyanidins (PAs) are polymeric phenolic compounds found in plants and used in many industrial applications. Despite strong evidence of herbivore and pathogen resistance-related properties of PAs, their in planta function is not fully understood. Determining the location and dynamics of PAs in plant tissues and cellular compartments is crucial to understand their mode of action. Such an approach requires microscopic localization with fluorescent dyes that specifically bind to PAs. Such dyes have hitherto been lacking. Here, we show that 4-dimethylaminocinnamaldehyde (DMACA) can be used as a PA-specific fluorescent dye that allows localization of PAs at high resolution in cell walls and inside cells using confocal microscopy, revealing features of previously unreported wall-bound PAs. We demonstrate several novel usages of DMACA as a fluorophore by taking advantage of its double staining compatibility with other fluorescent dyes. We illustrate the use of the dye alone and its co-localization with cell wall polymers in different Populus root tissues. The easy-to-use fluorescent staining method, together with its high photostability and compatibility with other fluorogenic dyes, makes DMACA a valuable tool for uncovering the biological function of PAs at a cellular level in plant tissues. DMACA can also be used in other plant tissues than roots, however care needs to be taken when tissues contain compounds that autofluoresce in the red spectral region which can be confounded with the PA-specific DMACA signal.},
	urldate = {2023-02-10},
	journal = {Frontiers in Plant Science},
	author = {Chowdhury, Jamil and Ferdous, Jannatul and Lihavainen, Jenna and Albrectsen, Benedicte Riber and Lundberg-Felten, Judith},
	month = feb,
	year = {2023},
	keywords = {⛔ No DOI found},
}

Proanthocyanidins (PAs) are polymeric phenolic compounds found in plants and used in many industrial applications. Despite strong evidence of herbivore and pathogen resistance-related properties of PAs, their in planta function is not fully understood. Determining the location and dynamics of PAs in plant tissues and cellular compartments is crucial to understand their mode of action. Such an approach requires microscopic localization with fluorescent dyes that specifically bind to PAs. Such dyes have hitherto been lacking. Here, we show that 4-dimethylaminocinnamaldehyde (DMACA) can be used as a PA-specific fluorescent dye that allows localization of PAs at high resolution in cell walls and inside cells using confocal microscopy, revealing features of previously unreported wall-bound PAs. We demonstrate several novel usages of DMACA as a fluorophore by taking advantage of its double staining compatibility with other fluorescent dyes. We illustrate the use of the dye alone and its co-localization with cell wall polymers in different Populus root tissues. The easy-to-use fluorescent staining method, together with its high photostability and compatibility with other fluorogenic dyes, makes DMACA a valuable tool for uncovering the biological function of PAs at a cellular level in plant tissues. DMACA can also be used in other plant tissues than roots, however care needs to be taken when tissues contain compounds that autofluoresce in the red spectral region which can be confounded with the PA-specific DMACA signal.

@article{chowdhury_laccaria_2022,
	title = {Laccaria bicolor pectin methylesterases are involved in ectomycorrhiza development with {Populus} tremula × {Populus} tremuloides},
	volume = {236},
	issn = {1469-8137},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/nph.18358},
	doi = {10.1111/nph.18358},
	abstract = {The development of ectomycorrhizal (ECM) symbioses between soil fungi and tree roots requires modification of root cell walls. The pectin-mediated adhesion between adjacent root cells loosens to accommodate fungal hyphae in the Hartig net, facilitating nutrient exchange between partners. We investigated the role of fungal pectin modifying enzymes in Laccaria bicolor for ECM formation with Populus tremula × Populus tremuloides. We combine transcriptomics of cell-wall-related enzymes in both partners during ECM formation, immunolocalisation of pectin (Homogalacturonan, HG) epitopes in different methylesterification states, pectin methylesterase (PME) activity assays and functional analyses of transgenic L. bicolor to uncover pectin modification mechanisms and the requirement of fungal pectin methylesterases (LbPMEs) for ECM formation. Immunolocalisation identified remodelling of pectin towards de-esterified HG during ECM formation, which was accompanied by increased LbPME1 expression and PME activity. Overexpression or RNAi of the ECM-induced LbPME1 in transgenic L. bicolor lines led to reduced ECM formation. Hartig Nets formed with LbPME1 RNAi lines were shallower, whereas those formed with LbPME1 overexpressors were deeper. This suggests that LbPME1 plays a role in ECM formation potentially through HG de-esterification, which initiates loosening of adjacent root cells to facilitate Hartig net formation.},
	language = {en},
	number = {2},
	urldate = {2022-10-03},
	journal = {New Phytologist},
	author = {Chowdhury, Jamil and Kemppainen, Minna and Delhomme, Nicolas and Shutava, Iryna and Zhou, Jingjing and Takahashi, Junko and Pardo, Alejandro G. and Lundberg-Felten, Judith},
	month = oct,
	year = {2022},
	keywords = {Laccaria bicolor, Populus, cell wall, cell-wall, cell-wall remodelling, cell-wall-modifying enzymes, ectomycorrhiza, pectin, pectin methylesterase},
	pages = {639--655},
}

The development of ectomycorrhizal (ECM) symbioses between soil fungi and tree roots requires modification of root cell walls. The pectin-mediated adhesion between adjacent root cells loosens to accommodate fungal hyphae in the Hartig net, facilitating nutrient exchange between partners. We investigated the role of fungal pectin modifying enzymes in Laccaria bicolor for ECM formation with Populus tremula × Populus tremuloides. We combine transcriptomics of cell-wall-related enzymes in both partners during ECM formation, immunolocalisation of pectin (Homogalacturonan, HG) epitopes in different methylesterification states, pectin methylesterase (PME) activity assays and functional analyses of transgenic L. bicolor to uncover pectin modification mechanisms and the requirement of fungal pectin methylesterases (LbPMEs) for ECM formation. Immunolocalisation identified remodelling of pectin towards de-esterified HG during ECM formation, which was accompanied by increased LbPME1 expression and PME activity. Overexpression or RNAi of the ECM-induced LbPME1 in transgenic L. bicolor lines led to reduced ECM formation. Hartig Nets formed with LbPME1 RNAi lines were shallower, whereas those formed with LbPME1 overexpressors were deeper. This suggests that LbPME1 plays a role in ECM formation potentially through HG de-esterification, which initiates loosening of adjacent root cells to facilitate Hartig net formation.

@article{escamez_fluorescence_2021,
	title = {Fluorescence {Lifetime} {Imaging} as an {In} {Situ} and {Label}-{Free} {Readout} for the {Chemical} {Composition} of {Lignin}},
	volume = {9},
	url = {https://doi.org/10.1021/acssuschemeng.1c06780},
	doi = {10/gnr3sb},
	abstract = {Naturally fluorescent polymeric molecules such as collagen, resilin, cutin, suberin, or lignin can serve as renewable sources of bioproducts. Theoretical physics predicts that the fluorescence lifetime of these polymers is related to their chemical composition. We verified this prediction for lignin, a major structural element in plant cell walls that form woody biomass. Lignin is composed of different phenylpropanoid units, and its composition affects its properties, biological functions, and the utilization of wood biomass. We carried out fluorescence lifetime imaging microscopy (FLIM) measurements of wood cell wall lignin in a population of 90 hybrid aspen trees genetically engineered to display differences in cell wall chemistry and structure. We also measured the wood cell wall composition by classical analytical methods in these trees. Using statistical modeling and machine learning algorithms, we identified parameters of fluorescence lifetime that predict the content of S-type and G-type lignin units, the two main types of units in the lignin of angiosperm (flowering) plants. In a first step toward tailoring lignin biosynthesis toward improvement of woody biomass feedstocks, we show how FLIM can reveal the dynamics of lignin biosynthesis in two different biological contexts, including in vivo while lignin is being synthesized in the walls of living cells.},
	number = {51},
	urldate = {2021-12-14},
	journal = {ACS Sustainable Chemistry \& Engineering},
	author = {Escamez, Sacha and Terryn, Christine and Gandla, Madhavi Latha and Yassin, Zakiya and Scheepers, Gerhard and Näsholm, Torgny and Sundman, Ola and Jönsson, Leif J. and Lundberg-Felten, Judith and Tuominen, Hannele and Niittylä, Totte and Paës, Gabriel},
	month = dec,
	year = {2021},
	pages = {17381--17392},
}

Naturally fluorescent polymeric molecules such as collagen, resilin, cutin, suberin, or lignin can serve as renewable sources of bioproducts. Theoretical physics predicts that the fluorescence lifetime of these polymers is related to their chemical composition. We verified this prediction for lignin, a major structural element in plant cell walls that form woody biomass. Lignin is composed of different phenylpropanoid units, and its composition affects its properties, biological functions, and the utilization of wood biomass. We carried out fluorescence lifetime imaging microscopy (FLIM) measurements of wood cell wall lignin in a population of 90 hybrid aspen trees genetically engineered to display differences in cell wall chemistry and structure. We also measured the wood cell wall composition by classical analytical methods in these trees. Using statistical modeling and machine learning algorithms, we identified parameters of fluorescence lifetime that predict the content of S-type and G-type lignin units, the two main types of units in the lignin of angiosperm (flowering) plants. In a first step toward tailoring lignin biosynthesis toward improvement of woody biomass feedstocks, we show how FLIM can reveal the dynamics of lignin biosynthesis in two different biological contexts, including in vivo while lignin is being synthesized in the walls of living cells.

@article{plett_novel_2021,
	title = {Novel {Microdialysis} {Technique} {Reveals} a {Dramatic} {Shift} in {Metabolite} {Secretion} during the {Early} {Stages} of the {Interaction} between the {Ectomycorrhizal} {Fungus} {Pisolithus} microcarpus and {Its} {Host} {Eucalyptus} grandis},
	volume = {9},
	copyright = {http://creativecommons.org/licenses/by/3.0/},
	url = {https://www.mdpi.com/2076-2607/9/9/1817},
	doi = {10.3390/microorganisms9091817},
	abstract = {The colonisation of tree roots by ectomycorrhizal (ECM) fungi is the result of numerous signalling exchanges between organisms, many of which occur before physical contact. However, information is lacking about these exchanges and the compounds that are secreted by each organism before contact. This is in part due to a lack of low disturbance sampling methods with sufficient temporal and spatial resolution to capture these exchanges. Using a novel in situ microdialysis approach, we sampled metabolites released from Eucalyptus grandis and Pisolithus microcarpus independently and during indirect contact over a 48-h time-course using UPLC-MS. A total of 560 and 1530 molecular features (MFs; ESI- and ESI+ respectively) were identified with significant differential abundance from control treatments. We observed that indirect contact between organisms altered the secretion of MFs to produce a distinct metabolomic profile compared to either organism independently. Many of these MFs were produced within the first hour of contact and included several phenylpropanoids, fatty acids and organic acids. These findings show that the secreted metabolome, particularly of the ECM fungus, can rapidly shift during the early stages of pre-symbiotic contact and highlight the importance of observing these early interactions in greater detail. We present microdialysis as a useful tool for examining plant–fungal signalling with high temporal resolution and with minimal experimental disturbance.},
	language = {en},
	number = {9},
	urldate = {2021-10-14},
	journal = {Microorganisms},
	author = {Plett, Krista L. and Buckley, Scott and Plett, Jonathan M. and Anderson, Ian C. and Lundberg-Felten, Judith and Jämtgård, Sandra},
	month = sep,
	year = {2021},
	pages = {1817},
}

The colonisation of tree roots by ectomycorrhizal (ECM) fungi is the result of numerous signalling exchanges between organisms, many of which occur before physical contact. However, information is lacking about these exchanges and the compounds that are secreted by each organism before contact. This is in part due to a lack of low disturbance sampling methods with sufficient temporal and spatial resolution to capture these exchanges. Using a novel in situ microdialysis approach, we sampled metabolites released from Eucalyptus grandis and Pisolithus microcarpus independently and during indirect contact over a 48-h time-course using UPLC-MS. A total of 560 and 1530 molecular features (MFs; ESI- and ESI+ respectively) were identified with significant differential abundance from control treatments. We observed that indirect contact between organisms altered the secretion of MFs to produce a distinct metabolomic profile compared to either organism independently. Many of these MFs were produced within the first hour of contact and included several phenylpropanoids, fatty acids and organic acids. These findings show that the secreted metabolome, particularly of the ECM fungus, can rapidly shift during the early stages of pre-symbiotic contact and highlight the importance of observing these early interactions in greater detail. We present microdialysis as a useful tool for examining plant–fungal signalling with high temporal resolution and with minimal experimental disturbance.

@article{seyfferth_populuspterf85_2021,
	title = {{PopulusPtERF85} {Balances} {Xylem} {Cell} {Expansion} and {Secondary} {Cell} {Wall} {Formation} in {Hybrid} {Aspen}},
	volume = {10},
	copyright = {http://creativecommons.org/licenses/by/3.0/},
	url = {https://www.mdpi.com/2073-4409/10/8/1971},
	doi = {10.3390/cells10081971},
	abstract = {Secondary growth relies on precise and specialized transcriptional networks that determine cell division, differentiation, and maturation of xylem cells. We identified a novel role for the ethylene-induced Populus Ethylene Response Factor PtERF85 (Potri.015G023200) in balancing xylem cell expansion and secondary cell wall (SCW) formation in hybrid aspen (Populus tremula x tremuloides). Expression of PtERF85 is high in phloem and cambium cells and during the expansion of xylem cells, while it is low in maturing xylem tissue. Extending PtERF85 expression into SCW forming zones of woody tissues through ectopic expression reduced wood density and SCW thickness of xylem fibers but increased fiber diameter. Xylem transcriptomes from the transgenic trees revealed transcriptional induction of genes involved in cell expansion, translation, and growth. The expression of genes associated with plant vascular development and the biosynthesis of SCW chemical components such as xylan and lignin, was down-regulated in the transgenic trees. Our results suggest that PtERF85 activates genes related to xylem cell expansion, while preventing transcriptional activation of genes related to SCW formation. The importance of precise spatial expression of PtERF85 during wood development together with the observed phenotypes in response to ectopic PtERF85 expression suggests that PtERF85 contributes to the transition of fiber cells from elongation to secondary cell wall deposition.},
	language = {en},
	number = {8},
	urldate = {2021-09-02},
	journal = {Cells},
	author = {Seyfferth, Carolin and Wessels, Bernard A. and Vahala, Jorma and Kangasjärvi, Jaakko and Delhomme, Nicolas and Hvidsten, Torgeir R. and Tuominen, Hannele and Lundberg-Felten, Judith},
	month = aug,
	year = {2021},
	keywords = {ERF85 (CRF4), cell wall thickness, lignin, ribosome biogenesis, wood development, xylem expansion},
	pages = {1971},
}

Secondary growth relies on precise and specialized transcriptional networks that determine cell division, differentiation, and maturation of xylem cells. We identified a novel role for the ethylene-induced Populus Ethylene Response Factor PtERF85 (Potri.015G023200) in balancing xylem cell expansion and secondary cell wall (SCW) formation in hybrid aspen (Populus tremula x tremuloides). Expression of PtERF85 is high in phloem and cambium cells and during the expansion of xylem cells, while it is low in maturing xylem tissue. Extending PtERF85 expression into SCW forming zones of woody tissues through ectopic expression reduced wood density and SCW thickness of xylem fibers but increased fiber diameter. Xylem transcriptomes from the transgenic trees revealed transcriptional induction of genes involved in cell expansion, translation, and growth. The expression of genes associated with plant vascular development and the biosynthesis of SCW chemical components such as xylan and lignin, was down-regulated in the transgenic trees. Our results suggest that PtERF85 activates genes related to xylem cell expansion, while preventing transcriptional activation of genes related to SCW formation. The importance of precise spatial expression of PtERF85 during wood development together with the observed phenotypes in response to ectopic PtERF85 expression suggests that PtERF85 contributes to the transition of fiber cells from elongation to secondary cell wall deposition.

@article{henriksson_mycorrhizal_2021,
	title = {The mycorrhizal tragedy of the commons},
	volume = {24},
	issn = {1461-023X, 1461-0248},
	url = {https://onlinelibrary.wiley.com/doi/10.1111/ele.13737},
	doi = {10/gkcr8h},
	language = {en},
	number = {6},
	urldate = {2021-06-03},
	journal = {Ecology Letters},
	author = {Henriksson, Nils and Franklin, Oskar and Tarvainen, Lasse and Marshall, John and Lundberg‐Felten, Judith and Eilertsen, Lill and Näsholm, Torgny},
	editor = {Selosse, Marc‐André},
	month = jun,
	year = {2021},
	pages = {1215--1224},
}

@article{kemppainen_fluorescent_2020,
	title = {Fluorescent protein expression in the ectomycorrhizal fungus {Laccaria} bicolor: a plasmid toolkit for easy use of fluorescent markers in basidiomycetes},
	volume = {66},
	issn = {0172-8083, 1432-0983},
	shorttitle = {Fluorescent protein expression in the ectomycorrhizal fungus {Laccaria} bicolor},
	url = {http://link.springer.com/10.1007/s00294-020-01060-4},
	doi = {10.1007/s00294-020-01060-4},
	language = {en},
	number = {4},
	urldate = {2021-06-07},
	journal = {Current Genetics},
	author = {Kemppainen, Minna and Chowdhury, Jamil and Lundberg-Felten, Judith and Pardo, Alejandro},
	month = aug,
	year = {2020},
	pages = {791--811},
}

@article{wessels_ap2erf_2019,
	title = {An {AP2}/{ERF} transcription factor {ERF139} coordinates xylem cell expansion and secondary cell wall deposition},
	volume = {224},
	issn = {0028-646X, 1469-8137},
	shorttitle = {An {\textless}span style="font-variant},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/nph.15960},
	doi = {10/gjcsfs},
	language = {en},
	number = {4},
	urldate = {2021-06-07},
	journal = {New Phytologist},
	author = {Wessels, Bernard and Seyfferth, Carolin and Escamez, Sacha and Vain, Thomas and Antos, Kamil and Vahala, Jorma and Delhomme, Nicolas and Kangasjärvi, Jaakko and Eder, Michaela and Felten, Judith and Tuominen, Hannele},
	month = dec,
	year = {2019},
	pages = {1585--1599},
}

@article{seyfferth_ethylene_2019,
	title = {Ethylene {Signaling} {Is} {Required} for {Fully} {Functional} {Tension} {Wood} in {Hybrid} {Aspen}},
	volume = {10},
	issn = {1664-462X},
	url = {https://www.frontiersin.org/article/10.3389/fpls.2019.01101/full},
	doi = {10.3389/fpls.2019.01101},
	urldate = {2021-06-07},
	journal = {Frontiers in Plant Science},
	author = {Seyfferth, Carolin and Wessels, Bernard A. and Gorzsás, András and Love, Jonathan W. and Rüggeberg, Markus and Delhomme, Nicolas and Vain, Thomas and Antos, Kamil and Tuominen, Hannele and Sundberg, Björn and Felten, Judith},
	month = sep,
	year = {2019},
	pages = {1101},
}

@article{felten_ethylene_2018,
	title = {Ethylene signaling induces gelatinous layers with typical features of tension wood in hybrid aspen},
	volume = {218},
	issn = {0028646X},
	url = {http://doi.wiley.com/10.1111/nph.15078},
	doi = {10.1111/nph.15078},
	language = {en},
	number = {3},
	urldate = {2021-06-07},
	journal = {New Phytologist},
	author = {Felten, Judith and Vahala, Jorma and Love, Jonathan and Gorzsás, András and Rüggeberg, Markus and Delhomme, Nicolas and Leśniewska, Joanna and Kangasjärvi, Jaakko and Hvidsten, Torgeir R. and Mellerowicz, Ewa J. and Sundberg, Björn},
	month = may,
	year = {2018},
	pages = {999--1014},
}

@article{seyfferth_ethylene-related_2018,
	title = {Ethylene-{Related} {Gene} {Expression} {Networks} in {Wood} {Formation}},
	volume = {9},
	issn = {1664-462X},
	url = {http://journal.frontiersin.org/article/10.3389/fpls.2018.00272/full},
	doi = {10/gc7vds},
	urldate = {2021-06-07},
	journal = {Frontiers in Plant Science},
	author = {Seyfferth, Carolin and Wessels, Bernard and Jokipii-Lukkari, Soile and Sundberg, Björn and Delhomme, Nicolas and Felten, Judith and Tuominen, Hannele},
	month = mar,
	year = {2018},
	pages = {272},
}

@article{waller_sharing_2018,
	title = {Sharing resources for mutual benefit: crosstalk between disciplines deepens the understanding of mycorrhizal symbioses across scales},
	volume = {217},
	issn = {0028646X},
	shorttitle = {Sharing resources for mutual benefit},
	url = {http://doi.wiley.com/10.1111/nph.14912},
	doi = {10/ghbzdd},
	language = {en},
	number = {1},
	urldate = {2021-06-07},
	journal = {New Phytologist},
	author = {Waller, Lauren P. and Felten, Judith and Hiiesalu, Inga and Vogt-Schilb, Hélène},
	month = jan,
	year = {2018},
	pages = {29--32},
}

@article{vayssieres_development_2015,
	title = {Development of the {Poplar}-{Laccaria} bicolor {Ectomycorrhiza} {Modifies} {Root} {Auxin} {Metabolism}, {Signaling}, and {Response}},
	volume = {169},
	issn = {1532-2548 (Electronic) 0032-0889 (Linking)},
	url = {https://www.ncbi.nlm.nih.gov/pubmed/26084921},
	doi = {10.1104/pp.114.255620},
	abstract = {Root systems of host trees are known to establish ectomycorrhizae (ECM) interactions with rhizospheric fungi. This mutualistic association leads to dramatic developmental modifications in root architecture, with the formation of numerous short and swollen lateral roots ensheathed by a fungal mantle. Knowing that auxin plays a crucial role in root development, we investigated how auxin metabolism, signaling, and response are affected in poplar (Populus spp.)-Laccaria bicolor ECM roots. The plant-fungus interaction leads to the arrest of lateral root growth with simultaneous attenuation of the synthetic auxin response element DR5. Measurement of auxin-related metabolites in the free-living partners revealed that the mycelium of L. bicolor produces high concentrations of the auxin indole-3-acetic acid (IAA). Metabolic profiling showed an accumulation of IAA and changes in the indol-3-pyruvic acid-dependent IAA biosynthesis and IAA conjugation and degradation pathways during ECM formation. The global analysis of auxin response gene expression and the regulation of AUXIN SIGNALING F-BOX PROTEIN5, AUXIN/IAA, and AUXIN RESPONSE FACTOR expression in ECM roots suggested that symbiosis-dependent auxin signaling is activated during the colonization by L. bicolor. Taking all this evidence into account, we propose a model in which auxin signaling plays a crucial role in the modification of root growth during ECM formation.},
	language = {en},
	number = {1},
	urldate = {2021-06-07},
	journal = {Plant Physiol},
	author = {Vayssieres, A. and Pencik, A. and Felten, J. and Kohler, A. and Ljung, K. and Martin, F. and Legue, V.},
	month = sep,
	year = {2015},
	note = {Edition: 2015/06/19},
	keywords = {*Signal Transduction/drug effects, Gene Expression Regulation, Plant/drug effects, Indoleacetic Acids/*metabolism/pharmacology, Laccaria/drug effects/*physiology, Metabolome/drug effects, Models, Biological, Multivariate Analysis, Mycorrhizae/drug effects/*physiology, Plant Proteins/metabolism, Plant Roots/drug effects/growth \& development/*metabolism/*microbiology, Populus/drug effects/*microbiology},
	pages = {890--902},
}

Root systems of host trees are known to establish ectomycorrhizae (ECM) interactions with rhizospheric fungi. This mutualistic association leads to dramatic developmental modifications in root architecture, with the formation of numerous short and swollen lateral roots ensheathed by a fungal mantle. Knowing that auxin plays a crucial role in root development, we investigated how auxin metabolism, signaling, and response are affected in poplar (Populus spp.)-Laccaria bicolor ECM roots. The plant-fungus interaction leads to the arrest of lateral root growth with simultaneous attenuation of the synthetic auxin response element DR5. Measurement of auxin-related metabolites in the free-living partners revealed that the mycelium of L. bicolor produces high concentrations of the auxin indole-3-acetic acid (IAA). Metabolic profiling showed an accumulation of IAA and changes in the indol-3-pyruvic acid-dependent IAA biosynthesis and IAA conjugation and degradation pathways during ECM formation. The global analysis of auxin response gene expression and the regulation of AUXIN SIGNALING F-BOX PROTEIN5, AUXIN/IAA, and AUXIN RESPONSE FACTOR expression in ECM roots suggested that symbiosis-dependent auxin signaling is activated during the colonization by L. bicolor. Taking all this evidence into account, we propose a model in which auxin signaling plays a crucial role in the modification of root growth during ECM formation.

@article{felten_vibrational_2015,
	title = {Vibrational spectroscopic image analysis of biological material using multivariate curve resolution-alternating least squares ({MCR}-{ALS})},
	volume = {10},
	issn = {1750-2799 (Electronic) 1750-2799 (Linking)},
	url = {https://www.ncbi.nlm.nih.gov/pubmed/25569330},
	doi = {10.1038/nprot.2015.008},
	abstract = {Raman and Fourier transform IR (FTIR) microspectroscopic images of biological material (tissue sections) contain detailed information about their chemical composition. The challenge lies in identifying changes in chemical composition, as well as locating and assigning these changes to different conditions (pathology, anatomy, environmental or genetic factors). Multivariate data analysis techniques are ideal for decrypting such information from the data. This protocol provides a user-friendly pipeline and graphical user interface (GUI) for data pre-processing and unmixing of pixel spectra into their contributing pure components by multivariate curve resolution-alternating least squares (MCR-ALS) analysis. The analysis considers the full spectral profile in order to identify the chemical compounds and to visualize their distribution across the sample to categorize chemically distinct areas. Results are rapidly achieved (usually {\textless}30-60 min per image), and they are easy to interpret and evaluate both in terms of chemistry and biology, making the method generally more powerful than principal component analysis (PCA) or heat maps of single-band intensities. In addition, chemical and biological evaluation of the results by means of reference matching and segmentation maps (based on k-means clustering) is possible.},
	language = {en},
	number = {2},
	urldate = {2021-06-07},
	journal = {Nat Protoc},
	author = {Felten, J. and Hall, H. and Jaumot, J. and Tauler, R. and de Juan, A. and Gorzsas, A.},
	month = feb,
	year = {2015},
	note = {Edition: 2015/01/09},
	keywords = {*Multivariate Analysis, *Spectroscopy, Fourier Transform Infrared, *Spectrum Analysis, Raman, Animals, Image Processing, Computer-Assisted/*methods, Islets of Langerhans/chemistry, Least-Squares Analysis, Mice, Inbred C57BL, Populus/chemistry, User-Computer Interface, Xylem/chemistry},
	pages = {217--40},
}

Raman and Fourier transform IR (FTIR) microspectroscopic images of biological material (tissue sections) contain detailed information about their chemical composition. The challenge lies in identifying changes in chemical composition, as well as locating and assigning these changes to different conditions (pathology, anatomy, environmental or genetic factors). Multivariate data analysis techniques are ideal for decrypting such information from the data. This protocol provides a user-friendly pipeline and graphical user interface (GUI) for data pre-processing and unmixing of pixel spectra into their contributing pure components by multivariate curve resolution-alternating least squares (MCR-ALS) analysis. The analysis considers the full spectral profile in order to identify the chemical compounds and to visualize their distribution across the sample to categorize chemically distinct areas. Results are rapidly achieved (usually \textless30-60 min per image), and they are easy to interpret and evaluate both in terms of chemistry and biology, making the method generally more powerful than principal component analysis (PCA) or heat maps of single-band intensities. In addition, chemical and biological evaluation of the results by means of reference matching and segmentation maps (based on k-means clustering) is possible.

@article{ditengou_volatile_2015,
	title = {Volatile signalling by sesquiterpenes from ectomycorrhizal fungi reprogrammes root architecture},
	volume = {6},
	issn = {2041-1723 (Electronic) 2041-1723 (Linking)},
	url = {https://www.ncbi.nlm.nih.gov/pubmed/25703994},
	doi = {10.1038/ncomms7279},
	abstract = {The mutualistic association of roots with ectomycorrhizal fungi promotes plant health and is a hallmark of boreal and temperate forests worldwide. In the pre-colonization phase, before direct contact, lateral root (LR) production is massively stimulated, yet little is known about the signals exchanged during this step. Here, we identify sesquiterpenes (SQTs) as biologically active agents emitted by Laccaria bicolor while interacting with Populus or Arabidopsis. We show that inhibition of fungal SQT production by lovastatin strongly reduces LR proliferation and that (-)-thujopsene, a low-abundance SQT, is sufficient to stimulate LR formation in the absence of the fungus. Further, we show that the ectomycorrhizal ascomycote, Cenococcum geophilum, which cannot synthesize SQTs, does not promote LRs. We propose that the LR-promoting SQT signal creates a win-win situation by enhancing the root surface area for plant nutrient uptake and by improving fungal access to plant-derived carbon via root exudates.},
	language = {en},
	number = {1},
	urldate = {2021-06-07},
	journal = {Nat Commun},
	author = {Ditengou, F. A. and Muller, A. and Rosenkranz, M. and Felten, J. and Lasok, H. and van Doorn, M. M. and Legue, V. and Palme, K. and Schnitzler, J. P. and Polle, A.},
	month = feb,
	year = {2015},
	note = {Edition: 2015/02/24},
	keywords = {*Sesquiterpenes, Arabidopsis, Ascomycota, Indoleacetic Acids/metabolism, Laccaria/*physiology, Mycorrhizae/*physiology, Plant Roots/*growth \& development/metabolism, Populus/*growth \& development, Superoxides/metabolism, Symbiosis, Volatile Organic Compounds},
	pages = {6279},
}

The mutualistic association of roots with ectomycorrhizal fungi promotes plant health and is a hallmark of boreal and temperate forests worldwide. In the pre-colonization phase, before direct contact, lateral root (LR) production is massively stimulated, yet little is known about the signals exchanged during this step. Here, we identify sesquiterpenes (SQTs) as biologically active agents emitted by Laccaria bicolor while interacting with Populus or Arabidopsis. We show that inhibition of fungal SQT production by lovastatin strongly reduces LR proliferation and that (-)-thujopsene, a low-abundance SQT, is sufficient to stimulate LR formation in the absence of the fungus. Further, we show that the ectomycorrhizal ascomycote, Cenococcum geophilum, which cannot synthesize SQTs, does not promote LRs. We propose that the LR-promoting SQT signal creates a win-win situation by enhancing the root surface area for plant nutrient uptake and by improving fungal access to plant-derived carbon via root exudates.

@article{vahala_genomewide_2013,
	title = {A genome‐wide screen for ethylene‐induced {Ethylene} {Response} {Factors} ( {\textless}span style="font-variant:small-caps;"{\textgreater}{ERF}{\textless}/span{\textgreater} s) in hybrid aspen stem identifies \textit{ {\textless}span style="font-variant:small-caps;"{\textgreater}{ERF}{\textless}/span{\textgreater} } genes that modify stem growth and wood properties},
	volume = {200},
	issn = {0028-646X, 1469-8137},
	shorttitle = {A genome‐wide screen for ethylene‐induced {Ethylene} {Response} {Factors} ( {\textless}span style="font-variant},
	url = {https://onlinelibrary.wiley.com/doi/10.1111/nph.12386},
	doi = {10/f2zvjg},
	language = {en},
	number = {2},
	urldate = {2021-06-08},
	journal = {New Phytologist},
	author = {Vahala, Jorma and Felten, Judith and Love, Jonathan and Gorzsás, András and Gerber, Lorenz and Lamminmäki, Airi and Kangasjärvi, Jaakko and Sundberg, Björn},
	month = oct,
	year = {2013},
	pages = {511--522},
}

@article{ranocha_arabidopsis_2013,
	title = {Arabidopsis {WAT1} is a vacuolar auxin transport facilitator required for auxin homoeostasis},
	volume = {4},
	issn = {2041-1723},
	url = {http://www.nature.com/articles/ncomms3625},
	doi = {10/f23w2p},
	language = {en},
	number = {1},
	urldate = {2021-06-08},
	journal = {Nature Communications},
	author = {Ranocha, Philippe and Dima, Oana and Nagy, Réka and Felten, Judith and Corratgé-Faillie, Claire and Novák, Ondřej and Morreel, Kris and Lacombe, Benoît and Martinez, Yves and Pfrunder, Stephanie and Jin, Xu and Renou, Jean-Pierre and Thibaud, Jean-Baptiste and Ljung, Karin and Fischer, Urs and Martinoia, Enrico and Boerjan, Wout and Goffner, Deborah},
	month = dec,
	year = {2013},
	pages = {2625},
}

@article{felten_ectomycorrhizal_2009,
	title = {The {Ectomycorrhizal} {Fungus} \textit{{Laccaria} bicolor} {Stimulates} {Lateral} {Root} {Formation} in {Poplar} and {Arabidopsis} through {Auxin} {Transport} and {Signaling}},
	volume = {151},
	issn = {1532-2548},
	url = {https://academic.oup.com/plphys/article/151/4/1991/6109870},
	doi = {10/dsjkhv},
	abstract = {Abstract
            The early phase of the interaction between tree roots and ectomycorrhizal fungi, prior to symbiosis establishment, is accompanied by a stimulation of lateral root (LR) development. We aimed to identify gene networks that regulate LR development during the early signal exchanges between poplar (Populus tremula × Populus alba) and the ectomycorrhizal fungus Laccaria bicolor with a focus on auxin transport and signaling pathways. Our data demonstrated that increased LR development in poplar and Arabidopsis (Arabidopsis thaliana) interacting with L. bicolor is not dependent on the ability of the plant to form ectomycorrhizae. LR stimulation paralleled an increase in auxin accumulation at root apices. Blocking plant polar auxin transport with 1-naphthylphthalamic acid inhibited LR development and auxin accumulation. An oligoarray-based transcript profile of poplar roots exposed to molecules released by L. bicolor revealed the differential expression of 2,945 genes, including several components of polar auxin transport (PtaPIN and PtaAUX genes), auxin conjugation (PtaGH3 genes), and auxin signaling (PtaIAA genes). Transcripts of PtaPIN9, the homolog of Arabidopsis AtPIN2, and several PtaIAAs accumulated specifically during the early interaction phase. Expression of these rapidly induced genes was repressed by 1-naphthylphthalamic acid. Accordingly, LR stimulation upon contact with L. bicolor in Arabidopsis transgenic plants defective in homologs of these genes was decreased or absent. Furthermore, in Arabidopsis pin2, the root apical auxin increase during contact with the fungus was modified. We propose a model in which fungus-induced auxin accumulation at the root apex stimulates LR formation through a mechanism involving PtaPIN9-dependent auxin redistribution together with PtaIAA-based auxin signaling.},
	language = {en},
	number = {4},
	urldate = {2021-06-08},
	journal = {Plant Physiology},
	author = {Felten, Judith and Kohler, Annegret and Morin, Emmanuelle and Bhalerao, Rishikesh P. and Palme, Klaus and Martin, Francis and Ditengou, Franck A. and Legué, Valérie},
	month = dec,
	year = {2009},
	pages = {1991--2005},
}

Abstract The early phase of the interaction between tree roots and ectomycorrhizal fungi, prior to symbiosis establishment, is accompanied by a stimulation of lateral root (LR) development. We aimed to identify gene networks that regulate LR development during the early signal exchanges between poplar (Populus tremula × Populus alba) and the ectomycorrhizal fungus Laccaria bicolor with a focus on auxin transport and signaling pathways. Our data demonstrated that increased LR development in poplar and Arabidopsis (Arabidopsis thaliana) interacting with L. bicolor is not dependent on the ability of the plant to form ectomycorrhizae. LR stimulation paralleled an increase in auxin accumulation at root apices. Blocking plant polar auxin transport with 1-naphthylphthalamic acid inhibited LR development and auxin accumulation. An oligoarray-based transcript profile of poplar roots exposed to molecules released by L. bicolor revealed the differential expression of 2,945 genes, including several components of polar auxin transport (PtaPIN and PtaAUX genes), auxin conjugation (PtaGH3 genes), and auxin signaling (PtaIAA genes). Transcripts of PtaPIN9, the homolog of Arabidopsis AtPIN2, and several PtaIAAs accumulated specifically during the early interaction phase. Expression of these rapidly induced genes was repressed by 1-naphthylphthalamic acid. Accordingly, LR stimulation upon contact with L. bicolor in Arabidopsis transgenic plants defective in homologs of these genes was decreased or absent. Furthermore, in Arabidopsis pin2, the root apical auxin increase during contact with the fungus was modified. We propose a model in which fungus-induced auxin accumulation at the root apex stimulates LR formation through a mechanism involving PtaPIN9-dependent auxin redistribution together with PtaIAA-based auxin signaling.