TY - GEN A1 - Lenhard, Michael T1 - All's well that ends well BT - arresting cell proliferation in leaves T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - The transition from cell proliferation to cell expansion is critical for determining leaf size. Andriankaja et al. (2012) demonstrate that in leaves of dicotyledonous plants, a basal proliferation zone is maintained for several days before abruptly disappearing, and that chloroplast differentiation is required to trigger the onset of cell expansion. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 906 KW - arabidopsis-thaliana KW - genetic-control KW - growth KW - size KW - curvature Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-438035 SN - 1866-8372 IS - 906 SP - 9 EP - 11 ER - TY - JOUR A1 - Kierzkowski, Daniel A1 - Lenhard, Michael A1 - Smith, Richard A1 - Kuhlemeier, Cris T1 - Interaction between meristem tissue layers controls phyllotaxis JF - Developmental cell N2 - Phyllotaxis and vein formation are among the most conspicuous patterning processes in plants. The expression and polarization of the auxin efflux carrier PIN1 is the earliest marker for both processes, with mathematical models indicating that PIN1 can respond to auxin gradients and/or auxin flux. Here, we use cell-layer-specific PIN1 knockouts and partial complementation of auxin transport mutants to examine the interaction between phyllotactic patterning, which occurs primarily in the L1 surface layer of the meristem, and midvein specification in the inner tissues. We show that PIN1 expression in the L1 is sufficient for correct organ positioning, as long as the L1-specific influx carriers are present. Thus, differentiation of inner tissues can proceed without PIN1 or any of the known polar transporters. On theoretical grounds, we suggest that canalization of auxin flux between an auxin source and an auxin sink may involve facilitated diffusion rather than polar transport. Y1 - 2013 U6 - https://doi.org/10.1016/j.devcel.2013.08.017 SN - 1534-5807 SN - 1878-1551 VL - 26 IS - 6 SP - 616 EP - 628 PB - Cell Press CY - Cambridge ER - TY - JOUR A1 - Lenhard, Michael ED - Breuninger, Holger T1 - Expression of the central growth regulator BIG Brother is regulated by multiple cis-elements Y1 - 2012 UR - http://www.biomedcentral.com/content/pdf/1471-2229-12-41.pdf U6 - https://doi.org/10.1186/1471-2229-12-41 SN - 1471-2229 ER - TY - JOUR A1 - Eriksson, Sven A1 - Stransfeld, Lena A1 - Adamski, Nikolai Maria A1 - Breuninger, Holger A1 - Lenhard, Michael T1 - KLUH/CYP78A5-dependent growth signaling coordinates floral organ growth in Arabidopsis Y1 - 2010 SN - 0960-9822 ER - TY - JOUR A1 - Breuninger, Holger A1 - Lenhard, Michael T1 - Control of tissue and organ growth in plants Y1 - 2010 SN - 0070-2153 ER - TY - JOUR A1 - Vi, Son Lang A1 - Trost, Gerda A1 - Lange, Peggy A1 - Czesnick, Hjördis A1 - Rao, Nishta A1 - Lieber, Diana A1 - Laux, Thomas A1 - Gray, William M. A1 - Manley, James L. A1 - Groth, Detlef A1 - Kappel, Christian A1 - Lenhard, Michael T1 - Target specificity among canonical nuclear poly(A) polymerases in plants modulates organ growth and pathogen response JF - PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA N2 - Polyadenylation of pre-mRNAs is critical for efficient nuclear export, stability, and translation of the mature mRNAs, and thus for gene expression. The bulk of pre-mRNAs are processed by canonical nuclear poly(A) polymerase (PAPS). Both vertebrate and higher-plant genomes encode more than one isoform of this enzyme, and these are coexpressed in different tissues. However, in neither case is it known whether the isoforms fulfill different functions or polyadenylate distinct subsets of pre-mRNAs. Here we show that the three canonical nuclear PAPS isoforms in Arabidopsis are functionally specialized owing to their evolutionarily divergent C-terminal domains. A strong loss-of-function mutation in PAPS1 causes a male gametophytic defect, whereas a weak allele leads to reduced leaf growth that results in part from a constitutive pathogen response. By contrast, plants lacking both PAPS2 and PAPS4 function are viable with wild-type leaf growth. Polyadenylation of SMALL AUXIN UP RNA (SAUR) mRNAs depends specifically on PAPS1 function. The resulting reduction in SAUR activity in paps1 mutants contributes to their reduced leaf growth, providing a causal link between polyadenylation of specific pre-mRNAs by a particular PAPS isoform and plant growth. This suggests the existence of an additional layer of regulation in plant and possibly vertebrate gene expression, whereby the relative activities of canonical nuclear PAPS isoforms control de novo synthesized poly(A) tail length and hence expression of specific subsets of mRNAs. Y1 - 2013 U6 - https://doi.org/10.1073/pnas.1303967110 SN - 0027-8424 VL - 110 IS - 34 SP - 13994 EP - 13999 PB - NATL ACAD SCIENCES CY - WASHINGTON ER - TY - JOUR A1 - Breuninger, Holger A1 - Lenhard, Michael T1 - Expression of the central growth regulator BIG BROTHER is regulated by multiple cis-elements JF - BMC PLANT BIOLOGY N2 - Background: Much of the organismal variation we observe in nature is due to differences in organ size. The observation that even closely related species can show large, stably inherited differences in organ size indicates a strong genetic component to the control of organ size. Despite recent progress in identifying factors controlling organ growth in plants, our overall understanding of this process remains limited, partly because the individual factors have not yet been connected into larger regulatory pathways or networks. To begin addressing this aim, we have studied the upstream regulation of expression of BIG BROTHER (BB), a central growth-control gene in Arabidopsis thaliana that prevents overgrowth of organs. Final organ size and BB expression levels are tightly correlated, implying the need for precise control of its expression. BB expression mirrors proliferative activity, yet the gene functions to limit proliferation, suggesting that it acts in an incoherent feedforward loop downstream of growth activators to prevent over-proliferation. Results: To investigate the upstream regulation of BB we combined a promoter deletion analysis with a phylogenetic footprinting approach. We were able to narrow down important, highly conserved, cis-regulatory elements within the BB promoter. Promoter sequences of other Brassicaceae species were able to partially complement the A. thaliana bb-1 mutant, suggesting that at least within the Brassicaceae family the regulatory pathways are conserved. Conclusions: This work underlines the complexity involved in precise quantitative control of gene expression and lays the foundation for identifying important upstream regulators that determine BB expression levels and thus final organ size. Y1 - 2012 U6 - https://doi.org/10.1186/1471-2229-12-41 SN - 1471-2229 VL - 12 PB - BIOMED CENTRAL LTD CY - LONDON ER - TY - JOUR A1 - Sicard, Adrien A1 - Stacey, Nicola A1 - Hermann, Katrin A1 - Dessoly, Jimmy A1 - Neuffer, Barbara A1 - Bäurle, Isabel A1 - Lenhard, Michael T1 - Genetics, evolution, and adaptive significance of the selfing syndrome in the genus Capsella JF - The plant cell N2 - The change from outbreeding to selfing is one of the most frequent evolutionary transitions in flowering plants. It is often accompanied by characteristic morphological and functional changes to the flowers (the selfing syndrome), including reduced flower size and opening. Little is known about the developmental and genetic basis of the selfing syndrome, as well as its adaptive significance. Here, we address these issues using the two closely related species Capsella grandiflora (the ancestral outbreeder) and red shepherd's purse (Capsella rubella, the derived selfer). In C. rubella, petal size has been decreased by shortening the period of proliferative growth. Using interspecific recombinant inbred lines, we show that differences in petal size and flower opening between the two species each have a complex genetic basis involving allelic differences at multiple loci. An intraspecific cross within C. rubella suggests that flower size and opening have been decreased in the C. rubella lineage before its extensive geographical spread. Lastly, by generating plants that likely resemble the earliest ancestors of the C. rubella lineage, we provide evidence that evolution of the selfing syndrome was at least partly driven by selection for efficient self-pollination. Thus, our studies pave the way for a molecular dissection of selfing-syndrome evolution. Y1 - 2011 U6 - https://doi.org/10.1105/tpc.111.088237 SN - 1040-4651 VL - 23 IS - 9 SP - 3156 EP - 3171 PB - American Society of Plant Physiologists CY - Rockville ER - TY - JOUR A1 - Powell, Anahid E. A1 - Lenhard, Michael T1 - Control of organ size in plants JF - Current biology N2 - The size of plant organs, such as leaves and flowers, is determined by an interaction of genotype and environmental influences. Organ growth occurs through the two successive processes of cell proliferation followed by cell expansion. A number of genes influencing either or both of these processes and thus contributing to the control of final organ size have been identified in the last decade. Although the overall picture of the genetic regulation of organ size remains fragmentary, two transcription factor/microRNA-based genetic pathways are emerging in the control of cell proliferation. However, despite this progress, fundamental questions remain unanswered, such as the problem of how the size of a growing organ could be monitored to determine the appropriate time for terminating growth. While genetic analysis will undoubtedly continue to advance our knowledge about size control in plants, a deeper understanding of this and other basic questions will require including advanced live-imaging and mathematical modeling, as impressively demonstrated by some recent examples. This should ultimately allow the comparison of the mechanisms underlying size control in plants and in animals to extract common principles and lineage-specific solutions. Y1 - 2012 U6 - https://doi.org/10.1016/j.cub.2012.02.010 SN - 0960-9822 VL - 22 IS - 9 SP - R360 EP - R367 PB - Cell Press CY - Cambridge ER - TY - INPR A1 - Lenhard, Michael T1 - All's well that ends well arresting cell proliferation in leaves T2 - Developmental cell N2 - The transition from cell proliferation to cell expansion is critical for determining leaf size. Andriankaja et al. (2012) demonstrate that in leaves of dicotyledonous plants, a basal proliferation zone is maintained for several days before abruptly disappearing, and that chloroplast differentiation is required to trigger the onset of cell expansion. Y1 - 2012 U6 - https://doi.org/10.1016/j.devcel.2011.12.004 SN - 1534-5807 VL - 22 IS - 1 SP - 9 EP - 11 PB - Cell Press CY - Cambridge ER -