Biology subjects

Mitsuda, N.

Publications and source records attributed to Mitsuda, N..

8 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↗

bioRxiv2025

Ethylene modulates cell wall mechanics for root responses to compaction

Soil stresses impact crop yields, presenting global agricultural challenges. Soil compaction triggers root length reduction and radial expansion driven by the plant hormone ethylene. We report how ethylene controls cell wall properties to promote root radial expansion. We demonstrate how soil compaction stress, via ethylene, upregulates Auxin Response Factor1 in the root cortex, which represses Cellulose Synthase (CESA) genes. CESA repression drives radial expansion of root cortical cells by modifying the thickness and mechanics of their cell walls, which result in a "stiff epidermis-soft cortex" contrast. Our research thus connects ethylene signaling with root mechanics via cell wall strength, and reveals how dynamic regulation of cellulose synthesis crucially controls root growth in compacted soil.

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↗

bioRxiv2024

Florigen-producing cells express FPF1-LIKE PROTEIN 1 that accelerates flowering and stem growth in long days with sunlight red/far-red ratio in Arabidopsis

Seasonal changes in spring induce flowering by expressing the florigen, FLOWERING LOCUS T (FT), in Arabidopsis. FT is expressed in unique phloem companion cells with unknown characteristics. The question of which genes are co-expressed with FT and whether they have roles in flowering remains elusive. Through tissue-specific translatome analysis, we discovered that under long-day conditions with the natural sunlight red/far-red ratio, the FT-producing cells express a gene encoding FPF1-LIKE PROTEIN 1 (FLP1). The master FT regulator, CONSTANS (CO), controls FLP1 expression, suggesting FLP1s involvement in the photoperiod pathway. FLP1 promotes early flowering independently of FT, is active in the shoot apical meristem, and induces the expression of SEPALLATA 3 (SEP3), a key E-class homeotic gene. Unlike FT, FLP1 facilitates inflorescence stem elongation. Our cumulative evidence indicates that FLP1 may act as a mobile signal. Thus, FLP1 orchestrates floral initiation together with FT and promotes inflorescence stem elongation during reproductive transitions.

plant biology↗

bioRxiv2022

Nicotiana benthamiana XYLEM CYSTEINE PROTEASE genes facilitate tracheary element formation in interfamily grafting

Grafting is a plant propagation technique widely used in agriculture. A recent discovery of the capability of interfamily grafting in Nicotiana has expanded the potential combinations of grafting. In this study, we showed that xylem connection is essential for the achievement of interfamily grafting and investigated the molecular basis of xylem formation at the graft junction. Transcriptome and gene network analyses revealed gene modules for tracheary element (TE) formation during grafting that include genes associated with xylem cell differentiation and immune response. The reliability of the drawn network was validated by examining the role of the Nicotiana benthamiana XYLEM CYSTEINE PROTEASE (NbXCP) genes in TE formation during interfamily grafting. Promoter activities of NbXCP1 and NbXCP2 genes were found in differentiating TE cells in the stem and callus tissues at the graft junction. Analysis of a Nbxcp1;Nbxcp2 loss-of-function mutant indicated that NbXCPs control the timing of de novo TE formation at the graft junction. Moreover, grafts of the NbXCP1 overexpressor increased the scion growth rate as well as the fruit size. Thus, we identified gene modules for TE formation at the graft boundary and demonstrated potential ways to enhance Nicotiana interfamily grafting.

plant biology↗

bioRxiv2020

Ancestral duplicated DL/CRC orthologs display function on orchid reproductive organ innovation

The orchid flower is renowned for complexity of flower organ morphogenesis and has attracted great interest from scientists. The YABBY genes encode plant-specific transcription factors with important roles in vegetative and reproductive development in seed plants. DROOPING LEAF/CRABS CLAW (DL/CRC) orthologs are involved in reproductive organ development (especially carpels) of angiosperms. Orchid gynostemium (the fused organ of the androecium and gynoecium) and ovule development are unique developmental processes. Understanding the DL/CRC-like genes controlling the developmental program of the gynostemium and ovule could provide accessible information for reproductive organ molecular regulation in orchids. Two DL/CRC-like genes, named PeDL1 and PeDL2, were cloned from Phalaenopsis equestris. The orchid DL/CRC forms a monophyletic clade with two subclades including AshDL, PeDL1 and DcaDL1 in subclade I, and PeDL2 and DcaDL2 in subclade II. The temporal and spatial expression analysis indicated PeDL genes are specifically expressed in the gynostemium and at the early stages of ovule development. Both PeDLs could partially complement an Arabidopsis crc-1 mutant. Transient overexpression of PeDL1 in Phalaenopsis orchids caused abnormal development of ovule and stigmatic cavity of gynostemium. PeDL1, instead of PeDL2, could form a heterodimer with PeCIN8. Paralogue retention and subsequent divergence of the gene sequence of PeDL1 and PeDL2 in P. equestris might result in the differentiation of function and protein behaviors. These results reveal the important roles of PeDLs involved in orchid gynostemium and ovule development and provide new insights for further understanding the molecular mechanisms underlying orchid reproductive organ development.

developmental biology↗

bioRxiv2018

High-throughput Analysis of Arabidopsis Stem Vibrations to Identify Mutants with Altered Mechanical Properties

Mechanical properties are rarely used as quantitative indices for the large-scale mutant screening of plants, even in the model plant Arabidopsis thaliana. The mechanical properties of plant stems generally influence their vibrational characteristics. Here, we developed Python-based software, named AraVib, for the high-throughput analysis of free vibrations of plant stems, focusing specifically on Arabidopsis stem vibrations, and its extended version, named AraVibS, to identify mutants with altered mechanical properties. These programs can be used without knowledge of Python and require only an inexpensive handmade setting stand and an iPhone/iPad with a high-speed shooting function for data acquisition. Using our system, we identified an nst1 nst3 double-mutant lacking secondary cell walls in fiber cells and a wrky12 mutant displaying ectopic formation of secondary cell wall compared with wild type by employing only two growth traits (stem height and fresh weight) in addition to videos of stem vibrations. Furthermore, we calculated the logarithmic decrement, the damping ratio, the natural frequency and the stiffness based on the spring-mass-damper model from the video data using AraVib. The stiffness was estimated to be drastically decreased in nst1 nst3, which agreed with previous tensile test results. However, in wrky12, the stiffness was significantly increased. These results demonstrate the effectiveness of our new system. Because our method can be applied in a high-throughput manner, it can be used to screen for mutants with altered mechanical properties.

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↗