Plant growth promoter and method for raising poaceae plants

Abstract

To provide a plant growth promoter and a method for raising Poaceae plants in which metal concentration in a plant body can be properly adjusted.SOLUTION: A plant growth promoter promotes growth of Poaceae plants, and contains Epigallocatechin gallate. By adding Epigallocatechin gallate to the plant growth promoter, reduction of a pectin methylation degree of roots is suppressed, and a pectin amount of roots can be increased more than WT.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a plant growth promoter and a method for growing a grass plant. [Background technology]

[0002] Known techniques for promoting plant growth include techniques using plant hormones such as cytokinin, auxin, and gibberellin, and growth regulation techniques using gene modification. For example, Patent Document 1 describes that growth is regulated by introducing into plant cells or plant tissue a recombinant vector containing a gene in which the sequence encoding a biomembrane-crossing protein has been modified and which is linked so as to be regulated by a transcription and translation regulatory factor that can be expressed in plants, thereby changing the tolerance or accumulation of heavy metals and salt in the plant. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4648352 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, in plants, for example, Gramineae plants, copper is involved in redox reactions and functions as a cofactor for various enzymes. Copper also plays an important role in photosynthesis, respiration, cell wall metabolism, ligninization, etc. However, depending on the concentration of copper in the plant body, it can affect the above-mentioned functions, and for example, when copper is deficient or excessive in the plant body, toxicity occurs. In addition to copper, aluminum, lead, and strontium can also have a negative effect on growth depending on the concentration. For this reason, in order to promote plant growth, it is necessary to appropriately regulate the metal concentration in the plant body.

[0005] The present invention has been made in view of the above, and aims to provide a plant growth promoter and a method for growing a grass family plant, which are capable of appropriately adjusting metal concentrations in a plant body. [Means for solving the problem]

[0006] In order to solve the above problems and achieve the object, the plant growth promoter of the present invention is a plant growth promoter that promotes the growth of Gramineous plants, and contains epigallocatechin gallate.

[0007] The plant growth promoter according to the present invention, in the above-mentioned invention, is obtained by adding the epigallocatechin gallate to water.

[0008] The plant growth promoter according to the present invention, in the above-mentioned invention, contains epigallocatechin gallate at 25 μM or more and 100 μM or less.

[0009] The plant growth promoter according to the present invention, in the above-mentioned invention, contains epigallocatechin gallate at 25 μM or more and 50 μM or less.

[0010] The method for growing a grass family plant according to the present invention comprises cultivating the grass family plant using a plant growth promoter that promotes the growth of the grass family plant and contains epigallocatechin gallate. Effect of the Invention

[0011] According to the present invention, it is possible to appropriately adjust the metal concentration in a plant body. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram for explaining the cell wall of a plant. [Diagram 2] FIG. 2 is a diagram for explaining the enzymes involved in pectin regulation. [Diagram 3] FIG. 3 is a diagram (part 1) for explaining the demethylation of methylated pectin. [Figure 4] FIG. 4 is a diagram (part 2) for explaining the demethylation of methylated pectin. [Diagram 5] FIG. 5 is a diagram illustrating the concentration effect of EGCG on PME enzyme activity. [Figure 6] FIG. 6 is a diagram illustrating the relationship between the elongation of rice roots and the concentration of EGCG. [Figure 7] FIG. 7 is a diagram (part 1) showing pectin staining of rice roots. [Figure 8] FIG. 8 is a second image showing pectin staining of rice roots. [Figure 9] FIG. 9 is a diagram for explaining the change in pectin amount due to the addition / non-addition of EGCG. [Figure 10] FIG. 10 is a diagram for explaining the growing point in rice. [Figure 11] FIG. 11 is a diagram illustrating the effect of copper on the elongation of rice roots. [Figure 12] FIG. 12 is a diagram for explaining the relative amount of root elongation of rice plants at different copper concentrations. [Figure 13] FIG. 13 is a diagram for explaining the change in pectin amount depending on the copper concentration. [Figure 14] FIG. 14 is a diagram for explaining the amount of pectin contained in rice roots relative to the copper concentration. [Figure 15] FIG. 15 is a diagram for explaining the relative amount of rice root elongation at different copper concentrations in Nipponbare and PG2-FOX. [Figure 16] FIG. 16 is a diagram illustrating the relative elongation amounts of above-ground rice parts at different copper concentrations in Nipponbare and PG2-FOX. [Figure 17] FIG. 17 is a diagram illustrating the relative amounts of pectin accumulated in rice roots at different copper concentrations in Nipponbare and PG2-FOX. [Figure 18] FIG. 18 is a diagram for explaining the relative amount of rice root elongation at different copper concentrations in Nipponbare and Kasalath. [Figure 19] FIG. 19 is a diagram for explaining the relative elongation amounts of above-ground rice parts at different copper concentrations in Nipponbare and Kasalath. [Figure 20] FIG. 20 is a diagram illustrating the relative amount of pectin accumulated in rice roots at different copper concentrations in Nipponbare and Kasalath. [Figure 21] FIG. 21 is a diagram for explaining the relative amount of rice root elongation at different copper concentrations in Nipponbare and PM3-FOX. [Figure 22] FIG. 22 is a diagram for explaining the relative elongation amounts of above-ground rice parts at different copper concentrations in Nipponbare and PM3-FOX. [Figure 23] FIG. 23 is a diagram for explaining the relative amount of pectin accumulated in rice roots at different copper concentrations in Nipponbare and PM3-FOX. [Figure 24] FIG. 24 is a diagram illustrating the relative amount of rice root elongation at different copper concentrations when EGCG is added / not added to Nipponbare. [Diagram 25] FIG. 25 is a diagram illustrating the relative amount of elongation of above-ground rice parts at different copper concentrations when EGCG is added / not added to Nipponbare. [Figure 26] FIG. 26 is a diagram illustrating the relative amount of pectin accumulated in rice roots at different copper concentrations when EGCG is added / not added to Nipponbare. [Figure 27] FIG. 27 is a diagram for explaining the analysis of copper dynamics using PETIS. [Figure 28] FIG. 28 shows images of rice (Nipponbare and PM3-FOX) used in the analysis of copper dynamics using PETIS. [Figure 29] FIG. 29 shows the results of an analysis of copper dynamics using PETIS (0.3 h) in Nipponbare and PM3-FOX. [Diagram 30] FIG. 30 shows the results of an analysis of copper dynamics using PETIS in Nipponbare and PM3-FOX (20.0 h). [Diagram 31]FIG. 31 shows the results of an analysis of copper dynamics using PETIS (50.0 h) in Nipponbare and PM3-FOX. [Diagram 32] FIG. 32 shows the change in copper adsorption of Nipponbare and PG2-FOX under appropriate conditions. [Diagram 33] FIG. 33 shows the change in copper adsorption by Nipponbare and PG2-FOX under excess conditions. [Diagram 34] FIG. 34 shows the change in copper adsorption of Nipponbare and Kasalath under appropriate conditions. [Diagram 35] FIG. 35 shows the change in copper adsorption of Nipponbare and Kasalath under excess conditions. [Diagram 36] FIG. 36 shows the change in copper adsorption by Nipponbare and PM3-FOX under appropriate conditions. [Figure 37] FIG. 37 shows the change in copper adsorption by Nipponbare and PM3-FOX under excess conditions. [Figure 38] FIG. 38 shows the change in copper adsorption in Nipponbare with or without the addition of EGCG under optimal conditions. [Figure 39] FIG. 39 shows the change in copper adsorption to Nipponbare with or without the addition of EGCG under excess conditions (1.0 μM). [Diagram 40] FIG. 40 shows the change in copper adsorption to Nipponbare with or without the addition of EGCG under excess conditions (2.5 μM). [Diagram 41] FIG. 41 shows images of rice (with / without EGCG addition) used in the analysis of copper dynamics using PETIS. [Diagram 42] FIG. 42 shows images visualizing elemental copper in rice (with / without EGCG addition) used in the analysis of copper dynamics using PETIS. [Diagram 43] FIG. 43 is a diagram illustrating the amount of copper contained in the roots per 1 μg of pectin in Nipponbare, PG2-FOX, PM3-FOX, Kasalath, and EGCG-added Nipponbare. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, modes for carrying out the present invention (hereinafter, referred to as "embodiments") will be described with reference to the accompanying drawings.

[0014] (Embodiment) Fig. 1 is a diagram for explaining the cell wall of a plant. A cell of a land plant is composed of a nucleus, a vacuole, a chloroplast, a Golgi apparatus, a cytoplasm, and a cell membrane, all of which are surrounded by a cell wall 10. In this embodiment, a gramineous plant belonging to the family Poaceae is targeted. An example of adding to rice will be described below.

[0015] The cell wall 10 is composed of three polysaccharide components classified as cellulose 11, hemicellulose 12, and pectin 13. The cell wall 10 has a structure in which cellulose 11 is cross-linked by hemicellulose 12, and pectin 13 fills the gaps formed by cellulose 11 and hemicellulose 12. Cellulose 11, hemicellulose 12, and pectin 13 are synthesized in the Golgi apparatus.

[0016] Fig. 2 is a diagram for explaining the enzymes involved in pectin regulation, and Fig. 3 and Fig. 4 are diagrams for explaining the demethylation of methylated pectin. Pectin 13 is mainly composed of galacturonic acid 131. Pectin 13 is synthesized in cells by galacturonoyltransferase (GAUT) and is composed of multiple galacturonic acids 131 linked together. In addition, some of the galacturonic acids 131 in pectin 13 are methylated. For example, the carboxyl group in the galacturonic acid 131 is methylated with a methyl group 132.

[0017] The pectin 13 released into the cell wall is then demethylated by pectin methylesterase (PME). The demethylated pectin 13 is converted to calcium ion 133 (Ca 2+) is formed. Pectin 13 that has formed a cross-linked structure with calcium ions 133 gels and becomes more viscous than before the cross-linked structure was formed. Therefore, the viscosity of pectin 13 can be adjusted by controlling the formation of the cross-linked structure with calcium ions 133.

[0018] Here, as described above, the methylated pectin 13 is demethylated by pectin methylesterase (PME) 14 (see FIG. 3). At this time, demethylation is suppressed by inhibiting the activity of PME14. In this embodiment, epigallocatechin gallate (EGCG) 15 is bound to PME14 to inhibit the activity of PME14 (see FIG. 4). By binding EGCG15 to PME14, the demethylation activity by PME14 can be reduced.

[0019] EGCG15 is a type of catechin that is found in abundance in plants, particularly in tea. EGCG15 can be obtained, for example, by extracting tea leaves with hot water. EGCG15 is added to grasses (here, rice) during the period of root growth, such as seed, germination including root formation, and root elongation. In the growth of grasses, EGCG is added to the hydroponic solution to prepare an EGCG aqueous solution containing 25 μM to 100 μM of EGCG. The EGCG concentration is more preferably 25 μM to 50 μM. The EGCG aqueous solution will be described as being water to which EGCG has been added, but various additives may be added in addition to water.

[0020] Here, the effect of EGCG15 on PME enzyme activity will be described. Figure 5 is a diagram for explaining the concentration effect of EGCG on PME enzyme activity. When the PME enzyme activity of rice samples with and without EGCG addition was examined, as shown in Figure 5, when the enzyme activity of the sample without EGCG addition (0 μM) is taken as 100, it was shown that the PME enzyme activity was reduced in both the sample with 25 μM EGCG addition and the sample with 100 μM EGCG addition.

[0021] Next, we will explain the effect of EGCG15 on the elongation of rice roots. Figure 6 is a diagram for explaining the effect of EGCG on the elongation of rice roots relative to the concentration of EGCG. When the amount of root elongation was examined for rice samples with and without EGCG added, as shown in Figure 6, it was confirmed that the amount of root elongation of the sample without EGCG added (0 μM) was about 0.4 cm, whereas the amount of root elongation of the sample with 50 μM EGCG added was about 0.75 cm. From this result, it can be said that the addition of EGCG promotes root elongation. In FIG. 6, * indicates p<0.05.

[0022] Next, the amount of pectin in rice roots with and without the addition of EGCG will be described. Figures 7 and 8 are diagrams showing pectin staining of rice roots. Figure 7 shows pectin staining (ruthenium red staining) of roots to which EGCG was not added. Figure 8 shows pectin staining of roots to which EGCG was added. In each figure, (a) shows the whole root, (b) shows the tip of the main root or subroot, and (c) shows the tip of a root hair. In Figures 7 and 8, the darker the color, the higher the amount of pectin. As shown in Figures 7 and 8, it can be said that the total amount of pectin in the roots is higher when EGCG is added. The white bar in the figure is a scale bar indicating a length of 100 μm.

[0023] FIG. 9 is a diagram for explaining the change in pectin amount due to the addition / non-addition of EGCG. FIG. 9 shows the results of quantifying the amount of uronic acid (μg / mg) in rice roots using the carbazole sulfate method. Galacturonic acid is an uronic acid derived from galactose, and by quantifying this uronic acid, the amount of pectin in which galacturonic acid is linked in a linear chain can be quantified. As shown in FIG. 9, the amount of uronic acid was greater in the case where EGCG was added than in the case where it was not added, and from this result, it can be said that the total amount of pectin in the roots is greater in the case where EGCG was added.

[0024] As explained above, when the enzyme activity of PME is inhibited, the total pectin content of rice increases and root elongation is promoted. Thus, it has been shown that there is a positive correlation between pectin content and root elongation. Therefore, controlling the pectin content is necessary for root elongation, and by inhibiting the enzyme activity of PME by adding EGCG, it is possible to control the pectin content and promote root elongation.

[0025] Next, we will explain the role of copper in plants. Copper is one of the essential trace elements that is indispensable for the normal growth of plants. Copper is involved in redox reactions in plants and functions as a cofactor for various enzymes. Copper also plays an important role in photosynthesis, respiration, cell wall metabolism, lignin formation, etc.

[0026] However, copper becomes toxic when its content in a plant becomes deficient or excessive, and therefore the copper concentration in the plant body must be strictly controlled. Copper is known to accumulate mainly in the cytoplasm, chloroplasts, vacuoles and cell walls. Copper has a high affinity for pectin among divalent cations, and is known to bind well to pectin in cell walls. Therefore, controlling copper at an appropriate concentration is important for normal plant growth.

[0027] Therefore, the effects of adding / not adding EGCG were examined using Nipponbare, PG2-FOX, PME3-FOX and Kasalath. PG2-FOX and PME3-FOX are rice varieties that were modified based on Nipponbare. Nipponbare: Japonica rice. PG2-FOX: The pectin content of the cell wall was reduced by overexpressing polygalacturonase (PG), an enzyme that breaks down the pectin backbone. PME3-FOX: A PME-overexpressing mutant of Nipponbare, which has high calcium cross-linking of pectin (low degree of methyl esterification of pectin). Kasalath: An indica rice with longer and thinner grains than Nipponbare, it has a higher pectin content than Nipponbare.

[0028] <Cultivation method> Each rice plant was hydroponically grown in a 1.0 mM CaCl2 solution (pH 5.4). First, it was allowed to absorb water for 3 days, then it was hydroponically grown in the CaCl2 solution for 3 days, and after hydroponics, it was treated with copper for 7 days. At this time, the copper treatment was performed at each concentration, with different copper concentrations.

[0029] <Test Method> Measurement of elongation amount After copper treatment, the root and above-ground part growth was measured at each copper concentration. -Quantitative determination of pectin content Images of the rice stained with ruthenium red were taken, and the amount of pectin was quantified based on the intensity of the stained color. Resistant to copper Rice plants were grown under different copper concentrations, and the root and aboveground part growth was measured. The amount of pectin accumulated in the roots was quantified by pectin staining. Observation of copper dynamics in rice The dynamics of copper in rice was observed using a Positron-emitting Tracer Imaging System (PETIS), which uses radioisotopes to visualize the time course of the target element (copper in this case). Determination of copper and calcium in rice After copper treatment, the copper and calcium contents in the roots and aboveground parts of rice were quantified using ICP-AES (ICPS-8100).

[0030] FIG. 10 is a diagram for explaining the growing point in rice. Regarding the amount of elongation of rice, the boundary between the root and the aboveground part is the area P G Then, the region P G Measurements were taken with the lower part counting as the roots and the upper part counting as the above-ground parts.

[0031] <Test Results> (Measurement of elongation amount) FIG. 11 is a diagram for explaining the effect of copper on the elongation of rice roots. FIG. 12 is a diagram for explaining the relative amount of elongation of rice roots at different copper concentrations. FIG. 11 and FIG. 12 show the results of copper treatment of Nipponbare with copper concentrations of 0 μM (no copper added), 0.1 μM, 1.0 μM, and 2.5 μM. Here, the amount of root elongation was confirmed for two samples for each concentration. FIG. 12 shows the relative amount of elongation at each copper concentration when the amount of root elongation at a copper concentration of 0 μM (no copper added) is taken as 100.

[0032] Nipponbare was used with copper concentrations of 0μM (no copper added), 0.1μM, 1.0μM, and 2.5μM, and the amount of root elongation was checked for two samples at each concentration. It was confirmed that the root elongation amount generally decreased as the copper concentration increased. The copper concentration that produced the greatest amount of elongation was 0.1μM. From these results, it can be said that the optimum copper condition for rice root growth is 0.1μM. Furthermore, 2.5μM, where the relative elongation amount was extremely reduced, can be said to be an excessive condition.

[0033] (Quantitative determination of pectin content) FIG. 13 is a diagram for explaining the change in pectin amount depending on the copper concentration. FIG. 13(a) shows a part of a Nipponbare root stained with pectin when the copper concentration is 0 μM (no copper added), FIG. 13(b) shows a part of a Nipponbare root stained with pectin when the copper concentration is 0.1 μM, and FIG. 13(a) shows a part of a Nipponbare root stained with pectin when the copper concentration is 2.5 μM. As shown in FIG. 13, when the copper concentration is 0 μM and 0.1 μM (see FIG. 13(a) and (b)), it can be seen that a large amount of pectin accumulates at the tip of the root. In contrast, when the copper concentration is 2.5 μM (see FIG. 13(c)), it can be seen that pectin is sucked up from the tip of the root to the base side and accumulated throughout the root in the image.

[0034] Fig. 14 is a diagram for explaining the relative amount of pectin contained in rice roots at various copper concentrations. Fig. 14 shows the relative amount of pectin at each copper concentration, with the amount of pectin in roots at a copper concentration of 0 μM (no copper added) being set to 1. As shown in Fig. 14, it can be seen that the amount of pectin increases as the copper concentration increases. From the results shown in Figures 13 and 14, it can be said that the amount of pectin in the roots increases as the copper concentration increases.

[0035] (Copper Resistance) Comparison between Nipponbare and PG2-FOX Fig. 15 is a diagram for explaining the relative amount of elongation of rice roots at different copper concentrations in Nipponbare and PG2-FOX. Fig. 15 shows the relative amount of elongation at each copper concentration, with the amount of root elongation at a copper concentration of 0 µM (no copper added) taken as 100. Fig. 16 is a diagram for explaining the relative elongation amount of rice above-ground parts at different copper concentrations in Nipponbare and PG2-FOX. Fig. 16 shows the relative elongation amount at each copper concentration, assuming that the elongation amount of above-ground parts at a copper concentration of 0 µM (no copper added) is 100. FIG. 17 is a diagram illustrating the relative amounts of pectin accumulated in rice roots at different copper concentrations in Nipponbare and PG2-FOX.

[0036] As shown in Figures 15 and 16, the elongation of roots and aboveground parts was greater in Nipponbare than in PG2-FOX. In addition, the amount of pectin accumulated in roots was greater in Nipponbare (see Figure 17). These results suggest that PG2-FOX, which has a low pectin content, has lower tolerance to excess copper than Nipponbare.

[0037] Comparison between Nipponbare and Kasaras Fig. 18 is a diagram for explaining the relative amount of elongation of rice roots at different copper concentrations in Nipponbare and Kasalath. Fig. 18 shows the relative amount of elongation at each copper concentration, with the amount of root elongation at a copper concentration of 0 μM (no copper added) taken as 100. Fig. 19 is a diagram for explaining the relative elongation amount of rice above-ground parts at different copper concentrations in Nipponbare and Kasalath. Fig. 19 shows the relative elongation amount at each copper concentration, assuming that the elongation amount of above-ground parts at a copper concentration of 0 μM (no copper added) is 100. FIG. 20 is a diagram illustrating the relative amount of pectin accumulated in rice roots at different copper concentrations in Nipponbare and Kasalath.

[0038] As shown in Figures 18 and 19, the elongation of the roots and above-ground parts of Nipponbare and Kasalath is greater than that of Kasalath. Also, the amount of pectin accumulated in the roots is greater in Kasalath (see Figure 20). These results suggest that Kasalath, which has a high pectin content, is more tolerant to excess copper than Nipponbare.

[0039] Comparison between Nipponbare and PME3-FOX Fig. 21 is a diagram for explaining the relative amount of elongation of rice roots at different copper concentrations in Nipponbare and PME3-FOX. Fig. 21 shows the relative amount of elongation at each copper concentration, with the amount of root elongation at a copper concentration of 0 µM (no copper added) taken as 100. Fig. 22 is a diagram for explaining the relative elongation amount of rice above-ground parts at different copper concentrations in Nipponbare and PME3-FOX. Fig. 22 shows the relative elongation amount at each copper concentration, assuming that the elongation amount of above-ground parts at a copper concentration of 0 µM (no copper added) is 100. FIG. 23 is a diagram illustrating the relative amounts of pectin accumulated in rice roots at different copper concentrations in Nipponbare and PME3-FOX.

[0040] 21 and 22, the elongation of roots and aboveground parts was greater in Nipponbare than in PME3-FOX. In addition, the amount of pectin accumulated in roots was greater in Nipponbare (see FIG. 23). These results suggest that PME3-FOX, which has a low degree of pectin methyl esterification and a small amount of pectin, has a lower tolerance to excess copper than Nipponbare.

[0041] Comparison of Nipponbare with and without EGCG Fig. 24 is a diagram for explaining the relative amount of elongation of rice roots at various copper concentrations when EGCG was added / not added to Nipponbare. Fig. 24 shows the relative amount of elongation at each copper concentration, with the amount of root elongation at a copper concentration of 0 μM (no copper added) taken as 100. In Fig. 24, the amount of elongation at copper concentrations of 0.1 μM and 2.5 μM shows p<0.05, and the amount of elongation at a copper concentration of 1.0 μM shows p<0.01. Fig. 25 is a diagram for explaining the relative elongation amount of rice above-ground parts at different copper concentrations when EGCG is added / not added to Nipponbare. Fig. 25 shows the relative elongation amount at each copper concentration when the elongation amount of above-ground parts at a copper concentration of 0 μM (no copper added) is taken as 100. In Fig. 25, the elongation amounts at copper concentrations of 1.0 μM and 2.5 μM show p<0.01. FIG. 26 is a diagram for explaining the relative amount of pectin accumulated in rice roots at different copper concentrations when EGCG is added / not added to Nipponbare. 24 to 26 show the results of cultivating Nipponbare in a hydroponic solution containing 50 μM EGCG as the EGCG-added condition.

[0042] 24 and 25, the elongation of roots and above-ground parts is greater with and without the addition of EGCG. It is also found that the amount of pectin accumulated in roots is greater with the addition of EGCG (see FIG. 26). These results suggest that EGCG-added conditions, in which the degree of pectin methyl esterification is high and the amount of pectin is large, have higher tolerance to excess copper than conditions in which EGCG is not added.

[0043] (Observation of copper dynamics in rice) In the observation of copper dynamics, a radioisotope ( 64 A fixed amount (90 kBq) of copper was added, hydroponic solution was supplied from the bottom of the syringe so that the liquid level remained constant, and measurements were performed using PETIS for one week. FIG. 27 is a diagram for explaining the analysis of copper dynamics using PETIS. As shown in FIG. 27, a rice sample was placed in a syringe, and measurements were performed using PETIS while hydroponic solution was supplied from below. 64 Even if Cu is absorbed into the sample, 64 The total amount of Cu was kept constant. The copper concentrations were set to 0.1 μM, 1.0 μM, and 2.5 μM, and observations were performed under each condition.

[0044] Figure 28 shows images of rice (Nipponbare and PM3-FOX) used in the analysis of copper dynamics using PETIS. In observing the dynamics of copper, PETIS images were acquired with the roots facing downward and the aboveground parts facing upward, as shown in Figure 28. The PETIS images are 64 The lower the concentration of Cu, the closer the color temperature to blue, and the higher the concentration, the closer the color to red. PETIS images were also taken for samples of Nipponbare (WT) and PME3-FOX with copper concentrations of 0.1 μM, 1.0 μM, and 2.5 μM. The same was true for the other types of comparisons below.

[0045] The observation of copper dynamics will be described below with reference to PETIS images of Nipponbare and PM3-FOX. FIG. 29 shows the results of analysis of copper dynamics in Nipponbare and PM3-FOX using PETIS (0.3 h). FIG. 30 shows the results of analysis of copper dynamics in Nipponbare and PM3-FOX using PETIS (20.0 h). FIG. 31 shows the results of analysis of copper dynamics in Nipponbare and PM3-FOX using PETIS (50.0 h). Note that the following PETIS images are expressed using the same color temperature as the color temperature scale bar shown in FIG. 29.

[0046] As shown in Figures 29 to 31, in the case of PME3-FOX, after 20.0 hours, 64 Cu accumulates, and after 50 hours, in the sample with a copper concentration of 0.1 μM, 64 It was confirmed that Cu was transported to the aboveground part. On the other hand, at concentrations of 1.0 μM or more, 64 Cu was not observed being transported to the aboveground part. At this time, the number of cells at the growing point at the base of the aboveground part was large, so 64 The fluorescence of Cu becomes stronger. As described below, PETIS images were observed for Nipponbare, PG2-FOX, PME3-FOX and Kasalath at a copper concentration of 0.1 μM (optimum condition) and 1.0 μM (excess condition).

[0047] Comparison between Nipponbare (WT) and PG2-FOX Figure 32 shows the change in copper adsorption in Nipponbare and PG2-FOX under optimal conditions. As shown in Figure 32, the amount and speed of copper adsorption to the roots under optimal conditions was greater and faster in Nipponbare. It was also confirmed that copper was transported to the aboveground parts over time.

[0048] Figure 33 shows the change in copper adsorption in Nipponbare and PG2-FOX under excess conditions. As shown in Figure 33, the amount and speed of copper adsorption to the roots under excess conditions was greater and faster in PG2-FOX.

[0049] 32 and 33, it can be seen that the greater the amount of pectin, the faster and greater the amount of copper adsorption to the roots.

[0050] Comparison between Nipponbare (WT) and Kasaras Figure 34 shows the change in copper adsorption in Nipponbare and Kasalath under optimal conditions. As shown in Figure 34, the amount and speed of copper adsorption to the roots under optimal conditions was greater and faster in Nipponbare. It was also confirmed that copper was transported to the aboveground parts over time, and the amount and speed of transport was greater and faster in Nipponbare.

[0051] Figure 35 shows the change in copper adsorption in Nipponbare and Kasalath under excess conditions. As shown in Figure 35, the amount and speed of copper adsorption to the roots under excess conditions is greater and faster in Nipponbare. It was also confirmed that copper was transported to the aboveground parts over time, and the amount and speed of transport were greater and faster in Nipponbare.

[0052] 34 and 35, it can be seen that when the amount of pectin is high, the amount and speed of copper adsorption to the roots, and the amount and speed of copper transport to the above-ground parts are slow and small.

[0053] Comparison between Nipponbare (WT) and PME3-FOX Figure 36 shows the change in copper adsorption in Nipponbare and PME3-FOX under optimal conditions. As shown in Figure 36, the amount and speed of copper adsorption to the roots under optimal conditions was greater and faster in Nipponbare. It was also confirmed that copper was transported to the aboveground parts over time, and the amount and speed of transport was greater and faster in Nipponbare.

[0054] Figure 37 shows the change in copper adsorption in Nipponbare and PME3-FOX under excess conditions. As shown in Figure 37, there was almost no difference in the amount / speed of copper adsorption to the roots under excess conditions. It was also confirmed that copper was transported to the aboveground parts over time (see red frame), and the amount and speed of transport were greater and faster in PME3-FOX.

[0055] 36 and 37, it can be said that when the degree of methyl esterification of pectin is low and the amount of pectin is small, the amount and speed of copper transport to the aboveground parts is high and large.

[0056] Comparison of Nipponbare with and without EGCG Figure 38 shows the change in copper adsorption in Nipponbare with / without the addition of EGCG under optimal conditions. As shown in Figure 38, the amount and speed of copper adsorption to the roots under optimal conditions is greater and faster in the absence of EGCG addition. It was also confirmed that copper was transported to the aboveground part over time, and the amount and speed of transport was greater and faster in the absence of EGCG addition.

[0057] Figure 39 shows the change in copper adsorption to Nipponbare with / without the addition of EGCG under excess conditions (1.0 μM). Figure 40 shows the change in copper adsorption to Nipponbare with / without the addition of EGCG under excess conditions (2.5 μM). As shown in Figures 39 and 40, the amount and speed of copper adsorption to the roots under excess conditions is greater and faster under EGCG-added conditions. It was also confirmed that copper was transported to the aboveground parts over time (see red frame), and it was found that the amount and speed of transport was greater and faster under conditions without EGCG addition.

[0058] 38 to 40, it can be seen that when the degree of methyl esterification of pectin is high and the amount of pectin is large, the amount and speed of copper transport to the above-ground parts is slow and small.

[0059] FIG. 41 shows images of rice (with / without EGCG added) used in the analysis of copper dynamics using PETIS. FIG. 42 shows images visualizing elemental copper in rice (with / without EGCG added) used in the analysis of copper dynamics using PETIS. As shown in FIG. 42, EGCG-added rice (see FIG. 41) treated with each copper concentration takes up copper, but under excess conditions (here, 1.0 μM or more), it can be seen that copper is not transported to the aboveground parts. From these results, it can be said that in rice to which EGCG has been added, copper absorbed from the roots is not transported to the aboveground parts.

[0060] (Determination of copper in rice) FIG. 43 is a diagram illustrating the amount of copper contained in the roots per 1 μg of pectin in Nipponbare, PG2-FOX, PM3-FOX, Kasalath, and EGCG-added Nipponbare. In addition, FIG. 43 shows the results of cultivating Nipponbare in a hydroponic solution containing 50 μM EGCG as the EGCG-added condition.

[0061] As shown in Figure 43, PME3-FOX, which has a low pectin content and a low degree of methyl esterification in the roots, accumulated more copper in the roots than Nipponbare (WT). On the other hand, Nipponbare, which has a high pectin content and a high degree of methyl esterification in the roots, which has been treated with EGCG, accumulated less copper in the roots than Nipponbare (WT). When the copper concentration was 0 μM (no addition) or 0.1 μM, no copper was detected when 1 μg of pectin was used.

[0062] These test results showed that rice plants with altered pectin content or degree of methyl esterification in the cell wall showed differences in copper adsorption to the roots, transport to the aboveground parts, and accumulation. Here, a high pectin content and a high degree of methyl esterification resulted in fewer calcium cross-links in the pectin, and higher tolerance to conditions with excess copper. On the other hand, a low pectin content and a low degree of methyl esterification resulted in more calcium cross-links in the pectin, and lower tolerance to conditions with excess copper.

[0063] It was also revealed that rice changes the amount of pectin accumulated in the roots and its degree of methyl esterification depending on the copper concentration, thereby changing the dynamics of copper within the plant and mitigating the toxicity of excess copper.

[0064] Therefore, it can be said that rice has a system that, in response to excess copper, increases the amount of pectin accumulated in the roots, controls the degree of methyl esterification, and adsorbs the toxic metal onto pectin, thereby suppressing its transport to the aboveground parts and mitigating its toxicity to the plant body.

[0065] It was also shown that the control of the amount of pectin and the degree of methyl esterification in the roots was effective when EGCG, which has the effect of epigallocatechin gallate, was added. This EGCG suppresses the decrease in the degree of pectin methylation in the roots and increases the amount of pectin in the roots more than WT (here, Nipponbare is exemplified). This has the effect of promoting root growth and promoting the toxicity alleviation mechanism against excess copper. According to this embodiment, by cultivating rice in a hydroponic solution containing EGCG, the metal concentration in the plant body can be appropriately adjusted. The above-mentioned effect is effective not only for rice but also for gramineous plants belonging to the family Poaceae.

[0066] The plant growth promoter according to the above-mentioned embodiment can promote growth, and by suppressing the toxicity of metals (e.g., heavy metals) contained in the soil, it can suppress various disorders such as whitening or yellowing of young leaves, generation of reactive oxygen species (ROS) having chemical reactivity containing oxygen, and excess symptoms such as induction of iron deficiency in leaves. In this way, by using the plant growth promoter according to the present embodiment, it is expected that cultivation will be possible even on land unsuitable for cultivation that contains excess heavy metals.

[0067] Although the embodiments for carrying out the present invention have been described above, the present invention should not be limited to the above-described embodiments.

[0068] In this manner, the present invention can include various embodiments without departing from the technical concept described in the claims.

[0069] INDUSTRIAL APPLICABILITY As described above, the plant growth promoter and the method for growing a grass family plant according to the present invention are useful for appropriately adjusting metal concentrations in a plant body. [Explanation of symbols]

[0070] 10 cell wall 11 Cellulose 12 Hemicellulose 13 Pectin 14 Pectin methylesterase (PME) 15 Epigallocatechin gallate (EGCG) 131 Galacturonic acid 132 Methyl group 133 Calcium ion

Claims

1. A plant growth promoter that promotes the growth of a grass family plant, Contains epigallocatechin gallate, Plant growth promoter.

2. The epigallocatechin gallate is added to water. The plant growth promoter according to claim 1 .

3. Contains 25 μM to 100 μM of epigallocatechin gallate; The plant growth promoter according to claim 2.

4. Contains 25 μM to 50 μM of epigallocatechin gallate; The plant growth promoter according to claim 3.

5. A plant growth promoter for promoting the growth of a grass family plant, the plant growth promoter including epigallocatechin gallate is used to cultivate the grass family plant. How to grow grasses.

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