Biology subjects

Sugita, R.

Publications and source records attributed to Sugita, R..

8 recordsLinked to original sources

bioRxiv2026

Beyond Peak Wavelength: Spectral Bandwidth of Blue and Red-Blue Laser Diodes (LDs) Reprograms Photosynthesis, Canopy Architecture, Senescence, and Whole-Plant Growth

In indoor horticulture high planting densities often accelerate the senescence of lower leaves, increasing trimming frequency, reducing effective photosynthetic area, and raising labor costs. While spectral composition has been widely studied, the role of spectral bandwidth, particularly when peak wavelength is identical, remains poorly understood. Here, we used laser diodes (LDs) as narrow-band light sources to examine how spectral bandwidth influences photosynthesis, canopy architecture, leaf senescence, and plant growth under monochromatic blue light and combined red and blue (R+B) light in tobacco (Nicotiana tabacum L. Wisconsin-38), lettuce (Lactuca sativa L. Red Fire), and Arabidopsis thaliana (L.) Heynh. Col-0. Under monochromatic blue light, narrow-band LD blue (LDB) reduced CO{square} assimilation rates and shoot dry weight compared with broad-band LED blue (LEDB) across species. However, LEDB cultivation was accompanied by accelerated the senescence of lower leaves, a major limitation under dense planting. In contrast, plants grown under LDB developed a more upright canopy architecture, characterized by larger leaf angles, which was associated with improved light penetration and delayed the senescence of lower leaves. When red and blue light were combined, narrow-band LD lighting (LDR+B) mitigated stress induced by 24-hour continuous illumination and promoted coordinated improvements in photosynthetic performance, leaf expansion, and canopy architecture. These integrated responses resulted in consistently higher shoot fresh weight and a healthier physiological state, as indicated by higher chlorophyll content and lower anthocyanin accumulation, compared with broad-band LEDR+B. Together, our results demonstrate that spectral bandwidth, even when peak wavelength is held constant, is a critical parameter shaping plant growth strategies. Precise control of bandwidth enables partial decoupling of traits traditionally linked in the classic sun or shade leaf syndromes, allowing independent regulation of canopy architecture, leaf senescence, and plant growth. This study highlights spectral bandwidth as a powerful yet underutilized lever for optimizing canopy health and yield in indoor horticulture.

plant biology↗

bioRxiv2024

CqHKT1 and CqSOS1 mediate genotype-dependent Na+ exclusion under high salt stress in quinoa

Salinity threatens crop production worldwide, and salinized areas are steadily increasing. As most crops are sensitive to salt, there is a need to improve the salt tolerance of major crops and promote the cultivation of under-utilized salt-tolerant crops. Quinoa, a pseudocereal and leafy vegetable from the Andean region of South America, is highly salt-tolerant, thrives in marginal environments, and has excellent nutritional properties. Research has often focused on epidermal bladder cells, a feature of quinoa thought to contribute to salt tolerance; however recent evidence suggests that these cells are not directly involved. The salt tolerance mechanism in quinoa remains unclear. Here, we show genotype-dependent differences in Na+ and K+ accumulation mechanisms using representative 18 lines of three genotypes by focusing on young quinoa seedlings at a stage without epidermal bladder cells. High salinity (600 mM NaCl) did not affect the early growth of all three quinoa genotypes. Under high salinity, lowland quinoa lines accumulated the most Na+ in the aerial parts, whereas southern highland lines accumulated the least. By contrast, K+ accumulation was slightly reduced in the aerial parts but significantly decreased in roots of all the genotypes. Resequencing of 18 quinoa lines supports the notion that genotype determines aboveground Na+ uptake and gene expression in response to salt stress. Using virus-induced gene silencing, we further demonstrated that CqHKT1 and CqSOS1 mediate Na+ exclusion in quinoa. These findings provide insight into salt tolerance mechanisms, serving as a basis for improving crop production under salt stress.

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↗

bioRxiv2022

A fungal secondary metabolism gene cluster enables mutualist-pathogen transition in root endophyte Colletotrichum tofieldiae

Plant-associated fungi show diverse lifestyles from pathogenic to mutualistic to the host; however, the principles and mechanisms through which they shift the lifestyles require elucidation. The root fungus Colletotrichum tofieldiae (Ct) promotes Arabidopsis thaliana growth under phosphate limiting conditions. We reveal a Ct strain, designated Ct3, that severely inhibits plant growth. Ct3 pathogenesis occurs through activation of host abscisic acid (ABA) pathways via a fungal secondary metabolism gene cluster related to sesquiterpene ABA and botrydial (BOT) biosynthesis. ABA-BOT cluster activation during root infection suppresses host nutrient uptake-related genes and changes the mineral contents, suggesting its role in manipulating host nutrition states. Conversely, disruption or environmental suppression of the cluster renders Ct3 beneficial for plant growth, in a manner dependent on host phosphate starvation response regulators. Our findings indicate that a fungal metabolism cluster provides a means by which infectious fungi modulate lifestyles along the parasitic-mutualistic continuum in fluctuating environments.

microbiology↗

bioRxiv2022

Isotope-based visualization of element distribution in phloem provides functional evidence for the operation of SOS1 Na+/H+ exchangers in mature zones of Arabidopsis root

In the phloem, various solutes such as photosynthates, mineral nutrients, or toxic elements move from the source organs to sinks. One of them is the root. While this process may mediate significant quantities of solutes delivered to the root, it is unclear how the solutes are distributed along the root axis. To elucidate the distributing pattern of solutes, we visually analyzed the movement of solutes in Arabidopsis roots using a radioisotope imaging technique. The distribution patterns fell into four different groups: (1) root tip accumulation for 14C-photosynthates, 28Mg2+, 32PO43-, and 35SO42-; (2) homogenous distribution along the root axis for 42K+ and 137Cs+; (3) no detectable accumulation in the root for 45Ca2+ and 59Fe2+; and (4) transient accumulation in the root for 22Na+. The latter phenomenon was explored in more detail using Arabidopsis knockout mutants lacking functional sodium efflux transporter SOS1 (operating as Na+/H+ exchanger). By utilizing a non-invasive microelectrode MIFE ion flux measuring technique, we found that Na+ efflux was active in the mature root zone of wild-type Arabidopsis plants but not in root apex as initially thought, and that in sos1 mutants lacking functional Na+/H+ exchangers, shoot-derived 22Na+ remained in the root. These findings challenge the notion that Na+ exclusion via SOS1 is confined to the root apex and demonstrates the power of combining the radioisotope imaging technique and the MIFE ion flux measuring technique to study the kinetics of ion transport in the root and root-to-shoot communication.

plant biology↗

bioRxiv2020

Visualization of seasonal shifts of phosphorus re-translocation and overwintering recycling in a shortened annual cycle system of the deciduous poplar tree (Populus alba L.).

Phosphorus (P) is an essential macronutrient for plant growth. In deciduous trees, P is remobilized from senescing leaves and stored in perennial tissues during winter for further growth. Annual internal recycling and accumulation of P is considered an important strategy to support vigorous growth of trees. However, the pathways of seasonal re-translocation of P and the molecular mechanisms of this transport have not been clarified. Here we show the seasonal P re-translocation route visualized using the real-time radioisotope imaging and the macro- and micro-autoradiography. We analyzed the seasonal re-translocation P in poplar (Populus alba. L) cultivated under "a shortened annual cycle system", which mimicked seasonal phenology in a laboratory. From growing to senescing season, sink tissues of 32P and/or 33P shifted from young leaves and the apex to the lower stem and roots. The radioisotope P re-translocated from a leaf was stored in phloem and xylem parenchyma cells and redistributed to new shoots after dormancy. Seasonal expression profile of phosphate transporters (PHT1, PHT5 and PHO1 family) was obtained in the same system. Our results reveal the seasonal P re-translocation routes at the organ and tissue levels and provide a foothold for elucidating its molecular mechanisms.

plant biology↗

bioRxiv2020

Autophagy is induced during plant grafting for wound healing

O_LIGrafting is an important technique in agriculture to obtain several good traits such as high disease tolerance and high yield by exchanging root system. However, the underlined cellular processes to compensate the wound damage and repair tissues were largely unknown. C_LIO_LIWe analyzed two graft combinations: Nicotiana benthamiana (Nb) homograft as a compatible, wound repairing model and Nb heterograft with Arabidopsis thaliana (At) as an incompatible and more stressful model, which we recently identified as an exceptional maintainable interfamily grafting. C_LIO_LIIn both graft combinations, nutrient loss was observed in gene expression after grafting, where the level of nutrient loss was more sever in heterografts. Transmission electron micrographs of Nb/At heterografts suggested that microautophagy was induced in cells near the graft boundary. In At seedling micrografting, the fluorescence of autophagy protein marker GFP-ATG8 was highly observed at graft junction especially in cambial region. In At atg2 mutant homografts, growth after grafting decreased compared with wild-type homografts. Moreover, when NbATG5 knocked-down Nb scion was grafted to At stock, the successful rate of grafting was significantly decreased. C_LIO_LIAltogether, these results suggest that component of autophagy is induced during grafting and has a role in wound healing. C_LI

plant biology↗

bioRxiv2019

ATP Binding Cassette Proteins ABCG37 and ABCG33 are required for potassium-independent cesium uptake in Arabidopsis roots

Radiocesium, accumulated in the soil by nuclear accidents is a major environmental concern. The transport process of cesium (Cs+) is tightly linked to the indispensable plant nutrient potassium (K+) as they both belong to the group I alkali metal with similar chemical properties. Most of the transporters that had been characterized to date as Cs+ transporters are directly or indirectly linked to K+. Using a combinatorial approach of physiology, genetics, cell biology and root uptake assay, here we identified two ATP-Binding Cassette (ABC) proteins, ABCG37 and ABCG33 as facilitators of Cs+ influx. The gain-of-function mutant of ABCG37 (abcg37-1) showed hypersensitive response to Cs+-induced root growth inhibition, while the double knock out mutant of ABCG33 and ABCG37 (abcg33-1abcg37-2) showed resistance. Single loss-of-function mutant of ABCG33 and ABCG37 did not show any alteration in Cs+ response. Short term uptake experiment with radioactive Cs+ revealed reduced Cs+ uptake in abcg33-1abgc37-2 compared with wild type in presence or absence of K+. Potassium response and content were unaffected in the double mutant background confirming that Cs+ uptake by ABCG33 and ABCG37 is independent of K+. Collectively, this work identified two ABC proteins as new Cs+ influx carriers, which act redundantly and independent of K+ uptake pathway.

plant biology↗