A method for creating a special germplasm of sesame with high quality and stress resistance

Abstract

This invention discloses a method for creating a stress-resistant, high-quality, and unique purple-fruited sesame germplasm, belonging to the field of plant breeding technology. The method utilizes the purple-fruited material "Tieqing Sesame" for genetic improvement of the sesame variety "Zhongzhi 14," which has poor stress and disease resistance. Through a systematic breeding method involving one generation of hybridization, six generations of self-pollination, one generation of backcrossing, and six generations of self-pollination, a homozygous and stable high-quality inbred line is created, which is the stress-resistant, high-quality, and unique purple-fruited sesame germplasm. Experimental results show that the sesame germplasm resource "25SP19" obtained according to the method provided by this invention has advantages such as purple capsules, a high number of capsules per plant, a low initial capsule position, short and pointed empty tips, strong disease and stress resistance, high oil content, and normal self-pollination and seed setting. It represents a significant improvement over the original parent "Zhongzhi 14" in all aspects. This invention not only provides new germplasm resources for the breeding of new sesame varieties but can also be directly used for large-scale cultivation.

Description

Technical Field

[0001] This invention relates to the field of plant breeding technology, and in particular to a method for creating a stress-resistant, high-quality, and unique germplasm of purple sesame fruit. Background Technology

[0002] Sesame( Sesamum indicum Sesame (L.) is one of the world's seven major oilseed crops and a traditional specialty oilseed crop, widely distributed in tropical and subtropical regions worldwide and cultivated in various regions. Sesame seeds are rich in unsaturated fatty acids, protein, vitamin E, and trace elements such as calcium, iron, zinc, and selenium. They are fragrant, of excellent quality, and beneficial to human health, making them very popular. With the improvement of living standards, sesame consumption continues to grow rapidly. Therefore, breeding high-yielding and stable-yielding superior sesame varieties is urgently needed to promote the development of sesame production and solve the problem of insufficient self-sufficiency. However, sesame is a crop extremely sensitive to environmental conditions, greatly affected by adverse environments such as high temperature, high humidity, and drought, resulting in low and unstable yields. Therefore, breeding high-yielding, stable-yielding, and stress-resistant varieties is of great significance to promoting the development of the sesame industry.

[0003] Sesame varieties are numerous and can be categorized by capsule color into green, yellowish-green, yellow, and purple, with green and yellowish-green being the most common, followed by yellow, and purple being the rarest. The purple color of plants is usually due to the presence of anthocyanins. Anthocyanins belong to the flavonoid family and are important antioxidants. When facing environmental stresses (such as strong light, drought, and disease), they can help plant cells scavenge excess reactive oxygen species, reducing oxidative damage and potentially enhancing the plant's resistance. In field breeding, researchers have often observed that sesame varieties with purple stems, leaves, and capsules typically exhibit stronger waterlogging tolerance, drought resistance, cold resistance, and disease and pest resistance. The depth of the purple color, to some extent, visualizes the plant's "health" and stress resistance. Therefore, breeding sesame varieties with purple stems, leaves, and capsules and strong stress resistance is of great significance in ensuring high and stable yields.

[0004] Germplasm resources carry all the genetic information of crops and are the original materials for breeding experts to screen superior genes and cultivate new varieties. They are an indispensable material basis for crop breeding. Stress-resistant and cold-resistant germplasm resources are the foundation and prerequisite for breeding stress-resistant and cold-resistant varieties. In the process of creating stress-resistant and high-quality purple sesame germplasm resources, traditional breeding methods such as self-pollination, hybridization, and backcrossing were used, relying on observations of plant growth and natural disease incidence in the field. However, this approach suffers from problems such as low breeding efficiency and significant susceptibility to human and environmental factors. Summary of the Invention

[0005] The purpose of this invention is to provide a method for creating a high-quality and unique purple-fruited sesame germplasm that is resistant to adverse conditions, in order to solve the problems existing in the prior art. The sesame produced by the method of this invention has the advantages of purple capsules, a large number of capsules per plant, high oil content, strong disease and adverse condition resistance, and normal self-pollination and fruit setting. It not only provides new germplasm resources for the breeding of new sesame varieties, but can also be directly used for large-scale cultivation and production.

[0006] To achieve the above objectives, the present invention provides the following solution: This invention provides a method for creating stress-resistant, high-quality, and unique germplasm of purple sesame fruit, comprising the following steps: Using sesame germplasm resources with purple fruits, purple stems, and strong disease and stress resistance as the female parent, and sesame varieties with purple spots at the base of the stem, a large number of capsules per plant, and relatively large capsules as the male parent, hybridization was carried out to obtain F1 generation seeds; Plant the F1 generation seeds to obtain F1 generation individual plants, then self-pollinate to obtain F2 generation seeds; Plant the F2 generation seeds, screen and test their quality, save the seeds, and obtain the F3 generation seeds; Plant the F3 generation seeds, screen and test their quality, save the seeds, and obtain the F4 generation seeds; Plant the F4 generation seeds, screen and test their quality, save the seeds, and obtain the F5 generation seeds; Plant the F5 generation seeds, screen and test their quality, save the seeds, and obtain the F6 generation seeds; Plant the F6 generation seeds, perform backcrossing and screening to obtain F6 generation single plants, use them as backcrossing female parents, and backcross with the male parents to obtain F6BC1 seeds; The F6BC1 seeds were planted, screened, and their quality was tested. F6BC2 seeds were then saved to obtain F6BC2 seeds. The F6BC2 seeds were planted, screened, and their quality was tested. Seeds were then saved to obtain F6BC3 seeds. The F6BC3 seeds were planted, screened, and their quality was tested. F6BC4 seeds were then saved to obtain F6BC4 seeds. The F6BC4 seeds were planted, screened, and their quality was tested. F6BC5 seeds were then saved to obtain F6BC5 seeds. The F6BC5 seeds were planted, screened, and their quality was tested. Seeds were saved to obtain F6BC6 seeds, and a stable inbred line was obtained, which is the stress-resistant, high-quality, and unique germplasm of purple sesame.

[0007] Furthermore, the parent plant is *Sesame ferox*.

[0008] Furthermore, the parent is Zhongzhi 14.

[0009] Furthermore, the screening includes the following steps: Remove weak and unhealthy plants during the seedling stage; Remove plants with short capsules, long internodes, high capsule position, long and pointed hollow stems, or fewer than 6 capsules per node at maturity. Remove infected plants during harvest; After harvesting, select plants with purple stems at the base and purple capsules.

[0010] Furthermore, the quality determination includes the following steps: After harvesting and threshing the selected sesame plants, the oil content of the seeds was tested, and the sesame plants with the highest oil content were selected for seed saving.

[0011] Furthermore, the backcross screening includes the following steps: Remove weak and unhealthy plants during the seedling stage; Select plants with strong growth, short internodes, large capsules, low capsule position, short and pointed hollow tips, and purple capsules at maturity.

[0012] The present invention also provides an application of the high-quality and stress-resistant sesame purple fruit germplasm obtained according to the above-described creation method in the breeding of sesame varieties with high stress resistance and mechanized cultivation.

[0013] The present invention also provides an application of the stress-resistant, high-quality, and unique sesame purple fruit germplasm obtained according to the above-described creation method in oilseed production.

[0014] The present invention discloses the following technical effects: 1. This invention provides a method for creating a high-quality, stress-resistant sesame germplasm resource with purple pods. First, the genetic law of purple coloration is determined from experiments on purple stem base and purple capsules, revealing the correlation between the degree of purple coloration at the base of the sesame stem and disease resistance. Then, the genetic law determines that the deeper the purple coloration, the stronger the disease resistance. Subsequently, high-yield and high-quality materials are selected. Utilizing the characteristics of "Tieqing Sesame"—purple stem base, purple capsules, and strong disease resistance—other varieties are improved. Through systematic breeding methods of self-pollination, hybridization, and backcrossing, a unique sesame germplasm resource, "25SP19," with strong disease resistance, stress resistance, purple capsules, and excellent quality is created.

[0015] 2. As a specific example, this invention improves the original variety "Zhongzhi 14" by transferring the disease and stress resistance characteristics of the sesame germplasm resource "Tieqing Sesame," which has purple capsules and strong disease and stress resistance, to the commercial variety "Zhongzhi 14." It creatively utilizes the difference in color content at the base of the plant stem to screen for disease-resistant and stress-resistant sesame germplasm resources, creating a new sesame germplasm "25SP19" with high-quality purple capsules and strong disease and stress resistance. It elucidates the genetic patterns of purple stem base and purple capsule coloration, and establishes a rapid and accurate method for identifying high-quality, disease-resistant, and stress-resistant purple-fruited sesame germplasm resources. This improves the accuracy and efficiency of screening high-quality, disease-resistant, and stress-resistant purple-fruited sesame germplasm resources, accelerating the creation of germplasm resources and the breeding of new varieties.

[0016] 3. The sesame germplasm resource “25SP19” bred in this invention has purple capsules, high oil content, strong disease and stress resistance, a large number of capsules per plant, low capsule position, short and pointed empty tips, and excellent quality. The new variety has been significantly improved in terms of disease and stress resistance, oil content, and quality compared with the original parent “Zhongzhi 14”. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram illustrating the systematic breeding of the germplasm resource "25SP19" as an example of the present invention; Figure 2 This is a field photo of the original parent plant of this invention, "Tieqing Sesame". Figure 3 This is a field photo of the original parent variety "Zhongzhi 14" of this invention under cultivation. Figure 4 This is a photograph of the field planting of the resource "25SP19" created in this invention. Detailed Implementation

[0019] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0020] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0021] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0022] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0023] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0024] In this invention, hybrid F1 is a hybrid of "Tieqing Sesame" as the female parent and "Zhongzhi 14" as the male parent.

[0025] The backcross F1 is a hybrid with (Tieqing Sesame × Zhongzhi 14) F6 as the female parent and "Zhongzhi 14" as the male parent.

[0026] Information regarding the sesame biomaterials used in this invention is as follows: The parent 'Tieqing Sesame' is a germplasm resource material collected and preserved in China. It is currently deposited in the National Sesame Germplasm Resource Intermediate-term Bank, cataloged as ZMZ02041.

[0027] The male parent, “Zhongzhi 14”, is a new variety bred by the Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences. It is currently preserved in the National Sesame Germplasm Resources Mid-term Bank, catalogue ZMZ04729.

[0028] Example 1 Specifically, the method for creating the purple-fruited, stress-resistant, and high-quality germplasm resource "25SP19" includes the following steps: 1. Determination of the correlation between purple trait and stress resistance One hundred seeds each of sesame germplasm materials with varying degrees of purple hue at the base of the stem (including "Tieqing Sesame" and "Zhongzhi 14") were selected and sown in 50-cell trays, two seeds per cell. When the seedlings had 3-4 pairs of true leaves, they were transplanted to the field with a row spacing of 40 cm and a plant spacing of 16 cm. Disease occurrence was investigated before maturity, and the incidence and disease index were calculated. Yield data were measured after harvest. The results showed a positive correlation between the degree of purple hue at the base of the stem and disease resistance; the deeper the purple hue, the stronger the disease resistance, and the significantly improved lodging resistance and stress tolerance.

[0029] 2. Analysis of the inheritance patterns of the purple trait The male parent was "Zhongzhi 14", which has slightly purple spots at the base of the stem (field planting conditions are as follows). Figure 3 As shown), and the purple-capsule "Iron Green Sesame" (field planting situation as shown). Figure 2 (As shown) F1 generation was obtained through hybridization, and F2 population was obtained through self-pollination of F1. Statistical analysis of traits such as the degree of purple at the base of the stem and the color of the capsule in the parents and offspring populations revealed that purple capsules were dominant over green, and the degree of purple was controlled by multiple genes, exhibiting a continuous distribution. This result indicates that selecting parents with deep purple stem bases and purple capsules for hybridization can significantly improve the aggregation efficiency of stress resistance traits in the offspring.

[0030] 3. Breeding process of the stress-resistant and high-oil germplasm resource "25SP19" of purple fruit The breeding pedigree of "25SP19", a purple-capsule, stress-resistant, high-oil sesame germplasm resource, is as follows: Figure 1 As shown, the specific process is as follows: In the summer of 2016, 300 F1 seeds were obtained by hybridization in Wuhan using "Tieqing Sesame" as the female parent and "Zhongzhi 14" as the male parent. In the summer of 2017, the F1 population was planted, and 19 robust individual plants with distinct purple bases on their stems were selected for self-pollination.

[0031] In the winter of 2017, 130 plants of the F2 population were planted in Sanya, Hainan. Weak, disease-prone, excessively long internodes, and plants with few capsules were eliminated, leaving 25 plants. The oil content of the seeds was determined using a near-infrared spectroscopy quality analyzer, and the third plant with the highest oil content was selected for seed production.

[0032] Between 2018 and 2020, alternating generations of cultivation were conducted in Wuhan and Sanya. Each generation was selected according to the following criteria: weak plants were removed during the seedling stage; during the maturity stage, plants with non-purple capsules, long internodes, high capsule position, or those susceptible to disease were removed; after harvest, oil content was measured, and the plants with the highest oil content were selected for continued propagation. By the summer of 2020, a superior F6 generation with high-oil purple capsules was obtained.

[0033] In the summer of 2021, using the F6 superior line as the female parent, it was backcrossed with "Zhongzhi 14" to obtain F6BC1 seeds. From 2021 to 2025, the backcross progeny underwent six consecutive generations of self-pollination and directional selection, with each generation having a population size of 30-40 plants, strictly selecting according to the aforementioned stress resistance traits and oil content indicators. By the summer of 2025, the F6BC6 population showed stable and consistent traits, and this stable inbred line was named "25SP19." Its field planting status is as follows... Figure 4 As shown.

[0034] This germplasm combines the advantages of "Tieqing Sesame" (purple fruit, strong resistance to adverse conditions) and "Zhongzhi 14" (high yield, high oil content), with more capsules per plant, strong disease resistance, and significantly higher oil content than conventional varieties.

[0035] 4. Trait verification and effect testing After years of multi-location trials, “25SP19” has shown stable purple fruit characteristics in the Yangtze River Basin production area. The base of the stem is deep purple, and its resistance to stem blight and wilt is more than 50% higher than that of “Zhongzhi 14”. The average oil content is 58.5%, which is about 3 percentage points higher than that of the parent.

[0036] To comprehensively evaluate the agronomic traits and production adaptability of the newly created germplasm “25SP19”, a comparative experiment was conducted in 2025 at the Sanya experimental base using “25SP19” and its parents “Tieqing Sesame” (a stress-resistant donor) and “Zhongzhi 14” (a high-oil, high-yield donor) as materials.

[0037] (1) Sowing Direct seeding was used. On May 25, the test material seeds were sown in rows with a row width of 2 m and a row spacing of 40 cm, with 1 g sown per row and a sowing depth of about 2 cm.

[0038] (2) Land preparation and base fertilizer The experimental field was previously planted with a non-sesame crop, and the land was leveled after deep plowing. Sesame is intolerant of waterlogging, so the raised beds need to be shaped like a turtle's back. Base fertilizer consisted mainly of organic fertilizer and phosphorus and potassium fertilizer, with 1000-1500 kg of well-rotted farmyard manure or 300 kg of commercial organic fertilizer per acre, supplemented with 20 kg of superphosphate and 10 kg of potassium sulfate. This was evenly spread and incorporated into the soil before plowing. Excessive nitrogen fertilizer was avoided to prevent excessive vegetative growth.

[0039] (3) Field management Thinning and transplanting should be done promptly. Thinning should be done when the seedlings have two pairs of true leaves, and transplanting should be completed at the predetermined plant spacing when the seedlings have three to four pairs of true leaves, ensuring a density of approximately 10,000 plants per acre. During the seedling stage, pay attention to weeding and cultivating strong seedlings. If the sesame plants are weak during the mid-growth stage (budding to initial flowering), apply 5-8 kg of urea per acre as a top dressing. Throughout the entire growth period, pay attention to clearing ditches and draining waterlogged areas to prevent waterlogging damage.

[0040] (4) Pest and disease control The main diseases affecting sesame include stem blight, wilt, and bacterial wilt; the main pests are cutworms, aphids, and sesame borers. Control should be based on agricultural methods, combined with physical and biological control, and, when necessary, the scientific use of highly effective and low-toxicity pesticides. The occurrence of diseases and pests on each material should be investigated regularly during the experiment.

[0041] (5) Timely harvesting and seed testing “25SP19” matured in early September. Harvesting was carried out on a sunny morning when the lower capsules split open and the middle and upper capsules turned the varietal characteristic purple. After harvesting, key traits of the three materials were evaluated, and the results are shown in Table 1.

[0042] Table 1. Comparison of main traits between sesame germplasm resource "25SP19" and its parents. Comparative trials have shown that "25SP19" successfully combines the superior traits of its parents, stably inheriting the deep purple fruit color and strong disease resistance (disease index close to that of the resistant parents) of "Tieqing Sesame," while maintaining the high yield potential (number of capsules per plant and thousand-grain weight) of "Zhongzhi 14" and further improving the oil content of the seeds. It is a new, unique, high-oil-content sesame variety with excellent comprehensive traits and resistance to adverse conditions. Its cultivation and management methods are similar to those of conventional high-yield sesame varieties, making it suitable for promotion and application in the main sesame-producing areas of the Yangtze River Basin.

[0043] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for creating a stress-resistant, high-quality, and unique germplasm of purple sesame fruit, characterized in that, Includes the following steps: Using sesame germplasm resources with purple fruits, purple stems, and strong disease and stress resistance as the female parent, and sesame varieties with purple spots at the base of the stem, a large number of capsules per plant, and relatively large capsules as the male parent, hybridization was carried out to obtain F1 generation seeds; Plant the F1 generation seeds to obtain F1 generation individual plants, then self-pollinate to obtain F2 generation seeds; Plant the F2 generation seeds, screen and test their quality, save the seeds, and obtain the F3 generation seeds; Plant the F3 generation seeds, screen and test their quality, save the seeds, and obtain the F4 generation seeds; Plant the F4 generation seeds, screen and test their quality, save the seeds, and obtain the F5 generation seeds; Plant the F5 generation seeds, screen and test their quality, save the seeds, and obtain the F6 generation seeds; Plant the F6 generation seeds, perform backcrossing and screening to obtain F6 generation single plants, use them as backcrossing female parents, and backcross with the male parents to obtain F6BC1 seeds; The F6BC1 seeds were planted, screened, and their quality was tested. F6BC2 seeds were then saved to obtain F6BC2 seeds. The F6BC2 seeds were planted, screened, and their quality was tested. Seeds were then saved to obtain F6BC3 seeds. The F6BC3 seeds were planted, screened, and their quality was tested. F6BC4 seeds were then saved to obtain F6BC4 seeds. The F6BC4 seeds were planted, screened, and their quality was tested. F6BC5 seeds were then saved to obtain F6BC5 seeds. The F6BC5 seeds were planted, screened, and their quality was tested. Seeds were saved to obtain F6BC6 seeds, and a stable inbred line was obtained, which is the stress-resistant, high-quality, and unique germplasm of purple sesame.

2. The creation method as described in claim 1, characterized in that, The parent plant is *Sesame ferox*.

3. The creation method as described in claim 1, characterized in that, The parent is Zhongzhi 14.

4. The method of creation as described in claim 1, characterized in that, The screening process includes the following steps: Remove weak and unhealthy plants during the seedling stage; Remove plants with short capsules, long internodes, high capsule position, long and pointed hollow stems, or fewer than 6 capsules per node at maturity. Remove infected plants during harvest; After harvesting, select plants with purple stems at the base and purple capsules.

5. The method of creation as described in claim 1, characterized in that, The quality determination includes the following steps: After harvesting and threshing the selected sesame plants, the oil content of the seeds was tested, and the sesame plants with the highest oil content were selected for seed saving.

6. The method of creation as described in claim 1, characterized in that, The backcross screening includes the following steps: Remove weak and unhealthy plants during the seedling stage; Select plants with strong growth, short internodes, large capsules, low capsule position, short and pointed hollow tips, and purple capsules at maturity.

7. The application of a high-quality, stress-resistant sesame germplasm obtained by the creation method according to any one of claims 1-6 in the breeding of sesame varieties with high stress resistance and mechanized cultivation.

8. The application of a stress-resistant, high-quality, and unique germplasm of purple sesame seeds obtained by the creation method according to any one of claims 1-6 in oilseed production.

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