Method for efficiently promoting slash pine somatic embryo maturation

Abstract

The invention discloses a method for efficiently promoting slash pine somatic embryo maturation, and relates to the technical field of plant breeding. According to the method, the slash pine embryogenic callus is inoculated into a somatic embryo maturation culture medium containing sulfonatin and / or activated carbon, or PEG8000 and / or chitosan oligosaccharide for somatic embryo induction culture, so that early maturation of slash pine somatic embryos can be remarkably promoted. Results of the invention show that when the concentration of the sulfokine added in the culture medium is 0.5 mg / L, the total number of mature somatic embryos is as high as 109 / dish; when 0.5 mg / L of sulfonatin and 1 mg / L of activated carbon are added at the same time, the number of mature somatic embryos is up to 288 / dish; when 120g / L of PEG 8000 and 6mg / L of chitosan oligosaccharide are added at the same time, the number of mature somatic embryos is up to 123 / dish. In conclusion, the method disclosed by the invention can efficiently promote slash pine somatic embryo maturation, and is high in somatic embryo induction efficiency and strong in practicability.

Description

Technical Field

[0001] The invention belongs to the technical field of plant breeding, and more specifically relates to a method for efficiently promoting the maturation of somatic embryos of elliottii. Background Art

[0002] The slash pine (Pinus elliottii) is an evergreen tree of the Pinaceae family native to the southeastern coast of the United States. After being introduced into my country, it has been widely planted in the Yangtze River Basin and South China. It has the characteristics of fast growth, strong adaptability, and resistance to pests and diseases. It can be widely used in barren hill management, soil and water conservation, and afforestation. It has now become an important afforestation tree species in southern my country. In addition, the slash pine has a high yield of rosin and excellent quality. It is one of the main resin-wood dual-purpose tree species in southern China. The current market demand for slash pine improved varieties is increasing, but the existing slash pine improved varieties are single and lacking, and improved seedlings are in short supply. To a certain extent, they rely on imported seeds, which greatly increases the cost of afforestation. To solve this problem, somatic embryogenesis technology has become a feasible option. Somatic embryogenesis is the process in which somatic cells produce embryoids through a pathway similar to zygotic embryogenesis under the induction of certain hormones or stresses. However, coniferous plants still have problems such as difficulty in maturation of somatic embryos.

[0003] Phytosulfokine (PSK) is a new type of plant peptide growth regulator. Mature PSK is a sulfonated short peptide composed of 5 or 4 amino acids. In plants, PSK transmits signals to the cell through the leucine-rich receptor like kinase protein (LRR-RLK) protein family on the cell membrane as a receptor. The PSK receptor PSKR reported in Arabidopsis has dual signal perception functions of kinase activity and guanylate cyclase activity. PSK regulates a variety of physiological and biochemical reactions in plants, including in vitro differentiation of plant cells, cell growth, regulation of root apical meristem cells and quiescent central cells, development of pollen tube cells, regulation of plant immunity, etc.; participates in abiotic stress response, and coordinated regulation with plant hormones such as auxin, cytokinin, jasmonic acid, and brassinolide, etc. However, its role in promoting cell growth and differentiation and inducing somatic embryo maturation under in vitro culture conditions of plant cells has rarely been reported.

[0004] Activated carbon is a specially treated carbon with a surface micropore diameter of 2 to 50 nm. Even a small amount of activated carbon has a huge surface area. The surface area of ​​each gram of activated carbon is 500 to 1500 m 2. Activated carbon can improve the browning of propagation materials and promote the elongation growth of plants, so it is widely used in plant tissue culture. Previous studies have shown that activated carbon added to the culture medium can affect the plant's acquisition of metal elements in the culture medium. Some scholars believe that the role of activated carbon in pine tissue culture is mainly its absorption of phenolic acids and residual hormones. However, there are no reports on the use of activated carbon in the induction of embryo maturation in Pinus elliottii. Summary of the invention

[0005] In view of the above problems existing in the prior art, the technical problem to be solved by the present invention is to provide a method for efficiently promoting the maturation of somatic embryos of Pinus elliottii, which can achieve the regulation of the maturation speed of somatic embryos of Pinus elliottii and improve the efficiency of somatic embryo induction.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0007] A method for efficiently promoting the maturation of somatic embryos of slash pine, wherein embryonic callus of slash pine is inoculated into a somatic embryo maturation medium containing sulfopeptide to perform somatic embryo induction culture, thereby promoting the early maturation of somatic embryos of slash pine.

[0008] The somatic embryo maturation medium formula is: basic medium mLP, and the following components are added in concentration: 30 g / L maltose, 9 mg / L ABA, 120 g / L PEG 8000, 450 mg / L L-glutamine, 500 mg / L hydrolyzed casein, 500 mg / L inositol, 250 mg / L 2-(N-morpholine)ethanesulfonic acid monohydrate, 4 g / L gellan gum, and no more than 3 mg / L sulfopeptide.

[0009] The somatic embryo maturation medium formula is a basic medium mLP, and the following components are added: 30 g / L maltose, 9 mg / L ABA, 120 g / L PEG 8000, 450 mg / L L-glutamine, 500 mg / L hydrolyzed casein, 500 mg / L inositol, 250 mg / L 2-(N-morpholino)ethanesulfonic acid monohydrate, 4 g / L gellan gum, and 0.5 mg / L sulfopeptide.

[0010] A method for efficiently promoting the maturation of somatic embryos of slash pine, wherein embryonic callus of slash pine is inoculated into a somatic embryo maturation medium containing sulfopeptide and activated carbon for somatic embryo induction culture, thereby promoting the early maturation of somatic embryos of slash pine.

[0011] The somatic embryo maturation medium formula is a basic medium mLP, and the following components are added: 30 g / L maltose, 9 mg / L ABA, 120 g / L PEG 8000, 450 mg / L L-glutamine, 500 mg / L hydrolyzed casein, 500 mg / L inositol, 250 mg / L 2-(N-morpholine)ethanesulfonic acid monohydrate, 4 g / L gellan gum, 0.5 mg / L sulfopeptide, and no more than 1.5 mg / L activated carbon.

[0012] The somatic embryo maturation medium formula is a basic medium mLP, and the following components are added: 30 g / L maltose, 9 mg / L ABA, 120 g / L PEG 8000, 450 mg / L L-glutamine, 500 mg / L hydrolyzed casein, 500 mg / L inositol, 250 mg / L 2-(N-morpholine)ethanesulfonic acid monohydrate, 4 g / L gellan gum, 0.5 mg / L sulfopeptide, and 1 mg / L activated carbon.

[0013] A method for efficiently promoting the maturation of somatic embryos of slash pine, wherein embryonic callus of slash pine is inoculated into a somatic embryo maturation medium containing PEG8000 for somatic embryo induction culture, thereby promoting the early maturation of somatic embryos of slash pine.

[0014] The somatic embryo maturation medium formula is: basic medium mLP, and the following components are added in concentration: maltose 30g / L, ABA 9mg / L, activated carbon 1g / L, L-glutamine 450mg / L, hydrolyzed casein 500mg / L, inositol 500mg / L, 2-(N-morpholine)ethanesulfonic acid monohydrate 250mg / L, gellan gum 4g / L, PEG 8000 60-160g / L.

[0015] A method for efficiently promoting the maturation of somatic embryos of slash pine, wherein embryonic callus of slash pine is inoculated into a somatic embryo maturation medium containing PEG8000 and chitosan oligosaccharide for somatic embryo induction culture, thereby promoting the early maturation of somatic embryos of slash pine.

[0016] The somatic embryo maturation medium formula is: basic medium mLP, and the following components are added: maltose 30g / L, ABA 9mg / L, activated carbon 1g / L, L-glutamine 450mg / L, hydrolyzed casein 500mg / L, inositol 500mg / L, 2-(N-morpholine)ethanesulfonic acid monohydrate 250mg / L, gellan gum 4g / L, PEG 8000 120g / L, and chitosan oligosaccharide not higher than 8mg / L (preferably 6mg / L).

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1) The optimal concentration of sulfopeptide for inducing immature somatic embryos of slash pine using the present invention is 0.5 mg / L. After culturing in the dark at 24°C for 60 days, the total number of somatic embryos is as high as 109 / dish, the number of mature somatic embryos is 41 / dish, the embryonic callus is in good condition, the somatic embryos of slash pine mature ahead of time, and the development speed is significantly faster than that of other treatment groups.

[0019] 2) The optimal concentrations of sulfonyltransferase and activated carbon for inducing immature somatic embryos of Pinus elliottii in the present invention are 0.5 mg / L sulfonyltransferase and 1 mg / L activated carbon. The cells were cultured in the dark at 24°C for 55 days, which promoted the early maturation of somatic embryos of Pinus elliottii. At this time, the number of spherical embryos reached 1163 per dish, and the number of mature somatic embryos reached 288 per dish, and the development speed was significantly faster than that of other treatment groups.

[0020] 3) The optimal concentration of PEG 8000 and chitosan oligosaccharide for inducing immature somatic embryos of Pinus elliottii using the present invention is 120 g / L PEG 8000 and 6 mg / L chitosan oligosaccharide. After dark culture at 24° C. for 45 days, cotyledonary embryos begin to appear. Dark culture is continued for 75 days. At this time, the total number of somatic embryos is as high as 292 / dish, the number of mature somatic embryos is as high as 123 / dish, the development speed is significantly faster than that of other treatment groups, and the somatic embryo induction efficiency is significantly higher than that of other treatment groups. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The images of the embryonic callus v30 cell line of Pinus elliottii under a microscope (A is the morphological image of the embryonic callus under a v30 stereomicroscope, and B is the morphological image of the embryonic callus cells under a v30 optical microscope);

[0022] Figure 2 The morphological observation diagram of the embryonic callus v30 cell line of Pinus elliottii cultured for 60 days in the somatic embryo maturation medium supplemented with different concentrations (0 mg / L, 0.1 mg / L, 0.5 mg / L, 1 mg / L, 3 mg / L) of sulfopeptidase;

[0023] Figure 3 The figure is the number of mature embryos of the embryonic callus v30 cell line of Pinus elliottii after 60 days of culture in the somatic embryo maturation medium supplemented with different concentrations (0 mg / L, 0.1 mg / L, 0.5 mg / L, 1 mg / L, 3 mg / L) of sulfopeptidase;

[0024] Figure 4 This is a graph showing the total number of embryos after 60 days of culture of the embryonic callus v30 cell line of Pinus elliottii in a somatic embryo maturation medium supplemented with different concentrations (0 mg / L, 0.1 mg / L, 0.5 mg / L, 1 mg / L, 3 mg / L) of sulfopeptidase;

[0025] Figure 5This is a morphological observation of the embryonic callus v30 cell line of Pinus elliottii cultured in a somatic embryo maturation medium containing 0.5 mg / L sulfopeptide and 1 g / L activated carbon after 55 days of culture.

[0026] Figure 6 The figure is the number of mature embryos of the embryonic callus v30 cell line of Pinus elliottii after 45 days of culture in the somatic embryo maturation medium supplemented with different concentrations (60g / L, 80g / L, 100g / L, 120g / L, 140g / L, 160g / L) of PEG 8000;

[0027] Figure 7 The morphological observation diagram of the embryonic callus v30 cell line of Pinus elliottii cultured for 75 days in a somatic embryo maturation medium supplemented with different concentrations (0 mg / L, 2 mg / L, 4 mg / L, 6 mg / L, 8 mg / L) of chitosan oligosaccharide and 120 g / L PEG 8000;

[0028] Figure 8 The figure is a statistical result of the number of mature embryos of the embryonic callus v30 cell line of Pinus elliottii cultured in a somatic embryo maturation medium containing 6 mg / L chitosan oligosaccharide and 120 g / L PEG 8000 for 75 days;

[0029] Fig. 9 This is the result of the number of immature embryos of the embryonic callus v30 cell line of Pinus elliottii cultured in a somatic embryo maturation medium containing 6 mg / L chitosan oligosaccharide and 120 g / L PEG 8000 for 75 days;

[0030] Fig.10 This is a graph showing the total number of embryos when the embryonic callus v30 cell line of Pinus elliottii was cultured for 75 days in a somatic embryo maturation medium containing 6 mg / L chitosan oligosaccharide and 120 g / L PEG 8000. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described below in conjunction with specific embodiments. Unless otherwise specified in the following embodiments, the technical means used are conventional means well known to those skilled in the art.

[0032] The embryonic callus v30 cell line material of Pinus elliottii used in the following examples was obtained by the applicant of the present invention using immature embryos of Pinus elliottii with high resin yield as the material (eg Figure 1 The biomaterial has a compact and fine structure, moderate viscosity, and is white and transparent like Tremella. The applicant has conducted a number of studies on the biomaterial and has published it publicly (DOI: 10.11931 / guihaia.gxzw202403025). The biomaterial is well known to the public, and the public can obtain the biomaterial from the applicant.

[0033] Example 1

[0034] Different concentrations (0 mg / L, 0.1 mg / L, 0.5 mg / L, 1 mg / L, 3 mg / L) of sulfopeptide were added to the culture medium (basic culture medium mLP, and the following concentrations of components were added: maltose 30 g / L, ABA 9 mg / L, PEG 8000 120 g / L, L-glutamine 450 mg / L, hydrolyzed casein 500 mg / L, inositol 500 mg / L, 2-(N-morpholine)ethanesulfonic acid monohydrate 250 mg / L, gellan gum 4 g / L) to prepare the somatic embryo maturation medium; the basic culture medium without sulfopeptide was used as the control. At least 3 dishes were inoculated for each concentration, and 1 g of embryonic callus was inoculated in each dish for somatic embryo induction. Culture was carried out in the dark at 24°C, and subculture was performed every 30 days.

[0035] The embryonic callus was morphologically observed at different time points during somatic embryo induction, and the somatic embryos at each developmental stage were counted at 60 days of somatic embryo induction as the total embryo number, and the somatic embryos that had developed into cotyledon-shaped somatic embryos were classified as mature somatic embryos. The total embryo number refers to the embryoid bodies with smooth surfaces and easy separation, and in spherical, ellipsoidal, cotyledon-shaped, etc. shapes after the embryonic callus tissues after somatic embryo induction were flattened and dispersed.

[0036] The results are as follows Figure 2 As shown in the figure, the embryonic callus v30 cell line material of Pinus elliottii was cultured on the somatic embryo maturation medium containing 0.5 mg / L sulfopeptide. After 25 days of culture, a large number of spherical embryos began to appear on the callus surface; cotyledonary embryos appeared around 35 days, and a large number of spherical embryos were produced successively; after 45 days of culture, some somatic embryos had matured, and the rest of the embryoids continued to grow and develop; after 60 days of culture, most of the cotyledonary embryos had matured, and a large number of mature embryos appeared, which were transferred to the germination medium for further culture.

[0037] The results are shown in 3 and 4. The optimal concentration of sulfopeptide for inducing immature somatic embryos of Pinus elliottii is 0.5 mg / L. At this time, the total number of somatic embryos is as high as 109 / dish, the number of mature somatic embryos is 41 / dish, the embryonic callus is in good condition, most of the somatic embryos have matured, and the development speed is significantly faster than that of other treatment groups.

[0038] In summary, the number of mature somatic embryos induced by Pinus elliottii on the somatic embryo maturation medium containing 0.5 mg / L sulfopeptide was large and the somatic embryo maturation speed was fast. It can be seen that adding appropriate concentrations of sulfopeptide can promote the production of somatic embryos of Pinus elliottii, accelerate the development process of somatic embryos, and improve the efficiency of somatic embryo maturation.

[0039] Example 2

[0040] Different concentrations (0 mg / L, 1 mg / L) of activated carbon and 0.5 mg / L sulfopeptide were added to the culture medium (basic culture medium mLP, and the following concentrations of components were added: 30 g / L maltose, 9 mg / L ABA, 120 g / L PEG 8000, 450 mg / L L-glutamine, 500 mg / L hydrolyzed casein, 500 mg / L inositol, 250 mg / L 2-(N-morpholine)ethanesulfonic acid monohydrate, 4 g / L gellan gum) to prepare the somatic embryo maturation medium. At least 3 dishes were inoculated for each concentration, and 1 g of embryonic callus was inoculated in each dish for somatic embryo induction. Culture was carried out in the dark at 24°C, and subculture was performed every 30 days.

[0041] The embryonic callus was morphologically observed at different time points during somatic embryo induction, and the somatic embryos at each developmental stage were counted at 55 days of somatic embryo induction as the total embryo number, and the somatic embryos that had developed into cotyledon-shaped somatic embryos were classified as mature somatic embryos. The total embryo number refers to the embryoid bodies with smooth surfaces and easy separation, and in spherical, ellipsoidal, cotyledon-shaped, etc. shapes after the embryonic callus tissues after somatic embryo induction were flattened and dispersed.

[0042] The results are as follows Figure 5 As shown in the figure, when the embryonic callus V30 cell line of Pinus elliottii was cultured in a medium containing 0.5 mg / L sulfopeptide and 1 g / L activated carbon for 55 days, a large number of mature embryos appeared. The optimal concentration of activated carbon was 1 g / L, at which time the number of globular embryos reached 1163 per dish and the number of mature somatic embryos reached 288 per dish. Most of the somatic embryos had matured, and the development speed was significantly faster than that of other treatment groups.

[0043] In summary, the number of mature somatic embryos induced by Pinus elliottii on the somatic embryo maturation medium containing 0.5 mg / L sulfopeptide and 1 g / L activated carbon was large. It can be seen that adding appropriate concentrations of sulfopeptide and activated carbon can promote the production of somatic embryos of Pinus elliottii, accelerate the development of somatic embryos, and improve the efficiency of somatic embryo maturation.

[0044] Example 3

[0045] Different concentrations (60 g / L, 80 g / L, 100 g / L, 120 g / L, 140 g / L, 160 g / L) of PEG 8000 were added to the culture medium (basic culture medium mLP, and the following concentrations of components were added: maltose 30 g / L, ABA 9 mg / L, activated carbon 1 g / L, L-glutamine 450 mg / L, hydrolyzed casein 500 mg / L, inositol 500 mg / L, 2-(N-morpholine)ethanesulfonic acid monohydrate 250 mg / L, gellan gum 4 g / L) to prepare the somatic embryo maturation medium; the basic culture medium without PEG 8000 was used as the control. At least 3 dishes were inoculated for each concentration, and 1 g of embryonic callus was inoculated in each dish for somatic embryo induction. Culture was carried out in the dark at 24°C, and subculture was performed every 30 days.

[0046] The embryonic callus was morphologically observed at different time points of somatic embryo induction, and the cotyledon embryos were counted at day 45 of somatic embryo induction. The number of cotyledon embryos refers to the embryoid bodies with smooth surface and easy separation in the shape of cotyledons after the embryonic callus tissues were flattened and dispersed after somatic embryo induction.

[0047] The results are as follows Figure 6 As shown in the results, the optimal concentration of PEG 8000 for inducing the embryonic callus v30 cell line material of Pinus elliottii was 120 g / L. The total number of cotyledon embryos reached 3.25 per dish after 45 days of induction, and the development speed was significantly faster than that of other treatment groups. In summary, adding appropriate concentrations of PEG 8000 can promote the production of somatic embryos in Pinus elliottii and accelerate the development of somatic embryos; when 120 g / L PEG 8000 was added to the somatic embryo maturation medium, the number of cotyledon embryos was large and the somatic embryo maturation speed was fast.

[0048] Example 4

[0049] Chitosan oligosaccharides of different concentrations (0 mg / L, 2 mg / L, 4 mg / L, 6 mg / L, 8 mg / L) and 120 g / L PEG 8000 were added to the culture medium (basic culture medium mLP, and the following concentrations of components were added: maltose 30 g / L, ABA 9 mg / L, activated carbon 1 g / L, L-glutamine 450 mg / L, hydrolyzed casein 500 mg / L, inositol 500 mg / L, 2-(N-morpholine)ethanesulfonic acid monohydrate 250 mg / L, gellan gum 4 g / L) to prepare the somatic embryo maturation medium; the basic culture medium without chitosan oligosaccharides was used as the control. At least 3 dishes were inoculated for each concentration, and 1 g of embryonic callus was inoculated in each dish for somatic embryo induction. Culture was carried out in the dark at 24°C, and subculture was performed every 30 days.

[0050] The embryonic callus was morphologically observed at different time points during somatic embryo induction, and the somatic embryos at each developmental stage were counted at 75 days of somatic embryo induction as the total embryo number, and the somatic embryos that had developed into cotyledon-shaped somatic embryos were classified as mature somatic embryos. The total embryo number refers to the embryoid bodies with smooth surfaces and easy separation, and in spherical, ellipsoidal, cotyledon-shaped, etc. shapes after the embryonic callus tissues after somatic embryo induction were flattened and dispersed.

[0051] The results are as follows Figure 7 As shown, when the embryonic callus v30 cell line of Pinus elliottii was cultured on a medium containing 6 mg / L chitosan oligosaccharide and 120 g / L PEG 8000, a large number of globular embryos began to appear on the surface of the embryonic callus after 30 days of culture; cotyledonary embryos appeared around 45 days, and a large number of globular embryos were produced successively; when the culture was cultured to 60 days, some somatic embryos had matured, and the remaining embryoids continued to grow and develop; when the culture was cultured to 75 days, a large number of mature embryos appeared, and the cells could be transferred to the germination medium for further culture.

[0052] The results are as follows Figure 8-10 As shown in the figure, according to the statistical results of the number of mature embryos ( Figure 8 ), Immature embryo number result chart ( Fig. 9 ) and the total number of fetuses ( Fig.10 ) concluded that the optimal concentration of chitosan oligosaccharide was 6 mg / L, at which time the total number of somatic embryos was as high as 292 / dish, the number of mature somatic embryos was as high as 123 / dish, the embryonic callus was in good condition, and the development speed was significantly faster than that of other treatment groups.

[0053] In summary, the number of mature somatic embryos induced by Pinus elliottii on the medium containing 6 mg / L chitosan oligosaccharide and 120 g / L PEG 8000 was large and the somatic embryos matured quickly. It can be seen that adding appropriate concentrations of chitosan oligosaccharide and PEG 8000 can promote the production of somatic embryos of Pinus elliottii, accelerate the development of somatic embryos, and improve the efficiency of somatic embryo maturation.

[0054] The above description is only illustrative rather than restrictive of the present invention. Those skilled in the art will understand that many modifications, changes or equivalents may be made without departing from the spirit and scope defined by the appended claims, but all will fall within the scope of protection of the present invention.

Claims

1. A method for efficiently promoting the maturation of somatic embryos of Pinus elliottii, characterized in that: The embryonic callus of Pinus elliottii was inoculated into a somatic embryo maturation medium containing sulfopeptide for somatic embryo induction culture, thereby promoting the early maturation of somatic embryos of Pinus elliottii.

2. The method for efficiently promoting the maturation of somatic embryos of Pinus elliottii according to claim 1, characterized in that: The somatic embryo maturation medium formula is: basic medium mLP, and the following components are added in concentration: 30g / L maltose, 9mg / L ABA, 120g / L PEG8000, 450mg / L L-glutamine, 500mg / L hydrolyzed casein, 500mg / L inositol, 250mg / L 2-(N-morpholine)ethanesulfonic acid monohydrate, 4g / L gellan gum, and sulfopeptide not higher than 3mg / L.

3. The method for efficiently promoting the maturation of somatic embryos of Pinus elliottii according to claim 2, characterized in that: In the somatic embryo maturation medium formula, the concentration of sulfopeptide is 0.5 mg / L.

4. A method for efficiently promoting the maturation of somatic embryos of Pinus elliottii, characterized in that: The embryonic callus of Pinus elliottii was inoculated into a somatic embryo maturation medium containing sulfonyltransferase and activated carbon for somatic embryo induction culture, thereby promoting the early maturation of somatic embryos of Pinus elliottii.

5. The method for efficiently promoting the maturation of somatic embryos of Pinus elliottii according to claim 4, characterized in that: The somatic embryo maturation medium formula is: basic medium mLP, and the following components are added in concentration: 30g / L maltose, 9mg / L ABA, 120g / L PEG8000, 450mg / L L-glutamine, 500mg / L hydrolyzed casein, 500mg / L inositol, 250mg / L 2-(N-morpholine)ethanesulfonic acid monohydrate, 4g / L gellan gum, 0.5mg / L sulfopeptide, and no more than 1.5mg / L activated carbon.

6. The method for efficiently promoting the maturation of somatic embryos of Pinus elliottii according to claim 5, characterized in that: In the somatic embryo maturation medium formula, the activated carbon concentration is 1 mg / L.

7. A method for efficiently promoting the maturation of somatic embryos of Pinus elliottii, characterized in that: Embryogenic callus of Pinus elliottii was inoculated into somatic embryo maturation medium containing PEG 8000 and chitosan oligosaccharide for somatic embryo induction culture, so as to promote early maturation of somatic embryos of Pinus elliottii.

8. The method for efficiently promoting the maturation of somatic embryos of Pinus elliottii according to claim 7, characterized in that: The somatic embryo maturation medium formula is: basic medium mLP, and the following components are added in concentration: 30g / L maltose, 9mg / L ABA, 1g / L activated carbon, 450mg / L L-glutamine, 500mg / L hydrolyzed casein, 500mg / L inositol, 250mg / L 2-(N-morpholine)ethanesulfonic acid monohydrate, 4g / L gellan gum, 60-160g / L PEG 8000, and chitosan oligosaccharide not higher than 8mg / L.

9. The method for efficiently promoting the maturation of somatic embryos of Pinus elliottii according to claim 8, characterized in that: In the somatic embryo maturation medium formula, the concentration of PEG 8000 is 120 g / L.

10. The method for efficiently promoting the maturation of somatic embryos of Pinus elliottii according to claim 8 or 9, characterized in that: In the somatic embryo maturation medium formula, the chitosan oligosaccharide concentration is 6 mg / L.

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