CN113331051A

CN113331051A - Culture medium and method for inducing plants to form storage roots

Info

Publication number: CN113331051A
Application number: CN202010134201.6A
Authority: CN
Inventors: 张鹏; 吴晓运; 张博伦
Original assignee: Center for Excellence in Molecular Plant Sciences of CAS
Current assignee: Center for Excellence in Molecular Plant Sciences of CAS
Priority date: 2020-03-02
Filing date: 2020-03-02
Publication date: 2021-09-03

Abstract

The invention provides a plant culture medium, which comprises a basic culture medium, 0.05mg/L-0.2mg/L of 6-BA, optional NAA, optional cane sugar and optional jasmonic acid compounds, wherein the jasmonic acid compounds are jasmonic acid or derivatives thereof. The plant culture medium is used to form plant storage roots. The present invention also provides a method of inducing a plant to form storage roots.

Description

Culture medium and method for inducing plants to form storage roots

Technical Field

The invention belongs to the field of plant culture, and particularly relates to a culture medium and a method for inducing plants to form storage roots.

Background

Storage roots are important organs of root crops, and the growth and development state of the storage roots directly determines the yield and productivity of the crops. However, to date, little is known about the process of storage root development in root crops. The main difficulty of research is that the storage root is the underground organ of the plant, which is not beneficial to direct continuous observation; and the field environment is unstable, and the research is greatly interfered by environmental factors.

The test-tube plantlet culture is an important method for preserving plant germplasm, and has the advantages of no pollution, stable environment, convenient observation and the like. The induction of the formation of the storage root of the test-tube plantlet is not only favorable for developing the research on the development of the storage root, but also hopeful for shortening the growth cycle of the crop and improving the annual yield of the crop. Cassava and sweet potatoes are ideal materials for researching the formation of storage roots of test-tube plantlets as typical root crops.

In cassava, there have been reports of inducing test-tube plantlets to form storage roots. The article published by Medina et al in 2007 first reported the induction of organs like storage roots in cassava tube seedlings. The method uses MS to add 5% of sucrose, 0.54 mu M of NAA, 0.44 mu M of MBAP and 0.75% of agar (pH5.8) as an induction culture medium, and 5-8mm long stem segments of cassava test-tube seedlings as induction materials. After the induction culture for 6-9 days, the cassava roots begin to expand and accumulate starch. The method has the disadvantage that the induced root enlargement is not sufficient, and is not obvious compared with the fibrous root. Although the roots accumulate starch, they only have a primary structure, which is significantly different from the tissue structure of the storage roots in their naturally grown state. In 2011 Fan et al improved the process and explored the effect of each component of the medium. The culture medium used in this method is MS plus 6% sucrose, 0.5mg/L NAA, 0.5mg/LBA (pH5.8). Although the root diameter induced by the method is increased, the growth time is shortened, and the root is closer to the natural expansion state, only primary growth still exists, no secondary structure appears, and the later growth of the root is also limited. In sweetpotato, it was found as early as 1997 that the application of a certain dose of TIBA (2,3, 5-triiodobenzoic acid) or cyprodinil in the medium can induce a weak enlargement of the sweet potato root, but not a mature system.

Storage root development is a complex process regulated by hormones, a process that gradually changes from primary growth to secondary growth, thereby accumulating starch. In the past, only starch in the roots of the test-tube seedlings is accumulated, a secondary structure is not formed, and the process of the cassava roots from expansion to real storage root formation is not obtained. There remains a need in the art for effective methods for inducing tube plantlets of root crops to form storage roots.

Disclosure of Invention

The method improves the condition of inducing the test-tube plantlet, leads the expanded root formed by the test-tube plantlet to be closer to the natural state, successfully induces the test-tube plantlet to form the expanded root and initially establishes the method for forming the storage root by the test-tube plantlet of the root tuber crop.

In a first aspect herein there is provided a plant culture medium comprising a basal medium, 0.05mg/L to 0.2mg/L of 6-BA, NAA, sucrose and optionally a jasmonate compound which is jasmonic acid or a derivative thereof.

In one or more embodiments, the basal medium comprises inorganic nutrients, vitamins, and amino acids required for plant growth. The inorganic nutrients include: nitrogen sources such as nitrate or ammonium nitrogen, phosphorus such as phosphate, sulphur such as sulphate, potassium such as potassium, calcium such as calcium, sodium such as sodium, magnesium such as magnesium, chlorine such as chloride, trace elements. Wherein the trace elements include: boron, iodine, manganese, zinc, molybdenum, copper, cobalt and iron. The vitamins include vitamin B1, vitamin B6, biotin, nicotinic acid, and inositol. The amino acid may be glycine.

In one or more embodiments, the plant culture medium further comprises a substrate. The matrix is a coagulant (e.g., agar), peatmoss and/or vermiculite.

In one or more embodiments, the basal medium is MS medium, B5 medium, or N6 medium.

In one or more embodiments, the plant medium comprises 0.5-100 μ g/L NAA, 0-4 mg/L jasmonate, and 2-6% sucrose w/v.

In one or more embodiments, the plant culture medium further comprises 0-5 μ M CuSO₄。

In one or more embodiments, the pH of the plant medium is 5.8.

In one or more embodiments, the plant culture medium is used to form plant storage roots. Preferably, the storage root has a secondary structure. More preferably, the storage root has secondary cells, secondary cambium and/or secondary xylem.

In one or more embodiments, the reservoir root is a root tuber.

In one or more embodiments, the derivative is methyl jasmonate.

In one or more embodiments, the jasmonic acid or derivative thereof is a racemic mixture.

In one or more embodiments, the plant is selected from the group consisting of: sweet potato, cassava, tuber fleeceflower root, dahlia, cochinchnese asparagus root and stemona root. Preferably, the cassava variety is TMS60444 or cultivar south china No. 8, and the sweet potato variety is SP 001.

In one or more embodiments, the sucrose concentration is 1% to 6%, 2% to 6%, 3% to 6%, 4% to 6%, or 4% to 5%, or a range between any of the foregoing values. Preferably, the sucrose concentration is 4-5%. More preferably, the sucrose concentration is 4% or 5%.

In one or more embodiments, the NAA concentration is 0.5 μ g/L to 100 μ g/L, 10 μ g/L to 100 μ g/L, 20 μ g/L to 100 μ g/L, 30 μ g/L to 100 μ g/L, 40 μ g/L to 100 μ g/L, 50 μ g/L to 100 μ g/L, 30 μ g/L to 80 μ g/L, 40 μ g/L to 70 μ g/L, or 50 μ g/L to 60 μ g/L, or a range between any of the foregoing. Preferably, the concentration of NAA is 50. mu.g/L to 100. mu.g/L. More preferably, the NAA concentration is 50. mu.g/L or 100. mu.g/L.

In one or more embodiments, the concentration of 6-BA is 0.05mg/L to 0.2mg/L, 0.06mg/L to 0.2mg/L, 0.07mg/L to 0.2mg/L, 0.08mg/L to 0.2mg/L, 0.09mg/L to 0.2mg/L, 0.1mg/L to 0.2mg/L, 0.06mg/L to 0.18mg/L, 0.07mg/L to 0.16mg/L, 0.08mg/L to 0.14mg/L, or 0.09mg/L to 0.12mg/L, or a range between any of the foregoing. Preferably, the concentration of 6-BA is 0.1mg/L to 0.2 mg/L. More preferably, the concentration of 6-BA is 0.1mg/L or 0.2 mg/L.

In one or more embodiments, the jasmonate concentration is 1mg/L to 4mg/L, 1.2mg/L to 4mg/L, 1.4mg/L to 4mg/L, 1.6mg/L to 4mg/L, 1.8mg/L to 4mg/L, 2mg/L to 4mg/L, 1.2mg/L to 3.6mg/L, 1.4mg/L to 3.2mg/L, 1.6mg/L to 2.8mg/L, 1.8mg/L to 2.4mg/L, or 1mg/L to 2mg/L, or a range between any of the foregoing. Preferably, the concentration of jasmonates is 1mg/L-2mg/L or 2mg/L-4 mg/L. More preferably, the jasmonate concentration is 1mg/L, 2mg/L or 4 mg/L.

In the culture medium, the concentration ranges of the sucrose, the NAA, the 6-BA and the jasmonic acid compound can be combined at will.

In one or more embodiments, the medium comprises the following concentrations of the components in any combination:

the concentration of the sucrose is 1% -6%, 2% -6%, 3% -6%, 4% -6% or 4% -5%; preferably, the sucrose concentration is 4-5%; more preferably, the sucrose concentration is 2%, 4%, 5% or 6%;

NAA concentration is 0.5-100. mu.g/L, 10-100. mu.g/L, 20-100. mu.g/L, 30-100. mu.g/L, 40-100. mu.g/L, 50-100. mu.g/L, 30-80. mu.g/L, 40-70. mu.g/L or 50-60. mu.g/L; preferably, the concentration of NAA is 50 μ g/L-100 μ g/L; more preferably, the NAA concentration is 50. mu.g/L or 100. mu.g/L;

the concentration of 6-BA is 0.05mg/L-0.2mg/L, 0.06mg/L-0.2mg/L, 0.07mg/L-0.2mg/L, 0.08mg/L-0.2mg/L, 0.09mg/L-0.2mg/L, 0.1mg/L-0.2mg/L, 0.06mg/L-0.18mg/L, 0.07mg/L-0.16mg/L, 0.08mg/L-0.14mg/L, or 0.09mg/L-0.12 mg/L; preferably, the concentration of 6-BA is 0.1mg/L-0.2 mg/L; more preferably, the concentration of 6-BA is 0.05mg/L, 0.1mg/L or 0.2 mg/L; and

the optional jasmonic acid compound is methyl jasmonate, wherein the concentration of the methyl jasmonate is 1mg/L-4mg/L, 1.2mg/L-4mg/L, 1.4mg/L-4mg/L, 1.6mg/L-4mg/L, 1.8mg/L-4mg/L, 2mg/L-4mg/L, 1.2mg/L-3.6mg/L, 1.4mg/L-3.2mg/L, 1.6mg/L-2.8mg/L, 1.8mg/L-2.4mg/L or 1mg/L-2 mg/L; preferably, the concentration of methyl jasmonate is 1mg/L-2mg/L or 2mg/L-4 mg/L; more preferably, the concentration of methyl jasmonate is 1mg/L, 2mg/L or 4 mg/L.

In one or more embodiments, the sucrose concentration is 2% to 6%, the NAA concentration is 10 μ g/L to 100 μ g/L, the 6-BA concentration is 0.05mg/L to 0.2mg/L, and the optional jasmonate concentration is 1.2mg/L to 3.6 mg/L.

In one or more embodiments, the sucrose concentration is 3% to 6%, the NAA concentration is 20 μ g/L to 100 μ g/L, the 6-BA concentration is 0.06mg/L to 0.2mg/L, and the optional jasmonate concentration is 1.4mg/L to 4 mg/L.

In one or more embodiments, the sucrose concentration is 4% to 6%, the NAA concentration is 30 μ g/L to 100 μ g/L, the 6-BA concentration is 0.08mg/L to 0.2mg/L, and the optional jasmonate concentration is 1.6mg/L to 4 mg/L.

In one or more embodiments, the sucrose concentration is 4% to 5%, the NAA concentration is 40 μ g/L to 100 μ g/L, the 6-BA concentration is 0.09mg/L to 0.2mg/L, and optionally the jasmonate concentration is 1.8mg/L to 4 mg/L.

In one or more embodiments, the sucrose concentration is 4% to 5%, the NAA concentration is 50 μ g/L to 100 μ g/L, the 6-BA concentration is 0.1mg/L to 0.2mg/L, and optionally the jasmonate concentration is 2mg/L to 4 mg/L.

In one or more embodiments, the sucrose concentration is 2%, 4% or 5%, the NAA concentration is 10. mu.g/L, 50. mu.g/L or 100. mu.g/L, the 6-BA concentration is 0.05mg/L, 0.1mg/L or 0.2mg/L, and optionally the jasmonate concentration is 1mg/L, 2mg/L or 4 mg/L.

In one or more embodiments, the sucrose concentration is 4% or 5%, the NAA concentration is 50. mu.g/L or 100. mu.g/L, the 6-BA concentration is 0.1mg/L or 0.2mg/L, and optionally the jasmonate concentration is 1mg/L or 2 mg/L.

In one or more embodiments, the sucrose concentration is 4%, the NAA concentration is 50 μ g/L, the 6-BA concentration is 0.1mg/L, and the optional jasmonate concentration is 2 mg/L. The culture medium is used for culturing cassava. The preferred cassava variety is TMS60444 or cultivar south China No. 8.

In one or more embodiments, the sucrose concentration is 5%, the NAA concentration is 100. mu.g/L, the 6-BA concentration is 0.2mg/L, and optionally the jasmonate concentration is 2 mg/L. The culture medium is used for culturing sweet potatoes. The preferred sweet potato variety is SP 001.

The invention also provides a composition comprising 6-BA, NAA, optional cane sugar and optional jasmonic acid compounds, wherein the concentration ratio of the 6-BA to the NAA to the cane sugar to the jasmonic acid compounds is 0.05-0.2:0.005-0.1: 10000-.

In one or more embodiments, the concentration ratio of 6-BA: NAA: sucrose: jasmonates in the composition is 0.06-0.2:0.01-0.1: 20000-.

In one or more embodiments, the concentration ratio of 6-BA: NAA: sucrose: jasmonates in the composition is 0.07-0.2:0.02-0.1:30000-60000:1.4-4 or 0.07-0.2:0.02-0.1:30000-60000: 1-3.2.

In one or more embodiments, the concentration ratio of 6-BA: NAA: sucrose: jasmonates in the composition is 0.08-0.2:0.03-0.1: 40000-.

In one or more embodiments, the concentration ratio of 6-BA: NAA: sucrose: jasmonates in the composition is from 0.09-0.2:0.04-0.1:40000-50000:1.8-4 or from 0.09-0.2:0.04-0.1:40000-50000: 1-2.4.

In one or more embodiments, the concentration ratio of 6-BA: NAA: sucrose: jasmonates in the composition is from 0.1-0.2:0.05-0.1:40000-50000:2-4 or from 0.1-0.2:0.05-0.1:40000-50000: 1-2.

In one or more embodiments, the concentration ratio of 6-BA: NAA: sucrose: jasmonates in the composition is 0.1:0.05:40000:2-4 or 0.1:0.05:40000: 1-2.

In one or more embodiments, the concentration ratio of 6-BA: NAA: sucrose: jasmonates in the composition is 0.2:0.1:50000:2-4 or 0.2:0.1:50000: 1-2.

The invention also provides the use of sucrose, 6-BA, NAA, a jasmonate compound, or a composition as described herein, to induce a plant to form storage roots or to cultivate a plant. The plant is preferably selected from: sweet potato, cassava, tuber fleeceflower root, dahlia, cochinchnese asparagus root and stemona root.

In one or more embodiments, the jasmonate compound is jasmonic acid or a derivative thereof.

In one or more embodiments, the sucrose concentration is from 1% to 6%, preferably from 3 to 6%.

In one or more embodiments, the concentration of 6-BA ranges from 0.05mg/L to 0.2mg/L, preferably from 0.06mg/L to 0.2 mg/L.

In one or more embodiments, the concentration of NAA is between 0.5. mu.g/L and 100. mu.g/L, preferably between 10. mu.g/L and 100. mu.g/L.

In one or more embodiments, the concentration of jasmonates is 1mg/L to 4mg/L, preferably 1.2mg/L to 4 mg/L.

In one or more embodiments, the use comprises culturing the plant in a medium containing the sucrose, 6-BA, NAA, jasmonate, or composition. In one or more embodiments, the plant has roots. In one or more embodiments, the root comprises one or more roots selected from the group consisting of: primary root, secondary root, adventitious root, fibrous root and enlarged root. In one or more embodiments, the roots are 0.1 to 5cm in length. For example 0.2-4cm, 0.3-3cm, 0.4-2cm or 0.5-1 cm.

In one or more embodiments, the culture medium further comprises a basal medium. Preferably, the basal medium is MS medium, B5 medium, or N6 medium.

The invention also provides the use of NAA, 6-BA and optionally a jasmonate and optionally sucrose to induce formation of storage roots in cassava or to cultivate cassava, wherein the jasmonate is jasmonic acid and/or methyl jasmonate.

In one or more embodiments, the sucrose concentration is 4%, the NAA concentration is 50. mu.g/L, the 6-BA concentration is 0.1mg/L, and the jasmonate concentration is 2 mg/L.

In one or more embodiments, the cassava variety is TMS60444 or cultivar south china No. 8.

In one or more embodiments, the use comprises culturing cassava in a medium comprising the NAA, 6-BA and jasmonates, and optionally sucrose. In one or more embodiments, the cassava has roots. In one or more embodiments, the root comprises one or more roots selected from the group consisting of: primary root, secondary root, adventitious root, fibrous root and enlarged root. In one or more embodiments, the roots are 0.1 to 5cm in length. For example 0.2-4cm, 0.3-3cm, 0.4-2cm or 0.5-1 cm.

In one or more embodiments, the culture medium further comprises a basal medium as described herein. Preferably, the basal medium is MS medium, B5 medium, or N6 medium.

The invention also provides the use of NAA, 6-BA and optionally sucrose to induce sweetpotato to form storage roots or to culture sweetpotato.

In one or more embodiments, the sucrose concentration is 5%, the NAA concentration is 100. mu.g/L, and the 6-BA concentration is 0.2 mg/L.

In one or more embodiments, the sweet potato variety is SP 001.

In one or more embodiments, the use comprises culturing sweetpotato in a medium comprising the NAA, 6-BA and optionally sucrose. In one or more embodiments, the sweet potato has a root. In one or more embodiments, the root comprises one or more roots selected from the group consisting of: primary root, secondary root, adventitious root, fibrous root and enlarged root. In one or more embodiments, the roots are 0.1 to 5cm in length. For example 0.2-4cm, 0.3-3cm, 0.4-2cm or 0.5-1 cm.

The invention also provides a preparation method of the plant culture medium, which comprises the steps of mixing a basic culture medium, 6-BA, NAA, cane sugar and optional jasmonic acid compounds, wherein the plant culture medium comprises 0.05mg/L-0.2mg/L of 6-BA, 10-100 mu g/L of NAA, 2-6% of cane sugar and 1mg/L-4mg/L of jasmonic acid compounds, and the jasmonic acid compounds are jasmonic acid or derivatives thereof. The plant culture medium is used for inducing plants to form storage roots. The plant is preferably selected from: sweet potato, cassava, tuber fleeceflower root, dahlia, cochinchnese asparagus root and stemona root. Preferably, the medium is as described herein in the first aspect.

The invention also provides a method of inducing a plant to form storage roots or to grow a plant comprising growing a plant or part of a plant with the plant culture medium described herein.

In one or more embodiments, the plant has roots.

In one or more embodiments, the plant part comprises or is a root.

In one or more embodiments, the root comprises one or more roots selected from the group consisting of: primary root, secondary root, adventitious root, fibrous root and enlarged root.

In one or more embodiments, the roots are 0.1 to 5cm in length. For example 0.2-4cm, 0.3-3cm, 0.4-2cm or 0.5-1 cm.

In one or more embodiments, the storage root has a secondary structure. More preferably, the storage root has secondary cells, secondary cambium and/or secondary xylem.

In one or more embodiments, the reservoir root is a root tuber.

The present invention also provides a method for inducing cassava to form storage roots or culturing cassava, comprising the step of culturing cassava with a medium containing NAA, 6-BA and optionally a jasmonate compound and optionally sucrose, wherein the jasmonate compound is jasmonic acid and/or methyl jasmonate.

In one or more embodiments, the cassava has roots.

The present invention also provides a method for inducing sweetpotato to form storage root or culturing sweetpotato, comprising the step of culturing sweetpotato in a medium containing NAA, 6-BA and optionally sucrose.

In one or more embodiments, the sweet potato has a root.

In one or more embodiments, the sweet potato variety is SP 001.

The present invention also provides a method of obtaining a plant having storage roots comprising inoculating a plant or part into a plant culture medium as described herein for cultivation.

The present invention also provides a method for obtaining plant storage roots comprising inoculating a plant or part thereof into a plant culture medium as described herein for cultivation, and collecting the storage roots.

The invention has the beneficial effects that:

different from the fact that the induced expanded root only has a primary root structure in the previous research, the invention enables the induced expanded root to have secondary cells and has the tendency of forming a secondary cambium and a secondary xylem by adjusting the hormone concentration. In addition, the method simultaneously induces one variety of sweet potatoes and two varieties of cassava in vitro, and proves that the induction method has universality in the two root crops.

Drawings

FIG. 1 shows the result of inducing toluidine blue staining of 4-week epitype paraffin sections (cross-section) by cassava test-tube plantlets at a sucrose concentration of 2%.

FIG. 2 shows the result of iodine staining of cassava test-tube plantlets induced a 4-week phenotype and enlarged root paraffin sections (cross-sections) at a sucrose concentration of 4%.

FIG. 3 shows the result of iodine staining of cassava test-tube plantlets induced a 4-week phenotype and enlarged root paraffin sections (cross-sections) at a sucrose concentration of 5%.

FIG. 4 shows that cassava test-tube plantlets induce a 4-week phenotype at an NAA concentration of 0.5. mu.g/L and the enlarged root paraffin sections (cross-cut) are stained with iodine.

FIG. 5 shows that cassava test-tube plantlets induce a 4-week phenotype at an NAA concentration of 10. mu.g/L and the expanded root paraffin sections (cross-sections) are stained with iodine.

FIG. 6 shows that cassava test-tube plantlets induce a 4-week phenotype at an NAA concentration of 50. mu.g/L and the expanded root paraffin sections (cross-sections) are stained with iodine.

FIG. 7 shows that cassava test-tube plantlets induced a 4-week phenotype at an NAA concentration of 100. mu.g/L and the expanded root paraffin sections (cross-sections) were stained with iodine.

FIG. 8, the results of toluidine blue staining of cassava test-tube plantlets induced a 4-week phenotype and enlarged root paraffin sections (cross-cut) at a concentration of 0.05 mg/L.

FIG. 9, the results of toluidine blue staining of cassava test-tube plantlets induced a 4-week phenotype and enlarged root paraffin sections (cross-cut) at a concentration of 0.1 mg/L.

FIG. 10, the results of toluidine blue staining of cassava test-tube plantlets induced a 4-week phenotype and enlarged root paraffin sections (cross-cut) at a concentration of 0.2 mg/L.

FIG. 11 shows toluidine blue staining results of cassava test-tube plantlets induced a 4-week phenotype and expanded root paraffin sections (cross-sections) at JA concentration of 1 mg/L.

FIG. 12 shows the toluidine blue staining results of cassava test-tube plantlets induced a 4-week phenotype and expanded root paraffin sections (cross-sections) at a JA concentration of 2 mg/L.

FIG. 13 shows toluidine blue staining results of cassava test-tube plantlets induced a 4-week phenotype and expanded root paraffin sections (cross-sections) at JA concentration of 4 mg/L.

Fig. 14, results of toluidine blue staining of cassava test-tube plantlets, No. 8, south China induced a 3-week phenotype and expanded root paraffin sections (cross-section).

Figure 15 TMS60444 cassava test-tube plantlets induced a 3-week phenotype and enlarged root paraffin sections (cross-cut) toluidine blue staining results.

FIG. 16, sweetpotato SP001 tube plantlet induced a 3-week swelling root phenotype.

FIG. 17, sweetpotato SP001 tube plantlet induced a 3-week swelling root phenotype.

FIG. 18, sweetpotato SP001 tube plantlet induced a 3-week swelling root phenotype.

FIG. 19, sweetpotato SP001 tube plantlet induced a 3-week swelling root phenotype.

FIG. 20, sweetpotato SP001 tube plantlet induced a 3-week swelling root phenotype.

Detailed Description

According to the invention, the concentrations of hormone and sucrose are adjusted in the induction culture medium, and Jasmonic Acid (JA) is added, so that the in-vitro induced expanded roots generate secondary growth, and the development process of the storage roots in a natural state is better simulated.

Adjusting hormones in the medium herein includes adjusting 6-BA and/or NAA. 6-BA is 6-benzylaminoadenine, a cytokinin. 6-BA can promote the formation of buds and can also induce the generation of callus. The concentration of 6-BA in the plant culture medium in the prior art is more than 0.5 mg/L. NAA is naphthylacetic acid, a plant growth regulator, and can promote cell division and enlargement, and induce the formation of adventitious roots.

As used herein, "jasmonates" includes jasmonic acid, derivatives thereof, isomers thereof and structural analogs thereof. In one or more embodiments, the derivative is methyl jasmonate. The jasmonate compound may be an isomer or racemic mixture of jasmonic acid or a derivative thereof.

As used herein, a "basal medium" is a medium for plants that contains essential nutrients required for plant growth. Typically, the basal medium contains inorganic nutrients, vitamins and amino acids required for plant growth. The inorganic nutrients include: nitrogen sources such as nitrate or ammonium nitrogen, phosphorus such as phosphate, sulphur such as sulphate, potassium such as potassium, calcium such as calcium, sodium such as sodium, magnesium such as magnesium, chlorine such as chloride, trace elements. The trace elements include: boron, iodine, manganese, zinc, molybdenum, copper, cobalt and iron. The vitamins include vitamin B1, vitamin B6, biotin, nicotinic acid, and inositol. The amino acid may be glycine. The basal medium may be MS medium, B5 medium, N6 medium or Hoagland medium. The basic culture medium can be used as the basic component of some special culture media, and other required nutrients are added into the basic culture medium according to the special requirements of plants or the growth stage of the plants. The basal medium may be in solid or liquid form, e.g., solution, suspension, powder, gel, granular, etc. In embodiments herein, the plant culture medium further comprises 6-BA, NAA, optionally sucrose, and optionally jasmonates. In one or more embodiments, the plant medium comprises 0.05mg/L to 0.2mg/L of 6-BA, 0.5 μ g/L to 100 μ g/L of NAA, 1 to 6% sucrose, 1mg/L to 4mg/L of jasmonates.

The composition and content of the basal medium are well known in the art. Exemplary components of the MS medium and the B5 medium and their contents are shown in the following tables.

MS culture medium

B5 Medium

The plant medium used to cultivate the plants may be a liquid, a solid or a mixture of solid and liquid, as long as the contents of the components therein are as described herein. As a solid, the plant culture medium also comprises a matrix. Typically, the substrate includes, but is not limited to, coagulants (e.g., agar), peatmoss, vermiculite, peat, humus, fine sand, roving, and the like.

As used herein, a "storage root" is a modified root that is common in plants and functions to store nutrients such as starch in addition to absorbing moisture and minerals. Storage roots are classified into fleshy taproots and tuberous roots according to their sources and forms. The root tuber is formed by the expansion of adventitious roots or lateral roots of a seedling of a vegetative propagation plant, a plurality of root tubers can be formed on one plant, the root tubers do not contain hypocotyls and stem parts, and the root tubers completely consist of roots. In one or more embodiments, a "plant" as described herein is a storage root plant, preferably a root tuber plant. The tuberous root plant is distributed in various families, such as sweet potato of Convolvulaceae, cassava of Euphorbiaceae, Polygonum multiflorum of Polygonaceae, dahlia of Compositae, Asparagus cochinchinensis of Liliaceae, and Stemona sessilifolia of Stemonaceae. Herein, the plant to be cultured may have roots or not. The root can be primary root, secondary root, adventitious root, fibrous root or enlarged root. The roots may be 0.1-5cm in length, for example 0.2-4cm, 0.3-3cm, 0.4-2cm or 0.5-1 cm. Preferably, the plant to be cultivated has roots or the plant part to be cultivated comprises roots.

The plant body generates a 'secondary structure' to thicken the stem and the root, and the secondary structure can enhance the functions of the plant body such as support, transmission, storage and the like. Adventitious root on the basis of primary growth, vascular stratification activity produces secondary xylem containing a large number of wood parenchyma cells, forming a tuberous root. The wood parenchyma cells scattered around the catheter then transform into a secondary cambium, forming a triclosan structure. As the vascular formation layer is continuously generated and activated, the sub-formation layer can be generated and grown for multiple times, and the root tuber is rapidly expanded. Parenchymal cells of the triclosan structure store large amounts of sugars and starch. Therefore, it is crucial to generate secondary structures in the reservoir/root tuber. The storage roots described herein have a secondary structure. Preferably, the storage root has secondary cells, secondary cambium and/or secondary xylem.

Provided herein is a plant culture medium comprising a basal medium, 0.05mg/L to 0.2mg/L of 6-BA, NAA, sucrose, and optionally a jasmonate compound, which is jasmonic acid or methyl jasmonate. In one or more embodiments, the plant medium comprises 0.5-100 μ g/L NAA, 0-4 mg/L jasmonate, and 2-6% sucrose w/v. In one or more embodiments, the plant culture medium further comprises 0-5 μ M CuSO₄. In one or more embodiments, the plant culture medium is used to form plant storage roots. In one or more embodiments, the plant is selected from the group consisting of: sweet potato, cassava, tuber fleeceflower root, dahlia, cochinchnese asparagus root and stemona root. Preferably, the cassava variety is TMS60444 or cultivar south china No. 8, and the sweet potato variety is SP 001.

The sucrose concentration in the plant medium herein is 1% to 6%, 2% to 6%, 3% to 6%, 4% to 6%, or 4% to 5%, or a range between any of the foregoing values. Preferably, the sucrose concentration is 4-5%. More preferably, the sucrose concentration is 4% or 5%. In the plant culture medium herein, the concentration of NAA is 0.5. mu.g/L-100. mu.g/L, 10. mu.g/L-100. mu.g/L, 20. mu.g/L-100. mu.g/L, 30. mu.g/L-100. mu.g/L, 40. mu.g/L-100. mu.g/L, 50. mu.g/L-100. mu.g/L, 30. mu.g/L-80. mu.g/L, 40. mu.g/L-70. mu.g/L or 50. mu.g/L-60. mu.g/L, or a range between any of the foregoing. Preferably, the concentration of NAA is 50. mu.g/L to 100. mu.g/L. More preferably, the NAA concentration is 50. mu.g/L or 100. mu.g/L. In the plant culture medium herein, the concentration of 6-BA is 0.05mg/L-0.2mg/L, 0.06mg/L-0.2mg/L, 0.07mg/L-0.2mg/L, 0.08mg/L-0.2mg/L, 0.09mg/L-0.2mg/L, 0.1mg/L-0.2mg/L, 0.06mg/L-0.18mg/L, 0.07mg/L-0.16mg/L, 0.08mg/L-0.14mg/L, or 0.09mg/L-0.12mg/L, or a range between any of the foregoing. Preferably, the concentration of 6-BA is 0.1mg/L to 0.2 mg/L. More preferably, the concentration of 6-BA is 0.1mg/L or 0.2 mg/L. In the plant culture medium, the concentration of jasmonate compound is 1mg/L-4mg/L, 1.2mg/L-4mg/L, 1.4mg/L-4mg/L, 1.6mg/L-4mg/L, 1.8mg/L-4mg/L, 2mg/L-4mg/L, 1.2mg/L-3.6mg/L, 1.4mg/L-3.2mg/L, 1.6mg/L-2.8mg/L, 1.8mg/L-2.4mg/L or 1mg/L-2mg/L, or a range between any of the above values. Preferably, the concentration of jasmonates is 1mg/L-2mg/L or 2mg/L-4 mg/L. More preferably, the jasmonate concentration is 1mg/L, 2mg/L or 4 mg/L. In the plant culture medium, the concentration ranges of the sucrose, the NAA, the 6-BA and the jasmonic acid compound can be combined at will.

Specifically, a plant culture medium herein comprises a basal medium, 6-BA, NAA, sucrose and methyl jasmonate, wherein the concentration of sucrose is 1% -6%, 2% -6%, 3% -6%, 4% -6% or 4% -5%; NAA concentration is 0.5-100. mu.g/L, 10-100. mu.g/L, 20-100. mu.g/L, 30-100. mu.g/L, 40-100. mu.g/L, 50-100. mu.g/L, 30-80. mu.g/L, 40-70. mu.g/L or 50-60. mu.g/L; the concentration of 6-BA is 0.05mg/L-0.2mg/L, 0.06mg/L-0.2mg/L, 0.07mg/L-0.2mg/L, 0.08mg/L-0.2mg/L, 0.09mg/L-0.2mg/L, 0.1mg/L-0.2mg/L, 0.06mg/L-0.18mg/L, 0.07mg/L-0.16mg/L, 0.08mg/L-0.14mg/L, or 0.09mg/L-0.12 mg/L; the concentration of methyl jasmonate is 1mg/L-4mg/L, 1.2mg/L-4mg/L, 1.4mg/L-4mg/L, 1.6mg/L-4mg/L, 1.8mg/L-4mg/L, 2mg/L-4mg/L, 1.2mg/L-3.6mg/L, 1.4mg/L-3.2mg/L, 1.6mg/L-2.8mg/L, 1.8mg/L-2.4mg/L or 1mg/L-2 mg/L. In one or more embodiments, the sucrose concentration is 2% to 6%, the NAA concentration is 10. mu.g/L to 100. mu.g/L, the 6-BA concentration is 0.05mg/L to 0.2mg/L, and the methyl jasmonate concentration is 1.2mg/L to 3.6 mg/L. Preferably, the concentration of sucrose is 4% -5%, the concentration of NAA is 50-100. mu.g/L, the concentration of 6-BA is 0.1-0.2 mg/L, and the concentration of methyl jasmonate is 2-4 mg/L. More preferably, the sucrose concentration is 4%, the NAA concentration is 50. mu.g/L, the 6-BA concentration is 0.1mg/L, and the methyl jasmonate concentration is 2 mg/L. The culture medium is used for culturing cassava. The preferred cassava variety is TMS60444 or cultivar south China No. 8.

Another plant culture medium herein comprises a basal medium, 6-BA, NAA, and sucrose, wherein the sucrose concentration is 1% -6%, 2% -6%, 3% -6%, 4% -6%, or 4% -5%; NAA concentration is 0.5-100. mu.g/L, 10-100. mu.g/L, 20-100. mu.g/L, 30-100. mu.g/L, 40-100. mu.g/L, 50-100. mu.g/L, 30-80. mu.g/L, 40-70. mu.g/L or 50-60. mu.g/L; the concentration of 6-BA is 0.05mg/L-0.2mg/L, 0.06mg/L-0.2mg/L, 0.07mg/L-0.2mg/L, 0.08mg/L-0.2mg/L, 0.09mg/L-0.2mg/L, 0.1mg/L-0.2mg/L, 0.06mg/L-0.18mg/L, 0.07mg/L-0.16mg/L, 0.08mg/L-0.14mg/L, or 0.09mg/L-0.12 mg/L. In one or more embodiments, the sucrose concentration is 2% to 6%, the NAA concentration is 10. mu.g/L to 100. mu.g/L, and the 6-BA concentration is 0.05mg/L to 0.2 mg/L. Preferably, the concentration of the sucrose is 4-5%, the concentration of the NAA is 50-100 mug/L, and the concentration of the 6-BA is 0.1-0.2 mg/L. More preferably, the sucrose concentration is 5%, the NAA concentration is 100. mu.g/L and the 6-BA concentration is 0.2 mg/L. The culture medium is used for culturing sweet potatoes. The preferred sweet potato variety is SP 001.

The invention also provides a composition comprising 6-BA and JA and optional NAA and/or sucrose, wherein the concentration ratio of the 6-BA: NAA: sucrose: jasmonic acid compounds is 0.05-0.2:0.005-0.1: 10000-. In one or more embodiments, the concentration ratio of 6-BA: NAA: sucrose: jasmonates in the composition is 0.06-0.2:0.01-0.1: 20000-. In one or more embodiments, the concentration ratio of 6-BA: NAA: sucrose: jasmonates in the composition is 0.07-0.2:0.02-0.1:30000-60000:1.4-4 or 0.07-0.2:0.02-0.1:30000-60000: 1-3.2. In one or more embodiments, the concentration ratio of 6-BA: NAA: sucrose: jasmonates in the composition is 0.08-0.2:0.03-0.1: 40000-. In one or more embodiments, the concentration ratio of 6-BA: NAA: sucrose: jasmonates in the composition is from 0.09-0.2:0.04-0.1:40000-50000:1.8-4 or from 0.09-0.2:0.04-0.1:40000-50000: 1-2.4. In one or more embodiments, the concentration ratio of 6-BA: NAA: sucrose: jasmonates in the composition is from 0.1-0.2:0.05-0.1:40000-50000:2-4 or from 0.1-0.2:0.05-0.1:40000-50000: 1-2. In one or more embodiments, the concentration ratio of 6-BA: NAA: sucrose: jasmonates in the composition is 0.1:0.05:40000:2-4 or 0.1:0.05:40000: 1-2. In one or more embodiments, the concentration ratio of 6-BA: NAA: sucrose: jasmonates in the composition is 0.2:0.1:50000:2-4 or 0.2:0.1:50000: 1-2.

The invention also provides the use of sucrose, 6-BA, NAA, jasmonic acid or a derivative thereof or a composition as described herein to induce a plant to form storage roots. The plant is preferably selected from: sweet potato, cassava, tuber fleeceflower root, dahlia, cochinchnese asparagus root and stemona root. Typically, the composition is used to cultivate plants after mixing with a basal medium and optionally a substrate, which induces the plants to form storage roots. Wherein, the concentration of the sucrose is 1 to 6 percent, and the preferential concentration is 3 to 6 percent; the concentration of 6-BA is 0.05mg/L-0.2mg/L, preferably 0.06mg/L-0.2 mg/L; the concentration of NAA is 0.5-100 μ g/L, preferably 10-100 μ g/L; the concentration of jasmonates is 1mg/L-4mg/L, preferably 1.2mg/L-4 mg/L. The use comprises culturing the plant in a medium comprising the sucrose, 6-BA, NAA, jasmonate, or composition. Wherein the plant has roots selected from one or more of the following: primary root, secondary root, adventitious root, fibrous root and enlarged root. The roots may be 0.1-5cm in length. For example 0.2-4cm, 0.3-3cm, 0.4-2cm or 0.5-1 cm. The above medium also contains the basal medium described herein.

The invention also provides application of NAA, 6-BA, methyl jasmonate and/or sucrose in inducing cassava to form a storage root or culturing cassava, wherein the jasmonate compound is jasmonic acid and/or methyl jasmonate. Wherein the sucrose concentration is 4%, the NAA concentration is 50 μ g/L, the 6-BA concentration is 0.1mg/L, and the jasmonic acid compound concentration is 2 mg/L. The cassava variety is TMS60444 or cultivar No. 8 Huanan. The use comprises culturing cassava in a medium comprising the NAA, 6-BA, methyl jasmonate and sucrose. In one or more embodiments, the cassava has roots selected from one or more of the following: primary root, secondary root, adventitious root, fibrous root and enlarged root. The length of the root is 0.1-5 cm. For example 0.2-4cm, 0.3-3cm, 0.4-2cm or 0.5-1 cm. The culture medium also contains a basal medium as described herein.

The invention also provides the application of NAA, 6-BA and/or sucrose in inducing the sweet potato to form storage root or culturing the sweet potato. Wherein the sucrose concentration is 5%, the NAA concentration is 100 mug/L, and the 6-BA concentration is 0.2 mg/L. The sweet potato variety is SP 001. The use comprises culturing sweet potato in a medium containing the NAA, 6-BA and/or sucrose. In one or more embodiments, the sweet potato has roots selected from one or more of the following: primary root, secondary root, adventitious root, fibrous root and enlarged root. The length of the root is 0.1-5 cm. For example 0.2-4cm, 0.3-3cm, 0.4-2cm or 0.5-1 cm. The culture medium also contains a basal medium as described herein.

The invention also provides a preparation method of the plant culture medium, which comprises the steps of mixing a basic culture medium, 6-BA, NAA, cane sugar and optional jasmonic acid compounds, wherein the plant culture medium comprises 0.05mg/L-0.2mg/L of 6-BA, 10-100 mu g/L of NAA, 2-6% of cane sugar and 1mg/L-4mg/L of jasmonic acid compounds, and the jasmonic acid compounds are jasmonic acid or derivatives thereof. The plant culture medium is used for inducing plants to form storage roots. The plant is preferably selected from: sweet potato, cassava, tuber fleeceflower root, dahlia, cochinchnese asparagus root and stemona root.

The invention also provides a plant culture method for inducing a plant to form storage roots, comprising culturing a plant or part of a plant with the plant culture medium described herein. Plants having storage roots can be obtained using the cultivation methods herein. "culture" as used herein includes various types of plant culture such as tissue culture, plant culture, potting culture, field culture, and tissue culture of a plant refers to a technique of separating a desired portion (e.g., tissue, organ or cell, protoplast, etc.) from a plant body, performing culture by aseptic manipulation, inoculating on a culture medium under aseptic conditions to obtain a regenerated whole plant, or producing other products having economic value. Tissue culture also includes callus culture. The plant culture refers to the culture process of the plant test-tube plantlet on a culture medium. Potting culture refers to a culture mode in which plant plants are cultured or seeds are grown in soil. The field culture refers to culture in the field in a natural environment or an artificial environment. Herein, the plant preferably has roots; the plant part preferably comprises or is a root. The roots comprise one or more roots selected from the group consisting of: primary root, secondary root, adventitious root, fibrous root and enlarged root. The length of the root is 0.1-5 cm. For example 0.2-4cm, 0.3-3cm, 0.4-2cm or 0.5-1 cm. The storage root has a secondary structure. More preferably, the storage root has secondary cells, secondary cambium and/or secondary xylem.

Specifically, the present invention provides a method for inducing cassava to form storage roots or culturing cassava, comprising the step of culturing cassava with a medium containing NAA, 6-BA, methyl jasmonate and sucrose. Wherein the sucrose concentration is 4%, the NAA concentration is 50 μ g/L, the 6-BA concentration is 0.1mg/L, and the jasmonic acid compound concentration is 2 mg/L. The cassava variety is TMS60444 or cultivar No. 8 Huanan. The cassava has roots selected from one or more of the following: primary root, secondary root, adventitious root, fibrous root and enlarged root. The length of the root is 0.1-5 cm. For example 0.2-4cm, 0.3-3cm, 0.4-2cm or 0.5-1 cm. The culture medium also contains a basal medium as described herein.

The present invention also provides a method for inducing sweetpotato to form storage root or culturing sweetpotato, comprising the step of culturing sweetpotato in a medium containing NAA, 6-BA and sucrose. Wherein, the concentration of sucrose is 5%, the concentration of NAA is 100 mug/L, and the concentration of 6-BA is 0.2 mg/L. The sweet potato variety is SP 001. The sweet potato has roots selected from one or more of the following: primary root, secondary root, adventitious root, fibrous root and enlarged root. The length of the root is 0.1-5 cm. For example 0.2-4cm, 0.3-3cm, 0.4-2cm or 0.5-1 cm. The culture medium also contains a basal medium as described herein.

In one embodiment, in order to induce cassava to form storage roots or to culture cassava, cassava having primary roots (e.g., about 1cm primary roots) is cultured using a medium containing NAA, 6-BA, a jasmonate compound, sucrose and MS medium, wherein the jasmonate compound is jasmonic acid and/or methyl jasmonate, the sucrose concentration is 4%, the NAA concentration is 50. mu.g/L, the 6-BA concentration is 0.1mg/L, and the jasmonate compound concentration is 2 mg/L. The cassava varieties can be TMS60444 or cultivar No. 8 Huanan. Thus, the medium of the present invention may be a medium containing MS medium and having a sucrose concentration of 4%, an NAA concentration of 50. mu.g/L, a 6-BA concentration of 0.1mg/L, and a jasmonate concentration of 2 mg/L.

In another embodiment, in order to induce the formation of storage roots from sweet potatoes or to culture sweet potatoes, the sweet potatoes having primary roots (e.g., about 1cm of primary roots) are cultured using an MS medium containing NAA, 6-BA, sucrose and MS medium at a sucrose concentration of 5%, NAA concentration of 100. mu.g/L and 6-BA concentration of 0.2 mg/L. The sweet potato variety is SP 001. Thus, the medium of the present invention may be a medium containing MS medium and having a sucrose concentration of 5%, an NAA concentration of 100. mu.g/L and a 6-BA concentration of 0.2 mg/L.

Examples

Test materials and methods

Cassava culture medium:

(1) sucrose concentration gradient treatment (TMS60444)

Basic cassava medium (MS powder, 2. mu.M CuSO4, 2% Gelrite), NAA at final concentration 0.25. mu.M and 6-BA at final concentration 0.5. mu.M were added, and sucrose at final concentration 2%, 4%, 5% was added, respectively, to adjust the pH to 5.8.

(2) NAA concentration gradient treatment (TMS60444)

Basic cassava medium (MS powder, 2. mu.M CuSO4, 2% Gelrite), sucrose at a final concentration of 2% and 6-BA at a final concentration of 0.5. mu.M, NAA at a final concentration of 0.5. mu.g/L, 10. mu.g/L, 50. mu.g/L, 100. mu.g/L were added, respectively, and the pH was adjusted to 5.8.

(3)6-BA concentration gradient treatment (TMS60444)

Basic cassava medium (MS powder, 2. mu.M CuSO4, 2% Gelrite), sucrose at a final concentration of 2% and NAA at a final concentration of 0.05mg/L were added, and 6-BA at final concentrations of 0.05mg/L, 0.1mg/L and 0.2mg/L, respectively, were added to adjust the pH to 5.8.

(4) JA concentration gradient treatment (TMS60444)

Basic cassava culture medium (MS powder, 2 mu M CuSO4, 2% Gelrite), sucrose with a final concentration of 4%, 6-BA with a final concentration of 0.1mg/L and NAA with a final concentration of 0.05mg/L, adjusting the pH to 5.8, and then JA with a final concentration of 1mg/L, 2mg/L and 4mg/L respectively.

(5) Integrated culture medium (TMS60444 and south China No. 8)

Basic cassava medium (MS powder, 2. mu.M CuSO4, 2% Gelrite), sucrose at a final concentration of 4%, 0.1 mg/L6-BA, 0.05mg/L NAA, 2mg/L JA were added and the pH was adjusted to 5.8.

Sweet potato culture medium:

(1) basal sweet potato medium BBM (MS powder, 2% Gelrite), final concentration of 3% sucrose, final concentration of 0.1 mg/L6-BA, 0.05mg/L NAA.

(2) Basal sweet potato medium BBM (MS powder, 2% Gelrite), sucrose at a final concentration of 4%, 6-BA at a final concentration of 0.1mg/L, NAA at a final concentration of 0.1 mg/L.

Experimental methods

Subculturing the cassava model seed TMS60444 and the No. 8 test-tube plantlet of the cultivar south China into a CBM culture medium for 7-10 days until primary roots within 1cm grow out, transferring the cassava model seed TMS60444 and the cultivar south China to an induction culture medium, and continuing to grow for 3 weeks.

The sweet potato SP001 is subcultured into BBM culture medium to grow for about 5 days until primary roots within 1cm grow out, and transferred into induction culture medium to continue to grow for 3-4 weeks.

Immediately after the enlarged roots are cut, they are fixed with FAA fixative, followed by a paraffin sectioning step. After slicing, staining with iodine staining solution to observe starch grain accumulation, or staining with toluidine blue to observe secondary structure of root.

Example 1 cassava root induced by different sucrose concentrations

The results with a sucrose concentration of 2% are shown in FIG. 1, where the primary roots have an expanding tendency, but the roots retain the primary structure. There was temporarily no accumulation of starch granules in the roots.

The results of the sucrose concentration of 4% are shown in FIG. 2, where the tendency of root enlargement is already significant and the number of fibrous roots is increased. The roots of the plants all had a large accumulation of starch (dark colored parts), but the primary structure was still maintained.

The results of 5% sucrose concentration are shown in FIG. 3, where root expansion is inhibited more than in the case of 4% sucrose treatment, and the number of wild-type fibrous roots increases. The slicing results showed that starch accumulation in the roots disappeared.

Example 2 different concentrations of NAA-induced cassava root

As a result of the concentration of NAA of 0.5. mu.g/L, the roots had a tendency to thicken and the results of slicing showed that starch had accumulated in the roots (stained dark portions) as shown in FIG. 4.

As a result of NAA concentration of 10. mu.g/L, the number of fibrous roots was increased, the plant roots were significantly thickened, and starch was accumulated (dark colored portion) as shown in FIG. 5.

The result of NAA concentration of 50. mu.g/L is shown in FIG. 6, and a significant swelling phenotype appears, and a small amount of starch is accumulated in the swelling root, but the root structure is still primary.

The results are shown in FIG. 7, where the roots are thickened or enlarged with a small amount of starch (dark colored parts), but the cell structure of the roots is loose, at an NAA concentration of 100. mu.g/L.

Example 3 different concentrations of 6-BA induced cassava root

The result of the concentration of 6-BA of 0.05mg/L is shown in FIG. 8, the roots have a tendency to swell, and a small amount of secondary structure appears.

The results are shown in FIG. 9 for a concentration of 0.1mg/L of 6-BA, which is clearly enlarged and has a clearly secondary structure.

The results for the 6-BA concentration of 0.2mg/L are shown in FIG. 10, where the roots are further enlarged, but the amount is reduced compared to the 0.1mg/L concentration, and no secondary structure appears on the roots, which is probably an inhibitory effect at high concentration.

Example 4 different concentrations of JA-induced cassava root

The results of JA concentration of 1mg/L are shown in FIG. 11, where the roots are significantly enlarged and the structure is relatively compact, but the secondary structure is not significant.

The results of JA concentration of 2mg/L are shown in FIG. 12, where the roots had some enlargement and the slicing results showed that secondary structure had occurred.

The results of JA concentration 4mg/L are shown in FIG. 13, the root expansion degree is equivalent to that of the 2mg/L concentration group, the secondary structure is obvious, and the cells have starch granule accumulation (dark granular shape).

Example 5 cassava root at Integrated culture concentration

The results of the final concentrations of 4% sucrose, 0.1 mg/L6-BA, 0.05mg/L NAA, 2mg/L JA are shown in FIGS. 14 and 15, and the thickening of the plant roots is evident in both south China No. 8 and TMS60444, and the slicing results show that secondary structures have been formed, secondary ducts and cambium are evident, and starch grains (dark granular) are accumulated in the parenchyma cells.

Example 6 sweet Potato root at Integrated culture concentration

The results of 3% sucrose, 0.1 mg/L6-BA, 0.05mg/L NAA at the final concentration are shown in FIG. 16, where the roots showed a tendency to swell, but more lateral roots grew on the roots.

The results of sucrose with a final concentration of 4%, 6-BA with a final concentration of 0.1mg/L and NAA with a final concentration of 0.1mg/L are shown in FIG. 17, and the roots are remarkably enlarged and are similar to the enlarged roots induced by the cassava test-tube plantlet.

The results for 5% sucrose, 0.2mg/L6-BA, 0.05mg/L NAA at the final concentration are shown in FIG. 18, with some roots swelling and turning red. Since the red fibrous root of sweetpotato at the initial development stage gradually develops into a storage root, the swelling becomes red more closely to the early state of the storage root.

The results of 5% sucrose, 0.1 mg/L6-BA and 0.1mg/L NAA at the final concentration are shown in FIG. 19, and the multiple roots have an expanding trend, which is similar to the phenotype of 4% sucrose.

The results of 5% sucrose, 0.2mg/L6-BA, 0.1mg/L NAA at the final concentration are shown in FIG. 20, with obvious root swelling and partial reddening.

In conclusion, the culture media can induce the root expansion of the sweet potatoes, wherein the culture media with the final concentration of 5% of sucrose, 0.2mg/L of 6-BA and 0.1mg/L of NAA have better induction effect, and the induced roots are closer to the root expansion state of the sweet potatoes.

Claims

1. A plant culture medium comprising a basal medium, 0.05mg/L to 0.2mg/L of 6-BA, NAA, sucrose and optionally a jasmonate compound, wherein the jasmonate compound is jasmonic acid or a derivative thereof,

preferably, the plant culture medium is used to form plant storage roots.

2. The plant culture medium of claim 1, further comprising one or more characteristics selected from the group consisting of:

the basic medium comprises inorganic nutrients, vitamins and amino acids required for plant growth, preferably, the inorganic nutrients comprise: nitrogen source, phosphorus, sulfur, potassium, calcium, sodium, magnesium, chlorine, trace elements; preferably, the vitamins include vitamin B1, vitamin B6, biotin, niacin, inositol; preferably, the amino acid comprises glycine; preferably, the trace elements include: boron, iodine, manganese, zinc, molybdenum, copper, cobalt, iron;

the basic culture medium is MS culture medium, B5 culture medium, N6 culture medium or Hoagland culture medium;

the storage root has a secondary structure; preferably, the storage root has secondary cells, secondary cambium and/or secondary xylem;

the derivative is methyl jasmonate;

the jasmonic acid or derivative thereof is a racemic mixture;

the plant is sweet potato, cassava, tuber fleeceflower root, dahlia, asparagus or stemona;

the concentration of the sucrose is 1-6%, preferably 3-6%;

the concentration of NAA is 0.5-100 mug/L, preferably 10-100 mug/L;

the concentration of 6-BA is 0.05mg/L-0.2mg/L, preferably 0.06mg/L-0.2 mg/L;

the concentration of jasmonic acid compounds is 1mg/L-4mg/L, preferably 1.2mg/L-4 mg/L;

more preferably, the sucrose concentration is 4-6%, the NAA concentration is 40-100. mu.g/L, the 6-BA concentration is 0.08-0.2 mg/L, and the optional jasmonate compound concentration is 1.6-4 mg/L.

3. A composition comprising 6-BA, NAA, optionally sucrose and optionally jasmonic acid compounds, wherein the concentration ratio of 6-BA: NAA: sucrose: jasmonic acid compounds is 0.05-0.2:0.005-0.1: 10000-.

4. The composition of claim 3, wherein the concentration ratio of 6-BA: NAA: sucrose: jasmonates is 0.06-0.2:0.010-0.1: 20000-;

preferably, the concentration ratio of 6-BA: NAA: sucrose: jasmonic acid compound is 0.08-0.2:0.03-0.1: 30000-.

Use of 6-BA, NAA, a jasmonate compound, or a composition of claim 3 or 4, to induce the formation of storage roots in a plant, the jasmonate compound being jasmonic acid or a derivative thereof,

preferably, the first and second electrodes are formed of a metal,

the concentration of 6-BA is 0.05mg/L-0.2mg/L, preferably 0.06mg/L-0.2 mg/L;

the concentration of NAA is 0.5-100 μ g/L, preferably 10-100 μ g/L;

the concentration of jasmonates is 1mg/L-4mg/L, preferably 1.2mg/L-4 mg/L.

6. A preparation method of a plant culture medium is characterized by comprising the steps of mixing a basic culture medium, 6-BA, NAA, cane sugar and optional jasmonic acid compounds, wherein the plant culture medium comprises 0.05mg/L-0.2mg/L of 6-BA, 0.5 mu g/L-100 mu g/L of NAA, 1% -6% of cane sugar and 1mg/L-4mg/L of jasmonic acid compounds, and the jasmonic acid compounds are jasmonic acid or derivatives thereof;

preferably, the plant culture medium is used to induce the plant to form storage roots.

7. A method of inducing storage root formation in a plant, comprising growing a plant or part thereof with the plant culture medium of claim 1 or 2, preferably wherein the storage root is a root tuber.

8. The method of claim 7, wherein the method has one or more characteristics selected from the group consisting of:

the plant or part comprises roots; preferably, the root comprises one or more roots selected from the group consisting of: primary root, secondary root, adventitious root, fibrous root, and enlarged root;

the plant is sweet potato, cassava, polygonum multiflorum, dahlia, asparagus or stemona.

9. A method for obtaining storage roots, comprising growing a plant or part thereof in the plant culture medium of claim 1 or 2 and collecting the storage roots,

preferably, the reservoir root is a tuberous root; more preferably, the storage root has a secondary structure;

preferably, the plant or part comprises roots; more preferably, the root comprises one or more roots selected from the group consisting of: primary root, secondary root, adventitious root, fibrous root, and enlarged root.

10. A method of plant cultivation comprising cultivating a plant or part of a plant with the plant culture medium of claim 1 or 2,