Biology subjects

Kanno, Y.

Publications and source records attributed to Kanno, Y..

8 recordsLinked to original sources

bioRxiv2026

Root-to-shoot ABA transport by NPF2.4 and NPF2.5 links stomatal regulation to photosynthetic performance

Fluctuating light strongly limits photosynthetic efficiency in plants, yet the mechanisms coordinating stomatal dynamics with rapid photosynthetic induction remain incompletely understood. Here, through a forward physiological screen in Arabidopsis, we identify the abscisic acid (ABA) transporters NPF2.4 and NPF2.5 as regulators of photosynthetic responses to fluctuating light. Loss-of-function npf2.4 and npf2.5 mutants exhibited accelerated stomatal opening and photosynthetic induction during light transitions, resulting in enhanced biomass accumulation and seed yield without compromising long-term drought tolerance. NPF2.4 and NPF2.5 mediated ABA uptake in yeast and were predominantly expressed in the root pericycle and cortex/epidermal tissues, respectively. Reciprocal grafting, xylem sap ABA measurements, and ABA treatment to the roots demonstrated that both transporters regulate root-to-shoot ABA transport. Our findings reveal that root-derived ABA modulates stomatal dynamics and photosynthetic efficiency under fluctuating light, establishing long-distance hormone transport as a key regulator of plant carbon gain in dynamic environments.

plant biology↗

bioRxiv2023

Orchid seed germination through auto-activation of mycorrhizal symbiosis signaling regulated by gibberellin

Orchids parasitically depend on external nutrients from mycorrhizal fungi for seed germination. Previous findings suggest that orchids utilize a genetic system of mutualistic arbuscular mycorrhizal (AM) symbiosis to establish parasitic symbiosis. In AM symbiosis, recent studies have revealed that the plant hormone gibberellin (GA) negatively affects fungal colonization and development. Although previous studies imply that GA is important for orchid mycorrhizal symbiosis, the molecular mechanism of seed germination in which mycorrhizal symbiosis co-occurs remains unclear because, in AM plants, GA regulates seed germination and symbiosis positively and negatively, respectively. To elucidate this conflict, we investigated the effect of GA on Bletilla striata seed germination and mycorrhizal symbiosis using asymbiotic and symbiotic germination methods. Additionally, we compared the transcriptome profiles between asymbiotically and symbiotically germinated seeds. Exogenous GA negatively affected seed germination and fungal colonization, and endogenous bioactive GA was actively converted to the inactive form during seed germination. Transcriptome analysis showed that B. striata shared many of the induced genes between asymbiotically and symbiotically germinated seeds, including GA metabolism- and signaling-related genes and AM-specific marker homologs. Our study suggests that orchids have evolved in a manner that they do not use bioactive GA as a positive regulator of seed germination and instead, auto-activate the mycorrhizal symbiosis pathway through GA inactivation to accept the fungal partner immediately during seed germination.

plant biology↗

bioRxiv2022

Complete loss of RelA and SpoT homologs in Arabidopsis reveals the importance of the plastidial stringent response in the interplay between chloroplast metabolism and plant defense response

The highly phosphorylated nucleotide, guanosine tetraphosphate (ppGpp), functions as a secondary messenger in bacteria and chloroplasts. The accumulation of ppGpp alters plastidial gene expression and metabolism, which are required for proper photosynthetic regulation and robust plant growth. However, because four plastid-localized ppGpp synthases/hydrolases function redundantly, the impact of the loss of ppGpp-dependent stringent response on plant physiology remains unclear. We used the CRISPR/Cas9 technology to generate an Arabidopsis thaliana mutant lacking all four ppGpp synthases/hydrolases, and characterized its phenotype. The mutant showed 20-fold less ppGpp levels than the wild type (WT) under normal growth conditions, and exhibited leaf chlorosis and increased expression of defense-related genes as well as salicylic acid and jasmonate levels upon transition to nitrogen-starvation conditions. These results demonstrate that proper levels of ppGpp in plastids are required for controlling not only plastid metabolism but also phytohormone signaling, which is essential for plant defense.

plant biology↗

bioRxiv2022

Remodeling of Il4-Il13-Il5 locus underlies selective gene expression

The type 2 cytokines, interleukin (IL)-4, IL-5 and IL-13 reside within a tandem multi-gene cluster in mammals. These cytokines represent the hallmark of type 2 immune responses controlling parasites, promoting tissue repair as well as causing allergic diseases. Both innate and adaptive lymphocytes secrete type 2 cytokines with discordant production spectra. We took a holistic structural and functional view of the type 2 cytokine locus before and after activation, comparing innate (ILC2) and adaptive (Th2) lymphocytes to understand mechanisms underlying their distinctive programs. Rapid induction of IL-5 dominates in ILC2, whereas IL-4 does so in Th2 cells. Using high-resolution chromatin conformation capture we found that global cellular chromatin architecture remained constant, whereas the type 2 cytokine locus rapidly remodeled. In ILC2, Il13 and Il5 loci were aligned in proximity whereas Il4 locus was insulated. In Th2 cells, Il4 and Il13 positioned in proximity while the Il5 locus remained distal. Select REs were separately deleted in mice to confirm cell-type specific and activation-dependent roles in type 2 responses in vivo. Thus, contrary to the premise that chromatin architecture plays a minimal role in steady-state gene induction, signal-dependent remodeling of 3D configuration underlies the discordant cytokine outputs in ILC2s versus Th2 cells.

immunology↗

bioRxiv2021

Chitin-induced systemic disease resistance in rice requires both OsCERK1 and OsCEBiP and is mediated via perturbation of cell-wall biogenesis in leaves

O_LIChitin is a well-known elicitor of disease resistance whose recognition by plants is crucial to perceive fungal infections. Chitin can induce both a local immune response and a systemic disease resistance when provided as a supplement in soils. Unlike local immune responses, how chitin-induced systemic disease resistance is deployed has not been studied in detail. C_LIO_LIIn this study, we evaluated systemic disease resistance against the fungal pathogen Bipolaris oryzae by performing a transcriptome analysis and monitoring cell-wall composition in rice plants grown in chitin-supplemented soils. We also examined the local immune response to chitin by measuring the production of reactive oxygen species in leaves. C_LIO_LIChitins induced both local immune response and systemic disease resistance with differing requirements for the receptors OsCERK1 and OsCEBiP. Transcriptome analysis suggested that a perturbation in cell-wall biogenesis is involved in the induction of systemic disease resistance, an idea which was supported by the induction of disease resistance by treatment with a cellulose biosynthesis inhibitor and alterations of cell-wall composition. C_LIO_LIThese findings suggest that chitin-induced systemic disease resistance in rice is caused by a perturbation of cell-wall biogenesis in leaves through long-distance signalling after recognition of chitins by OsCERK1 and OsCEBiP. C_LI

plant biology↗

bioRxiv2020

Combining an alarmin HMGN1 peptide with PD-L1 blockade facilitates stem-like CD8+ T cell expansion and results in robust antitumor effects

BackgroundThe expansion of intratumoral stem-like CD8+ T (Tstem) cells provides a potential approach to improving the therapeutic efficacy of immune checkpoint blockade (ICB). Thus, here we demonstrate a strategy to facilitate Tstem cell expansion by combining an alarmin high-mobility group nucleosome binding domain 1 (HMGN1) peptide with programmed death-ligand 1 (PD-L1) blockade. MethodsThe antitumor effects of HMGN1, anti-PD-L1 antibody, and their combined treatment were monitored in the B16F10, LLC, Colon26, or the EO771 tumor-bearing mice. The comprehensive immunologic analyses, such as high-dimensional flow cytometry, transcriptome analysis, and single-cell RNA sequencing, were used to investigate the cellular and molecular mechanisms of antitumor immune responses after treatments. ResultsThe HMGN1 peptide synergizes with PD-L1 blockade in augmenting the number of mature DCs enriched in immunoregulatory molecules (mregDCs) in tumors, and enhancing their MHC class I antigen-presenting program, which is correlated with the expansion of intratumoral Tstem cells, specifically promoting the Tstem cells but restricting terminally exhausted CD8+ T (Tex) cells, owing to the regulatory molecules expressed on mregDCs. ConclusionOur results indicate that HMGN1 peptide serves as an immunoadjuvant to promote effective anti-PD-L1 immunotherapy and implicate that mregDCs play a role beyond facilitating Tstem cell expansion.

immunology↗

bioRxiv2020

The Arabidopsis NRT1/PTR FAMILY Protein NPF7.3/NRT1.5 is an Indole-3-butyric Acid Transporter Involved in Root Gravitropism

Active membrane transport of plant hormones and their related compounds is an essential process that determines the distribution of the compounds within plant tissues and, hence, regulates various physiological events. Here, we report that the Arabidopsis NITRATE TRANSPORTER 1/PEPTIDE TRANSPORTER FAMILY 7.3 (NPF7.3) protein functions as a transporter of indole-3-butyric acid (IBA), a precursor of the major endogenous auxin indole-3-acetic acid (IAA). When expressed in yeast, NPF7.3 mediated cellular IBA uptake. Loss-of-function npf7.3 mutants showed defective root gravitropism with reduced IBA levels and auxin responses. Nevertheless, the phenotype was restored by exogenous application of IAA but not by IBA treatment. NPF7.3 was expressed in pericycle cells and the root tip region including root cap cells of primary roots where the IBA-to-IAA conversion occurs. Our findings indicate that NPF7.3-mediated IBA uptake into specific cells is required for the generation of appropriate auxin gradients within root tissues.

plant biology↗

bioRxiv2020

The tomato DELLA protein PROCERA promotes ABA responses in guard cells by upregulating ABA transporter

Plants reduce transpiration to avoid drought stress by stomatal closure. While abscisic acid (ABA) has a central role in the regulation of stomatal closure under water-deficit conditions, we demonstrated in tomato that the gibberellin (GA) response inhibitor, the DELLA protein PROCERA (PRO), promotes ABA-induced stomatal closure and gene transcription in guard cells. To study how PRO affects stomatal closure, we performed RNAseq analysis of isolated guard cells and identified the ABA transporters ABA-IMPORTING TRANSPORTER1.1 (AIT1.1) and AIT1.2, also called in Arabidopsis NPF4.6, as upregulated by PRO. Tomato has four AIT1 genes, but only AIT1.1 and AIT1.2 were upregulated by PRO, and only AIT1.1 exhibited high expression in guard cells. Functional analysis of AIT1.1 in yeast confirmed its activity as an ABA transporter, possibly importer. CRISPR-Cas9-defrived ait1.1 mutant exhibited increased transpiration, larger stomatal aperture and reduced response to ABA. Moreover, ait1.1 suppressed the promoting effects of PRO on ABA-induced stomatal closure and gene expression in guard cells. The negative interaction between GA and ABA has been studied for many years in numerous plant species. These studies suggest that the crosstalk is mediated by changes in hormone biosynthesis and signaling. Our results suggest that it is also mediated by changes in hormone transport. One-sentence SummaryThe tomato DELLA protein PROCERA promoted abscisic acid-induced stomatal closure and gene expression by upregulating the expression of the ABA transporter ABA-IMPORTING TRANSPORTER 1 in guard cells.

plant biology↗