A method for fast breeding of homozygous cotton based on creating markers

Abstract

The application provides a cotton homozygous type rapid breeding method based on a created marker, and comprises the following steps: step one, using breeding material with a functional marker trait as a donor parent, and crossing the donor parent with an upland cotton with a target excellent trait, and continuously performing multiple generations of backcrossing and sister crossing to create a batch of core marker germplasm which gradually penetrates excellent genes of the upland cotton and stably carries the functional marker trait. The application uses the functional marker trait as a morphological index to realize rapid and nondestructive identification of the target trait in the early generation of cotton breeding, breaks through the technical bottleneck that the target trait is difficult to be accurately identified in the early stage in traditional backcross breeding, and improves the selection efficiency. The core marker germplasm created through multiple generations of backcrossing and sister crossing retains the excellent genes of the upland cotton, and stably carries the functional marker trait, so that the genetic marker provides reliable morphological selection basis for subsequent hybridization breeding, and avoids the problem of genetic background confusion caused by repeated backcrossing.

Description

Technical Field

[0001] This invention relates to the field of cotton breeding technology, and in particular to a rapid breeding method for homozygous cotton based on created markers. Background Technology

[0002] Cotton is an important economic crop and raw material for the textile industry in my country. Currently, upland cotton, which is widely cultivated, is adaptable and has high yields, but its fiber quality, especially fiber strength, still falls short of the demands of the high-end textile industry. Sea island cotton, with its superior fiber quality and good disease resistance, is a valuable genetic resource for improving upland cotton. Introducing the superior genes of sea island cotton into upland cotton through distant hybridization is a key breeding approach to improve the quality of upland cotton.

[0003] However, traditional backcross breeding methods have significant bottlenecks. To introduce and stabilize the target traits of Sea Island cotton into the genetic background of upland cotton, while simultaneously eliminating genes linked to undesirable traits, 6-8 generations or even more of backcrossing and self-pollination are typically required. This process is extremely lengthy, consuming substantial human, material, and time resources. More importantly, in the early generations of breeding, many key target traits are difficult to identify quickly and accurately at the individual plant level. These traits are mostly quantitative traits, easily affected by environmental factors, leading to low selection efficiency and poor accuracy, resulting in significant uncertainty and uncertainty in the breeding process.

[0004] To address this, a rapid breeding method for homozygous cotton based on created markers is proposed. Summary of the Invention

[0005] In view of this, the present invention provides a rapid breeding method for homozygous cotton based on creative markers, in order to solve or alleviate one of the technical problems existing in the prior art, and at least provide a beneficial option.

[0006] The technical solution of this invention is implemented as follows: A rapid breeding method for homozygous cotton based on creative markers, comprising the following steps:

[0007] Step 1: Using breeding materials with functional marker traits as donor parents, cross them with Sea Island cotton with the target superior traits. Perform multiple generations of backcrossing and sister crosses to create a batch of core marker germplasm that gradually infiltrates Sea Island cotton's superior genes and stably carries the aforementioned functional marker traits. Then, cross upland cotton with the functional marker trait (chicken-foot leaves and no glands) with Sea Island cotton with the target traits (extra-long fibers, disease resistance). Repeat the backcrossing process with upland cotton parents 4-6 times to maximize the restoration of the genetic background of the offspring to upland cotton while ensuring the introduction of the target superior genes. During or after the backcrossing process, perform 1-2 crosses between sister plants to promote the binding of genes controlling the functional marker traits, ensuring stable inheritance and expression in the offspring, forming homozygotes. Finally, obtain a batch of core marker germplasm with a genetic background close to upland cotton and stably carrying the chicken-foot leaves and no glands.

[0008] Step 2: Based on the breeding objectives, select materials with different target traits from the core marker germplasm created in Step 1 as male parents and improve parents with complementary agronomic traits as female parents to cross and obtain F1 generation seeds. The male parents are selected from the core marker germplasm bank, and the female parents are selected from an improved parent with excellent agronomic traits (such as yield, adaptability, plant type) and whose traits are complementary to those of the male parents.

[0009] Step 3: Plant the F2 generation population obtained by self-pollination of the F1 generation. During the seedling stage, perform early screening of plants based on the functional marker traits, eliminate individuals carrying the functional marker traits, and retain plants that meet the breeding objectives. The F1 generation is heterozygous, and the F2 generation produced by self-pollination will undergo phenotypic segregation. According to Mendel's laws of inheritance, if the marker trait is controlled by a pair of dominant genes, then in the F2 generation, plants with and without the marker trait will segregate in a certain proportion.

[0010] Step 4: Self-pollinate and select offspring from the plants selected and retained in Step 3 to quickly obtain homozygous and stable new cotton varieties. Since a large-scale and precise pre-screening has already been carried out in the F2 generation through marker traits, the number of subsequent planting and tracking populations is greatly reduced. Only a small number of these selected plants need to be self-pollinated to examine their agronomic traits, yield, quality, etc. Usually, after 2-3 generations, homozygous lines with stable and consistent traits can be obtained. This is much faster than the traditional method of blindly planting a large number of populations and testing each generation.

[0011] Further preferred: In step one, the functional marker trait is chicken foot leaf type and glandless trait.

[0012] A further preferred embodiment: In step one, the continuous backcrossing and sister crossing specifically includes:

[0013] Perform backcrossing with the upland cotton parent 4-6 times consecutively, and perform 1-2 sister crosses during or after the backcrossing process.

[0014] Further preferred: The core marker germplasm created in step one carries the functional marker traits as morphological markers in subsequent hybridization breeding, used for early, rapid, and non-destructive identification in the F2 generation and later generations.

[0015] Further preferred: In step two, the parent plant is an improved parent plant with duck-foot leaf type, glands, and excellent agronomic traits.

[0016] Further preferred: In step three, the early screening based on functional marker traits during the seedling stage specifically involves phenotypic identification and screening based on leaf shape and the presence or absence of glands around the four-leaf stage of the F2 generation plants.

[0017] Further preferred: when the functional marker trait is chicken foot leaf type and the maternal parent is duck foot leaf type, the leaf type segregation ratio in the F2 generation population is: one-quarter chicken foot leaf type, one-quarter duck foot leaf type, and one-half intermediate leaf type; plants with the duck foot leaf type are retained during screening.

[0018] Further preferred: The method is used for the rapid breeding of homozygous cotton varieties with excellent fiber quality, specific maturity, or disease resistance.

[0019] The embodiments of the present invention have the following advantages due to the adoption of the above technical solutions:

[0020] I. This invention utilizes functional marker traits as morphological indicators to achieve rapid and non-destructive identification of target traits in early generations of cotton breeding, breaking through the technical bottleneck of difficult early and accurate identification of target traits in traditional backcross breeding and improving selection efficiency.

[0021] Second, the core marker germplasm created by this invention through multiple generations of backcrossing and sister crosses retains the excellent genes of sea island cotton and stably carries functional marker traits. The genetic markers provide a reliable basis for morphological selection in subsequent hybridization breeding, avoiding the problem of genetic background confusion caused by repeated backcrossing.

[0022] Third, this invention shortens the traditional breeding cycle from 6-8 generations to 3-4 generations, doubles the breeding efficiency, and allows for phenotypic screening based on leaf shape and gland characteristics during the seedling stage, reducing the workload of subsequent self-pollination generations.

[0023] Fourth, the new varieties bred in this invention not only maintain the high-yield characteristics of upland cotton, but also improve fiber quality and disease resistance, thus meeting the needs of the high-end textile industry.

[0024] Fifth, the technical solution of this invention has wide applicability. Functional marker traits and parental combinations can be flexibly adjusted according to different breeding objectives. It can be used for fiber quality improvement, maturity regulation, or disease resistance enhancement, providing a new technical path for the targeted improvement of cotton varieties.

[0025] The above overview is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of the invention will become readily apparent from the accompanying drawings and the following detailed description. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0028] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings.

[0029] It should be understood that the following specific examples illustrate the implementation of this disclosure, and those skilled in the art can easily understand other advantages and effects of this disclosure from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. This disclosure can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this disclosure. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0030] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this disclosure, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0031] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this disclosure. The drawings only show the components related to this disclosure and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0032] Furthermore, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the described aspects can be practiced without these specific details.

[0033] like Figure 1 As shown, this embodiment of the invention provides a rapid breeding method for homozygous cotton based on creative markers, comprising the following steps:

[0034] Step 1: Using breeding materials with functional marker traits as donor parents, cross them with Sea Island cotton with the target superior traits. Perform multiple generations of backcrossing and sister crosses to create a batch of core marker germplasm that gradually infiltrates Sea Island cotton's superior genes and stably carries the functional marker traits. Then, cross upland cotton with the functional marker trait (chicken-foot leaves and no glands) with Sea Island cotton with the target traits (extra-long fibers, disease resistance, etc.). Repeat the backcrossing process with upland cotton parents 4-6 times to maximize the restoration of the genetic background of the offspring to upland cotton while ensuring the introduction of the target superior genes. During or after the backcrossing process, perform 1-2 crosses between sister plants to promote the binding of genes controlling the functional marker traits, ensuring stable inheritance and expression in the offspring, forming homozygotes. Finally, obtain a batch of core marker germplasm with a genetic background close to upland cotton and stably carrying the chicken-foot leaves and no glands.

[0035] Step Two: Based on the breeding objectives, select materials with different target traits from the core marker germplasm created in Step One as the male parent, and use improved parents with complementary agronomic traits as the female parent for hybridization to obtain F1 generation seeds. The male parent is selected from the core marker germplasm bank. For example, if a high-yielding variety with excellent fiber quality is desired, the core germplasm with the best fiber quality is selected as the male parent. The female parent is an improved parent with excellent agronomic traits (such as yield, adaptability, and plant type), and its traits are complementary to those of the male parent. For example, if the male parent is *Cercis chinensis* (chicken foot leaf), the female parent is *Cercis chinensis* (duck foot leaf). The male parent has no glands, while the female parent has glands. This contrasting trait is to produce clear segregation in the offspring, facilitating selection.

[0036] Step 3: Plant the F2 generation population obtained by self-pollination of the F1 generation. During the seedling stage, perform early screening based on functional marker traits, eliminating individuals carrying the functional marker traits and retaining those that meet the breeding objectives. The F1 generation is heterozygous, and the F2 generation produced by self-pollination will exhibit phenotypic segregation. According to Mendel's laws of inheritance, if a marker trait is controlled by a pair of dominant genes, then in the F2 generation, plants carrying and not carrying the marker trait will segregate in a certain proportion. Seedlings are very small, saving land, manpower, and time. Technicians can directly observe leaf shape and the presence or absence of glands in the field without the need for complex instrument testing.

[0037] Step 4: Self-pollinate and select offspring from the plants selected and retained in Step 3 to quickly obtain homozygous and stable new cotton varieties. Since a large-scale and precise pre-screening has already been carried out in the F2 generation through marker traits, the number of subsequent planting and tracking populations is greatly reduced. Only a small number of these selected plants need to be self-pollinated to examine their agronomic traits, yield, quality, etc. Usually, after 2-3 generations, homozygous lines with stable and consistent traits can be obtained. This is much faster than the traditional method of blindly planting a large number of populations and testing each generation.

[0038] In this embodiment, specifically: the functional marker traits in step one are chicken foot leaf type and glandless trait. The glandless trait is easy to identify with the naked eye and can improve the utilization value of cottonseed.

[0039] In this embodiment, specifically: the continuous backcrossing and sister crossing in step one includes:

[0040] Perform 4-6 consecutive backcrosses with upland cotton parents, and 1-2 sister crosses during or after the backcrossing process. Sister crosses are used to accelerate the homozygosity of marker genes. In the backcross offspring, the marker genes may be in a heterozygous state. Sister crosses can make homozygous individuals appear and be selected.

[0041] In this embodiment, specifically: the core marker germplasm created in step one carries functional marker traits that serve as morphological markers in subsequent hybridization breeding, and is used for early, rapid, and non-destructive identification of the F2 generation and subsequent generations. The core marker germplasm can be repeatedly used for hybridization with different superior maternal parents, and various new varieties with the superior characteristics of sea island cotton can be rapidly cultivated in a standardized and procedural manner.

[0042] In this embodiment, specifically: the maternal parent in step two is an improved parent with duck-foot leaf type, glands and excellent agronomic traits. In the F2 generation, the leaf type and gland traits will separate, which facilitates effective screening during the seedling stage. At the same time, the maternal parent itself has excellent agronomic traits, which can ensure that the new variety can obtain the advantages of gradually infiltrating sea island cotton while not losing the high yield and adaptability of upland cotton.

[0043] In this embodiment, specifically: in step three, early screening is carried out based on functional marker traits during the seedling stage. Specifically, around the four-leaf stage of the F2 generation plants, phenotypic identification and screening are performed based on leaf type and the presence or absence of glands. At the four-leaf stage, the traits are fully expressed and the plants are still small, making field operations convenient. Technicians only need to remove all seedlings with chicken-foot leaves, intermediate types, and those without glands, resulting in high work efficiency.

[0044] In this embodiment, specifically: when the functional marker trait is chicken foot leaf type and the maternal parent is duck foot type, the segregation ratio of leaf type in the F2 generation population is: one-quarter chicken foot leaf type, one-quarter duck foot leaf type, and half intermediate leaf type; during screening, plants with duck foot leaf type are retained;

[0045] Assuming that chicken foot leaf (A) is incompletely dominant over duck foot leaf (a), then:

[0046] The F1 generation has the genotype Aa and exhibits the intermediate leaf type.

[0047] After self-pollination of F1, the genotype segregation ratio of F2 generation is: AA (chicken foot leaf): Aa (intermediate leaf type): aa (duck foot leaf type) = 1:2:1.

[0048] Therefore, only the aa-type plants, which make up 1 / 4 of the population, are retained during screening because their target trait is homozygous, their offspring will not segregate, and they can be stabilized into varieties most quickly.

[0049] In this embodiment, the specific method is used to rapidly breed homozygous cotton varieties with excellent fiber quality, specific maturity, or disease resistance. As long as the sea island cotton parents used for hybridization in step one have different superior traits, the core marker germplasm created and the new varieties bred subsequently will correspondingly possess these characteristics. This method provides an efficient solution for multi-trait directional improvement of cotton.

[0050] This invention utilizes functional marker traits as morphological indicators to achieve rapid and non-destructive identification of target traits in early generations of cotton breeding, breaking through the technical bottleneck of difficult early and accurate identification of target traits in traditional backcross breeding and improving selection efficiency.

[0051] This invention creates core marker germplasm through multiple generations of backcrossing and sister crosses, which retains the excellent genes of sea island cotton and stably carries functional marker traits. The genetic markers provide a reliable basis for morphological selection in subsequent hybridization breeding, avoiding the problem of genetic background confusion caused by repeated backcrossing.

[0052] This invention shortens the traditional breeding cycle from 6-8 generations to 3-4 generations, doubling the breeding efficiency. Phenotypic screening can be performed at the seedling stage based on leaf shape and gland characteristics, reducing the workload of subsequent self-pollination generations.

[0053] The new varieties bred in this invention not only maintain the high-yield characteristics of upland cotton, but also improve fiber quality and disease resistance, meeting the needs of the high-end textile industry.

[0054] The technical solution of this invention has wide applicability. It can flexibly adjust the functional marker traits and parental combinations according to different breeding objectives. It can be used for fiber quality improvement, maturity regulation or disease resistance enhancement, providing a new technical path for the targeted improvement of cotton varieties.

[0055] Example 2

[0056] In this embodiment, a rapid breeding method for homozygous cotton based on creation markers is used to select homozygous cotton varieties with high fiber strength and long fiber length.

[0057] Parent selection:

[0058] The donor parent was selected from upland cotton material M1, which has chicken foot leaf type and no glandular characteristics;

[0059] The parent material for Sea Island cotton is high-quality material G1 with a fiber strength ≥40cN / dtex and a length ≥38mm;

[0060] The improved parent variety was selected from upland cotton variety L1, which has duck-foot leaf type, glands, and excellent agronomic traits.

[0061] Specific steps:

[0062] M1 was crossed with G1 and backcrossed for 5 generations, with one sister cross during the period, to obtain a batch of core marker germplasm C1 that stably carries the chicken foot leaf type and glandless trait;

[0063] The single plant with the best fiber quality in C1 was selected as the male parent and crossed with L1 to obtain the F1 generation.

[0064] After self-pollination of F1, F2 populations were planted, and plants with duck-foot-leaf type were selected at the four-leaf stage.

[0065] Self-pollination of the selected plants, combined with fiber quality testing, rapidly obtained homozygous lines with fiber strength ≥38cN / tex and length ≥36mm.

[0066] Finally, a stable line FQ-1 was obtained in the F4 generation, with fiber quality and other traits significantly better than the parent line L1, approaching the level of Sea Island cotton.

[0067] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0068] In this disclosure, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. The block diagrams of devices, apparatuses, devices, and systems involved in this disclosure are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, devices, and systems can be connected, arranged, and configured in any manner. Words such as "comprising," "including," "having," etc., are open-ended terms meaning "including but not limited to," and are used interchangeably with them. The terms "or" and "and" as used herein refer to the terms "and / or," and are used interchangeably with them unless the context clearly indicates otherwise. The term "such as" as used herein refers to the phrase "such as but not limited to," and is used interchangeably with it.

[0069] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various variations or substitutions within the technical scope disclosed in the present invention, and these should all be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A rapid breeding method for homozygous cotton based on creative markers, characterized in that, Includes the following steps: Step 1: Using breeding materials with functional marker traits as donor parents, cross them with sea island cotton with the target superior traits, and continuously perform backcrosses and sister crosses for multiple generations to create a batch of core marker germplasm that gradually infiltrates the superior genes of sea island cotton and stably carries the aforementioned functional marker traits. Step 2: Based on the breeding objectives, select materials with different target traits from the core marker germplasm created in Step 1 as male parents, and cross them with improved parents that complement agronomic traits as female parents to obtain F1 generation seeds. Step 3: Plant the F2 generation population obtained by self-pollination of the F1 generation, and conduct early screening of the plants according to the functional marker traits during the seedling stage, eliminating individuals carrying functional marker traits and retaining plants that meet the breeding objectives. Step 4: Self-pollinate and select offspring from the plants selected and retained in Step 3 to quickly obtain new cotton varieties that are homozygous and stable in traits.

2. The rapid breeding method for homozygous cotton based on creation markers according to claim 1, characterized in that, In step one, the functional marker traits are chicken foot leaf type and no glandular trait.

3. The rapid breeding method for homozygous cotton based on creation markers according to claim 1, characterized in that, In step one, the continuous backcrossing and sister crossing specifically includes: Perform backcrossing with the upland cotton parent 4-6 times consecutively, and perform 1-2 sister crosses during or after the backcrossing process.

4. The rapid breeding method for homozygous cotton based on creation markers according to claim 1, characterized in that, In step one, the core marker germplasm created carries the functional marker traits, which serve as morphological markers in subsequent hybridization breeding and are used for early and rapid identification of the F2 generation and later generations.

5. The rapid breeding method for homozygous cotton based on creation markers according to claim 1, characterized in that, In step two, the parent plant is an improved parent plant with duck-foot leaf type, glands, and excellent agronomic traits.

6. The rapid breeding method for homozygous cotton based on creation markers according to claim 1, characterized in that, In step three, the early screening based on functional marker traits during the seedling stage specifically involves phenotypic identification and screening based on leaf shape and the presence or absence of glands around the four-leaf stage of the F2 generation plants.

7. The rapid breeding method for homozygous cotton based on creation markers according to claim 1, characterized in that, When the functional marker trait is chicken foot leaf type and the maternal parent is duck foot leaf type, the segregation ratio of leaf type in the F2 generation population is: one-quarter chicken foot leaf type, one-quarter duck foot leaf type, and one-half intermediate leaf type; plants with the duck foot leaf type are retained during screening.

8. The rapid breeding method for homozygous cotton based on creation markers according to claim 1, characterized in that, The method is used to rapidly breed homozygous cotton varieties with excellent fiber quality, specific maturity, or disease resistance.

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