Coordination of meristem and boundary functions by transcription factors in the SHOOT MERISTEMLESS regulatory network

The Arabidopsis homeodomain transcription factor SHOOT MERISTEMLESS (STM) is crucial for shoot apical meristem (SAM) function, yet the components and structure of the STMgene regulatory network (GRN) are largely unknown. Here, we show that transcriptional regulators are overrepresented among STM-regulated genes and, using these as GRN components in Bayesian network analysis, we infer STM GRN associations and reveal regulatory relationships between STM and factors involved in multiple aspects of SAM function. These include hormone regulation, TCP-mediated control of cell differentiation, AIL/PLT-mediated regulation of pluripotency and phyllotaxis, and specification of meristem-organ boundary zones via CUC1. We demonstrate a direct positive transcriptional feedback loop between STM and CUC1, despite their distinct expression patterns in the meristem and organ boundary, respectively. Our further finding that STM activates expression of the CUC1-targeting microRNA miR164c combined with mathematical modelling provides a potential solution for this apparent contradiction, demonstrating that these proposed regulatory interactions coupled with STM mobility could be sufficient to provide a mechanism for CUC1 localisation at the meristem-organ boundary. Our findings highlight the central role for the STM GRN in coordinating SAM functions

Evaluation of physicochemical properties of black phosphorus nanosheets functionalized with PEG and glutathione stabilized doxorubicin drug-loaded gold nanoparticles for tumor target cancer therapy

静岡大学博士(工学)doctoral創造科学技術大学院甲第1288号application/pdfdoctoral thesi

Investigating the Roles of Three Aintegumenta-Like Genes In Maintenance of Arabidopsis Shoot Meristem Activity

The shoot apical meristem, a small dome-shaped structure at the shoot apex of higher plants, is established during development of the embryo. After germination, the indeterminate activity of the shoot apical meristem is responsible for the initiation of all aboveground parts of the plant. The shoot apical meristem continuously produces lateral organs on its periphery and provides cells to the elongating stem below the meristem while maintaining a small pluripotent stem cell population. Shoot meristem function is precisely regulated by the combined activities of genetic regulators and plant hormones. We have identified three novel regulators of shoot meristem activity in the model plant Arabidopsis thaliana. These three genes: AINTEGUMENTA (ANT), AINTEGUMENTA-LIKE6 (AIL6) and AINTEGUMENTA-LIKE7 (AIL7) encode related AIL/ PLT transcription factors. Loss of these genes results in plants that produce only a few abnormally-shaped leaves prior to termination of shoot meristem activity. Meristem termination is accompanied by reduced cell division in the meristem region, differentiation of meristematic cells and altered expression of the major meristem regulator genes WUSCHEL (WUS), CLAVATA3 (CLV3) and SHOOT MERISTEMLESS (STM). Genetic studies suggest that ANT, AIL6 and AIL7 do not act specifically in either of two major meristem regulatory pathways: one involving WUS and CLV genes and the other involving STM. Furthermore, these genetic results indicate that ANT, AIL6 and AIL7 have distinct functions within the meristem rather than acting in a strictly redundant manner. We also find that mutations in ANT, AIL6 and AIL7 alter plant hormone responses and/or accumulation although these changes are not strictly correlated with the meristem phenotype. Our study has thus identified three new genes whose distinct functions, perhaps in regulating hormone physiology, are together required for the indeterminate activity of the shoot apical meristem

<i>RNA Binding Motif Protein 48</i> is required for U12 splicing and maize endosperm differentiation

AbstractThe last eukaryotic common ancestor had two classes of introns that are still found in most eukaryotic lineages. Common U2-type and rare U12-type introns are spliced by the major and minor spliceosomes, respectively. Relatively few splicing factors have been shown to be specific to the minor spliceosome. We found that the maize RNA Binding Motif Protein48 (RBM48) is a U12 splicing factor that functions to promote cell differentiation and repress cell proliferation. RBM48 is coselected with the U12 splicing factor, ZRSR2/RGH3. Protein-protein interactions between RBM48, RGH3, and U2 Auxiliary Factor (U2AF) subunits suggest major and minor spliceosome factors may form complexes during intron recognition. Human RBM48 interacts with ARMC7. Maize RBM48 and ARMC7 have a conserved protein-protein interaction. These data predict that RBM48 is likely to function in U12 splicing throughout eukaryotes and that U12 splicing promotes endosperm cell differentiation in maize.</jats:p