Plant growth stimulant

Abstract

To provide a plant growth promoter. [Solution] A plant growth promoter comprising the culture supernatant of algae.

Description

Technical Field

[0001] The present disclosure relates to a plant growth promoter.

Background Art

[0002] Plant growth regulators are a type of pesticide aimed at promoting the growth and improving the quality of agricultural crops, and mainly composed of plant hormones and their analogs. In addition to those mainly composed of synthetic compounds, in recent years, many plant growth regulators containing natural-derived components have been developed. In particular, with the emphasis on reducing environmental impact and transitioning to sustainable agriculture, the use of natural components has attracted more attention.

[0003] Among them, plant growth regulators using photosynthetic organisms, algae, are regarded as promising from the perspective of environmental conservation. The photosynthesis in the process of culturing algae contributes to reducing carbon dioxide in the atmosphere and also contributes to the realization of sustainable agriculture.

[0004] Actually, research on the growth promoting effect by administering algae-derived substances to crops and on algae having the ability to synthesize plant hormones has been underway (Non-Patent Documents 1 to 5). However, in the production of useful substances derived from algae in the past, there has been a problem that a great deal of labor is required for extracting substances from algae. Also, in the extraction process, it is difficult to recover the entire amount, so an un-recovered portion is generated as waste. Furthermore, since direct extraction from algae destroys the algal cells, there is also a technical limitation that continuous biosynthesis is impossible.

[0005] There is a need to establish a more efficient and sustainable production method for plant growth regulators to overcome these problems.

Prior Art Documents

Non-Patent Documents

[0006]

Non-Patent Document 1

[0007] This disclosure was made to solve the problems described above and aims to provide a plant growth promoter. [Means for solving the problem]

[0008] One aspect of the present disclosure is a plant growth promoter, which comprises a culture supernatant of algae.

[0009] [Effects of the Invention]

[0010] According to the present disclosure, a plant growth promoter can be provided.

Brief Description of the Drawings

[0011] [Figure 1A] Photographs showing the growth status of lettuce on the 9th day after germination under each treatment condition are shown. [Figure 1B] The wet weights of lettuce on the 9th day after germination under each treatment condition are shown. [Figure 2A] Photographs showing the growth status of komatsuna on the 9th day after germination under each treatment condition are shown. [Figure 2B] The wet weights of komatsuna on the 9th day after germination under each treatment condition are shown. [Figure 3] Photographs showing the growth status of carrot on the 9th day after germination under each treatment condition are shown. [Figure 4] Photographs showing the growth status of scallion on the 9th day after germination under each treatment condition are shown. [Figure 5A] Photographs showing the growth status of lettuce on the 9th day after germination treated with supernatant NP04 and control medium are shown. [Figure 5B] The wet weights of lettuce on the 9th day after germination treated with supernatant NP04 and control medium are shown. [Figure 5C] The root lengths of lettuce on the 9th day after germination treated with supernatant NP04 and control medium are shown.

Modes for Carrying Out the Invention

[0012] Hereinafter, non-limiting embodiments of the present disclosure will be described. The present disclosure is not limited to the examples in the following embodiments.

[0013] The plant growth promoter of the embodiment comprises the culture supernatant of algae. In this specification, “plant growth promoter” may mean a substance that promotes plant germination, growth, flowering, fruiting, yield improvement, or root or leaf development. Such a plant growth promoter may also promote development in part or the whole of a plant, resulting in one or more of an increased growth rate, an increase in final size, or an increase in mass, wet weight, or dry weight. The growth promoter of the embodiment may be provided as a mixture comprising the culture supernatant of algae. Furthermore, the growth promoter of the embodiment may show a particularly significant effect on plant root growth.

[0014] The plants whose growth is promoted by the growth promoters of the present disclosure are not limited. Such plants may include terrestrial plants, aquatic plants, epiphytic plants, and lithophytes. The plants in the embodiments may include, but are not limited to, plants of the Malvaceae, Rubiaceae, Brassicaceae, Poaceae, Cucurbitaceae, Asteraceae, Moraceae, Sesameaceae, Araceae, Apiaceae, Solanaceae, Caryophyllaceae, Rosaceae, Amaryllidaceae, Fabaceae, Rutaceae, Oleaceae, Amaranthaceae, and Liliaceae. Brassicaceae, Asteraceae, Apiaceae, Solanaceae, Rosaceae, Amaranthaceae, and Fabaceae are particularly preferred. More specific examples of plants in the embodiments include kiwi fruit (Actinidia deliciosa), onion (Allium cepa), leek (Allium fistulosum), garlic (Allium sativum), celery (Apium graveolens var. dulce), Arabidopsis thaliana (Arabidopsis thaliana), peanut (Arachis hypogaea), beet (Beta vulgaris subsp. Vulgaris), cauliflower (Brassica oleracea var. botrytis), cabbage (Brassica oleracea var. capitata), broccoli (Brassica oleracea var. italica), rapeseed (Brassica rapa), bok choy (Brassica rapa var. chinensis), mizuna (Brassica rapa var. nipposinica), and komatsuna (Brassica rapa var. perviridis), turnip (Brassica rapa var.rapa), tea plant (Camellia sinensis), bell pepper (Capsicum annuum), paprika (Capsicum annuum), safflower (Carthamus tinctorius), lime (Citrus aurantifolia), lemon (Citrus limon), orange (Citrus sinensis), grapefruit (Citrus x paradisi), coconut palm (Cocos nucifera), coffee plant (Coffea arabica), taro (Colocasia esculenta), coriander (Coriandrum sativum), Japanese parsley (Cryptotaenia japonica), cucumber (Cucumis sativus), pumpkin (Cucurbita maxima), persimmon tree (Diospyros kaki), carrot (Daucus carota), oil palm (Elaeis spp.), buckwheat (Fagopyrum) esculentum), fig (Ficus carica), strawberry (Fragaria × ananassa), garland chrysanthemum (Glebionis coronaria), soybean (Glycine max), sunflower (Helianthus annuus), barley (Hordeum vulgare), sweet potato (Ipomoea batatas), morning glory (Ipomoea nil), lettuce (Lactuca sativa), leaf lettuce (Lactuca sativa var. crispa), lentil (Lens culinaris), apple (Malus domestica), peppermint (Mentha x piperita), banana (Musa spp.), watercress (Nasturtium officinale), tobacco (Nicotiana tabacum), basil (Ocimum basilicum), olive (Olea europaea), rice (Oryza) sativa), perilla (Perilla frutescens var.crispa), avocado (Persea americana), parsley (Petroselinum crispum), kidney bean (Phaseolus vulgaris), black pepper (Piper nigrum), pea (Pisum sativum), Japanese pear (Pyrus pyrifolia), rosemary (Rosmarinus officinalis), sugarcane (Saccharum officinarum), tomato (Solanum lycopersicum), eggplant (Solanum melongena), potato (Solanum tuberosum), sorghum (Sorghum bicolor), spinach (Spinacia oleracea), cacao (Theobroma cacao), thyme (Thymus vulgaris), wheat (Triticum aestivum), blueberry (Vaccinium spp.), grape (Vitis spp.), adzuki bean (Vigna angularis), corn (Zea mays), Japanese ginger (Zingiber mioga), ginger (Zingiber officinale) and their related species can be mentioned, but are not limited thereto.

[0015] The algae in the present disclosure are not limited. The algae can be non-attached algae. The algae can be, for example, single-celled algae and can be microalgae. Examples of the algae include classifications such as Aurantiochytrium, Chlamydomonas, Chlorella, red alga Schizothamnion, Spirulina, Botryococcus, Euglena, haptophyte, prasinophyte, green alga, brown alga, red alga, cyanobacterium, diatom, yellow-green alga, golden alga, dinoflagellate, seaweed, etc.

[0016] The algae of the embodiments may include cyanobacteria, red algae, or green algae. As will be understood by those skilled in the art, cyanobacteria are prokaryotes that perform oxygen-evolving photosynthesis. Red algae are eukaryotic algae that have phycobilins as photosynthetic pigments. Green algae are eukaryotic algae that have chlorophyll a and b as their main photosynthetic pigments. The algae of the embodiments preferably include cyanobacteria or green algae. Examples of cyanobacteria in this disclosure include algae of the genera Leptolingbya and Calothrix of the family Leptolingbyaceae, Nostoc and Trichomus of the family Nostocaceae, Oscillatoria of the family Oscillatoriaceae, and Nodosilinea of ​​the family Phormidesmiaceae. Examples of green algae include algae of the families Scenedesmaceae and Chlorellaceae.

[0017] In this disclosure, the culture supernatant of algae is the liquid obtained by removing the solid components containing algal cells from a culture obtained by culturing algae in a liquid medium. Separation of the culture supernatant from the culture can be carried out by methods known to those skilled in the art, including filtration and / or centrifugation.

[0018] The culture medium used for culturing algae to prepare the culture supernatant of algae according to this disclosure is not limited to any medium that can be used for culturing algae. Examples of media include BG11 medium, BG11-1 / 10N medium which has a nitrogen source concentration of about one-tenth that of BG11, or Modified Allen's medium. BG11 medium is prepared by adding 1.5 g of sodium nitrate, 40 mg of dipotassium hydrogen phosphate, 75 mg of magnesium sulfate heptahydrate, 36 mg of calcium chloride dihydrate, 6 mg of citric acid, 6 mg of ferric ammonium citrate, 1 mg of disodium ethylenediaminetetraacetate dihydrate, 20 mg of sodium carbonate, 2.86 mg of boric acid, 1.81 mg of manganese chloride tetrahydrate, 222 μg of zinc sulfate heptahydrate, 39 μg of sodium molybdate dihydrate, 79 μg of copper sulfate pentahydrate, and 49 μg of cobalt nitrate hexahydrate to 1000 mL of water, and adjusting the pH to 7.4. BG11-1 / 10N medium is a medium in which the amount of sodium nitrate added has been changed to 150 mg from the composition of BG11.

[0019] Algae can be cultured under natural light or under light irradiation. If light irradiation is used, the light intensity should be, for example, 10-800 μmol photons m -2 s -1 , 50~400 μmol photon m -2 s -1 , or 100-200 μmol photon m -2 s -1 The temperature can be adjusted within a certain range. The culture temperature can be maintained in a range of, for example, 15-35°C or 20-30°C. Algae can be cultured using either static or shaking methods, and in the case of shaking, the shaking speed can be adjusted in a range of, for example, 60-200 rpm. The culture period can be set in a range of, for example, 1-4 weeks, depending on the amount of useful substance to be produced. The culture supernatant can be recovered by centrifugation or filtration of the culture solution.

[0020] In embodiments, the culture supernatant may contain at least one of indole-3-acetaldehyde, indole-3-acetamide, tryptophan, 4-pyridoxic acid, pyridoxamine, pyridoxine, spermidine, prostaglandin E2, or benzoylformic acid. As will be understood by those skilled in the art, indole-3-acetaldehyde, indole-3-acetamide, and tryptophan are important intermediates in the biosynthetic pathway of the plant hormone indole-3-acetic acid (auxin, also known as IAA). Pyridoxamine and pyridoxine belong to the vitamin B6 group, which function as coenzyme precursors, and 4-pyridoxic acid is their metabolite. Spermidine is a type of polyamine, a bioactive substance involved in plant cell division, growth, and stress tolerance. Prostaglandin E2 is known as a bioactive substance. Benzoylformic acid is a compound that can serve as a building block for plant hormones.

[0021] In embodiments, the culture supernatant may contain at least one of indole-3-acetaldehyde, indole-3-acetamide, or tryptophan. It will be understood by those skilled in the art that indole-3-acetaldehyde, indole-3-acetamide, or tryptophan are compounds that can serve as precursors in auxin biosynthesis.

[0022] The growth promoter of the embodiment can be applied to plant seeds, plant bodies, soil, or culture solutions. Application to seeds can be carried out by immersion in a liquid containing the growth promoter, spraying the seed surface, or coating the seeds. Alternatively, application to seeds may be carried out by soaking a substrate with the culture supernatant or a culture solution containing it, and then placing the seeds on top to promote germination. Specific treatment times and other treatment conditions can be adjusted according to the plant species, etc.

[0023] Application to the soil can be carried out by mixing the growth promoter into the soil before sowing or transplanting, by spraying it on the soil surface and then allowing it to penetrate with irrigation, or by supplying it into the soil through drenching treatment.

[0024] Application to plants can be carried out by foliar spraying or root drenching. Foliar sprayed growth stimulants can be absorbed through stomata or the epidermis. Root drenching allows the active ingredient to be delivered to the roots.

[0025] The addition of growth promoters to the culture solution in hydroponics or hydroponic cultivation can be performed at the time of planting or at any time during the growing season. When the culture solution is changed or added, growth promoters may be added to reach a predetermined concentration. In this case, the amount added may be adjusted so that the final concentration of indole-3-acetaldehyde, indole-3-acetamide, tryptophan, 4-pyridoxic acid, pyridoxamine, pyridoxine, spermidine, prostaglandin E2, or benzoylformic acid in the culture supernatant reaches a predetermined concentration. [Examples]

[0026] Examples of the present disclosure are described below, but the present disclosure is not limited to the examples described below.

[0027] Nine algal species (NP03, NP04, NP06, NP12, NP13-1, NP13-2, NR5, NR6-1, NR11) isolated from soil in Kumejima and Uruma City, Okinawa Prefecture, were cultured for 21 days in 1 / 10N BG11 medium, which had a nitrogen concentration diluted to one-tenth of the normal level. After culturing, the algal bodies and the supernatant of the culture medium were separated by centrifugation, and the supernatant was purified by filtration.

[0028] In the experiment, a sheet of cooking paper was placed in a petri dish, and 10 seeds each of leaf lettuce, komatsuna, carrot, and green onion were placed on top. The entire cooking paper was moistened with 5 mL of the supernatant of each alga, and the plants were cultivated for 9 days, with the sowing day being considered day 0, while supplying them with pure water.

[0029] On day 9, growth-promoting effects were determined if the visual size (Figures 1A, 2A, 3, 4) or wet weight (Figures 1B, 2B) of the plant body increased compared to the control (1 / 10N BG11). As a result, growth promotion was observed in the supernatants of NP03, NP04, NP06, NP12, NP13-1, NP13-2, NR5, NR6-1, and NR11 for leaf lettuce. Growth promotion was also observed in the supernatants of NP04, NP06, NP12, NR5, NR6-1, and NR11 for komatsuna, in the supernatants of NP03, NP04, NP06, NP13-1, and NP13-2 for carrots, and in the supernatants of NP03, NP04, NP06, NP13-2, and NR5 for green onions.

[0030] In another experiment, cooking paper was moistened with supernatant NP04 and control medium, and leaf lettuce seeds were placed on it. After cultivating for 9 days with pure water, starting from day 0 (sowing day), the plants were visually assessed for size, wet weight, and root length. Similar to the experiment shown in Figure 1A, NP04 resulted in an increase in the visual size of the plants (Figure 5A). Furthermore, NP04 increased the wet weight of the plants by 1.76 times and the root length by 3.89 times compared to the control (Figures 5B, 5C; n=9).

[0031] The species identification of the algae tested was performed based on 16S rRNA or rbcL sequence analysis and metagenomic shotgun analysis. The results are shown in Table 1. Furthermore, the results of metabolome analysis of the supernatant applied to plants are shown in Table 2. Metabolome measurements were performed using capillary electrophoresis-Fourier transform mass spectrometry (CE-FTMS) based on the conditions described in Japanese Patent No. 6106864. [Table 1]

[0032] [Table 2]

[0033] The supernatant of NP03 promoted the growth of leaf lettuce, carrots, and leeks. This supernatant contained tryptophan, a precursor of auxin (IAA), and indole-3-acetamide, an intermediate in bacterial IAA synthesis. While we do not intend to limit the mechanism of action, these substances may have been converted to IAA by bacteria in the environment, contributing to the promotion of crop growth. In addition, the supernatant of NP03 also contained 4-pyridoxic acid, a metabolite of vitamin B6, which is also thought to have been involved in growth promotion.

[0034] The supernatant of NP04 promoted the growth of all tested crops, with particularly significant root elongation observed in leaf lettuce (Figure 5C). This supernatant contained auxin precursors indole-3-acetaldehyde and tryptophan, spermidine, vitamin B6 (pyridoxamine, pyridoxine), and vitamin B6-related substances (4-pyridoxic acid). Furthermore, this supernatant contained the bioactive substance prostaglandin E2.

[0035] The supernatants of NP06, NP13-1, and NP13-2 also showed growth-promoting effects in several crops. These strains are thought to belong to the genus Nostoc. Tryptophan and other compounds were detected in these supernatants.

[0036] The supernatant of NP12 promoted the growth of leaf lettuce and leeks and contained tryptophan.

[0037] The supernatants of NR5, NR6-1, and NR11 also showed growth-promoting effects in specific crops. These algae are thought to belong to the genus Chlorella. Some or all of the culture supernatants of these algae contained tryptophan, vitamin B6 (pyridoxamine, pyridoxine), and vitamin B6-related substances (4-pyridoxic acid), among others.

[0038] The results above demonstrate that plant growth regulators are secreted in the algal supernatant, offering the advantage of directly utilizing the culture supernatant without the need for extraction from the algae. Furthermore, since supernatant recovery can be performed non-destructively, it was revealed that useful substances can be continuously obtained from the same algal culture system. In addition, it was demonstrated that the supernatants of the tested algal species have organ-specific growth-promoting effects on plants. Specifically, algae exhibiting root system development-promoting effects were identified. These findings indicate that the optimal algal species can be selected according to the growth stage or target organ of the target crop, and its supernatant can be efficiently utilized as a plant growth regulator.

[0039] This disclosure includes the following embodiments. (Section 1) It is a plant growth stimulant, Contains culture supernatant of algae Growth stimulant. (Section 2) The aforementioned algae, Includes cyanobacteria, red algae, or green algae The growth promoter described in item 1. (Section 3) The culture supernatant contains at least one of indole-3-acetaldehyde, indole-3-acetamide, tryptophan, 4-pyridoxic acid, pyridoxamine, pyridoxine, spermidine, prostaglandin E2, or benzoylformic acid. A growth promoter as described in item 1 or 2. (Section 4) A growth promoter according to any one of claims 1 to 3, wherein the growth promoter is applied to the seeds of the plant. (Section 5) The culture supernatant contains at least one of indole-3-acetaldehyde, indole-3-acetamide, or tryptophan. A growth promoter as described in any one of items 1 to 4.

[0040] While this disclosure has been described with reference to several embodiments described above, it is not limited to the examples given in those embodiments. Various modifications can be made to the structure and details of this disclosure within the scope of this disclosure.

Claims

1. It is a plant growth stimulant, Contains culture supernatant of algae Growth stimulant.

2. The aforementioned algae, Includes cyanobacteria, red algae, or green algae The growth promoter according to claim 1.

3. The culture supernatant contains at least one of indole-3-acetaldehyde, indole-3-acetamide, tryptophan, 4-pyridoxic acid, pyridoxamine, pyridoxine, spermidine, prostaglandin E2, or benzoylformic acid. The growth promoter according to claim 1.

4. The growth promoter according to any one of claims 1 to 3, wherein the growth promoter is applied to the seeds of the plant.

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