WO2025030164A1

WO2025030164A1 - Method for promoting plant growth and modulating plant architecture

Info

Publication number: WO2025030164A1
Application number: PCT/US2024/040873
Authority: WO
Inventors: Alexandra Jazz DICKINSON; Abigail TRIPKA
Original assignee: University of California Berkeley; University of California San Diego UCSD
Current assignee: University of California Berkeley; University of California San Diego UCSD
Priority date: 2023-08-03
Filing date: 2024-08-02
Publication date: 2025-02-06
Anticipated expiration: 2026-02-03

Abstract

The disclosure provides a method for enhancing plant growth and root growth in plants using benzoxazinoid or a derivative thereof such as 6-methoxybenzoxazolin-2-one (6-MBOA). The method includes applying the benzoxazinoid and/or 6-MBOA to plants or soil to stimulate root development, thereby improving plant health and productivity. Effective application methods include soil incorporation, foliar spraying, and hydroponic nutrient solutions.

Description

METHOD FOR PROMOTING PLANT GROWTH AND MODULATING PLANT ARCHITECTURE

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application Serial No. 63/530, 645, filed August 3, 2023, the disclosures of which are incorporated herein by reference in its entirety.

TECHNICAL FIELD

[0002] The present invention relates to the field of plant biology and agriculture, specifically to compositions and methods for enhancing plant tissue growth such as root growth using benzoxazinoids . More particularly, this invention provides novel formulations and applications of benzoxazinoid compounds and derivative thereof to promote robust plant development, root development, increase plant resilience, and improve agricultural yields.

BACKGROUND

[0003] Climate change has created a major crisis for the agricultural field. Unpredictable weather patterns directly impact crop production and affect the fields crops are grown on. As global temperatures rise, water supply decreases leading to droughts in agricultural land. These extended droughts not only decrease water for crops, but also increase the salinity of the soil due to increased leaching as seen in the droughts in California's San Joaquin Valley. The increase of salt along with decrease of water in soil is detrimental to plant growth and greatly diminishes crop yield. Salt stress itself affects the development of plants through several ways in the root and the shoot, including closure of the stomata in the shoot and accumulation of ions in the root. Ultimately, prolonged exposure to these conditions affects metabolism and are eventually lethal to the plant. The effects of salt stress on metabolism is one of the main causes for the lethality, due to hindering of cellular .

[0004] Th us, new ways to mitigate climate change are constantly being sought after and many advancements have been made in improving stress tolerance in crops. These include techniques such as in vitro selection, which use exogenous treatments that simulate biotic stresses on plant tissue cultures to select and regenerate strains that are most resistant. Research demonstrates that optimizing root traits can have a profound impact on abiotic stress resistance. For example, potato roots with longer roots were more resistant to drought stress compared to their short root counterparts, leading farmers to pursue the trait in breed selection. The structure of the root contributes to this resistance and adaptability. The root is comprised of an organized set of cells that are divided into 3 zones: the meristem zone, elongation zone, and maturation zone. The meristem zone consists of a group of undifferentiated cells at the root tip that divide from the quiescent center (QC) cells and quickly elongate in the elongation zone before fully differentiating in the maturation zone higher in the longitudinal axis of the root. This organized structure allows plants to adapt to their environment effectively as abiotic stresses in soil ranging from acidity, accumulation of heavy metals, low nutrient levels, and drought, all can be countered by some type of adaptation in the root. For instance, in response to cadmium stress, maize produces a wax-like substance that coats the root to protect itself and allow it to continue exchanging nutrients with the soil. Additionally, increased root growth can significantly increase the tolerance of the plants in salt and drought induced environments by allowing roots to grow deeper in search for nutrients and water. Therefore, further understanding of root biology in response to stress may lead to significant discoveries that enable plant resilience against environmental stresses .

SUMMARY [0005] Root growth is a critical factor in plant health and productivity. Traditional methods for enhancing root growth often involve fertilizers, growth hormones, and other chemical treatments. However, there is a growing interest in natural and environmentally friendly approaches to improve root development. Benzoxazinoids are naturally occurring compounds found in various plant species and are known for their role in plant defense mechanisms. The disclosure demonstrates that benzoxazinoids can also influence root growth and development.

[0006] The disclosure provides a method of promoting plant tissue growth including root growth, comprising: contacting the plant or plant tissue (e.g., a seedling, embryo etc.) with a composition that comprises benzoxazinoid at an amount effective to stimulate the growth of the plant tissue or plant' s root. In one embodiment, the plant or plant tissue is contacted with a composition comprising a benzoxazinoid (e.g. , 6-MBOA) at a concentration from about 0.020 mM to 20 mM (e.g. , 250 pM to 1.0 M) . In another or further embodiment, the plant or plant tissue is an ornamental plant or an edible plant. In still a further embodiment, the ornamental plant is a houseplant, a plant grown for its flowers and/or foliage, or a plant that is displayed. In still another embodiment, the edible plant is selected from a crop plant, a vegetable, or a fruiting plant. In still another embodiment, the plant is selected from maize, cotton, rice, soybean, pulse, sugar cane, wheat, cassava, plantain, sorghum, sweet potato, yam, quinoa, potato, millet, rye, barley, oat, chickpea, bean, rapeseed, peanut, sunflower, and vegetable. In a further embodiment, the cultivated plant is maize. In still another or further embodiment, the plant is treated at the seedling stage of the plant. In still another or further embodiment, the plant is treated when the plant is under an environmental stress. In a further embodiment, the environmental stress is a reduction in water. In still another or further embodiment, leaves, calluses, embryos, stems and/or roots of the plant are contacted with the composition comprising a benzoxazinoid . In yet another or further embodiment, the composition further comprises a surface-active agent, an inert carrier, a preservative, a humectant, an encapsulating agent, a binder, an emulsifier, a dye, a UV protective and/or a buffer. In still another or further embodiment, one or more fields or greenhouses of plants are contacted with the composition comprising a benzoxazinoid.

[0007] The details of one or more embodiments of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The accompanying drawings, which are incorporated into and constitute a part of this specification, illustrate one or more embodiments of the disclosure and, together with the detailed description, serve to explain the principles and implementations of the invention.

[0009] Figure 1 shows 6-methoxy-benzoxazolin-2-one (6-MBOA) is one of the BX compounds that localized strongly to the stem cell niche of maize roots. 6-MBOA increases total root length and stimulates root branching.

[0010] Figure 2 is a graph illustrating differences in total root length between control and 0.05 mM 6-MBOA treatment .

[0011] Figure 3 is a graph illustrating differences in seminal root length between control and 0.05 mM 6-MBOA treatment .

[0012] Figure 4 shows a graph illustrating the difference in meristem cell counts between Arabidopsis DR5 : GFP roots in control and 250pM 6-MBOA treatment. [0013] Figure 5 shows a graph illustrating the difference in DR5:GFP expression area between Arabi dopsis DR5:GFP roots of control and 250p 6-MBOA conditions.

[0014] Figure 6 shows a graph of seminal root area when roots were treated with 0.025 mM DIMBOA.

DETAILED DESCRIPTION

[0015] As used herein and in the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a plant" includes a plurality of such plants and reference to "the metabolite" includes reference to one or more metabolites, and so forth.

[0016] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this disclosure belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice of the disclosed methods and compositions, the exemplary methods, devices, and materials are described herein .

[0017] Also, the use of "or" means "and/or" unless stated otherwise. Similarly, "comprise," "comprises," "comprising" "include," "includes," and "including" are interchangeable and not intended to be limiting.

[0018] It is to be further understood that where descriptions of various embodiments use the term "comprising," those skilled in the art would understand that in some specific instances, an embodiment can be alternatively described using language "consisting essentially of" or "consisting of."

[0019] All publications mentioned herein are incorporated by reference in full for the purpose of describing and disclosing methodologies that might be used in connection with the description herein. Moreover, with respect to any term that is presented in one or more publications that is similar to, or identical with, a term that has been expressly defined in this disclosure, the definition of the term as expressly provided in this disclosure will control in all respects.

[0020] A "control" or "control plant cell" or "control tissue" or "control organ" or "control plant" provides a reference point for measuring changes in phenotype of a subject plant or plant part. A control plant or control plant part (e.g. control plant cell, control tissue, or control organ) may comprise, for example: (a) a wildtype plant of the same genotype as the plant to be treated with a BX composition of the disclosure.

[0021] Climate change is a potent and escalating threat to the environment, food security, and human health. Plants are nature' s solution to climate change; they remove CO₂ from the air, prevent erosion, serve as keystone species in many ecosystems, and provide sustainable sources of food, biofuel, and material .

[0022] To advance root traits that increase stress tolerance, it is necessary to understand root development. Small molecules such as sugars, lipids, metabolites, and hormones play an important role in the maintenance of life and in the development of all organisms .

[0023] Benzoxazinoids (BXs) were identified in the 1960s as secondary plant metabolites functioning as natural pesticides. BXs are a class of secondary metabolites found in maize and other cereal species and certain dicots and contain a 2- hydroxy-2H-l , 4-benzoxazin-3 ( 4H ) -one skeleton (Niemeyer, Hermann M. "Hydroxamic acids derived from 2-hydroxy-2H-l , 4- benzoxazin-3 (4H) -one: key defense chemicals of cereals." Journal of Agricultural and Food Chemistry 57.5 (2009) : 1677 - 1696) . BXs are synthesized in seedlings and stored as glucosides. The main aglucone moieties are 2,4-dihydroxy-2H-

1, 4-benzoxazin-3 ( 4H) -one (DIBOA) , 2-hydroxy-l, 4-benzoxazin-3- one (HO-BOA) and 2, 4-dihydroxy-7-methoxy-2H-l, 4-benzoxazin- 3 (4H)-one (DIMBOA) . BXs are synthesized in two subfamilies of the Poaceae and sporadically found in single species of the dicots. BXs are predominantly stored as inactive glucosides, while upon biotic stress they are hydrolyzed to the respective toxic hydroxamic acids (e.g., DIMBOA) .

[0024] The first step in BX biosynthesis converts indole-3- glycerol phosphate into indole. In maize (Zea mays) , this reaction is catalyzed by either Benzoxazinelessl (BX1) , or Indole glycerol phosphate lyase (IGL or Igl herein) . The bxl gene is under developmental control and is mainly responsible for BX production, whereas the Igl gene is inducible by stress signals, such as wounding, herbivory, or jasmonates. The enzymatic properties of IGL are similar to BX1, but the transcriptional regulation of their corresponding genes is different. Like other Bx genes, bxl is constitutively expressed during the early developmental stages of the plant, which correlates with endogenous BX levels. The introduction of four oxygen atoms into the indole moiety that yields DIBOA is catalyzed by four cytochrome P450 monooxygenases termed BX2 to BX5. A further Bx enzyme, BX6, is responsible for the hydroxylation in position C-7 of the benzoxazinoids in maize (Frey, Monika, et al. "A 2-oxoglutarate-dependent dioxygenase is integrated in DIMBOA-biosynthesis . " Phytochemistry 62.3 (2003) : 371-376) . Bx7 , as a further example, is an 0- methyltransf erase (OMT) catalyzing the formation of DIMBOA-glc from TRIBOA-glc.

[0025] Benzoxazinoids (BXs) are common tryptophan-derived secondary metabolites that regulate below-ground and aboveground biotic interactions; they have mainly been studied for their role in maize chemical defense. In particular, BXs have been investigated for their ability to alter root-associated fungal and bacterial communities, inhibit herbivore feeding, and increase jasmonate signaling (a defense pathway for biotic stress) and corresponding plant defenses. Generally, defensive compounds decrease plant growth, and previously published reports in the literature suggest that BX can inhibit the growth of other plants.

[0026] The disclosure demonstrates through mass spectrometry imaging studies, that BXs strongly localize to the maize stem cell niche (SCN) . This is unexpected, as SCN- enriched molecules typically promote growth. The studies presented herein show that a BX compound, 6-methoxy- benzoxazolin-2-one (6-MBOA) , can promote an increase in the total amount of root growth. MBOA increases total root growth by promoting root branching (FIG. 1) . This data suggests that BXs may be more than just defense compounds - they may also provide new ways to increase plant growth and control plant architecture .

[0027] The disclosure demonstrates that a class of compounds called Benzoxazinoids (BXs) , e.g. , 6-methoxy- benzoxazolin-2-one (6-MBOA) , can increase the total size of the root system and increase root branching. In these studies 6-MBOA was directly applied to the maize root and its effect on root growth and branching was monitored. The data demonstrate that 6-MBOA increases the size of the root system by promoting branched root growth. The disclosure contemplates applying different BX compounds to improve root growth. The disclosure also envisions treating other parts of the plant with BXs to stimulate growth. The disclosure also contemplates treating plants to stimulate root growth in plants under stress, such as drought stress. The disclosure envisions treating plants and more particularly root systems or root environment with BXs to improve their resilience to environmental stress.

[0028] The benzoxazinoids useful in the methods and compositions of the disclosure are selected from the group consisting of benzoxazinones such as HBOA, DHBOA, HMBOA, HM2B0A, DIBOA, TRIBOA, DIMBOA, DIM2BOA, HDMBOA, and HDM2BOA; and benzoxazolinones such as BOA, MBOA (6-MBOA) , M2BOA; and combinations of any of the foregoing (see, Table 1) .

[0029] Table 1:

[0030] In some embodiments, the aforementioned benzoxazinoid being in a glucoside or aglucone form, or a benzoxazolinone, or any combination of the aforementioned benzoxazinoids .

[0031] The benzoxazinoids may be used in their pure form or as part of a mixture with other active or non-active ingredients. The benzoxazinoid compositions can be formulated as: Liquid solutions for foliar application or soil drenching; Granular formulations for incorporation into the soil; Powdered forms for mixing with other growth media; and Slow- release formulations to provide sustained effects.

[0032] A benzoxazinoid or formulation comprising a benzoxazinoid (e.g., 6-MBOA) can be applied to a plant, root system or environment for plating. Such methods includes foliar spraying comprising applying the composition to the leaves and stems of plants; soil drenching comprising applying the composition directly to the soil around the plant roots; and seed treatment comprising coating seeds with the benzoxazinoid composition before planting. The application of a BX compound or formulations can be carried out at various stages of plant growth, from seedling to mature plants, depending on the desired effect.

[0033] The effectiveness of the benzoxazinoid compositions in promoting root growth can be measured by assessing root length, root biomass, and overall plant health. Comparative studies with untreated control plants can demonstrate the enhanced root growth achieved through the use of benzoxazinoid compositions of the disclosure.

[0034] The concentration of benzoxazinoids in a formulation typically ranges from 0.01% to 5% by weight, depending on the method and plant species. For example, the concentration of 6-MBOA can vary depending on the specific plant species and growth conditions . Generally, concentrations ranging from 0.008 mg/mL to 1 mg/mL in water or nutrient solutions are effective. In another embodiment, a concentration of 0.08-1 mg/ml of soil is effective. For foliar spray, a solution concentration of 0.008-1 mg/ml (or any value therebetween) is useful. For hydroponic systems, a concentration of 0.001-1 mg/ml in the nutrient solution is effective.

[0035] The compositions of the disclosure that comprise a BX compound or derivative thereof may further include a surface-active agent, an inert carrier, a preservative, a humectant, a feeding stimulant, an attractant, an encapsulating agent, a binder, an emulsifier, a dye, a UV protective, a buffer, a flow agent or fertilizers, micronutrient donors, or other preparations that influence plant growth. One or more agrochemicals including, but not limited to, herbicides, insecticides, fungicides, bactericides, nematicides, molluscicides, acaracides, plant growth regulators, harvest aids, and fertilizers, can be combined with carriers, surfactants or adjuvants customarily employed in the art of formulation or other components to facilitate product handling and application for particular plants. Suitable carriers and adjuvants can be solid or liquid and correspond to the substances ordinarily employed in formulation technology, e.g., natural or regenerated mineral substances, solvents, dispersants, wetting agents, tackifiers, binders, or fertilizers. The active ingredients of the disclosure are normally applied in the form of compositions and can be applied to the crop area, plant, or seed to be treated or in the case of cuttings (e.g., cut flowers) to the water. For example, the compositions of the disclosure may be applied during growth, seeding or storage.

[0036] Suitable surface-active agents include, but are not limited to, anionic compounds such as a carboxylate of, for example, a metal; carboxylate of a long chain fatty acid; an N-acylsarcosinate ; mono or di-esters of phosphoric acid with fatty alcohol ethoxylates or salts of such esters; fatty alcohol sulfates such as sodium dodecyl sulfate, sodium octadecyl sulfate or sodium cetyl sulfate; ethoxylated fatty alcohol sulfates; ethoxylated alkylphenol sulfates; lignin sulfonates; petroleum sulfonates; alkyl aryl sulfonates such as alkyl-benzene sulfonates or lower alkylnaphtalene sulfonates, e.g. , butyl-naphthalene sulfonate; salts of sulfonated naphthalene-f ormaldehyde condensates; salts of sulfonated phenol-f ormaldehyde condensates; more complex sulfonates such as the amide sulfonates, e.g., the sulfonated condensation product of oleic acid and N-methyl taurine; or the dialkyl sulfosuccinates, e.g. , the sodium sulfonate or dioctyl succinate. Non-ionic agents include condensation products of fatty acid esters, fatty alcohols, fatty acid amides or fatty-alkyl- or alkenyl-substituted phenols with ethylene oxide, fatty esters of polyhydric alcohol ethers, e.g., sorbitan fatty acid esters, condensation products of such esters with ethylene oxide, e.g., polyoxyethylene sorbitar fatty acid esters, block copolymers of ethylene oxide and propylene oxide, acetylenic glycols such as 2, 4,7,9- tetraethyl-5-decyn-4 , 7-diol, or ethoxylated acetylenic glycols. Examples of a cationic surface-active agent include, for instance, an aliphatic mono-, di-, or polyamine such as an acetate, naphthenate or oleate; or oxygen-containing amine such as an amine oxide of polyoxyethylene alkylamine; an amide-linked amine prepared by the condensation of a carboxylic acid with a di- or polyamine; or a guaternary ammonium salt.

[0037] Examples of inert materials include, but are not limited to, inorganic minerals such as kaolin, phyllosilicates, carbonates, sulfates, phosphates, or botanical materials such as cork, powdered corncobs, peanut hulls, rice hulls, and walnut shells.

[0038] The compositions of the disclosure can be in a suitable form for direct application or as a concentrate of primary composition that requires dilution with a suitable quantity of water or other diluent before application. The concentration of a BX compound will vary depending upon the nature of the particular formulation, specifically, whether it is a concentrate or to be used directly.

[0039] A composition of the disclosure can be applied to the environment of a plant, for example, spraying, atomizing, dusting, scattering, coating or pouring, introducing into or on the soil, introducing into irrigation water, by seed treatment or general application or dusting. The compositions of the disclosure can conveniently contain an insecticide if this is thought necessary. Compositions of the disclosure may be applied simultaneously or in succession with other compounds. The number of applications and the rate of application depend on the particular purpose and plant.

[0040] There are no particular limitations on the genus or species of plants that can be treated in the methods and compositions of the disclosure. Examples include useful agricultural crops such as grains, vegetables, and fruits (including feed crops) , fiber raw material plants such as pulp, and plants valued for their aesthetic beauty such as foliage plants. The methods and compositions of the disclosure can be used in Eucalyptus, pine, acacia, poplar, cedar, cypress, bamboo, yew, rice, corn, wheat, barley, rye, potato, tobacco, sugar beet, sugar cane, rapeseed, soybean, sunflower, cotton, orange, grape, peach, pear, apple, tomato, Chinese cabbage, cabbage, radish, carrot, squash, cucumber, melon, parsley, orchid, chrysanthemum, lily, and saffron.

[0041] A wide variety of plants, seeds and seedlings can be treated by the methods and compositions of the disclosure. In certain embodiments, target plants (including seeds and seedlings) include, but are not limited to, those monocotyledonous and dicotyledonous plants, such as crops including grain crops (e.g., wheat, maize, rice, millet, barley) ; fruit crops (e.g., tomato, apple, pear, strawberry, orange) ; forage crops (e.g., alfalfa) ; root vegetable crops (e.g., carrot, potato, sugar beets, yam) ; leafy vegetable crops (e.g. , lettuce, spinach) ; flowering plants (e.g., petunia, rose, chrysanthemum) ; conifers and pine trees (e.g. , pine fir, spruce) ; plants used in phytoremediation (e.g. , heavy metal accumulating plants) ; oil crops (e.g., sunflower, rape seed) and plants used for experimental purposes (e.g., Arabidopsis) . Thus, the disclosed methods and compositions have use over a broad range of plants, including, but not limited to, species from the genera Asparagus, Avena, Brassica, Citrus, Citrullus, Capsicum, Cucurbita, Daucus, Glycine, Hordeum, Lactuca, Lycopersicon, Malus, Manihot, Nicotiana, Oryza, Persea, Pisum, Pyrus, Prunus, Raphanus, Secale, Solanum, Sorghum, Triticum, Vitis, Vigna, and Zea. The methods and compositions of the disclosure can be used to increase root growth in a plant selected from the group consisting of Hordeum vulgare , Hordeum bulbusom, Sorghum bicolor, Saccharum oficinarium, Zea spp., including Zea mays, Setaria italica , Oryza minuta, Oryza sativa, Oryza australiensis , Oryza alta, Triticum aestivum, Triticum durum, Secale cereale, Triticale , Malus domestica, Brachypodium di stachyon, Hordeum marinum, Aegilops tauschii , Caucus glochidiatus , Beta spp., including Beta vulgaris, Caucus pusillus , Caucus muricatus , Caucus carota, Eucalyptus grandis, Nicotiana sylvestris, Nicotiana tomentosiformis, Nicotiana tabacum, Nicotiana benthamiana, Solanum lycopersicum, Solanum tuberosum, Cofea canephora, Vitis vinifera, Erythrante guttata , Genlisea aurea, Cucumis sativus , Marus notabilis , Arabidopsis arenosa, Arabidopsis lyrata, Arabidopsis thaliana , Crucihimalaya himalaica, Crucihimalaya wallichin, Cardamine nexuosa, Lepidium virginicum, Capsella bursa pastoris, Olmarabidopsis pumila, Arabis hirsute, Brassica napus, Brassica oleracea , Brassica rapa, Raphanus sativus, Brassica juncacea , Brassica nigra, Eruca vesicaria subsp. sativa, Citrus sinensis , Jatropha curcas, Populus trichocarpa , Medicago truncatula, Cicer yamashitae, Cicer bjugum, Cicer arietinum, Cicer reticulatum, Cicer judaicum, Cajanus cajanmfolius, Cajanus scarabaeoides , Phaseolus vulgaris , Glycine max, Gossypium sp. , Astragalus sinicus, Lotus japonicas , Torenia fournieri , Allium cepa, Allium fistulosum, Allium sativum, Helianthus annuus, Helianthus tuberoses and Allium tuberosum, or any variety or subspecies belonging to one of the aforementioned plants.

EXAMPLE 1

[0042] Using Desorption Electrospray Ionization Mass Spectrometry Imaging (DESI-MSI) to map small molecule localization patterns across maize root meristems a molecular signatures with strong localization to the SCN, including those that correspond to a series of benzoxazinoids (BXs) was identified (FIG. 1) . BXs have been studied extensively for their role in biochemical defense against a variety of biotic stresses . The results suggest that a BX compound can promote certain aspects of root growth, suggesting that BXs may be more than just defense compounds.

Example 2

[0043] To determine if BXs such as 6-MBOA can stimulate root growth, 6-MBOA was exogenously contacted with maize roots at 0.05 mM and total root length measured (FIG. 2) and seminal root lengths measured (FIG. 3) . As can be seen exogenous 6- MBOA increased total and seminal root growth.

Example 3

[0044] The plant hormone auxin plays a central role in almost every facet of root development from the cellular to the whole-root-system level. To study the effect of 6-MBOA on auxin regulation, Arabidopsis having a DR5:GFP reporter were contacted with and without 250pM 6-MBOA and meristem cell counts (FIG. 4) and GFP expression area (FIG. 5) were measured. Fluorescence microscopy on the Arabidopsis auxin reporter line, DR5 : GFP revealed that 250pM 6-MBOA increased the expression area of the DR5 auxin reporter.

Example 4

[0045] To determine if other BXs in addition to 6-MBOA can stimulate root growth, DIMBOA was exogenously contacted with maize roots at 0.025 mM and seminal root are measured (FIG. 6) . As can be seen exogenous DIMBOA increased seminal root area compared to control.

[0046] Certain embodiments of the invention have been described. It will be understood that various modifications may be made without departing from the spirit and scope of the invention. Other embodiments are within the scope of the following claims.

Claims

WHAT IS CLAIMED IS:

1. A method of promoting root growth of a plant, comprising: contacting a plant, a seed or a soil environment with a composition that comprises a benzoxazinoid at an amount effective to stimulate the growth of the plant' s root.

2. The method of claim 1, wherein the plant is contacted with the composition comprising the benzoxazinoid at a concentration from about 0.020 mM to 20 mM.

3 The method of claim 2, wherein the plant is contacted with the composition comprising the benzoxazinoid at a concentration from about 250 pM to about 1.0 mM.

4. The method of any one of the preceding claims, wherein the plant is an ornamental plant or an edible plant.

5. The method of claim 4, wherein the ornamental plant is a houseplant, a plant grown for its flowers and/or foliage, or a plant that is displayed.

6. The method of claim 4, wherein the edible plant is selected from a crop plant, a vegetable, or a fruiting plant.

7. The method of claim 1, wherein the plant is selected from maize, cotton, rice, soybean, pulse, sugar cane, wheat, cassava, plantain, sorghum, sweet potato, yam, quinoa, potato, millet, rye, barley, oat, chickpea, bean, rapeseed, peanut, sunflower, and vegetable.

8. The method of claim 7, wherein the plant is maize.

9. The method of claim 1, wherein the plant is treated at a seedling stage of the plant.

10. The method of claim 1, wherein the plant is treated when the plant is under an environmental stress.

11. The method of claim 10, wherein the environmental stress is a reduction in water.

12. The method of claim 1, wherein the leaves, stems and/or roots of the plant are contacted with the composition comprising the benzoxazinoid.

13. The method of claim 1, wherein the composition further comprises a surface-active agent, an inert carrier, a preservative, a humectant, an encapsulating agent, a binder, an emulsifier, a dye, a UV protective and/or a buffer.

14. The method of claim 1, wherein one or more fields or greenhouses of plants are contacted with the composition comprising the benzoxazinoid.

15. The method of claim 1, wherein the benzoxazinoid is 6- Methoxybenzoxazolin-2 -one (6-MBOA) .

16. A method of stimulating plant growth comprising contacting a leaves, calluses, embryos, stems and/or roots of a plant or plant tissue with a composition that comprises a benzoxazinoid at an amount effective to stimulate the growth of the plant or plant tissue.