Biology subjects

Ohme-Takagi, M.

Publications and source records attributed to Ohme-Takagi, M..

3 recordsLinked to original sources

bioRxiv2025

TCP3-mediated regulation of cell expansion in Arabidopsis thaliana

(1) Cell expansion is crucial for organ morphogenesis in multicellular organisms. Apoplast acidification triggers plant cell expansion. Plant hormones and transcription factors such as TEOSINTE BRANCHED, CYCLOIDEA, and PROLIFERATING CELL NUCLEAR ANTIGEN BINDING FACTORs (TCPs) control cell expansion. However, details regarding the regulatory mechanism of cell expansion for organ morphogenesis remain unclear. (2) In this study, we used molecular, biochemical, cellular, genetic, atomic force microscopy, and tensile testing analyses and showed that miR319-targeted TCPs integrated cell expansion with organ morphogenesis in Arabidopsis thaliana. (3) We found that TCPs directly induce the expression of genes encoding cell wall loosening proteins and SMALL AUXIN UP RNAs (SAURs), activators of plasma membrane-localized H+-ATPases. TCP-mediated activation of plasma membrane- localized H+-ATPases stimulates apoplast acidification, reduce cell stiffness, promote cell expansion, and thus exaggerate elongation of the hypocotyl. Ectopic expression of a SAUR gene in sextuple tcp mutant plants substantially recovered the hypocotyl morphology of the tcp mutant, providing genetic evidence of TCP-mediated SAUR regulation. (4) Collectively, our data show that TCPs regulate apoplast acidification for cell expansion.

plant biology↗

bioRxiv2024

LATE MERISTEM IDENTITY2 regulates cuticle formation on the seed surface and influences seed longevity

The seed coat protects the embryo from severe external environment. Like the aerial plant parts, the exterior surface of the seed coat is surrounded by a cuticle consisting of lipid polyesters and wax. However, the protective role of the cuticle in mature seeds has not been characterized. We herein study the transcriptional regulation of cuticle formation on the seed surface, which influences seed longevity. A chimeric repressor of Arabidopsis thaliana R2R3 MYB transcription factor gene LATE MERISTEM IDENTITY2 (LMI2) and a Torenia fournieri ortholog (TfMYBML3) was expressed in A. thaliana and T. fournieri, respectively. These lines and A. thaliana LMI2 T-DNA insertion lines were analyzed for cuticle deficiencies. A. thaliana LMI2 mutants and chimeric repressor lines exhibited a similar cuticle deficiency in immature seeds. Transmission electron microscopy observations, polyester composition analyses, and gene expression investigations revealed that LMI2 plays an essential role in cuticle development in the seed coat epidermis by regulating cutin biosynthesis. The lmi2-2 mutant exhibited shorter seed longevity than the wild-type controls in an accelerated aging test. These results indicate that LMI2 is a key regulator of cuticle formation in the seed coat, and is important for maintaining seed longevity. Significance statementCuticle is well known to have multiple important roles for surviving in the terrestrial environment, but their specific role on the seed coat and transcriptional regulation have not yet been elucidated. Here we show that LATE MERISTEM IDENTITY 2, encoding a transcription factor regulating floral meristem transition, is required for seed cuticle formation and maintaining seed longevity, providing evidence for a link between surface cuticle and seed longevity.

plant biology↗

bioRxiv2017

Blue Light Negatively Regulates Tolerance to Phosphate Deficiency in Arabidopsis

Plants have evolved mechanisms to improve utilization efficiency or acquisition of inorganic phosphate (Pi) in response to Pi deficiency, such as altering root architecture, secreting acid phosphatases, and activating the expression of genes related to Pi uptake and recycling. Although many genes responsive to Pi starvation have been identified, transcription factors that affect tolerance to Pi deficiency have not been well characterized. We show here that defect in the ELONGATED HYPOCOTYL 5 (HY5) transcription factor gene results in tolerance to Pi deficiency in Arabidopsis. The primary root length of hy5 was only slightly inhibited under Pi deficient condition and its fresh weight was significantly higher than that of wild type. The Pi deficiency-tolerant phenotype of hy5 was similarly observed when grown on the medium without Pi. In addition, a double mutant, hy5slr1, without lateral roots also showed tolerance to phosphate deficiency, indicating that the tolerance of hy5 does not result from increase of external Pi uptake and may be related to internal Pi utilization or recycling. Moreover, we found that blue light negatively regulates tolerance to Pi-deficiency and that hy5 exhibits tolerance to Pi deficiency due to blockage of blue-light responses. Collectively, this study points out light quality may play an important role in the regulation of internal Pi recycling and utilization efficiency. Also, it may contribute to reducing Pi fertilizer requirements in plants through a proper illumination.

plant biology↗