Technique for shortening breeding cycle of cotton and application thereof
By combining multispectral regulation and GA3 treatment with an optimized cotton embryo culture medium, the problem of long cotton breeding cycle was solved, achieving efficient seedling formation and shortening the growth period of cotton embryos, thus significantly accelerating the breeding process.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HEBEI AGRICULTURAL UNIV.
- Filing Date
- 2024-11-19
- Publication Date
- 2026-05-15
AI Technical Summary
Cotton breeding has a long cycle, especially distant hybridization, which takes even longer. Existing embryo culture media and methods have problems such as long embryo culture time and low seedling rate, which affect breeding efficiency.
A mixed light source combining blue, green, red, and far-red light was used, along with GA3-treated and created L-mAUH and mAUH cotton embryo culture media. Molecular marker selection and whole-genome resequencing were employed to optimize cotton embryo culture conditions. Multispectral LED plant growth lights were used to promote cotton development, and multiple cycles of culture and selection were conducted.
It significantly shortens the cotton breeding cycle, with the cotton embryo seedling rate reaching over 90%, shortening the growth period by 20-23 days, enabling five generations of breeding in one year, improving breeding efficiency, and rapidly transferring superior traits.
Smart Images
Figure CN119547727B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of agricultural technology, specifically relating to a technology and its application for shortening the cotton breeding cycle. Background Technology
[0002] Cotton belongs to the Malvaceae family ( Malvaceae ), genus Gossypium ( Gossypium Cotton is an important multi-purpose economic crop, widely cultivated worldwide. However, cotton is susceptible to diseases, pests, and other adverse conditions, resulting in significant losses in yield and quality. Variety improvement is the most economical and effective method to increase yield, quality, and resistance. Both traditional breeding techniques and bio-breeding techniques play crucial roles in cotton variety improvement. However, both traditional and molecular breeding share the common problem of long breeding cycles, which are even longer for distant hybridization. Therefore, accelerating the breeding process and improving breeding efficiency has become a key focus of breeding research.
[0003] Different light qualities or wavelengths have significantly different biological effects, including varying impacts on plant morphology, structure, chemical composition, photosynthesis, and organ growth and development. Researchers at the University of Queensland in Australia, by controlling light quality and photoperiod, accelerated the development of long-day plants such as wheat, barley, and rapeseed, achieving 4-6 generations of reproduction per year. Researchers at the National Institute for Plant Breeding at the University of Hohenheim in Germany promoted the rapid development of short-day crops such as soybeans and rice by adjusting light quality and photoperiod. Researchers at Huazhong Agricultural University, by controlling light quality and increasing far-red light, further shortened the growth cycle of two different rapeseed varieties by 12 days and 21 days, respectively. The cotton breeding team at Hebei Agricultural University, utilizing a greenhouse environment with controlled light and temperature, combined with cotton embryo culture, achieved a rapid three-generation cotton breeding technology per year. This study aims to further accelerate cotton development and shorten the cotton breeding cycle by controlling light quality conditions.
[0004] Plant seeds often possess the potential to develop into the next generation of plants before maturing, thus the embryo culture technique can be used to shorten the plant growth cycle. For example, wheat embryos 12 days after flowering can achieve a germination rate of over 95% through embryo culture; peanut embryos 30 days after flowering have a germination rate as high as 97.99%. Cotton embryo in vitro culture technology utilizes tissue culture methods to improve embryo development conditions and provide the necessary nutrients, thereby promoting direct germination and development into healthy plants. This technology significantly reduces the time required for cotton from flowering to seed maturation, effectively shortening the cotton generation cycle and providing an important pathway to accelerate breeding processes. Currently, the main in vitro culture media for cotton embryos include Mauney medium, BT medium, MS medium, and CEM medium. Although there are various culture media and methods for cotton embryo in vitro culture, problems such as long culture time and low germination rate still exist. Therefore, there is an urgent need to further improve embryo culture media and methods to shorten the embryo culture time, increase the germination rate, thereby accelerating cotton genetic improvement and promoting the rapid development of the cotton industry. Summary of the Invention
[0005] The above-mentioned technical objective of the present invention is achieved through the following technical solution: a technology and application for shortening the cotton breeding cycle.
[0006] This invention provides a method for shortening the cotton breeding cycle, comprising the following steps:
[0007] 1. Under mixed light consisting of blue, green, red, and far-red light, bud formation and flowering are accelerated;
[0008] II. GA3 treatment promotes embryo germination;
[0009] 3. Using the created L-mAUH and mAUH cotton embryo culture media, cotton embryos aged 25-28 days were cultured into seedlings.
[0010] The formulation of the mAUH medium is as follows: KNO3 950 mg / L, NH4NO3 825 mg / L, CaCl2·2H2O 220 mg / L, MgSO4·7H2O 185 mg / L, KH2PO4 85 mg / L, Na2-EDTA·2H2O 37.25 mg / L, FeSO4·7H2O 27.8 mg / L, MnSO4·4H2O 22.3 mg / L, ZnSO4·7H2O 8.6 mg / L, H3BO3 6.2 mg / L, KI 0.83 mg / L, Na2MoO4·2H2O 0.25 mg / L, CuSO4 4·5H2O 0.025 mg / L, CoCl2·6H2O 0.025 mg / L, inositol 100 mg / L, nicotinic acid 1 mg / L, thiamine hydrochloride 10 mg / L, pyridoxine hydrochloride 1 mg / L, indolebutyric acid 0.1 mg / L, 6-benzylaminopurine 0.1 mg / L, sucrose 20000 mg / L, agar 3500 mg / L.
[0011] The formulation of the L-mAUH medium is as follows: KNO3 475 mg / L, NH4NO3 412.5 mg / L, CaCl2·2H2O 110 mg / L, MgSO4·7H2O 92.5 mg / L, KH2PO4 42.5 mg / L, Na2-EDTA·2H2O 18.63 mg / L, FeSO4·7H2O 13.9 mg / L, MnSO4·4H2O 11.15 mg / L, ZnSO4·7H2O 8.6 mg / L, H3BO3 6.2 mg / L, KI 0.83 mg / L, Na2MoO4·2H2O 0.25 mg / L, CuSO4·2H2O 0.25 mg / L. 4· 5H2O 0.025 mg / L, CoCl2·6H2O 0.025 mg / L, inositol 100 mg / L, nicotinic acid 1 mg / L, thiamine hydrochloride 10 mg / L, pyridoxine hydrochloride 1 mg / L, indolebutyric acid 0.1 mg / L, 6-benzylaminopurine 0.1 mg / L, sucrose 20000 mg / L.
[0012] IV. Repeat steps one through three multiple times. During this process, use molecular markers to assist in the selection of promising traits and use whole-genome resequencing to assist in the selection of background traits.
[0013] Furthermore, step one utilizes a mixed light source consisting of 450 nm blue light, 530 nm green light, 660 nm red light, and 730 nm far-red light provided by an LED lamp.
[0014] Furthermore, the mixed light cycle in step one is 12 hours of light and 12 hours of darkness, with daytime temperature of 30-32°C, nighttime temperature of 25-26°C, and humidity of 35-45%.
[0015] Furthermore, step one includes the following specific contents:
[0016] (1) Developmental period survey
[0017] The investigation covered the stages of 1-9 true leaves on a single plant, the node of the first fruiting branch on a single plant, the budding stage of the first bud on a single plant, and the flowering stage of the first flower on a single plant.
[0018] (2) Detection of expression levels of cotton flowering-related genes
[0019] Total RNA was extracted from the first to fifth true leaf stage, with three biological replicates at each stage. The RNA was reverse transcribed into cDNA using cotton flowering factor as a template. GhSOC1 and GhFT Gene sequence-specific primers were designed, and qPCR technology was used to determine the gene sequence. GhSOC1 and GhFT Changes in gene expression;
[0020] (3) Observation of flower bud differentiation
[0021] From the first true leaf stage to the fifth true leaf stage, 0.5-1 cm of tissue was taken from the top of the stem tip. The leaf tissue was removed, leaving only the stem and the stem tip meristem. The tissue was immediately placed in FAA fixative for fixation. After fixation, the tissue was dehydrated, paraffin-embedded, embedded, sectioned, stained, and observed under a microscope.
[0022] Further, steps two and three are specifically as follows: Take young bolls 25-28 days after flowering, dry them for 3 days in a culture room at 28±2℃ and 40%–50% relative humidity, sterilize the surface of the bolls by soaking them in 70% ethanol for 1 min under sterile conditions in a laminar flow hood, cut along the suture between the carpels with a scalpel, remove the young embryos, soak them in GA3 at a concentration of 60 mmol / L for 4 h, then inoculate them into sterile L-mAUH medium and culture them in the dark with shaking at 45 r / min at 28℃; after 12 h, transfer the young embryos to sterile mAUH medium and culture them in a light-treated culture room.
[0023] Furthermore, the cultivation conditions in the light-enhanced culture chamber are as follows: 12h light / 12h darkness; under light conditions, the temperature is 28±2℃, the light intensity is 1500-2500 lux, and the relative humidity is 40%~50%; under darkness conditions, the temperature is 25±2℃, and the relative humidity is 40%-50%. The seedling emergence of cotton embryos is counted after 6-8 days of cultivation, and the rate of true leaf emergence is investigated after 10-12 days of cultivation.
[0024] This invention also provides an application of a method for shortening the cotton breeding cycle, characterized by containing... iaaM Using the IF1-1 gene as the donor parent and the high-yielding, disease-resistant Jinongda 24 as the recipient parent, backcross breeding was conducted. Utilizing the aforementioned method for shortening the cotton breeding cycle, steps one through three were executed sequentially and repeated multiple times. Simultaneously, molecular markers were used for prospective superior traits to assist selection, and whole-genome resequencing was used for background-assisted selection. This allowed for the rapid acquisition of multiple genes containing IF1-1 within 1.5 years. iaaM The BC4F3 generation of the improved Jinongda No. 24 line.
[0025] This invention provides a technology for shortening the cotton breeding cycle and its application. Through efficient blue, green, red, and far-red spectral modulation, combined with GA3 treatment, embryo culture, molecular marker selection, and whole-genome resequencing, cotton growth and development can be significantly accelerated, effectively shortening the cotton breeding cycle. A newly developed multispectral LED plant growth lamp promotes cotton flowering approximately 15-20 days earlier. GA3 treatment and embryo culture can achieve a seedling emergence rate of over 90% for cotton embryos at 25-28 days, shortening the cotton growth period by 20-23 days. The typical growth period for field cotton is 120-130 days; this method can shorten the cotton generation cycle to 71-85 days, achieving 5 generations per year locally, significantly reducing breeding years and providing technical support for improving the efficiency of new cotton variety breeding. This method can be effectively integrated into conventional backcross breeding processes, rapidly transferring superior traits and obtaining improved lines with high genetic background recovery rates within 1.5 years. Attached Figure Description
[0026] Figure 1 This refers to the combined light source in step one of this invention;
[0027] (a) is the red light spectrum; (b) is the far-red light spectrum; (c) is the blue-green combined spectrum (6500k); and (d) is the blue-green combined spectrum (13000k).
[0028] Figure 2 To optimize the spectrum of the LED lamp in step one of this invention;
[0029] Figure 3 This is the LED light layout in step one of the present invention;
[0030] Figure 4 This describes the cotton growth under optimized LED light spectrum conditions in step one of this invention. Figure 5 Expression levels of key flowering genes under optimized spectral conditions;
[0031] Figure 6 To optimize the initiation time of flower bud differentiation under spectral conditions;
[0032] Figure 7 This invention is applied to the process of creating new materials;
[0033] Figure 8 For the application of new materials in this invention iaaM Gene expression levels and IAA content;
[0034] Figure 9 This is a comparison image showing the application of the present invention to the creation of new materials with protruding seed coat fibers;
[0035] Figure 10 This is to show the genetic background restoration situation when the present invention is applied to the creation of new materials. Detailed Implementation
[0036] The following is in conjunction with the appendix Figure 1-10 The present invention will be further described in detail below with reference to the embodiments:
[0037] (1) Cotton varieties tested
[0038] Agricultural University 601 and Jishi 929.
[0039] (2) Spectral conditions
[0040] Based on the absorption spectra of chlorophyll a, chlorophyll b, and phytochromes in plants, and the effects of different light sources on plant growth and development, the radiation spectrum of the light source was controlled. A mixed light source consisting of 450nm blue light, 530nm green light, 660nm red light, and 730nm far-red light provided by an LED lamp was used; the spectrum is shown in the supplement. The photon flux density at 10cm under the lamp was 650μmol / m². 2 ·s.
[0041] (3) Cotton plant cultivation
[0042] Mature and healthy seeds of Nongda 601 and Jishi 929 were delinted, soaked at 28℃ for 8-12 hours, and germinated at 25-28℃ for 18-24 hours. When the roots grew to 0.5-1.0cm, the seeds were sown into seedling pots filled with nutrient soil, 4-5 germinated seeds per pot, and then placed in a cultivation room with controlled light, temperature and humidity for cotton seedling cultivation. The cultivation conditions were as follows: light conditions as described in (2) above, spectral conditions, photoperiod of 12h light / 12h darkness, daytime temperature of 30-32℃, nighttime temperature of 25-26℃, and humidity of 35-45%.
[0043] (4) Developmental period survey
[0044] The survey covered the stages of 1-9 true leaves per plant, the node of the first fruiting branch per plant, the budding stage of the first bud per plant, and the flowering stage of the first flower per plant.
[0045] (5) Detection of expression levels of cotton flowering-related genes
[0046] Total RNA was extracted from the first to fifth true leaf stage, with three biological replicates for each stage. The RNA was reverse transcribed into cDNA using cotton flowering factor as a template. GhSOC1 and GhFT Gene sequence-specific primers were designed, and qPCR technology was used to determine the gene sequence. GhSOC1 and GhFT Changes in gene expression.
[0047] (6) Observation of flower bud differentiation
[0048] From the first true leaf stage to the fifth true leaf stage, 0.5-1 cm of tissue was taken from the top of the stem tip. The leaf tissue was removed, leaving only the stem and the stem tip meristem. The tissue was immediately placed in FAA fixative for fixation. After fixation, the tissue was dehydrated, paraffin-embedded, embedded, sectioned, stained, and observed under a microscope. The specific steps were as described by Wu Hongping.
[0049] (7) Cotton embryos were cultured into seedlings using the created L-mAUH and mAUH cotton embryo culture media.
[0050] Young bolls, 25-28 days after flowering, were dried for 3 days in a culture room at 28±2℃ and 40%–50% relative humidity. The bolls were then sterilized by immersion in 70% ethanol for 1 minute under sterile conditions in a laminar flow hood. The embryos were removed by cutting along the suture between the carpels with a scalpel and immersed in 60 mmol / L GA3 for 4 hours. They were then inoculated onto sterile L-mAUH medium (Table 1) and cultured in the dark with shaking at 45 rpm for 12 hours. After 12 hours, the embryos were transferred to sterile mAUH medium (Table 2) and cultured in a light-controlled culture room. The light-controlled culture room conditions were: 12 hours light / 12 hours dark; under light conditions, the temperature was 28±2℃, the light intensity was 1500–2500 lux, and the relative humidity was 40%–50%; under dark conditions, the temperature was 25±2℃, and the relative humidity was 40%–50%. After 6-8 days of cultivation, the emergence rate of cotton seedlings was assessed, and after 10-12 days, the rate of true leaf emergence was investigated. Table 1 below shows the formulations of mAUH medium and L-mAUH medium.
[0051] Table 1
[0052] Element mAUH medium (mg / L) L-mAUH medium (mg / L) <![CDATA[KNO3]]> 950 475 <![CDATA[NH4NO3]]> 825 412.5 <![CDATA[CaCl2·2H2O]]> 220 110 <![CDATA[MgSO4·7H2O]]> 185 92.5 <![CDATA[KH2PO4]]> 85 42.5 <![CDATA[Na2-EDTA·2H2O]]> 37.25 18.63 <![CDATA[FeSO4·7H2O]]> 27.8 13.9 <![CDATA[MnSO4·4H2O]]> 22.3 11.15 <![CDATA[ZnSO4·7H2O]]> 8.6 8.6 <![CDATA[H3BO3]]> 6.2 6.2 KI 0.83 0.83 <![CDATA[Na2MoO4·2H2O]]> 0.25 0.25 <![CDATA[CuSO 4· 5H2O]]> 0.025 0.025 <![CDATA[CoCl2·6H2O]]> 0.025 0.025 Inositol 100 100 niacin 1 1 Thiamine hydrochloride 10 10 Pyridoxine hydrochloride 1 1 Indolebutyric acid 0.1 0.1 6-Benzylaminopurine 0.1 0.1 sucrose 20000 20000 Agar 3500 -
[0053] 3 Results and Analysis
[0054] (1) The expression of key flowering genes induced by the creation of multispectral conditions
[0055] The results of quantitative real-time PCR showed that, under optimized spectral conditions, GhSOC1 and GhFT Gene expression levels were significantly higher than those in the control group, and the peak expression occurred 3 days earlier. Figure 5 This indicates that the optimized spectral conditions in this study play an important regulatory role in the expression of key flowering genes.
[0056] (2) The created multispectral conditions promote the earlier start time of flower bud differentiation.
[0057] Microscopic observation of shoot tip differentiation tissue sections revealed that cotton plants grown under optimized spectral conditions exhibited earlier flower bud differentiation, beginning at the second true leaf stage, while control plants began differentiation at the third-to-fourth true leaf stage, 3-6 days earlier than the control. Figure 6 This indicates that optimized spectra play an important regulatory role in the initiation of cotton flower bud differentiation.
[0058] (3) The created multispectral conditions promote earlier budding and flowering time.
[0059] The developmental period survey results showed that the optimized spectrum group exhibited significantly faster vegetative and reproductive growth compared to the control group. Specifically, in Nongda 601, the second true leaf appeared 5.0-8.0 days earlier, with an average of 6.8 days earlier; the fourth true leaf appeared 5.3-9.3 days earlier, with an average of 7.2 days earlier; the sixth true leaf appeared 5.7-10.7 days earlier, with an average of 8.3 days earlier; the first bud formation stage appeared 4.5-9.5 days earlier, with an average of 6.5 days earlier; and the first flower bloomed 6.5-11.5 days earlier, with an average of 9.3 days earlier. Specifically, the second true leaf appeared 6.7-9.7 days earlier, with an average of 7.9 days earlier; the fourth true leaf appeared 6.7-10.7 days earlier, with an average of 9.2 days earlier; the sixth true leaf appeared 7.7-13.7 days earlier, with an average of 10.9 days earlier; the first bud appeared 8.3-12.3 days earlier, with an average of 9.7 days earlier; and the first flower bloomed 8.0-13.0 days earlier, with an average of 11.0 days earlier.
[0060] (4) The newly developed embryo culture method effectively shortens the cotton growth period.
[0061] This study developed a shaking culture method using L-mAUH medium. After 12 hours of shaking culture in L-mAUH medium, the cotyledons began to unfold, and the roots elongated to approximately 0.5-1 cm. After 6 days of culture in the newly developed mAUH medium, the seedling emergence rate reached 94.4%, and true leaves began to emerge after 8 days. The results indicate that in vitro embryo culture using L-mAUH and mAUH media can effectively promote cotton embryo germination and significantly improve the seedling emergence rate. This culture technique effectively solves the problems of long embryo culture time and low seedling emergence rate in cotton, and shortens the cotton growth period by approximately 22 days, providing an important approach to shortening the cotton generation cycle and accelerating breeding.
[0062] (5) Rapid creation of new germplasm with an average of 5 generations per year
[0063] With iaaM Using the IF1-1 gene as the donor parent and the high-yielding, disease-resistant Jinongda 24 as the recipient parent, backcross breeding was performed. This method allows for the rapid acquisition of multiple varieties containing [the gene's IF1-1] within 1.5 years. iaaM The BC4F3 generation of the Jinongda 24 improved line, with the Jinongda 24-i3 improved line achieving a background recovery rate of 97.36%, showed significant improvements in lint percentage and fiber quality. (Reference) Figure 7-10 , Figure 7 This invention is applied to the process of creating new materials; Figure 8 For the application of new materials in this invention iaaM Gene expression levels and IAA content; Figure 9 This is a comparison diagram of the protrusions in the seed coat fibers of the newly created material, showing an increase in the number of protrusions in the seed coat fibers of the newly created material. Figure 10 This is to show the genetic background restoration situation when the present invention is applied to the creation of new materials.
[0064] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.
Claims
1. A method for shortening the cotton breeding cycle, characterized in that, Includes the following steps:
1. Under mixed light consisting of blue, green, red, and far-red light, bud formation and flowering are accelerated; II. GA3 treatment promotes embryo germination; 3. Using the created L-mAUH and mAUH cotton embryo culture media, cotton embryos aged 25-28 days were cultured into seedlings. The formulation of the mAUH medium is as follows: KNO3 950 mg / L, NH4NO3 825 mg / L, CaCl2·2H2O 220 mg / L, MgSO4·7H2O 185 mg / L, KH2PO4 85 mg / L, Na2-EDTA·2H2O 37.25 mg / L, FeSO4·7H2O 27.8 mg / L, MnSO4·4H2O 22.3 mg / L, ZnSO4·7H2O 8.6 mg / L, H3BO3 6.2 mg / L, KI 0.83 mg / L, Na2MoO4·2H2O 0.25 mg / L, CuSO4 4· 5H2O 0.025 mg / L, CoCl2·6H2O 0.025 mg / L, inositol 100 mg / L, nicotinic acid 1 mg / L, thiamine hydrochloride 10 mg / L, pyridoxine hydrochloride 1 mg / L, indolebutyric acid 0.1 mg / L, 6-benzylaminopurine 0.1 mg / L, sucrose 20000 mg / L, agar 3500 mg / L; The formulation of the L-mAUH medium is as follows: KNO3 475 mg / L, NH4NO3 412.5 mg / L, CaCl2·2H2O 110 mg / L, MgSO4·7H2O 92.5 mg / L, KH2PO4 42.5 mg / L, Na2-EDTA·2H2O 18.63 mg / L, FeSO4·7H2O 13.9 mg / L, MnSO4·4H2O 11.15 mg / L, ZnSO4·7H2O 8.6 mg / L, H3BO3 6.2 mg / L, KI 0.83 mg / L, Na2MoO4·2H2O 0.25 mg / L, CuSO4·2H2O 0.25 mg / L. 4· 5H2O 0.025 mg / L, CoCl2·6H2O 0.025 mg / L, inositol 100 mg / L, nicotinic acid 1 mg / L, thiamine hydrochloride 10 mg / L, pyridoxine hydrochloride 1 mg / L, indolebutyric acid 0.1 mg / L, 6-benzylaminopurine 0.1 mg / L, sucrose 20000 mg / L; IV. Repeat steps one through three multiple times. During this process, use molecular markers to assist in the selection of promising traits and use whole-genome resequencing to assist in the selection of background traits.
2. The method for shortening the cotton breeding cycle according to claim 1, characterized in that, Step one utilizes a mixed light source consisting of 450 nm blue light, 530 nm green light, 660 nm red light, and 730 nm far-red light provided by an LED light.
3. A method for shortening the cotton breeding cycle according to claim 2, characterized in that, The mixed light cycle in step one is 12 hours of light and 12 hours of darkness, with daytime temperature of 30-32°C, nighttime temperature of 25-26°C, and humidity of 35-45%.
4. A method for shortening the cotton breeding cycle according to claim 1, characterized in that, Step one includes the following specific contents: (1) Developmental period survey The investigation covered the stages of 1-9 true leaves on a single plant, the node of the first fruiting branch on a single plant, the budding stage of the first bud on a single plant, and the flowering stage of the first flower on a single plant. (2) Detection of expression levels of cotton flowering-related genes Total RNA was extracted from the first to fifth true leaf stage, with three biological replicates at each stage. The RNA was then reverse transcribed into cDNA using cotton flowering factor as a template. GhSOC1 and GhFT Gene sequence-specific primers were designed, and qPCR technology was used to determine the gene sequence. GhSOC1 and GhFT Changes in gene expression; (3) Observation of flower bud differentiation From the first true leaf stage to the fifth true leaf stage, 0.5-1 cm of tissue was taken from the top of the stem tip. The leaf tissue was removed, leaving only the stem and the stem tip meristem. The tissue was immediately placed in FAA fixative for fixation. After fixation, the tissue was dehydrated, paraffin-embedded, embedded, sectioned, stained, and observed under a microscope.
5. A method for shortening the cotton breeding cycle according to claim 1, characterized in that, Steps two and three are as follows: Take young bolls 25-28 days after flowering, dry them for 3 days in a culture room at 28±2 ℃ and 40%~50% relative humidity, sterilize the surface of the bolls by soaking them in 70% ethanol for 1 min in a sterile environment of a laminar flow hood, cut along the gap between the carpels of the boll with a scalpel, take out the young embryos, soak them in GA3 at a concentration of 60 mmol / L for 4 h, and then inoculate them into sterile L-mAUH medium and culture them in the dark with shaking at 45 r / min at 28 ℃; after 12 h, transfer the young embryos to sterile mAUH medium and culture them in a light culture room.
6. A method for shortening the cotton breeding cycle according to claim 5, characterized in that, The cultivation conditions in the light culture chamber were as follows: 12h light / 12h darkness; under light conditions, the temperature was 28±2℃, the light intensity was 1500-2500 lux, and the relative humidity was 40%~50%; under darkness conditions, the temperature was 25±2℃, and the relative humidity was 40%-50%. The seedling emergence of cotton embryos was recorded after 6-8 days of cultivation, and the rate of true leaf emergence was investigated after 10-12 days of cultivation.
7. An application of a method for shortening the cotton breeding cycle, characterized in that, With iaaM Using the IF1-1 gene as the donor parent and the high-yielding, disease-resistant Jinongda 24 as the recipient parent, backcross breeding was carried out. Utilizing the method for shortening the cotton breeding cycle described in claim 1, steps one through three were executed sequentially and repeated multiple times. Simultaneously, molecular markers were used for assisted selection of promising traits, and whole-genome resequencing was used for background-assisted selection. This allowed for the rapid acquisition of multiple genes containing IF1-1 within 1.5 years. iaaM The BC4F3 generation of the improved Jinongda No. 24 line.