Dirk Inze

..Here, we review the molecular mechanisms that regulate cell division and endoreduplication and we discuss our understanding, albeit very limited, on how the cell cycle is integrated with plant development...

..These findings illustrate a cross talking mechanism between the G1-S and G2-M transition points...

..Hence, differentiation of the photosynthetic machinery is important for regulating the exit from proliferation...

....

..The data show that phosphorylation of the CDKA;1 site provokes a conformational change in the structure of KCA with implications in folding and dimerization...

..The lack of regulatory motifs in the upstream regions of the analyzed genes suggests the absence of a universal transcriptional control mechanism for all cell-cycle genes...

..Thus, photorespiratory H(2)O(2) has a direct impact on transcriptional programs in plants...

..The obtained interaction map constitutes a framework for further in-depth analysis of the cell cycle machinery...

..The genetic framework in which two successive auxin response modules control early steps of a developmental process adds an extra dimension to the complexity of auxin's action...

..We conclude that CCS52A1 participates in endocycle onset by down-regulating CDKB1;1 activity through the destruction of CYCA2;3...

..This work fits into an emerging view of DELLAs as regulators of cell division by regulating the transition to endoreduplication and differentiation...

..We demonstrate that these complexes promote cell proliferation in Arabidopsis and we discuss their putative mode of action in plant development...

..As E2Fe/DEL1 levels decreased upon UV-B treatment, we hypothesize that the coordinated transcriptional induction of PHR1 with the endoreduplication onset contributes to the adaptation of plants exposed to UV-B stress...

..Thus, transcriptional downregulation of CYCA2s represents a critical mechanism to coordinate proliferation during plant development...

..We conclude that cell division seems to occur independently from the status of cell expansion, whereas the cell cycle might act as a timer rather than as a size-regulated machinery...

..Based on the mutant characterization, we postulate that HUB1 mediates gene activation and cell cycle regulation probably through chromatin modifications...

..The analysis of transgenic lines simultaneously overexpressing two growth-enhancing genes further supports the concept that multiple pathways independently converge on organ size control in Arabidopsis...

..Moreover, the proposed model allowed a dynamical simulation of the in vivo observations, validating the sufficiency of the regulatory interactions between CDKA;1, KRP2, and CDKB1;1 in fine-tuning the mitosis-to-endocycle transition...

....

..Inactivation of SAMBA stabilized A2-type cyclins during early development. Our data suggest that SAMBA regulates cell proliferation during early development by targeting CYCLIN A2 for APC/C-mediated proteolysis...

..Nonetheless, the potential to partially recover the decreased cell numbers remains due to the activity of meristemoids. Together, these data present a conceptual framework to understand how environmental stress reduces plant growth...

..Mitotic divisions are observed only after the radicle has protruded and presumably rely on the de novo production of other cell cycle regulators...

..Thus, ACR4 function reveals a common mechanism of formative cell division control in the main root tip meristem and during lateral root initiation...

....

..Thus, we identified unknown spatiotemporal territories where functional cell cycle protein interactions are most likely to occur...

..This may point to a difference in the nature of the expansion process during the proliferating and non-dividing phase of leaf development...

..EB1 and Aurora, in addition to other regulatory proteins (homologs of Mob1, Sid1, and Sid2), were targeted to the nucleus, suggesting that this organelle operates as a coordinating hub for cytokinesis...

..In accordance, both the overexpression and silencing of CYCD5;1 were effective in changing DNA ploidy levels, confirming CYCD5;1 to be a previously undescribed quantitative trait gene underlying endoreduplication in Arabidopsis...

..Analogously, the atypical mammalian E2F7 protein was associated with the promoter of the APC/C-activating CDH1 gene, indicating that the transcriptional control of APC/C activator genes by atypical E2Fs might be evolutionarily conserved...

....

..We propose that plant type-I PHBs take part in protein complexes that are necessary for proficient mitochondrial function or biogenesis, thereby supporting cell division and differentiation in apical tissues...

..Our data indicate that the Elongator complex is evolutionarily conserved in structure and function but reveal that the mechanism by which it stimulates cell proliferation is different in yeast and plants...

..In addition, this study highlights the need for more thorough analysis of genes affecting seed yield...

....

..The latter groups increase the number of excellent candidates for new, direct E2F targets by almost twofold, from 181 to 334...

..These data suggest that TPLATE functions in vesicle-trafficking events required for site-specific cell wall modifications during pollen germination and for anchoring of the cell plate to the mother wall at the correct cortical position...

....

..Cohesion defects observed upon knockdown of its human counterpart suggest an equally important developmental role for the orthologous mammalian ETG1 protein...

..Our results provide evidence for the existence of at least two different input signals regarding JAZ1/TIFY10A expression and thus support the idea of an intimate molecular interplay between auxin and JA signalling...

..These data provide evidence that the plasma membrane is subject to localized endocytosis or membrane remodeling processes that are required for the fusion of the cell plate with a predefined region of the plasma membrane...

..This model can serve as a basis for future research, and prompts experimental approaches to encompass both measurements of cell growth and division parameters...

..Networks and associated evidence of the majority of currently available data types are visualized in Cytoscape. CORNET is available at https://bioinformatics.psb.ugent.be/cornet...

..The recent genome sequencing of Thalassiosira pseudonana and Phaeodactylum tricornutum allows us to explore the molecular conservation of cell cycle regulation in diatoms...

..This new insight reveals how stress-related and growth-related signalling cascades use common molecular mechanisms to regulate gene expression in plants...

..Therefore, we propose a threshold model in which the effect of the cell-cycle machinery on meristem organization is determined by the level of CDK activity...

..Our results show new interactions and contribute to the molecular and physiological understanding of biomass production at the whole plant level...

..Interestingly, based on molecular mass data of the unknown monomeric and dimeric substructures, at least 10 unknown monomeric units or interunit linkage types were observed, one of which was identified as an arylglycerol end unit...

..Cell divisions in the absence of a KDZ resulted in misplaced cell plates, suggesting that the PPB transmits a signal to the plasma membrane required for correct cell plate guidance and vesicular targeting to the cortical division site...

..This cysteine is absent in caspases and paracaspases but is conserved in all reported metacaspases...

..Also, spatial and temporal transcript detection in developing seeds suggests that Orysa;KRP1 plays an important role in the exit from the mitotic cell cycle during rice grain formation...

..Moreover, our data indicate that in addition to defense gene induction, sensitization of plants for potentiated gene expression might be an important factor in oxidative stress acclimation...

..Taken together, our data underline the value of analyzing stress responses in development and demonstrate the importance of mitochondrial respiration for sustaining cell proliferation under osmotic stress conditions...

....

..Lateral roots are formed at regular intervals along the main root by recurrent specification of founder cells. To date, the mechanism by which branching of the root system is controlled and founder cells become specified remains unknown...

..Therefore, we conclude that, in contrast to their specific roles in cortex/endodermis differentiation and stem cell maintenance in the root, SHR and SCR primarily function as general regulators of cell proliferation in leaves...

..Delivery of an auxin precursor in peripheral tissues such as the root cap might represent an important mechanism shaping root architecture...

....

..Our data suggest that within Arabidopsis, the genetic robustness of cell cycle-related processes is more due to functional redundancy than high selective constraint...

..In conclusion, proteomics using the (15)N labeling helped understand the mechanisms underlying growth adaptation to osmotic stress and allowed the identification of candidate genes to improve plant growth under limited water...

....

..Although division of stomatal precursors was inhibited, cells still acquired stomatal identity, illustrating that stomatal cell differentiation is independent of cellular and nuclear division...

....

..These fluctuations trigger transitions between the different stages of the cell cycle...

..annua plants. Analysis of phytohormone-modulated transcriptional regulons provides clues to dissect the concerted regulation of metabolism and development of plant trichomes...

....

....

....

..These findings indicate that development of LIMANI improves understanding of the interaction between vascular patterning and leaf growth...

..This work thereby provides a novel molecular mechanism for the regulation of the transition from cell division to expansion that controls organ growth and size...

..The expression of AtMAP65-4 peaked at mitosis, in agreement with a function related to spindle formation, whereas AtMAP65-1 and AtMAP65-5 were expressed throughout the cell cycle...

..This emphasizes that JA signal transduction is integrated into an elaborate signalling network...

..Although auxin is known to be involved in feeding site formation, our results suggest that, during early stages, auxin-independent signals might be at play to activate the initial expression of WRKY23...

..Moreover, networks and associated evidence are visualized in Cytoscape. Localization is visualized in pie charts, thereby allowing multiple localizations per protein. CORNET is available at http://bioinformatics.psb.ugent.be/cornet...

..We propose an alternative mechanism for polar auxin channeling, which is more consistent with recent molecular observations...

..This hitherto unknown role for TT8 in trichome formation further underscored the functional redundancy between the three TTG1-dependent bHLH proteins...

..Here, we discuss how intrinsic developmental signals and environmental cues affect cell-cycle entry and exit...

..Based on the altered CYCB1;1::uidA expression patterns in rcb root meristem, a model is proposed for RCB that mediates the tissue specificity of CYCB1;1 promoter activity...

..The opportunity to generate multiple and conditional knockouts in key regulators in the BR signaling pathway by bikinin represents a useful tool to further unravel regulatory mechanisms...

..Upregulation of the ANGUSTIFOLIA transcript in the strong drl1-2 allele supports this model...

..The review discusses recent developments in our understanding of the plant cell cycle machinery and highlights the role of the cell cycle in plant development...

..robusta is tightly regulated...

..Third, auxin signaling in the basal meristem triggers pericycle cells for lateral root initiation prior to the action of INDOLE-3-ACETIC ACID14 (SOLITARY ROOT)...

..This systemic approach provides new insights into the basic cell cycle control mechanisms and is generally applicable to other pathways in plants...

..The cell cycle is a point of control in both growth and development and deepening understanding of underlying processes and mechanisms may have many practical applications...

..These findings suggest that type II metacaspases are not directly responsible for earlier reported caspase-like activities in plants...

..Both cell proliferation and expansion are regulated by common signaling pathways involving gibberellins and DELLA proteins while down stream effector genes are stage specific...

....

....

....

..Both AtMC9 and AtSerpin1 were localized in the extracellular space, suggesting an in vivo interaction as well. To our knowledge, this is the first report of plant protease inhibition by a plant serpin...

..Furthermore, ex vivo scanning at sub-micron resolution allows the quantification and visualization of the cellular organization of plant tissue samples, making HRXCT a desired tool in developmental plant biology...