Potential of rice tillering for sustainable food production.

Tillering, also known as shoot branching, is a fundamental trait for cereal crops such as rice to produce sufficient panicle numbers. Effective tillering that guarantees successful panicle production is essential for achieving high crop yields. Recent advances in molecular biology have revealed the mechanisms underlying rice tillering; however, in rice breeding and cultivation, there remain limited genes or alleles suitable for effective tillering and high yields. A recently identified quantitative trait locus (QTL) called MORE PANICLES 3 (MP3) has been cloned as a single gene and shown to promote tillering and to moderately increase panicle number. This gene is an ortholog of the maize domestication gene TB1, and it has the potential to increase grain yield under ongoing climate change and in nutrient-poor environments. This review reconsiders the potential and importance of tillering for sustainable food production. Thus, I provide an overview of rice tiller development and the currently understood molecular mechanisms that underly it, focusing primarily on the biosynthesis and signaling of strigolactones, effective QTLs, and the importance of MP3 (TB1). The possible future benefits in using promising QTLs such as MP3 to explore agronomic solutions under ongoing climate change and in nutrient-poor environments are also highlighted.

Development of 12 sets of chromosome segment substitution lines that enhance allele mining in Asian cultivated rice.

Many agronomic traits that are important in rice breeding are controlled by multiple genes. The extensive time and effort devoted so far to identifying and selecting such genes are still not enough to target multiple agronomic traits in practical breeding in Japan because of a lack of suitable plant materials in which to efficiently detect and validate beneficial alleles from diverse genetic resources. To facilitate the comprehensive analysis of genetic variation in agronomic traits among Asian cultivated rice, we developed 12 sets of chromosome segment substitution lines (CSSLs) with the japonica background, 11 of them in the same genetic background, using donors representing the genetic diversity of Asian cultivated rice. Using these materials, we overviewed the chromosomal locations of 1079 putative QTLs for seven agronomic traits and their allelic distribution in Asian cultivated rice through multiple linear regression analysis. The CSSLs will allow the effects of putative QTLs in the highly homogeneous japonica background to be validated.

TLR7/8 stress response drives histiocytosis in SLC29A3 disorders.

Loss-of-function mutations in the lysosomal nucleoside transporter SLC29A3 cause lysosomal nucleoside storage and histiocytosis: phagocyte accumulation in multiple organs. However, little is known about the mechanism by which lysosomal nucleoside storage drives histiocytosis. Herein, histiocytosis in Slc29a3-/- mice was shown to depend on Toll-like receptor 7 (TLR7), which senses a combination of nucleosides and oligoribonucleotides (ORNs). TLR7 increased phagocyte numbers by driving the proliferation of Ly6Chi immature monocytes and their maturation into Ly6Clow phagocytes in Slc29a3-/- mice. Downstream of TLR7, FcRγ and DAP10 were required for monocyte proliferation. Histiocytosis is accompanied by inflammation in SLC29A3 disorders. However, TLR7 in nucleoside-laden splenic monocytes failed to activate inflammatory responses. Enhanced production of proinflammatory cytokines was observed only after stimulation with ssRNAs, which would increase lysosomal ORNs. Patient-derived monocytes harboring the G208R SLC29A3 mutation showed enhanced survival and proliferation in a TLR8-antagonist-sensitive manner. These results demonstrated that TLR7/8 responses to lysosomal nucleoside stress drive SLC29A3 disorders.

Prognostic impact of LILRB4 expression on tumor-infiltrating cells in resected non-small cell lung cancer.

BACKGROUND: Leukocyte immunoglobulin-like receptor subfamily B member 4 (LILRB4/ILT3) is an up-and-coming molecule that promotes immune evasion. We have previously reported that LILRB4 facilitates myeloid-derived suppressor cells (MDSCs)-mediated tumor metastasis in mice. This study aimed to investigate the impact of the LILRB4 expression levels on tumor-infiltrating cells on the prognosis of non-small cell lung cancer (NSCLC) patients. METHODS: We immunohistochemically evaluated the LILRB4 expression levels of completely resected 239 NSCLC specimens. Whether the blocking of LILRB4 on human PBMC-derived CD33+ MDSCs inhibited the migration ability of lung cancer cells was also examined using transwell migration assay. RESULTS: The LILRB4 high group, in which patients with a high LILRB4 expression level on tumor-infiltrating cells, showed a shorter overall survival (OS) (p = 0.013) and relapse-free survival (RFS) (p = 0.0017) compared to the LILRB4 low group. Multivariate analyses revealed that a high LILRB4 expression was an independent factor for postoperative recurrence, poor OS and RFS. Even in the cohort background aligned by propensity score matching, OS (p = 0.023) and RFS (p = 0.0046) in the LILRB4 high group were shorter than in the LILRB4 low group. Some of the LILRB4 positive cells were positive for MDSC markers, CD33 and CD14. Transwell migration assay demonstrated that blocking LILRB4 significantly inhibited the migration of human lung cancer cells cocultured with CD33+ MDSCs. CONCLUSION: Together, signals through LILRB4 on tumor-infiltrating cells, including MDSCs, play an essential role in promoting tumor evasion and cancer progression, impacting the recurrence and poor prognosis of patients with resected NSCLC.

Fibronectin on target cells attenuates natural cytotoxicity of NK cells via myeloid immune checkpoint ILT3/LILRB4/gp49B.

Natural killer (NK) cells play pivotal roles in innate immunity as well as in anti-tumor responses via natural killing, while their activity is tightly regulated by cell-surface inhibitory receptors. Immunoglobulin-like transcript 3/leukocyte immunoglobulin-like receptor B4 (ILT3/LILRB4, also known as gp49B in mice) is an inhibitory receptor expressed on activated NK cells as well as myeloid-lineage cells. The common physiologic ligand of human LILRB4 and gp49B was identified very recently as fibronectin, particularly the N-terminal 30 kDa domain (FN30). We hypothesized that LILRB4 could bind fibronectin on target cells in trans together with integrins, classical fibronectin receptors, in cis and deliver an inhibitory signal in NK cells, leading to attenuated natural killing. Flow cytometric and confocal microscopic analyses of NK cell-surface gp49B and integrins suggested that these novel and classical fibronectin receptors, respectively, co-engage fibronectin immobilized on a culture plate. Biochemical analyses indicated that tyrosine phosphorylation of spleen tyrosine kinase was augmented in gp49B-deficient NK cells upon binding to the immobilized fibronectin. While surface fibronectin-poor YAC-1 cells were evenly sensitive as to natural killing of both gp49B-positive and -negative NK cells, the killing of fibronectin-rich Lewis lung carcinoma cells, but not the FN30-knockout cells, was augmented among gp49B-deficient NK cells. These results suggest that the natural cytotoxicity of NK cells is negatively regulated through LILRB4/gp49B sensing fibronectin on target cells, which sheds light on the unexpected role of LILRB4 and fibronectin as a potential attenuator of NK cell cytotoxicity in the tumor microenvironment.

INPP5D modulates TREM2 loss-of-function phenotypes in a ß-amyloidosis mouse model.

The genetic associations of TREM2 loss-of-function variants with Alzheimer disease (AD) indicate the protective roles of microglia in AD pathogenesis. Functional deficiencies of TREM2 disrupt microglial clustering around amyloid ß (Aß) plaques, impair their transcriptional response to Aß, and worsen neuritic dystrophy. However, the molecular mechanism underlying these phenotypes remains unclear. In this study, we investigated the pathological role of another AD risk gene, INPP5D, encoding a phosphoinositide PI(3,4,5)P3 phosphatase expressed in microglia. In a Tyrobp-deficient TREM2 loss-of-function mouse model, Inpp5d haplodeficiency restored the association of microglia with Aß plaques, partially restored plaque compaction, and astrogliosis, and reduced phosphorylated tau+ dystrophic neurites. Mechanistic analyses suggest that TREM2/TYROBP and INPP5D exert opposing effects on PI(3,4,5)P3 signaling pathways as well as on phosphoproteins involved in the actin assembly. Our results suggest that INPP5D acts downstream of TREM2/TYROBP to regulate the microglial barrier against Aß toxicity, thereby modulates Aß-dependent pathological conversion of tau.

MORE PANICLES 3, a natural allele of OsTB1/FC1, impacts rice yield in paddy fields at elevated CO2 levels.

Improving crop yield potential through an enhanced response to rising atmospheric CO2 levels is an effective strategy for sustainable crop production in the face of climate change. Large-sized panicles (containing many spikelets per panicle) have been a recent ideal plant architecture (IPA) for high-yield rice breeding. However, few breeding programs have proposed an IPA under the projected climate change. Here, we demonstrate through the cloning of the rice (Oryza sativa) quantitative trait locus for MORE PANICLES 3 (MP3) that the improvement in panicle number increases grain yield at elevated atmospheric CO2 levels. MP3 is a natural allele of OsTB1/FC1, previously reported as a negative regulator of tiller bud outgrowth. The temperate japonica allele advanced the developmental process in axillary buds, moderately promoted tillering, and increased the panicle number without negative effects on the panicle size or culm thickness in a high-yielding indica cultivar with large-sized panicles. The MP3 allele, containing three exonic polymorphisms, was observed in most accessions in the temperate japonica subgroups but was rarely observed in the indica subgroup. No selective sweep at MP3 in either the temperate japonica or indica subgroups suggested that MP3 has not been involved and utilized in artificial selection during domestication or breeding. A free-air CO2 enrichment experiment revealed a clear increase of grain yield associated with the temperate japonica allele at elevated atmospheric CO2 levels. Our findings show that the moderately increased panicle number combined with large-sized panicles using MP3 could be a novel IPA and contribute to an increase in rice production under climate change with rising atmospheric CO2 levels.

In-frame mutation in rice TEOSINTE BRANCHED1 (OsTB1) improves productivity under phosphorus deficiency.

Tillering is an important trait in rice productivity. We introduced mutations into the coding region of rice TEOSINTE BRANCHED1 (OsTB1), which is a negative regulator of tillering, using CRISPR/Cas9. The frameshift mutants exhibited substantially enhanced tillering and produced 3.5 times more panicles than the non-mutated plants at maturity. This enhanced tillering resulted in increased spikelet number; however, grain yields did not increase due to substantially reduced filled grain rate and 1,000-grain weight. In contrast, in-frame mutations in OsTB1 had the effect of slightly increasing tiller numbers, and the in-frame mutants had 40% more panicles than non-mutated plants. The grain yield of in-frame mutants also did not increase on nutrient-rich soil; however, under phosphorus-deficient conditions, where tillering is constrained, the in-frame mutants gave a significantly higher grain yield than non-mutated plants due to higher spikelet number and maintained filled grain rate. Rice grassy tiller1 (OsGT1)/OsHox12, which is directly regulated by OsTB1 to suppress tillering, was moderately down-regulated in in-frame mutants, suggesting that OsTB1 with the in-frame mutation shows partial function of intact OsTB1 in regulating OsGT1/OsHox12. We propose that mildly enhanced tillering by in-frame mutation of OsTB1 can improve grain yield under low phosphorus conditions.

LILRB4/gp49B Co-Localizes with Integrin via Fibronectin at Focal Adhesion Sites on Mast Cells.

Mast cells protect a host from invasion by infectious agents and environmental allergens through activation of innate and adaptive immune receptors, their excessive activation being tightly regulated by inhibitory receptors, such as leukocyte immunoglobulin-like receptor (LILR)B4 (gp49B in mice). However, the regulatory mechanism of LILRB4/gp49B expressed on mast cells remains to be clarified in relation to their recently identified ligand, fibronectin (FN), a direct activator of integrins and an indirect stimulator of high-affinity Fc receptor for IgE (FcεRI). Confocal microscopic analysis suggested that gp49B is spatially close to integrin ß1 on non-adhered bone marrow-derived mast cells (BMMCs). Their spatial relatedness increases further at robust focal adhesion sites on cells adhering to immobilized FN. However, the confocal fluorescence signal of the α subunit of FcεRI was found to be correlated to neither gp49B nor integrin ß1 on non-adherent and adherent BMMCs. Stimulation of FcεRI with an immobilized antigen caused FcεRIα signals to accumulate in an inside area surrounded by robust focal adhesion with a concomitant slight increase in the signal correlation of FcεRIα and integrin ß1, accompanied by a less significant increase of the FcεRIα and gp49 correlation. Thus, activating and inhibitory FN receptors integrin and gp49B, respectively, were co-localized via FN at robust focal adhesion sites on BMMCs, while FcεRI was not close to gp49B spatially.

Fibronectin-LILRB4/gp49B interaction negatively regulates osteoclastogenesis through inhibition of RANKL-induced TRAF6/TAK1/NF-kB/MAPK signaling.

Dysregulation of osteoclasts, the multinucleated cells responsible for bone resorption, contributes to several degenerative bone disorders. Previously, we showed that blocking the leukocyte immunoglobulin (Ig)-like receptor B4 (LILRB4), a kind of inhibitory receptor that plays an important role in immune regulation, promotes osteoclast differentiation in vitro. Here, we explored whether gp49B, the murine ortholog of LILRB4, regulates osteoclastogenesis in vivo, and whether fibronectin (FN), a ligand of LILRB4/gp49B, certainly contributes to LILRB4/gp49B-mediated osteoclastogenesis. In comparison with wild-type mice, gp49B deficiency mice exhibited a loss of trabecular bone number and an increase in osteoclast formation. Gp49B knockout improved the bone resorptive capacity of osteoclasts derived from murine Raw264.7 cells by increasing osteoclast formation. We further revealed that gp49B deficiency increased the receptor activator of nuclear factor (NF)-κB ligand (RANKL)-induced signaling transduction by increasing the phosphorylation of transforming growth factor (TGF)-activated kinase 1 (TAK1), NF-κB and mitogen-activated protein kinases (MAPKs). Furthermore, the N-terminal 30 kDa proteolytic fragments of FN promoted gp49B-mediated inhibition of osteoclastogenesis by increasing Src homology-2-containing tyrosine phosphatase 1 (SHP-1) phosphorylation and tumor necrosis factor receptor-associated factor 6 (TRAF6)-SHP-1 association. In summary, the FN-LILRB4/gp49B interaction negatively regulates RANKL-induced TRAF6/TAK1/NF-κB/MAPK signaling in osteoclastogenesis.

Deep Learning Enables Instant and Versatile Estimation of Rice Yield Using Ground-Based RGB Images.

Rice (Oryza sativa L.) is one of the most important cereals, which provides 20% of the world's food energy. However, its productivity is poorly assessed especially in the global South. Here, we provide a first study to perform a deep-learning-based approach for instantaneously estimating rice yield using red-green-blue images. During ripening stage and at harvest, over 22,000 digital images were captured vertically downward over the rice canopy from a distance of 0.8 to 0.9 m at 4,820 harvesting plots having the yield of 0.1 to 16.1 t·ha-1 across 6 countries in Africa and Japan. A convolutional neural network applied to these data at harvest predicted 68% variation in yield with a relative root mean square error of 0.22. The developed model successfully detected genotypic difference and impact of agronomic interventions on yield in the independent dataset. The model also demonstrated robustness against the images acquired at different shooting angles up to 30° from right angle, diverse light environments, and shooting date during late ripening stage. Even when the resolution of images was reduced (from 0.2 to 3.2 cm·pixel-1 of ground sampling distance), the model could predict 57% variation in yield, implying that this approach can be scaled by the use of unmanned aerial vehicles. Our work offers low-cost, hands-on, and rapid approach for high-throughput phenotyping and can lead to impact assessment of productivity-enhancing interventions, detection of fields where these are needed to sustainably increase crop production, and yield forecast at several weeks before harvesting.

Myeloid immune checkpoint ILT3/LILRB4/gp49B can co-tether fibronectin with integrin on macrophages.

LILRB4 (B4, also known as ILT3/CD85k) is an immune checkpoint of myeloid lineage cells, albeit its mode of function remains obscure. Our recent identification of a common ligand for both human B4 and its murine ortholog gp49B as the fibronectin (FN) N-terminal 30 kDa domain poses the question of how B4/gp49B regulate cellular activity upon recognition of FN in the plasma and/or the extracellular matrix. Since FN in the extracellular matrix is tethered by FN-binding integrins, we hypothesized that B4/gp49B would tether FN in cooperation with integrins on the cell surface, thus they should be in close vicinity to integrins spatially. This scenario suggests a mode of function of B4/gp49B by which the FN-induced signal is regulated. The FN pull-down complex was found to contain gp49B and integrin ß 1 in bone marrow-derived macrophages. The confocal fluorescent signals of the three molecules on the intrinsically FN-tethering macrophages were correlated to each other. When FN-poor macrophages adhered to culture plates, the gp49-integrin ß 1 signal correlation increased at the focal adhesion, supporting the notion that gp49B and integrin ß 1 become spatially closer to each other there. Adherence of RAW264.7 and THP-1 cells to immobilized FN induced phosphorylation of spleen tyrosine kinase, whose level was augmented under B4/gp49B deficiency. Thus, we concluded that B4/gp49B can co-tether FN in cooperation with integrin in the cis configuration on the same cell, forming a B4/gp49B-FN-integrin triplet as a regulatory unit of a focal adhesion-dependent pro-inflammatory signal in macrophages.

Co-localization of Fibronectin Receptors LILRB4/gp49B and Integrin on Dendritic Cell Surface.

A myeloid immune checkpoint, leukocyte immunoglobulin-like receptor (LILR) B4 (B4, also known as ILT3/CD85k in humans and gp49B in mice) is expressed on dendritic cells (DCs). However, a mode of regulation of DCs by B4/gp49B is not identified yet in relation to the ligand(s) as well as to the counteracting, activation-type receptor. Our recent identification of the physiological/pathological ligand for B4/gp49B as the fibronectin (FN) N-terminal 30-kDa domain poses the question of the relationship between B4/gp49B and a classical FN receptor/cellular activator, integrin, on DCs. Here we showed that FN is not constitutively tethered on the surface of bone marrow-derived cultured DCs (BMDCs) or splenic DCs, even though the FN receptor integrin and gp49B are co-expressed on these cells. Confocal laser scanning microscopic analysis, however, revealed weak correlation of fluorescent signals between gp49B and integrin ß1, suggesting their partial co-localization on the BMDC surface even in the absence of FN. We found that the plating of BMDCs onto immobilized FN induced tyrosine phosphorylation of focal adhesion kinase (FAK) and spleen tyrosine kinase (Syk). In the absence of gp49B, while the FAK phosphorylation level was virtually unchanged, that of phosphorylation of Syk was markedly augmented. These results suggested that the immobilized FN induced a crosstalk between gp49B and integrin in terms of the intracellular signaling of BMDCs, in which gp49B suppressed the integrin-mediated pro-inflammatory cascade. Our observations may provide a clue for elucidating the mechanism of the therapeutic efficacy of B4/gp49B blocking in autoimmune disease and cancer.

LILRB4 promotes tumor metastasis by regulating MDSCs and inhibiting miR-1 family miRNAs.

Myeloid-derived suppressor cells (MDSCs) are a population of immune suppressive cells that are involved in tumor-associated immunosuppression, and dominate tumor progression and metastasis. In this study, we report that the leukocyte immunoglobulin-like receptor subfamily B member 4 (LILRB4, murine ortholog gp49B) orchestrates the polarization of MDSCs to exhibit pro-tumor phenotypes. We found that gp49B deficiency inhibited tumor metastases of cancer cells, and reduced tumor-infiltration of monocytic MDSCs (M-MDSCs) in tumor-bearing mice. Gp49B-/- MDSCs inhibited pro-tumor immune responses, such as activation of Treg cells, promotion of cancer cell migration, and stimulation of tumor angiogenesis. Treatment of wild-type tumor-bearing mice with gp49B-/- M-MDSCs reduced cancer metastasis. Furthermore, gp49B knockout affected plasma exosome composition in terms of increased miR-1 family microRNAs (miRNAs) expression, which correlates with the upregulation of gp49B-/- MDSC-derived anti-tumor miRNAs. Collectively, our findings reveal that LILRB4/gp49B promotes MDSC-mediated tumor metastasis by regulating the M2-polarization of MDSCs and suppressing the secretion of miR-1 family miRNAs, which facilitate tumor migration and invasion. Abbreviations CTLA-4: cytotoxic T-lymphocyte-associated protein-4; FBS: fetal bovine serum; G-MDSCs: granulocytic-MDSCs; GP49B: glycoprotein 49B; HE: hematoxylin-eosin; ICI: immune checkpoint inhibitor; ITIM: immunoreceptor tyrosine-based inhibition motif; LILRB4: leukocyte immunoglobulin-like receptor B4; M-CSF: macrophage colony stimulating factor; MDSC: myeloid-derived suppressor cell; M-MDSC: monocytic MDSC; MMP-9: metallopeptidase-9; mAb: monoclonal antibody; PBS: phosphate-buffered saline; PCR: polymerase chain reaction; PD-1: programmed death-1; PD-L1: programmed death ligand-1; PMN-MDSC: polymorphonuclear-MDSC; qRT-PCR: quantitative reverse transcription PCR; TAM: tumor associated macrophage; TME: tumor microenvironment; TMM: trimmed mean of M value; VEGFA: vascular endothelial growth factor A.

Upregulation of leukocyte immunoglobulin-like receptor B4 on interstitial macrophages in COPD; their possible protective role against emphysema formation.

BACKGROUND: Leukocyte immunoglobulin-like receptor B4 (LILRB4) is one of the inhibitory receptors in various types of immune cells including macrophages. Previous reports suggested that LILRB4 could be involved in a negative feedback system to prevent excessive inflammatory responses. However, its role has been unclear in chronic obstructive pulmonary disease (COPD), in which macrophages play a crucial role in the pathogenesis. In this study, we aimed to examine the changes of LILRB4 on macrophages both in the lung specimens of COPD patients and the lungs of a mouse emphysema model. We then tried to compare the differences in both inflammation and emphysematous changes of the model between wild-type and LILRB4-deficient mice in order to elucidate the role of LILRB4 in the pathogenesis of COPD. METHODS: We prepared single-cell suspensions of resected lung specimens of never-smokers (n = 21), non-COPD smokers (n = 16), and COPD patients (n = 14). The identification of LILRB4-expressing cells and the level of LILRB4 expression were evaluated by flow cytometry. We analyzed the relationships between the LILRB4 expression and clinical characteristics including respiratory function. In the experiments using an elastase-induced mouse model of emphysema, we also analyzed the LILRB4 expression on lung macrophages. We compared inflammatory cell accumulation and emphysematous changes induced by elastase instillation between wild-type and LILRB4-deficient mice. RESULTS: The levels of surface expression of LILRB4 are relatively high on monocyte linage cells including macrophages in the human lungs. The percentage of LILRB4+ cells in lung interstitial macrophages was increased in COPD patients compared to non-COPD smokers (p = 0.018) and correlated with the severity of emphysematous lesions detected by CT scan (rs = 0.559, p < 0.001), whereas the amount of smoking showed no correlation with LILRB4 expression. Increased LILRB4 on interstitial macrophages was also observed in elastase-treated mice (p = 0.008). LILRB4-deficient mice showed severer emphysematous lesions with increased MMP-12 expression in the model. CONCLUSIONS: LILRB4 on interstitial macrophages was upregulated both in human COPD lungs and in a mouse model of emphysema. This upregulated LILRB4 may have a protective effect against emphysema formation, possibly through decreasing MMP-12 expression in the lungs.

Blockade of checkpoint ILT3/LILRB4/gp49B binding to fibronectin ameliorates autoimmune disease in BXSB/Yaa mice.

The extracellular matrix (ECM) is the basis for virtually all cellular processes and is also related to tumor metastasis. Fibronectin (FN), a major ECM macromolecule expressed by different cell types and also present in plasma, consists of multiple functional modules that bind to ECM-associated, plasma, and cell-surface proteins such as integrins and FN itself, thus ensuring its cell-adhesive and modulatory role. Here we show that FN constitutes an immune checkpoint. Thus, FN was identified as a physiological ligand for a tumor/leukemia/lymphoma- as well as autoimmune-associated checkpoint, ILT3/LILRB4 (B4, CD85k). Human B4 and the murine ortholog, gp49B, bound FN with sub-micromolar affinities as assessed by bio-layer interferometry. The major B4-binding site in FN was located at the N-terminal 30-kDa module (FN30), which is apart from the major integrin-binding site present at the middle of the molecule. Blockade of B4-FN binding such as with B4 antibodies or a recombinant FN30-Fc fusion protein paradoxically ameliorated autoimmune disease in lupus-prone BXSB/Yaa mice. The unexpected nature of the B4-FN checkpoint in autoimmunity is discussed, referring to its potential role in tumor immunity.

Synergy between a shallow root system with a DRO1 homologue and localized P application improves P uptake of lowland rice.

Improved phosphorus (P) use efficiency for crop production is needed, given the depletion of phosphorus ore deposits, and increasing ecological concerns about its excessive use. Root system architecture (RSA) is important in efficiently capturing immobile P in soils, while agronomically, localized P application near the roots is a potential approach to address this issue. However, the interaction between genetic traits of RSA and localized P application has been little understood. Near-isogenic lines (NILs) and their parent of rice (qsor1-NIL, Dro1-NIL, and IR64, with shallow, deep, and intermediate root growth angles (RGA), respectively) were grown in flooded pots after placing P near the roots at transplanting (P-dipping). The experiment identified that the P-dipping created an available P hotspot at the plant base of the soil surface layer where the qsor1-NIL had the greatest root biomass and root surface area despite no genotyipic differences in total values, whereby the qsor1-NIL had significantly greater biomass and P uptake than the other genotypes in the P-dipping. The superior surface root development of qsor1-NIL could have facilitated P uptakes from the P hotspot, implying that P-use efficiency in crop production can be further increased by combining genetic traits of RSA and localized P application.

Development and evaluation of pyramiding lines carrying early or late heading QTLs in the indica rice cultivar 'IR64'.

The heading date is an important trait for determining regional and climatic adaptability in rice. To expand the adaptability of the indica rice cultivar 'IR64', we pyramided multiple early or late heading quantitative trait locus (QTLs) in the 'IR64' genetic background by crossing previously developed near-isogenic lines (NILs) with a single QTL for early or late heading. The effects of pyramiding QTLs were observed in three different climatic zones of the Philippines, Madagascar, and Japan. The early heading pyramiding lines (PYLs) headed 6.2 to 12.8 days earlier than 'IR64' while the late heading PYLs headed 18.8 to 27.1 days later than 'IR64'. The PYLs tended to produce low grain yield compared to 'IR64'. The low yield was not improved by combining SPIKE, which is a QTL that increases the number of spikelets per panicle. Conversely, 'IR64-PYL(7+10)' carrying Hd5 and Hd1 headed earlier, produced more tillers, and more panicles per m2 than 'IR64', and mitigated the yield decrease in early heading. These results suggest that the effects of pyramided QTLs on heading date were consistent across various environments and PYLs could be used to enhance the adaptation of 'IR64' in other rice growing environments.

Astrocytic phagocytosis is a compensatory mechanism for microglial dysfunction.

Microglia are the principal phagocytes that clear cell debris in the central nervous system (CNS). This raises the question, which cells remove cell debris when microglial phagocytic activity is impaired. We addressed this question using Siglechdtr mice, which enable highly specific ablation of microglia. Non-microglial mononuclear phagocytes, such as CNS-associated macrophages and circulating inflammatory monocytes, did not clear microglial debris. Instead, astrocytes were activated, exhibited a pro-inflammatory gene expression profile, and extended their processes to engulf microglial debris. This astrocytic phagocytosis was also observed in Irf8-deficient mice, in which microglia were present but dysfunctional. RNA-seq demonstrated that even in a healthy CNS, astrocytes express TAM phagocytic receptors, which were the main astrocytic phagocytic receptors for cell debris in the above experiments, indicating that astrocytes stand by in case of microglial impairment. This compensatory mechanism may be important for the maintenance or prolongation of a healthy CNS.

Nogo receptor antagonist LOTUS exerts suppression on axonal growth-inhibiting receptor PIR-B.

Damaged axons in the adult mammalian central nervous system have a restricted regenerative capacity mainly because of Nogo protein, which is a major myelin-associated axonal growth inhibitor with binding to both receptors of Nogo receptor-1 (NgR1) and paired immunoglobulin-like receptor (PIR)-B. Lateral olfactory tract usher substance (LOTUS) exerts complete suppression of NgR1-mediated axonal growth inhibition by antagonizing NgR1. However, the regulation of PIR-B functions in neurons remains unknown. In this study, protein-protein interactions analyses found that LOTUS binds to PIR-B and abolishes Nogo-binding to PIR-B completely. Reverse transcription-polymerase chain reaction and immunocytochemistry revealed that PIR-B is expressed in dorsal root ganglions (DRGs) from wild-type and Ngr1-deficient mice (male and female). In these DRG neurons, Nogo induced growth cone collapse and neurite outgrowth inhibition, but treatment with the soluble form of LOTUS completely suppressed them. Moreover, Nogo-induced growth cone collapse and neurite outgrowth inhibition in Ngr1-deficient DRG neurons were neutralized by PIR-B function-blocking antibodies, indicating that these Nogo-induced phenomena were mediated by PIR-B. Our data show that LOTUS negatively regulates a PIR-B function. LOTUS thus exerts an antagonistic action on both receptors of NgR1 and PIR-B. This may lead to an improvement in the defective regeneration of axons following injury.