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51 result(s) for "Shindo, Masato"
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Induced effects of electrical muscle stimulation and visual stimulation on visual sensory reweighting dynamics during standing on a balance board
Providing instruction cues on body motions using stimulations has the potential to induce sensory reweighting dynamics. However, there are currently very few quantitative investigations on the difference in the induced effects on the sensory reweighting dynamics between stimulation methods. We therefore investigated the difference in the induced effects of electrical muscle stimulation (EMS) and visual sensory augmentation (visual SA) on sensory reweighting dynamics during standing on a balance board. Twenty healthy participants controlled their posture to maintain the board horizontally in the balance-board task, which included a pre-test without stimulation, a stimulation test, and a post-test without stimulation. The EMS group (n = 10) received EMS to the tibialis anterior or soleus muscle based on the board tilt. The visual SA group (n = 10) received visual stimuli via a front monitor based on the board tilt. We measured the height of the board marker and calculated the board sway. Before and after the balance-board task, the participants performed static standing with their eyes open and closed. We measured postural sway and calculated the visual reweighting. The visual reweighting showed a strong negative correlation with the balance board sway ratio between the pre- and stimulation tests in the EMS group and a strong positive correlation with that in the visual SA group. Moreover, for those who reduced the balance board sway in the stimulation test, the visual reweighting was significantly different between the stimulation methods, demonstrating that the induced effect on sensory reweighting dynamics is quantitatively different depending on which method is used. Our findings suggest that there is an appropriate stimulation method to change to the targeted sensory weights. Future investigations on the relationship between sensory reweighting dynamics and stimulation methods could contribute to the proposal and implementation of new training methods for learning to control the target weights.
Strigolactones Decrease Leaf Angle in Response to Nutrient Deficiencies in Rice
Strigolactones (SLs) are a class of plant hormones that are synthesized from -carotene through sequential reactions catalyzed by DWARF (D) 27, D17, D10, and OsMORE AXILLARY GROWTH (MAX) 1 in rice ( L.). In rice, endogenous SL levels increase in response to deficiency of nitrogen, phosphate, or sulfate (-N, -P, or -S). Rice SL mutants show increased lamina joint (LJ) angle as well as dwarfism, delayed leaf senescence, and enhanced shoot branching. The LJ angle is an important trait that determines plant architecture. To evaluate the effect of endogenous SLs on LJ angle in rice, we measured LJ angle and analyzed the expression of SL-biosynthesis genes under macronutrient deficiencies. In the \"Shiokari\" background, LJ angle was significantly larger in SL mutants than in the wild-type (WT). In WT and SL-biosynthesis mutants, direct treatment with the SL synthetic analog GR24 decreased the LJ angle. In WT, deficiency of N, P, or S, but not of K, Ca, Mg, or Fe decreased LJ angle. In SL mutants, deficiency of N, P, or S had no such effect. We analyzed the time course of SL-related gene expression in the LJ of WT deficient in N, P, or S, and found that expression of SL-biosynthesis genes increased 2 or 3 days after the onset of deficiency. Expression levels of both the SL-biosynthesis and signaling genes was particularly strongly increased under -P. Rice cultivars \"Nipponbare\", \"Norin 8\", and \"Kasalath\" had larger LJ angle than \"Shiokari\", interestingly with no significant differences between WT and SL mutants. In \"Nipponbare\", endogenous SL levels increased and the LJ angle was decreased under -N and -P. These results indicate that SL levels increased in response to nutrient deficiencies, and that elevated endogenous SLs might negatively regulate leaf angle in rice.
Variations in the Leaf Angles of Different Rice Cultivars in Response to Nutrient Deficiencies
Leaf angle is an important agricultural trait of cereal crops because leaf inclination influences light interception, photosynthetic availability, cultivation density, and grain yield. Leaf angle enlargement in seedlings of a rice cultivar Shiokari is inhibited by increased strigolactone (SL) levels, which are produced by seedlings in response to nitrogen (N), phosphorus (P), and sulfur (S) deficiencies. In this study, we evaluated variations in the leaf angles of 12 rice cultivars in response to N-, P-, and S-limitation and analyzed the effects of SLs on leaf angle. The leaf angles of Shiokari, Koshihikari, and Hitomebore did not increase under N-, P-, and S-limitation when compared with each control. Under P- and S-deficient conditions, the leaf angles of Hinohikari, Kinumusume, Akitakomachi, Taichu 65, Kasalath, and Sasanishiki increased. However, under only N-deficient conditions, the leaves remained erect. The leaf angles of Hinohikari, Kinumusume, Akitakomachi, Taichu 65, Kasalath, and Sasanishiki increased under P- and S-deficient conditions, but the leaves were erect under only N-deficient condition. Expression levels of DWARF27 ( D27 ), D17 , and D10 increased and a natural SL 4-deoxyorobanchol was accumulated in Shiokari seedlings grown under N-deficient condition. Here, we showed that the leaf angles of all rice seedlings cannot increase under N-deficient condition and the influence of P- and S-deficiencies on the leaf angle depends on the rice cultivar. Moreover, we found that ammonium, but not nitrate, mainly affects the leaf angle in rice.
Upregulation of DWARF27 is associated with increased strigolactone levels under sulfur deficiency in rice
Plants produce strigolactones (SLs) in roots in response to nitrogen or phosphate deficiency. To evaluate SL levels under other mineral deficiencies in rice, we cultivated rice seedlings in hydroponic media without nitrogen, phosphorus, potassium, sulfur, calcium, magnesium, and iron. Tiller bud outgrowth was stimulated under calcium deficiency because of low SL levels. SL levels increased under sulfur deficiency, in addition to phosphate, and nitrogen deficiencies. To explore which genes are key regulators of SL production under sulfur deficiency, we analyzed the expression of SL‐related genes in sulfur‐sufficient and sulfur‐deficient conditions. An SL biosynthesis gene, DWARF27 (D27), was strongly expressed under sulfur deficiency, and its expression was decreased by sulfur supply. The levels of D10, D17, and OsMAX1 transcripts did not differ between sulfur‐sufficient and sulfur‐deficient conditions. These results suggest that the increased SL levels under sulfur deficiency are due to a high expression of D27. A combination of nitrogen, phosphorus, and sulfur deficiencies had no additive synergistic effect on SL production. Under combined phosphorus and sulfur deficiency, the expression levels of most SL biosynthesis genes were elevated. The number of tiller buds in the d27 mutant was higher than in the wild type, but lower than in other d mutants. Under sulfur deficiency, the chlorophyll content of d27 was lower than those of other d mutants. These results indicate that D27 plays an important role in adaptation to sulfur deficiency in rice.
Effects of Strigolactones on Grain Yield and Seed Development in Rice
Strigolactones (SLs) are well known as a class of endogenous phytohormones that regulate tiller bud outgrowth. Reduction of inorganic phosphate (Pi) induces the accumulation of SLs, which inhibit tiller bud outgrowth in wild-type (WT) rice plants, but not in SL mutants. This suggests that SLs are important for plant adaptation to Pi-deficient conditions. Thus, we investigated the effects of SLs on grain yield and seed size in WT and dwarf (d) mutant rice plants treated with various Pi concentrations. In both WT and d mutants, plant growth, chlorophyll levels, panicle number, number of hulls, and total grain number decreased as Pi decreased, indicating that SL is not required to mediate these Pi responses. The d mutants produced more panicles than the WT control, but there was no increase in grain yield, and the seed-setting rate decreased. Removal of outgrowing tillers did not affect grain yield in d mutants. GR24 (a synthetic SL) treatment rescued grain yield in d mutants. The d3 and d53 mutants had the lowest grain yields among d mutants. Furthermore, the endosperm of d mutants was 25% smaller than that of WT plants; there were no significant differences in embryo length between WT and d mutant plants, but the endosperm cell area of the d mutants was approximately 30% smaller than that of WT plants. We propose that SLs control grain yield and rice endosperm development.
Low Infection of Phelipanche aegyptiaca in Micro-Tom Mutants Deficient in CAROTENOID CLEAVAGE DIOXYGENASE 8
Strigolactones (SLs), a group of plant hormones, induce germination of root-parasitic plants and inhibit shoot branching in many plants. Shoot branching is an important trait that affects the number and quality of flowers and fruits. Root-parasitic plants, such as Phelipanche spp., infect tomato roots and cause economic damage in Europe and North Africa—hence why resistant tomato cultivars are needed. In this study, we found carotenoid cleavage dioxygenase 8-defective mutants of Micro-Tom tomato (slccd8) by the “targeting induced local lesions in genomes” (TILLING) method. The mutants showed excess branching, which was suppressed by exogenously applied SL. Grafting shoot scions of the slccd8 mutants onto wild-type (WT) rootstocks restored normal branching in the scions. The levels of endogenous orobanchol and solanacol in WT were enough detectable, whereas that in the slccd8 mutants were below the detection limit of quantification analysis. Accordingly, root exudates of the slccd8 mutants hardly stimulated seed germination of root parasitic plants. In addition, SL deficiency did not critically affect the fruit traits of Micro-Tom. Using a rhizotron system, we also found that Phelipanche aegyptiaca infection was lower in the slccd8 mutants than in wild-type Micro-Tom because of the low germination. We propose that the slccd8 mutants might be useful as new tomato lines resistant to P. aegyptiaca.
Upregulation of DWARF 27 is associated with increased strigolactone levels under sulfur deficiency in rice
Plants produce strigolactones ( SL s) in roots in response to nitrogen or phosphate deficiency. To evaluate SL levels under other mineral deficiencies in rice, we cultivated rice seedlings in hydroponic media without nitrogen, phosphorus, potassium, sulfur, calcium, magnesium, and iron. Tiller bud outgrowth was stimulated under calcium deficiency because of low SL levels. SL levels increased under sulfur deficiency, in addition to phosphate, and nitrogen deficiencies. To explore which genes are key regulators of SL production under sulfur deficiency, we analyzed the expression of SL ‐related genes in sulfur‐sufficient and sulfur‐deficient conditions. An SL biosynthesis gene, DWARF 27 ( D27 ), was strongly expressed under sulfur deficiency, and its expression was decreased by sulfur supply. The levels of D10 , D17 , and Os MAX 1 transcripts did not differ between sulfur‐sufficient and sulfur‐deficient conditions. These results suggest that the increased SL levels under sulfur deficiency are due to a high expression of D27 . A combination of nitrogen, phosphorus, and sulfur deficiencies had no additive synergistic effect on SL production. Under combined phosphorus and sulfur deficiency, the expression levels of most SL biosynthesis genes were elevated. The number of tiller buds in the d27 mutant was higher than in the wild type, but lower than in other d mutants. Under sulfur deficiency, the chlorophyll content of d27 was lower than those of other d mutants. These results indicate that D27 plays an important role in adaptation to sulfur deficiency in rice.
Low Infection of Phelipanche aegyptiaca in Micro-Tom Mutants Deficient in CAROTENOIDCLEAVAGE DIOXYGENASE 8
Strigolactones (SLs), a group of plant hormones, induce germination of root-parasitic plants and inhibit shoot branching in many plants. Shoot branching is an important trait that affects the number and quality of flowers and fruits. Root-parasitic plants, such as Phelipanche spp., infect tomato roots and cause economic damage in Europe and North Africa-hence why resistant tomato cultivars are needed. In this study, we found carotenoid cleavage dioxygenase 8-defective mutants of Micro-Tom tomato (slccd8) by the \"targeting induced local lesions in genomes\" (TILLING) method. The mutants showed excess branching, which was suppressed by exogenously applied SL. Grafting shoot scions of the slccd8 mutants onto wild-type (WT) rootstocks restored normal branching in the scions. The levels of endogenous orobanchol and solanacol in WT were enough detectable, whereas that in the slccd8 mutants were below the detection limit of quantification analysis. Accordingly, root exudates of the slccd8 mutants hardly stimulated seed germination of root parasitic plants. In addition, SL deficiency did not critically affect the fruit traits of Micro-Tom. Using a rhizotron system, we also found that Phelipanche aegyptiaca infection was lower in the slccd8 mutants than in wild-type Micro-Tom because of the low germination. We propose that the slccd8 mutants might be useful as new tomato lines resistant to P. aegyptiaca.Strigolactones (SLs), a group of plant hormones, induce germination of root-parasitic plants and inhibit shoot branching in many plants. Shoot branching is an important trait that affects the number and quality of flowers and fruits. Root-parasitic plants, such as Phelipanche spp., infect tomato roots and cause economic damage in Europe and North Africa-hence why resistant tomato cultivars are needed. In this study, we found carotenoid cleavage dioxygenase 8-defective mutants of Micro-Tom tomato (slccd8) by the \"targeting induced local lesions in genomes\" (TILLING) method. The mutants showed excess branching, which was suppressed by exogenously applied SL. Grafting shoot scions of the slccd8 mutants onto wild-type (WT) rootstocks restored normal branching in the scions. The levels of endogenous orobanchol and solanacol in WT were enough detectable, whereas that in the slccd8 mutants were below the detection limit of quantification analysis. Accordingly, root exudates of the slccd8 mutants hardly stimulated seed germination of root parasitic plants. In addition, SL deficiency did not critically affect the fruit traits of Micro-Tom. Using a rhizotron system, we also found that Phelipanche aegyptiaca infection was lower in the slccd8 mutants than in wild-type Micro-Tom because of the low germination. We propose that the slccd8 mutants might be useful as new tomato lines resistant to P. aegyptiaca.