@unpublished{21994, abstract = {Adaptive plant development is orchestrated, among others, by directional, intercellular transport of the phytohormone auxin. Self-organizing development, such as flexible vasculature formation, depends on so-called auxin canalization, manifested by the gradual formation of auxin transport channels through feedback between auxin signalling and transport. Herein, we identify MAKR6 as an important, novel component in this feedback. MAKR6 expression accumulates strongly in vascular cells and is tightly regulated by auxin via the Aux/IAA-ARF-WRKY23 transcriptional network. MAKR6 is required for auxin canalization-dependent processes, including leaf venation, vasculature regeneration, and de novo auxin channel formation from local auxin sources. Mechanistically, MAKR6 interacts with the PIN1 auxin transporter, modulating its trafficking and polarization. MAKR6 also associates with and integrates two key receptor-like kinase complexes involved in canalization, TMK1/4 and the CAMEL-CANAR. Together, our study establishes MAKR6 as a multifaceted regulator that couples transcriptional auxin signalling to PIN1 repolarization and coordinates multiple RLK-mediated signalling pathways during canalization. This provides mechanistic insights into auxin canalization and exemplifies a framework for exploring similar regulatory nodes in other developmental contexts.}, author = {Ge, Zengxiang and Koczka, Lilla and Mazur, Ewa and Molnar, Gergely and Vladimirtsev, Dmitrii and Kassem, Nada and Ait Ikene, Sara and Fiedler, Lukas and Friml, Jiří}, booktitle = {bioRxiv}, title = {{MAKR6 integrates TMK and CAMEL/CANAR signalling for auxin canalization in Arabidopsis}}, doi = {10.1101/2025.10.07.680881}, year = {2026}, } @phdthesis{20964, author = {Vladimirtsev, Dmitrii}, issn = {2791-4585}, pages = {22}, publisher = {Institute of Science and Technology Austria}, title = {{Armadillo repeat only proteins are master regulators of plant cyclic-nucleotide gated channels}}, doi = {10.15479/AT-ISTA-20964}, year = {2026}, } @article{21490, abstract = {Auxin canalization is a self-organizing process that governs the flexible formation of vasculature by reinforcing the formation of auxin transport channels. A key prerequisite is the feedback between auxin signaling and directional auxin transport, mediated by PIN transporters. Despite the developmental importance of canalization, the molecular components linking auxin perception to the regulation of PIN auxin transporters remain poorly understood. Here, we identify TOW, a novel and essential component of auxin canalization that links intracellular auxin signaling with cell surface auxin perception. TOW is regulated downstream of TIR1/AFB-Aux/IAA-WRKY23 transcriptional auxin signaling. tow mutants exhibit defects in regeneration and de novo vasculature formation, along with impaired formation of polarized, PIN-expressing auxin channels. At the subcellular level, these mutants display disrupted auxin-induced PIN polarization and altered PIN endocytic trafficking dynamics. TOW localizes predominantly to the plasma membrane, where it interacts with receptor-like kinases involved in auxin canalization, including the TMK1 auxin co-receptor and the CAMEL-CANAR complex. TOW promotes PIN interaction with these kinases and stabilizes PINs at the cell surface. Together, our findings identify TOW as a molecular link between intracellular and cell surface auxin signaling mechanisms that converge on PIN trafficking and polarity, providing new insights into how auxin signaling regulates directional auxin transport for the self-organizing formation of vasculature during flexible plant development.}, author = {Li, Mingyue and Rydza, Nikola and Mazur, Ewa and Molnar, Gergely and Nodzyński, Tomasz and Friml, Jiří}, issn = {0960-9822}, journal = {Current Biology}, number = {6}, pages = {1468--1480.e6}, publisher = {Elsevier}, title = {{Receptor-like-kinase-interacting protein TOW stabilizes PIN transporters for auxin canalization}}, doi = {10.1016/j.cub.2026.02.023}, volume = {36}, year = {2026}, } @article{21763, abstract = {Reactive oxygen species (ROS) have been implicated in multiple signaling processes in plants, but the underlying mechanisms and roles remain enigmatic. In this study, we developed a method of live imaging of apoplastic ROS at the root surface. Distinct signals, including auxin, extracellular adenosine triphosphate, and rapid alkalinization factor 1 peptide, induce cytosolic calcium transients and apoplastic ROS bursts. Genetic and optogenetic manipulations of Arabidopsis identified calcium transients as necessary and sufficient for ROS bursts through activation of reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidases RBOHC and RBOHF. Apoplastic ROS bursts are not required, but they do limit gravity-induced root bending. Root bending is sensed by the stretch-activated calcium channel MCA1, leading to NADPH oxidase activation. The resulting ROS production stiffens cell walls to facilitate soil penetration. Apoplastic ROS thus provides a means to balance tissue flexibility and stiffness to navigate soil.}, author = {Kulich, Ivan and Vladimirtsev, Dmitrii and Randuch, Marek and Gao, Shiqiang and Citterico, Matteo and Konrad, Kai R. and Nagel, Georg and Wrzaczek, Michael and Cascaro, Léa and Vinet, Pauline and Durand, Pauline and Asnacios, Atef and Verma, Lokesh and Bennett, Malcolm J. and Pandey, Bipin K. and Friml, Jiří}, issn = {1095-9203}, journal = {Science}, number = {6795}, pages = {296--300}, publisher = {AAAS}, title = {{Calcium-triggered apoplastic ROS bursts balance gravity and mechanical signals for soil navigation}}, doi = {10.1126/science.adu8197}, volume = {392}, year = {2026}, } @article{21914, abstract = {Cyclic adenosine monophosphate (cAMP) is a fundamental second messenger involved in diverse signaling pathways across both animals and plants. While the role of 3′,5′-cAMP has been extensively characterized, the biological significance of its structural isomer, 2′,3′-cAMP, remains largely unexplored, particularly in plants. Here, we show that 2′,3′-cAMP and 3′,5′-cAMP represent parallel signaling systems in Arabidopsis thaliana, with different enzymatic origins and largely distinct downstream effects. In vitro enzymatic assays show that plant adenylate cyclases (ACs), including AFB5 and HpAC1, produce specifically 3′,5′-cAMP from ATP, whereas the TIR domain of protein L7 also catalyzes the formation of 2′,3′-cAMP from RNA. Comprehensive multiomics analyses reveal that two isomers elicit distinct yet partially overlapping metabolic, proteomic, and transcriptional response: 2′,3′-cAMP activates broad, stress-adaptive gene expression reprogramming, while 3′,5′-cAMP fine-tunes responses related to nutrient status and cellular homeostasis. Our findings establish the existence of dual cAMP signaling systems in plants, each with specialized functions and provide insights into the complex regulatory networks governing plant physiology.}, author = {Li, Mingyue and Chodasiewicz, Monika and Muraleedharan, Malavika and Lopez, Israel M. and Gorka, Michal and Kerber, Olga and Alotaibi, Saqer S. and Nelson, Andrew D.L. and Lenobel, Rene and Friedecká, Jaroslava and Skirycz, Aleksandra and Friml, Jiří}, issn = {2375-2548}, journal = {Science Advances}, number = {19}, publisher = {AAAS}, title = {{Biogenesis and downstream effects of 3',5' and 2',3' cAMP isomers in plants}}, doi = {10.1126/sciadv.aea7828}, volume = {12}, year = {2026}, } @inbook{22293, abstract = {In order to cope with arid terrestrial environments, angiosperms have evolved a unique fertilization way—siphonogamy. The success of siphonogamy requires several prerequisites, including the normal development of the female gametophyte and male gametophyte (pollen). Appropriate pollination methods ensure the successful encounter between pollen and the stigma. After pollen lands on the stigma, pollen/pollen tube interacts with different tissues and cells of the pistil, completing a series of male-female communications. The smooth progress of these interactions ensures that the pollen tube can enter the female gametophyte, burst, and release sperm cells to complete the double fertilization. In this chapter, we provide an overview of pollination and the interactions between male and female, comprehensively summarizing the factors involved in these processes.}, author = {Zhong, Sheng and Lan, Zijun and Ge, Zengxiang and Qu, Li-Jia}, booktitle = {Regulation of Plant Development}, editor = {Chang, Fang and Wang, Yingxiang and Ma, Hong}, isbn = {9789819570324}, pages = {537--615}, publisher = {Springer Nature}, title = {{Pollination and Fertilization}}, doi = {10.1007/978-981-95-7033-1_14}, year = {2026}, } @article{22301, abstract = {Auxin, primarily indole-3-acetic acid (IAA), is a central regulator of growth and development in land plants, but its physiological role in chlorophyte algae remains unclear. Here, we show that exogenous IAA modulates growth in Chlorella sorokiniana, Chlorella variabilis, and Chlamydomonas reinhardtii in a concentration-dependent manner. Low IAA concentrations promoted growth by accelerating the onset of cell division without affecting cell size, whereas higher concentrations inhibited proliferation. Radiotracer assays showed that all three species take up and release IAA across the plasma membrane through a combination of passive diffusion and energy-dependent, saturable processes. Competition by excess unlabeled natural and synthetic auxins further supported the presence of carrier-mediated transport with broad substrate recognition. Phylogenetic analyses identified potential PIN-like auxin exporters in chlorophytes and other non-plant eukaryotes, and structural modeling supported conservation of the overall PIN fold and predicted auxin-binding residues. However, functional assays in Xenopus laevis oocytes, tobacco BY-2 cultured cells, and Arabidopsis thaliana did not support a role for these proteins in directional auxin export. Instead, non-plant PIN homologs localized predominantly to the endoplasmic reticulum and showed limited or no transport activity in heterologous systems. Together, these findings indicate that auxin responsiveness and basic cellular auxin transport predate canonical PIN-mediated directional auxin export, which appears to be a later innovation of the streptophyte lineage.}, author = {Smoljan, Adrijana and Koutnik‐Abele, Sarah and Vladimirtsev, Dmitrii and Klíma, Petr and Bírošíková, Anita and Zhang, Yuzhou and Merrin, Jack and Schuster, Maximilian and Kurtović, Katarina and Hammes, Ulrich Z. and Petrášek, Jan and Friml, Jiří}, issn = {1744-7909}, journal = {Journal of Integrative Plant Biology}, publisher = {Wiley}, title = {{Auxin response and PIN‐mediated transport in chlorophyte algae}}, doi = {10.1111/jipb.70309}, year = {2026}, } @article{22366, abstract = {Gravitropism is a fundamental adaptive response in plants that enables directional growth to optimize resource acquisition. In this study, we employed forward genetic screening to identify Arabidopsis mutants with defective hypocotyl gravitropism and isolated the short and agravitropic hypocotyl in dark1 (sad1) mutant, which carries a point mutation (G110E) in the SAC1 gene encoding a phosphoinositide phosphatase. Deficiency of SAC1 disrupted gravity-induced polar localization of PIN3 in endodermal cells, impairing auxin redistribution and leading to hypocotyl gravitropism defects. Subcellular localization analysis revealed that SAC1 is partially localized to the PVC/tonoplast and participates in late endosomal trafficking. The sac1 mutation leads to abnormal vacuolar morphology, which is associated with defects in amyloplast sedimentation during the gravitropic response in Arabidopsis shoots. We further revealed that SAC1 interacts with GRV2, a key regulator of the late endocytic pathway, and that both proteins cooperatively regulate shoot gravitropism. In summary, this study identified SAC1 as a regulator of shoot gravitropism, revealing its important role in modulating vacuolar homeostasis, amyloplast sedimentation, PIN3 trafficking, and auxin distribution. These findings provide insights into the molecular mechanisms linking membrane transport to environmental adaptation in plants.}, author = {Sun, Lianghanxiao and Jia, Wenxin and Mao, Yanbo and Li, Xin and Kong, Mengjuan and She, Ji and Friml, Jiří and Tan, Shutang}, issn = {1365-313X}, journal = {The Plant Journal}, keywords = {auxin, SAC1, GRV2, PIN3, vacuole, gravitropism, Arabidopsis}, number = {1}, publisher = {Wiley}, title = {{Regulation of shoot gravitropism and branching angle by the GRV2-SAC1 axis in Arabidopsis}}, doi = {10.1111/tpj.71042}, volume = {127}, year = {2026}, } @article{20725, abstract = {The canonical mechanism by which the phytohormone auxin regulates transcription has been one of the cornerstones of plant signaling. The recent unexpected discovery of cyclic AMP (cAMP) as a second messenger in this pathway has revised its foundations while leaving many open questions and gaps in our understanding; these will be discussed in this forum article.}, author = {Friml, Jiří}, issn = {1878-4372}, journal = {Trends in Plant Science}, number = {2}, pages = {136--138}, publisher = {Elsevier}, title = {{Role of cAMP in TIR1/AFB auxin signaling: Open issues}}, doi = {10.1016/j.tplants.2025.10.018}, volume = {31}, year = {2026}, } @article{20636, abstract = {The versatile and pivotal roles of the phytohormone auxin in regulating plant growth and development are typically linked to its directional transport, relying on the polarized PIN-FORMED (PIN) auxin exporters at the plasma membrane (PM). For decades, auxin has been proposed to promote PIN polarization, generating self-regulatory feedback mediating much of plant development, but mechanistic insight into this regulation is lacking. Here, we uncover an auxin-induced protein complex at the PM, containing auxin co-receptors transmembrane kinases (TMKs) and PIN1 auxin exporter, as the core machinery that underlies this feedback regulation. Auxin promotes PIN1 phosphorylation by TMKs, modulating PIN1 polarization and transport activity. We also provide evidence that PIN1-exported extracellular auxin is crucial for TMK activation and cell elongation, thus forming the simplest two-element self-regulatory feedback circuit. Thus, these findings offer direct mechanistic insights into a potential self-organizing circuit for auxin signaling and transport to ensure proper plant development in Arabidopsis.}, author = {Huang, R and Wang, J and Chang, M and Tang, W and Yu, Y and Zhang, Y and Peng, Y and Wang, Y and Guo, Y and Lu, T and Cao, Y and Zhou, Y and Zhang, Q and Huang, Y and Wu, A and Ren, L and Gallei, Michelle C and Dong, J and Chen, H and He, J and Wen, M and Friml, Jiří and Sun, L and Xiong, Y and Yang, Z and Xu, T}, issn = {1878-1551}, journal = {Developmental Cell}, number = {1}, pages = {73--84}, publisher = {Elsevier}, title = {{TMK-PIN1 drives a short self-organizing circuit for auxin export and signaling in Arabidopsis}}, doi = {10.1016/j.devcel.2025.09.009}, volume = {61}, year = {2026}, } @article{20818, abstract = {This study demonstrates that Marchantia non-canonical PINs are predominantly localized to the plasma membrane, with MpPINX and MpPINW exhibiting asymmetric distribution. A newly identified miniW domain within the MpPINW hydrophilic loop governs subcellular trafficking and asymmetric PM localization of non-canonical PINs in Marchantia.}, author = {Tang, Han and Smoljan, Adrijana and Zou, Minxia and Zhang, Yuzhou and Lu, Kuan Ju and Friml, Jiří}, issn = {1365-3040}, journal = {Plant Cell and Environment}, number = {3}, pages = {1505--1508}, publisher = {Wiley}, title = {{The miniW domain directs polarized membrane localization of non-canonical PINs in Marchantia polymorpha}}, doi = {10.1111/pce.70295}, volume = {49}, year = {2026}, } @article{21483, abstract = {Embryogenesis in the model plant Arabidopsis thaliana provides a framework for understanding how cell polarity and patterning coordinate with hormonal signalling to establish the plant body plan. Following fertilisation, the zygote divides asymmetrically to generate apical and basal lineages, establishing the apical–basal axis that defines future shoot and root poles. Genetic and molecular analyses of classical mutants including gnom, monopteros (mp), bodenlos (bdl) and topless revealed that localised auxin biosynthesis, directional transport and downstream transcriptional responses are central to apical–basal axis establishment and organ initiation. The main components of this regulation are polarly localised PIN auxin transporters and downstream modules involving MONOPTEROS and WUSCHEL-RELATED HOMEOBOX transcription factors. Advances in microscopy have transformed the study of Arabidopsis embryogenesis: fluorescence-compatible clearing reagents and three-dimensional reconstructions now permit quantitative analyses of cell geometry, division orientation, and cytoskeletal dynamics. Live ovule imaging setups with confocal laser scanning and multiphoton microscopes enable real-time observation of embryo development, while laser-assisted cell ablation can be used to probe cell-to-cell communication and fate plasticity. Together, these methodological breakthroughs position Arabidopsis embryos as a prime model for dissecting the chemical and biophysical cues that shape plant development.}, author = {Babic, David and Zupunski, Milan and Friml, Jiří}, issn = {1469-8137}, journal = {New Phytologist}, number = {3}, pages = {1483--1491}, publisher = {Wiley}, title = {{Imaging and genetic toolbox to study Arabidopsis embryogenesis}}, doi = {10.1111/nph.71072}, volume = {250}, year = {2026}, } @article{22647, abstract = {Within the plant endomembrane system, the vesicle coat protein clathrin localizes to the plasma membrane (PM) and the trans-Golgi Network/early endosome (TGN/EE). While the role of clathrin in endocytosis at the PM is well established, its function at TGN/EE, presumably in late secretion (trafficking from the TGN/EE to the cell surface) or en route to the vacuole, is debated. Similarly debated are potential homeostatic mechanisms balancing the trafficking routes, especially endocytosis and late secretion. We address these questions in Arabidopsis thaliana using conditional silencing of CLATHRIN HEAVY CHAIN (CHC), conditional overexpression of the clathrin uncoating factor AUXILIN-LIKE1, and secretory mutants. CHC silencing interferes with trafficking of cargoes destined for the apoplast and the PM, supporting a function of clathrin in late secretion. The secretory cargoes become abnormally rerouted from the TGN/EE to the vacuole. Unlike CHC silencing, overexpression of AUXILIN-LIKE1 selectively inhibits clathrin-mediated endocytosis while secretion continues normally at early points of induction. Conversely, secretory mutants exhibit a reduced PM recruitment of clathrin, and variably, of the TPLATE endocytic component. Together, our data show a role of clathrin in secretion and suggest secretion as a fundamental trafficking process to which endocytosis is adjusted by a weak homeostatic mechanism.}, author = {Adamowski, Maciek and Gackowski, Adam and Matijevic, Ivana and Alotaibi, Saqer S. and Friml, Jiří}, issn = {1469-8137}, journal = {New Phytologist}, publisher = {Wiley}, title = {{The role of clathrin in post‐Golgi secretion in plant cells}}, doi = {10.1111/nph.71454}, year = {2026}, } @article{22315, abstract = {Plant tropisms enable roots to navigate complex soils by responding to directional environmental cues. Biological decay, although central to nutrient cycling, also creates microbially active and potentially hostile niches. In this work, we identified “saprotropism,” a previously unrecognized growth response that enables roots to actively bend away from decaying plant-derived matter. Fungal-driven microbial decomposition released organic acids and formed stable pH gradients in surrounding soil, allowing roots to pinpoint decay without direct contact. Root epidermal cells sensed this acidic gradient through the root meristem growth factor peptide-receptor module, converting external pH asymmetry into asymmetric abscisic acid (ABA) distribution. ABA asymmetry drove microtubule reorganization, which was decoded into decay-avoidant root bending. Together, these findings establish microbial decay–derived chemical gradients as an instructive signal for root navigation and expand the framework of microbe-soil-plant communication.}, author = {Bao, Zhulatai and Wang, Huihui and Zhang, Ai and Gao, Ruxi and Gu, Wen and Fan, Ni and Friml, Jiří and Zhang, Yuzhou}, issn = {1095-9203}, journal = {Science}, number = {6807}, publisher = {American Association for the Advancement of Science}, title = {{Roots navigate around decay regions by sensing local pH gradients}}, doi = {10.1126/science.adw6568}, volume = {393}, year = {2026}, } @article{22712, abstract = {Ginseng (Panax ginseng) derives its renowned therapeutic properties from ginsenoside metabolites. However, the long cultivation cycle and susceptibility to diseases hinder the advancement of the ginseng industry. Here, we demonstrate that the embryonic protoderm of ginseng can efficiently produce ginsenosides. Single-cell transcriptome and mass spectrometry imaging analyses reveal that ginsenosides accumulate in the protoderm of ginseng embryonic callus (EC) at levels comparable to those in forest ginseng. Epigenetic analyses indicate that elevated histone acetylation and enhanced chromatin accessibility at regeneration- and ginsenoside metabolism-related gene loci are associated with the ginsenoside-producing capacity of EC. Increasing histone acetylation levels or overexpressing the regeneration-related WUSCHEL-RELATED HOMEOBOX11 (WOX11) gene further enhances ginsenoside production in EC. Our findings suggest that the protoderm of EC could serve as an in situ biological compartment for high-efficiency ginsenoside producion, offering a complementary approach to traditional ginseng cultivation.}, author = {Liu, Juan and Zhai, Ning and Zhang, Shiyi and Tamada, Yosuke and Li, Tonghui and Zhang, Linfan and Chen, Tong and Wang, Chenglin and Yang, Jian and Gao, Jiaqi and Li, Xiang and Zhou, Junhui and Zhang, Yonghong and Liu, Yu and Wang, Yuan and Friml, Jiří and Benková, Eva and Li, Chen and Xu, Lin and Huang, Luqi}, issn = {2041-1723}, journal = {Nature Communications}, publisher = {Springer Nature}, title = {{Single-cell analyses identify the ginseng embryonic protoderm as a native compartment for high-efficiency ginsenoside production}}, doi = {10.1038/s41467-026-74881-5}, volume = {17}, year = {2026}, } @unpublished{20982, abstract = {Plant cells respond to a wide range of stimuli through intracellular calcium (Ca2+) signaling. Cyclic nucleotide-gated channels (CNGCs) are a major class of plant Ca2+ channels, with 20 homologs in Arabidopsis. These tetrameric plasma membrane proteins act downstream of diverse signals, such as phytohormones, extracellular damage, cell wall integrity or temperature. Here, we identify a class of plant-specific proteins, Armadillo Repeat Only (ARO), as essential regulators of possibly all plant CNGCs. Abrogation of functional sporophytic AROs results in a phenotypic pattern strongly reminiscent of CNGC dysfunction, including defects in root gravitropism, root hair growth and morphology, stomatal movement, and responses to extracellular ATP and the phytohormone auxin. aro2/3/4 mutants are fully resistant to the toxic effects caused by overexpression of CNGCs. AROs colocalize and physically interact with multiple CNGCs and modulate CNGC-dependent currents in Xenopus oocytes. Structural modeling and site-directed mutagenesis reveal AROs tetramer formation surrounding the CNGC channel, interacting via its IQ domain. Taken together, plant CNGC channels don’t act alone, but in a larger complex - channelosome, first of a kind in plants.}, author = {Kulich, Ivan and Oulehlová, Denisa and Vladimirtsev, Dmitrii and Zou, Minxia and Lileikyte, Edita and Bondar, Alexey and Kulichová, Katarína and Janda, Martin and Iakovenko, Oksana and Neubergerová, Michaela and Studtrucker, Tanja and Pleskot, Roman and Dietrich, Petra and Fendrych, Matyas and Friml, Jiří}, booktitle = {bioRxiv}, title = {{Armadillo repeat only proteins are required for the function of plant CNGC channels}}, doi = {10.1101/2025.01.06.631460}, year = {2025}, } @article{21136, abstract = {The plant hormone auxin regulates growth and development through at least two distinct signaling pathways. The nuclear pathway, involving TIR1/AFB receptors, mediates transcription; whereas the cell surface ABP1-TMK1 auxin perception triggers global ultrafast phosphorylation response. Here, we revisit the rich history of the disputed ABP1 auxin receptor, highlighting recent findings of the involvement of TMKs and other molecular components and focusing on their role in auxin canalization-mediated development.}, author = {Monzer, Aline and Friml, Jiří}, issn = {3005-1401}, journal = {npj Science of Plants}, number = {1}, pages = {2}, publisher = {Springer Nature}, title = {{Historical and mechanistic perspective on ABP1-TMK1-mediated cell surface auxin signaling.}}, doi = {10.1038/s44383-025-00002-8}, volume = {1}, year = {2025}, } @inbook{21255, abstract = {As an important plant hormone to regulate growth and development, auxin has been investigated for more than a century. It had been clearly demonstrated and well-accepted that the intracellular auxin receptors, TIR1/AFBs, are F-box proteins mediating transcriptional auxin signaling by their E3 ubiquitin ligase activity, which targets and sends for degradation the Aux/IAA transcriptional repressors. The recent discovery of adenylate cyclase (AC) and guanylate cyclase (GC) activities for TIR1/AFBs open entirely new perspectives on how auxin signaling can operate. This chapter traces back the history of how canonical transcriptional auxin signaling was established and introduces the discovery of the TIR1/AFBs-mediated nontranscriptional signaling branch. Finally, the current understanding and open questions of how TIR1/AFBs’ AC and GC activities contribute to the transcriptional and nontranscriptional auxin signaling are discussed, highlighting the possibility that cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) act as second messengers in auxin signal transduction.}, author = {Qi, Linlin and Friml, Jiří}, booktitle = {Cryptic Enzymes and Moonlighting Proteins}, editor = {Irving, Helen and Gehring, Chris and Wong, Aloysius}, isbn = {9780443157196}, pages = {299--322}, publisher = {Elsevier}, title = {{Nucleotidyl cyclase activities of TIR1/AFB auxin receptors: new insights into the mechanism of auxin signaling}}, doi = {10.1016/b978-0-443-15719-6.00015-5}, year = {2025}, } @article{18619, abstract = {Brassinosteroids (BRs) are steroidal phytohormones indispensable for plant growth, development, and responses to environmental stresses. The export of bioactive BRs to the apoplast is essential for BR signalling initiation, which requires binding of BR molecule to the extracellular domains of the plasma membrane-localized receptor complex. We have previously shown that the Arabidopsis thaliana ATP-binding cassette (ABC) transporter, ABCB19, functions as a BR exporter, and together with its close homologue, ABCB1, positively regulate BR signalling. Here, we demonstrate that ABCB1 is another BR transporter. The ATP hydrolysis activity of ABCB1 was stimulated by bioactive BRs, and its transport activity was confirmed in proteoliposomes and protoplasts. Structures of ABCB1 in substrate-unbound (apo), brassinolide (BL)-bound, and ATP plus BL-bound states were determined. In the BL-bound structure, BL was bound to the hydrophobic cavity formed by the transmembrane domain, and triggered local conformational changes. Together, our data provide additional insights into the ABC transporter-mediated BR export.}, author = {Wei, H and Zhu, H and Ying, W and Janssens, H and Kvasnica, M and Winne, JM and Gao, Y and Friml, Jiří and Ma, Q and Tan, S and Liu, X and Russinova, E and Sun, L}, issn = {2590-3462}, journal = {Plant Communications}, number = {1}, publisher = {Elsevier}, title = {{Structural insights into brassinosteroid export mediated by the Arabidopsis ABC transporter ABCB1}}, doi = {10.1016/j.xplc.2024.101181}, volume = {6}, year = {2025}, } @article{19003, abstract = {Super-resolution methods provide far better spatial resolution than the optical diffraction limit of about half the wavelength of light (∼200-300 nm). Nevertheless, they have yet to attain widespread use in plants, largely due to plants’ challenging optical properties. Expansion microscopy improves effective resolution by isotropically increasing the physical distances between sample structures while preserving relative spatial arrangements and clearing the sample. However, its application to plants has been hindered by the rigid, mechanically cohesive structure of plant tissues. Here, we report on whole-mount expansion microscopy of thale cress (Arabidopsis thaliana) root tissues (PlantEx), achieving a four-fold resolution increase over conventional microscopy. Our results highlight the microtubule cytoskeleton organization and interaction between molecularly defined cellular constituents. Combining PlantEx with stimulated emission depletion (STED) microscopy, we increase nanoscale resolution and visualize the complex organization of subcellular organelles from intact tissues by example of the densely packed COPI-coated vesicles associated with the Golgi apparatus and put these into a cellular structural context. Our results show that expansion microscopy can be applied to increase effective imaging resolution in Arabidopsis root specimens. }, author = {Gallei, Michelle C and Truckenbrodt, Sven M and Kreuzinger, Caroline and Inumella, Syamala and Vistunou, Vitali and Sommer, Christoph M and Tavakoli, Mojtaba and Agudelo Duenas, Nathalie and Vorlaufer, Jakob and Jahr, Wiebke and Randuch, Marek and Johnson, Alexander J and Benková, Eva and Friml, Jiří and Danzl, Johann G}, issn = {1532-298X}, journal = {The Plant Cell}, number = {4}, publisher = {Oxford University Press}, title = {{Super-resolution expansion microscopy in plant roots}}, doi = {10.1093/plcell/koaf006}, volume = {37}, year = {2025}, }