@article{20080, abstract = {Introduction: Acid-growth theory has been postulated in the 70s to explain the rapid elongation of plant cells in response to the hormone auxin. More recently, it has been demonstrated that activation of the proton ATPs pump (H+-ATPs) promoting acidification of the apoplast is the principal mechanism by which auxin and other hormones such as brassinosteroids (BR) induce cell elongation. Despite these advances, the impact of this acidification on the mechanical properties of the cell wall remained largely unexplored. Methods: Here, we use elongation assays of Arabidopsis thaliana hypocotyls and Atomic Force Microscopy (AFM) to correlate hormone-induced tissue elongation and local changes in cell wall mechanical properties. Furthermore, employing transgenic lines over-expressing Pectin Methyl Esterase (PME), along with calcium chelators, we investigate the effect of pectin modification in hormone-driven cell elongation. Results: We demonstrate that acidification of apoplast is necessary and sufficient to induce cell elongation through promoting cell wall softening. Moreover, we show that enhanced PME activity can induce both cell wall softening or stiffening in extracellular calcium dependent-manner and that tight control of PME activity is required for proper hypocotyl elongation. Discussion: Our results confirm a dual role of PME in plant cell elongation. However, further investigation is needed to assess the status of pectin following short- or long-term PME treatments in order to determine if pectin methyl-esterification might promote its degradation as well as the role of PME inhibitors upon PME induction.}, author = {Gallemi, Marçal and Montesinos López, Juan C and Zarevski, Nikola and Pribyl, Jan and Skládal, Petr and Hannezo, Edouard B and Benková, Eva}, issn = {1664-462X}, journal = {Frontiers in Plant Science}, publisher = {Frontiers Media}, title = {{Dual role of pectin methyl esterase activity in the regulation of plant cell wall biophysical properties}}, doi = {10.3389/fpls.2025.1612366}, volume = {16}, year = {2025}, } @article{11589, abstract = {Calcium-dependent protein kinases (CPK) are key components of a wide array of signaling pathways, translating stress and nutrient signaling into the modulation of cellular processes such as ion transport and transcription. However, not much is known about CPKs in endomembrane trafficking. Here, we screened for CPKs that impact on root growth and gravitropism, by overexpressing constitutively active forms of CPKs under the control of an inducible promoter in Arabidopsis thaliana. We found that inducible overexpression of an constitutive active CPK30 (CA-CPK30) resulted in a loss of root gravitropism and ectopic auxin accumulation in the root tip. Immunolocalization revealed that CA-CPK30 roots have reduced PIN protein levels, PIN1 polarity defects and impaired Brefeldin A (BFA)-sensitive trafficking. Moreover, FM4-64 uptake was reduced, indicative of a defect in endocytosis. The effects on BFA-sensitive trafficking were not specific to PINs, as BFA could not induce aggregation of ARF1- and CHC-labeled endosomes in CA-CPK30. Interestingly, the interference with BFA-body formation, could be reverted by increasing the extracellular pH, indicating a pH-dependence of this CA-CPK30 effect. Altogether, our data reveal an important role for CPK30 in root growth regulation and endomembrane trafficking in Arabidopsis thaliana.}, author = {Wang, Ren and Himschoot, Ellie and Chen, Jian and Boudsocq, Marie and Geelen, Danny and Friml, Jiří and Beeckman, Tom and Vanneste, Steffen}, issn = {1664-462X}, journal = {Frontiers in Plant Science}, publisher = {Frontiers}, title = {{Constitutive active CPK30 interferes with root growth and endomembrane trafficking in Arabidopsis thaliana}}, doi = {10.3389/fpls.2022.862398}, volume = {13}, year = {2022}, } @article{8924, abstract = {Maintaining fertility in a fluctuating environment is key to the reproductive success of flowering plants. Meiosis and pollen formation are particularly sensitive to changes in growing conditions, especially temperature. We have previously identified cyclin-dependent kinase G1 (CDKG1) as a master regulator of temperature-dependent meiosis and this may involve the regulation of alternative splicing (AS), including of its own transcript. CDKG1 mRNA can undergo several AS events, potentially producing two protein variants: CDKG1L and CDKG1S, differing in their N-terminal domain which may be involved in co-factor interaction. In leaves, both isoforms have distinct temperature-dependent functions on target mRNA processing, but their role in pollen development is unknown. In the present study, we characterize the role of CDKG1L and CDKG1S in maintaining Arabidopsis fertility. We show that the long (L) form is necessary and sufficient to rescue the fertility defects of the cdkg1-1 mutant, while the short (S) form is unable to rescue fertility. On the other hand, an extra copy of CDKG1L reduces fertility. In addition, mutation of the ATP binding pocket of the kinase indicates that kinase activity is necessary for the function of CDKG1. Kinase mutants of CDKG1L and CDKG1S correctly localize to the cell nucleus and nucleus and cytoplasm, respectively, but are unable to rescue either the fertility or the splicing defects of the cdkg1-1 mutant. Furthermore, we show that there is partial functional overlap between CDKG1 and its paralog CDKG2 that could in part be explained by overlapping gene expression.}, author = {Nibau, Candida and Dadarou, Despoina and Kargios, Nestoras and Mallioura, Areti and Fernandez-Fuentes, Narcis and Cavallari, Nicola and Doonan, John H.}, issn = {1664-462X}, journal = {Frontiers in Plant Science}, publisher = {Frontiers}, title = {{A functional kinase is necessary for cyclin-dependent kinase G1 (CDKG1) to maintain fertility at high ambient temperature in Arabidopsis}}, doi = {10.3389/fpls.2020.586870}, volume = {11}, year = {2020}, } @article{7603, abstract = {Plants are exposed to a variety of abiotic and biotic stresses that may result in DNA damage. Endogenous processes - such as DNA replication, DNA recombination, respiration, or photosynthesis - are also a threat to DNA integrity. It is therefore essential to understand the strategies plants have developed for DNA damage detection, signaling, and repair. Alternative splicing (AS) is a key post-transcriptional process with a role in regulation of gene expression. Recent studies demonstrate that the majority of intron-containing genes in plants are alternatively spliced, highlighting the importance of AS in plant development and stress response. Not only does AS ensure a versatile proteome and influence the abundance and availability of proteins greatly, it has also emerged as an important player in the DNA damage response (DDR) in animals. Despite extensive studies of DDR carried out in plants, its regulation at the level of AS has not been comprehensively addressed. Here, we provide some insights into the interplay between AS and DDR in plants.}, author = {Nimeth, Barbara Anna and Riegler, Stefan and Kalyna, Maria}, issn = {1664-462X}, journal = {Frontiers in Plant Science}, publisher = {Frontiers}, title = {{Alternative splicing and DNA damage response in plants}}, doi = {10.3389/fpls.2020.00091}, volume = {11}, year = {2020}, } @article{7182, abstract = {During infection pathogens secrete small molecules, termed effectors, to manipulate and control the interaction with their specific hosts. Both the pathogen and the plant are under high selective pressure to rapidly adapt and co-evolve in what is usually referred to as molecular arms race. Components of the host’s immune system form a network that processes information about molecules with a foreign origin and damage-associated signals, integrating them with developmental and abiotic cues to adapt the plant’s responses. Both in the case of nucleotide-binding leucine-rich repeat receptors and leucine-rich repeat receptor kinases interaction networks have been extensively characterized. However, little is known on whether pathogenic effectors form complexes to overcome plant immunity and promote disease. Ustilago maydis, a biotrophic fungal pathogen that infects maize plants, produces effectors that target hubs in the immune network of the host cell. Here we assess the capability of U. maydis effector candidates to interact with each other, which may play a crucial role during the infection process. Using a systematic yeast-two-hybrid approach and based on a preliminary pooled screen, we selected 63 putative effectors for one-on-one matings with a library of nearly 300 effector candidates. We found that 126 of these effector candidates interacted either with themselves or other predicted effectors. Although the functional relevance of the observed interactions remains elusive, we propose that the observed abundance in complex formation between effectors adds an additional level of complexity to effector research and should be taken into consideration when studying effector evolution and function. Based on this fundamental finding, we suggest various scenarios which could evolutionarily drive the formation and stabilization of an effector interactome.}, author = {Alcântara, André and Bosch, Jason and Nazari, Fahimeh and Hoffmann, Gesa and Gallei, Michelle C and Uhse, Simon and Darino, Martin A. and Olukayode, Toluwase and Reumann, Daniel and Baggaley, Laura and Djamei, Armin}, issn = {1664-462X}, journal = {Frontiers in Plant Science}, number = {11}, publisher = {Frontiers}, title = {{Systematic Y2H screening reveals extensive effector-complex formation}}, doi = {10.3389/fpls.2019.01437}, volume = {10}, year = {2019}, }