A method for rapid selection of a limited sex egg color silkworm variety

Abstract

The application discloses a rapid breeding method of a limited egg color silkworm variety, and the whole breeding process is simple in operation technology, and the selection of female and male eggs can be completed by adopting one technical route, wherein only the real product line is needed to be backcrossed after the parent P is crossed to G4; moreover, the test cross inspection method is simple, strong in operability and accurate in detection and selection; the breeding time is short, and the breeding time is shortened by 5 generations compared with the prior art; by means of cross, backcross and test cross, the third white egg gene w3 is introduced into the original original female parent variety of the existing excellent real product variety, and the limited white egg original female parent variety (10 generations of breeding) with excellent properties is obtained; finally, the limited egg color variety (black eggs are female eggs, and white eggs are male eggs) with excellent economic properties is obtained by cross according to the seed production form of the original real product variety.

Description

Technical Field

[0001] This invention relates to the field of silkworm breeding technology, and in particular to a rapid breeding method for sex-limited egg-colored silkworm varieties. Background Technology

[0002] my country's sericulture industry has a long history and is an important component of the integrated development of industry and agriculture. The selection and breeding of superior silkworm varieties is a crucial technology supporting the development of the silk industry. Achieving sex control in silkworm rearing is of great significance to sericulture production: Separate rearing of male and female silkworms in cocoon rearing eliminates the need for pupal identification, alleviating the shortage of skilled workers for concentrated labor and pupal identification, and saving production costs; it also allows for appropriate adjustment of the male-to-female silkworm rearing ratio according to the characteristics of the silkworm species, increasing the seed production coefficient; separate rearing and reeling of male and female silkworms in silk cocoon rearing improves the quality of raw silk; female silkworms can also be used to produce immature silkworms, increasing the yield of immature silkworms; exclusive rearing of male silkworms results in a high leaf-to-silk conversion rate, and male silkworm cocoons can be used to reel high-quality raw silk, while male moths can be used for other medicinal purposes, thus improving economic benefits.

[0003] The sex determination of silkworms is heterogamous, meaning that female silkworms have ZW-type sex chromosomes and male silkworms have ZZ-type sex chromosomes. The W chromosome has the function of completely determining female sex. Utilizing the female-determining function of the W chromosome, scholars both domestically and internationally have conducted research on creating sex-restricted silkworm systems. Methods for breeding silkworm varieties to achieve sex control include: sex-restricted markings, sex-restricted cocoon color, sex-linked red ants, balanced lethal male silkworms, and sex-restricted egg color.

[0004] However, all methods have certain limitations:

[0005] (1) Sex-restricted patterned silkworm varieties have sex-restricted larval patterns, requiring sex identification and separate rearing during the 3rd to 5th instar larval stages. This requires a large amount of labor, and sex identification is practically impossible in silk production due to labor shortages. (2) Sex-restricted cocoon color silkworm varieties have yellow female cocoons and white male cocoons. Yellow cocoons can be used to reel colored silk or make "golden" silk quilts. These varieties can only be promoted and applied as special varieties at present, with a very small market share. (3) Sex-associated red ants cause female silkworms to die during high-temperature priming, allowing for the exclusive rearing of male silkworms. However, the silkworm egg utilization rate is only 50%, resulting in high production costs. At the same time, high-temperature priming may induce silkworm diseases. (4) Balanced lethal silkworm varieties have female silkworms that die during the priming period or in the first instar, allowing for the exclusive rearing of male silkworms. However, this has certain limitations in large-scale production. The main reason is that because all female silkworms die, the number of silkworm heads per batch of silkworm eggs is only half that of ordinary silkworm eggs, doubling the production cost of silkworm eggs. (5) Existing sex-limited egg color technology, such as the method for breeding sex-limited white-egg silkworm varieties adapted to separate rearing and reeling of male and female silkworms disclosed in Chinese Patent Application Publication CN114190339B, uses the Chinese system and Chinese line sex-limited white-egg materials of current excellent silkworm varieties as materials. Through hybridization and backcrossing, the sex-limited white-egg gene is introduced to obtain a sex-limited white-egg Chinese system with excellent traits; using the Japanese system and Japanese line sex-limited white-egg materials of current excellent silkworm varieties as materials, the sex-limited white-egg gene is introduced through hybridization and backcrossing to obtain a sex-limited white-egg Japanese system with excellent traits; the obtained sex-limited white-egg Chinese system and Japanese system with excellent traits are hybridized to obtain a hybrid variety that is an economically excellent sex-limited white-egg variety adapted to separate rearing and reeling of male and female silkworms. This invention allows for breeding four times a year, and the breeding of sex-limited white-egg silkworm varieties and strains can be completed within four years. However, the G1 to G9 generations involve two separate technical routes for male and female silkworms, which is quite complex to operate. The male silkworm selection process involves alternating hybridization, backcrossing, and self-pollination, resulting in a complex mating sequence that is prone to errors. Therefore, a rapid breeding method for sex-limited egg-colored silkworm varieties is urgently needed. Summary of the Invention

[0006] The purpose of this invention is to provide a rapid breeding method for sex-limited egg-colored silkworm varieties, which solves the problems mentioned in the background art.

[0007] The above-mentioned technical objective of the present invention is achieved through the following technical solution:

[0008] A rapid breeding method for sex-limited egg-colored silkworm varieties includes the following steps:

[0009] S1. Using males (black eggs ZZ++) of currently used varieties and females (white eggs ZW) of sex-limited albino eggs. +w3 The eggs of the G1 (F1) generation of the w3 / w3 crossbred silkworms showed black eggs (ZW). +w3 + / w3, ZZ+ / w3);

[0010] S2 and G1(F1) mixed breeding, female silkworms (ZW +W3 + / w3) was backcrossed with the male (ZZ++) of a practical variety, and the G2 (BC1) eggs were black eggs (ZW) +w3 ++、ZW +w3 + / w3, ZZ++, ZZ+ / w3);

[0011] S3 and G2(BC1) are mixed-breed, with female silkworms (ZW) +w3 ++、ZW +w3 + / w3) was backcrossed with the male (ZZ++) of a practical variety, and the G3 (BC2) eggs were black eggs (ZW) +w3 ++、ZW +w3 + / w3, ZZ++, ZZ+ / w3);

[0012] S4 and G3 (BC2) were raised individually in 10 breeding zones, which were randomly numbered. The female moths (ZW) in each breeding zone were then... +w3 ++、ZW +w3 One portion of the + / w3 moths was backcrossed with male silkworms of practical varieties to produce backcross silkworm seed G4 (BC3), and the other portion was used for test crosses with males of sex-limited white egg material (ZZ w3 / w3), or male moths (ZZ++, ZZ+ / w3) were used with females of sex-limited white egg material (ZW +w3 Test crosses were performed on w3 / w3 silkworms. The egg color of the test cross silkworm eggs was observed when they turned into their natural color. For example, if the test cross eggs were completely black, the corresponding backcross silkworm species G4(BC3)(♀ZW) in the moth-numbered area was selected. +w3 ++;♂ZZ++) Eliminate, if the moth area has white eggs among the testcross silkworm eggs, the corresponding backcross silkworm species G4(BC3)(♀ZW +w3 ++、ZW +w3 + / w3;♂ZZ++、ZZ+ / w3) Select and retain. In the breeding moth area, test crosses only need to be performed on females or males. The test cross method can be determined according to the number of females and males in the breeding single moth area and the number of sex-limited white egg materials.

[0013] S5 and G4(BC3) single moth breeding, repeat step 4, select the moth-keeping area G5(BC4)(♀ZW) +w3 ++、ZW +w3 + / w3; ♂ZZ++、ZZ+ / w3);

[0014] S6 and G5(BC4) are bred by single moths, and self-pollination produces G6 (black egg: ZW). +w3 ++、ZW +w3 + / w3、ZW +w3 w3 / w3, ZZ++, ZZ+ / w3; white egg: ZZw3 / w3);

[0015] S7. Select G6 moth areas containing black and white eggs for mixed breeding and continue self-pollination, or separate the black and white eggs and raise them separately before self-pollination. The female moths in the black eggs (ZW) +w3 When the male moth (w3 / w3) mates with the white-egg male moth (ZZ w3 / w3), the ratio of black to white eggs produced is approximately 1:1, which is the selected G7 generation (ZW). +w3 w3 / w3, ZZ w3 / w3);

[0016] S8 and G7-G10 generations were bred by single moths using conventional breeding methods, combining moth area selection with individual selection to stabilize the biological and economic traits of the strain. In spring, the focus was on the quality of the cocoon silk, and in summer and autumn, the focus was on the robustness of the strain. G10 was self-pollinated to produce a sex-limited white egg practical strain with stable biological traits and excellent economic traits.

[0017] S9. The original mother breeds are mated according to the mating method of the original practical lines. The first generation hybrids are the economically superior limited-egg silkworm varieties. Black eggs are female eggs, and white eggs are male eggs. During the conventional breeding of G9-G10, crossbreeding experiments are carried out. If new combinations with outstanding economic traits are found, they can be combined to form new economically superior limited-egg silkworm varieties.

[0018] Further preferred, the individual selection in step S8 includes weighing and selecting the total cocoon weight, cocoon layer weight, and cocoon layer rate, and using the ZHJ-20 intelligent live pupa reeling machine to select the individual silk length, unwinding, fineness, and knotting.

[0019] In summary, the present invention has the following beneficial effects:

[0020] Firstly, the operation of this invention is simple. The selection of male and female eggs can be completed through a single technical route. From P hybridization to G4, only male backcrossing of practical strains is required.

[0021] Secondly, the test cross inspection method of the present invention is simple to operate and has accurate detection and selection methods.

[0022] Thirdly, the breeding time of this invention is short. The breeding time is shortened by 5 generations compared with the existing technology. Through hybridization, backcrossing, and testcrossing, the third white egg gene w3 is simultaneously introduced into the original mother seed of the current excellent and practical varieties to obtain a sex-limited white egg original mother seed with excellent traits (developed in 10 generations). Finally, it is hybridized according to the seed production method of the original practical varieties, which is the economically excellent sex-limited egg variety. The black egg is the female egg and the white egg is the male egg. Attached Figure Description

[0023] Figure 1 This invention describes the breeding process for sex-limited egg-colored silkworm varieties. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to the accompanying drawings.

[0025] Example 1: A rapid breeding method for the sex-restricted egg-colored silkworm varieties "Yunxia No. 3 Limited" and "Yuncan No. 11 Limited" includes the following steps:

[0026] S1. Using the original male offspring (S1A, Xinxiu B, etc.) of the current practical varieties "Yunxia No. 3" and "Yuncan No. 11" (black eggs ZZ++) and the female offspring (white eggs ZW) of the sex-limited albino egg material, respectively. +w3 The eggs of the G1 (F1) generation of the w3 / w3 crossbred silkworms showed black eggs (ZW). +w3 + / w3, ZZ+ / w3);

[0027] S2 and G1(F1) mixed breeding, female silkworms (ZW +W3 + / w3) was backcrossed with the male (ZZ++) of a practical variety, and the G2 (BC1) eggs were black eggs (ZW) +w3 ++、ZW +w3 + / w3, ZZ++, ZZ+ / w3);

[0028] S3 and G2(BC1) are mixed-breed, with female silkworms (ZW) +w3 ++、ZW +w3 + / w3) was backcrossed with the male (ZZ++) of a practical variety, and the G3 (BC2) eggs were black eggs (ZW) +w3 ++、ZW +w3 + / w3, ZZ++, ZZ+ / w3);

[0029] S4 and G3 (BC2) were raised individually in 10 breeding zones, which were randomly numbered. The female moths (ZW) in each breeding zone were then... +w3 ++、ZW +w3 One portion of the + / w3 moths was backcrossed with male silkworms of practical varieties to produce backcross silkworm seed G4 (BC3), and the other portion was used for test crosses with males of sex-limited white egg material (ZZ w3 / w3), or male moths (ZZ++, ZZ+ / w3) were used with females of sex-limited white egg material (ZW +w3 Test crosses were performed on w3 / w3 silkworms. The egg color of the test cross silkworm eggs was observed when they turned into their natural color. For example, if the test cross eggs were completely black, the corresponding backcross silkworm species G4(BC3)(♀ZW) in the moth-numbered area was selected. +w3 ++;♂ZZ++) Eliminate, if the moth area has white eggs among the testcross silkworm eggs, the corresponding backcross silkworm species G4(BC3)(♀ZW +w3 ++、ZW +w3 + / w3;♂ZZ++、ZZ+ / w3) Select and retain. In the breeding moth area, test crosses only need to be performed on females or males. The test cross method can be determined according to the number of females and males in the breeding single moth area and the number of sex-limited white egg materials.

[0030] S5 and G4(BC3) single moth breeding, repeat step 4, select the moth-keeping area G5(BC4)(♀ZW) +w3 ++、ZW +w3 + / w3; ♂ZZ++、ZZ+ / w3);

[0031] S6 and G5(BC4) are bred by single moths, and self-pollination produces G6 (black egg: ZW). +w3 ++、ZW +w3 + / w3、ZW +w3 w3 / w3, ZZ++, ZZ+ / w3; white egg: ZZw3 / w3);

[0032] S7. Select G6 moth areas containing black and white eggs for mixed breeding and continue self-pollination, or separate the black and white eggs and raise them separately before self-pollination. The female moths in the black eggs (ZW) +w3 When the male moth (w3 / w3) mates with the white-egg male moth (ZZ w3 / w3), the ratio of black to white eggs produced is approximately 1:1, which is the selected G7 generation (ZW). +w3 w3 / w3, ZZ w3 / w3);

[0033] S8 and G7-G10 generations were bred by single moths using conventional breeding methods, combining moth area selection with individual selection to stabilize the biological and economic traits of the strains. In spring, the focus was on cocoon silk quality, and in summer and autumn, the focus was on robustness. G10 was self-pollinated to produce sex-limited white-egg practical strains with stable biological traits and excellent economic traits ("S1A limited", "Xinxiu B limited", etc.). The breeding process is shown in Tables 1 and 2.

[0034] S9. The original mother breeds were mated according to the mating method of the original practical strains, and the first generation hybrids were the economically superior sex-limited egg silkworm varieties "Yunxia No. 3 Limited" and "Yuncan No. 11 Limited" (black eggs are female eggs and white eggs are male eggs).

[0035] It should also be noted that: during the conventional breeding of G9 to G10, crossbreeding experiments are carried out. If a new combination with outstanding economic traits is found, it will be a new sex-limited egg color variety.

[0036] Table 1. Breeding of S1A-limited maternal-specific white eggs.

[0037]

[0038] Note: S1A is the original mother strain of the current economic and practical variety "Yunxia No. 3".

[0039] Table 2. Selection of original maternally limited albino rookies B-limited

[0040]

[0041]

[0042] Note: Newcomer B is the original Japanese mother strain of the current economic and practical variety "Yuncan 11".

[0043] Tables 1 and 2 only list the sex-limiting gene introduction and breeding process of one of the original mother varieties of "Yunxia No. 3" and "Yuncan No. 11". In actual operation, the third white egg gene w3 is introduced into the eight original mother varieties of the current excellent and practical varieties "Yunxia No. 3" and "Yuncan No. 11" at the same time. Hybridization, backcrossing and testcross are carried out. In addition to conventional breeding, hybridization experiments are carried out at G9 and G10. Finally, hybridization is carried out according to the seed production form of the original practical varieties, which are the economically excellent sex-limited egg color varieties "Yunxia No. 3 Limited" and "Yuncan No. 11 Limited" (black eggs are female eggs and white eggs are male eggs). In the hybridization combination experiment, if there is a new combination with outstanding economic traits, it is a new sex-limited egg color variety.

[0044] This specific embodiment is merely an explanation of the present invention and is not intended to limit the present invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A rapid breeding method for a sex-limited, egg-colored silkworm variety, characterized in that, Includes the following steps: S1. Using male black eggs ZZ++ from currently used varieties and female white eggs ZW from sex-limited white egg material. +w3 The eggs of the G1 generation of w3 / w3 hybrid silkworms exhibit black eggs (ZW). +w3 + / w3、ZZ + / w3; S2 and G1 mixed breeding, female silkworms ZW +W3 + / w3 was backcrossed with the male ZZ++ of a practical variety, and the G2 eggs were black eggs ZW. +w3 ++、ZW +w3 + / w3, ZZ++, ZZ + / w3; S3 and G2 mixed breeding, female silkworms ZW +w3 ++、ZW +w3 + / w3 was backcrossed with the male ZZ++ of a practical variety, and the G3 eggs were black eggs ZW. +w3 ++、ZW +w3 + / w3, ZZ++, ZZ + / w3; S4 and G3 are single-moth rearing, with 10 moth rearing areas, and are randomly numbered. The female moths in each rearing area are then reared (ZW). +w3 ++、ZW +w3 A portion of the + / w3 moths was backcrossed with male silkworms of practical varieties to produce backcross silkworm seed G4. Another portion was used for test crosses with male ZZ w3 / w3 of sex-limited white-egg material, or male moths ZZ++ or ZZ + / w3 were used with female ZW of sex-limited white-egg material. +w3 Test crosses were performed on w3 / w3 silkworms—the test crosses were observed to determine the egg color when the test cross eggs turned to their natural color. For example, if the test cross eggs were entirely black, the corresponding backcross silkworm species in the moth-numbered area was G4: ♀ZW. +w3 ++;♂ZZ ++ are eliminated. For example, in areas where white eggs appear among the testcross silkworm eggs, the corresponding backcross silkworm breed is G4: ♀ZW +w3 ++、ZW +w3 + / w3; ♂ZZ++, ZZ + / w3 selection, test crosses in breeding moth areas only require test crosses of females or males, the test cross method can be determined according to the number of females and males in breeding single moth areas and sex-limited white egg material; S5 and G4 single moth breeding, repeat step 4, select the moth-keeping area G5: ♀ZW +w3 ++、ZW +w3 + / w3; ♂ZZ ++、ZZ + / w3; S6 and G5 were bred by a single moth, and self-pollinated to produce G6: black eggs ZW +w3 ++、ZW +w3 + / w3、ZW +w3 w3 / w3, ZZ ++, ZZ + / w3; white egg ZZ w3 / w3; S7. Select G6 moth areas with black and white eggs for mixed breeding and continue self-pollination, or separate the black and white eggs and raise them separately before self-pollination. The female moths from the black eggs will be ZW. +w3 When w3 / w3 mates with the white-egg male moth ZZ, the ratio of black to white eggs produced is approximately 1:1, which is the selected G7 generation ZW. +w3 w3 / w3, ZZ w3 / w3; S8 and G7~G10 generations were bred by single moths using conventional breeding methods, combining moth area selection with individual selection to stabilize the biological and economic traits of the strain. In spring, the focus was on the quality of the cocoon silk, and in summer and autumn, the focus was on the robustness of the strain. G10 was self-pollinated to produce a sex-limited white egg practical strain with stable biological traits and excellent economic traits. S9. The original mother breeds are mated according to the mating method of the original practical lines. The first generation hybrids are the limited-egg silkworm varieties with excellent economic traits. Black eggs are female eggs and white eggs are male eggs. During the conventional breeding of G9~G10, the combination and hybridization experiments are carried out. If there are new combinations with outstanding economic traits, they can be combined to form new limited-egg silkworm varieties with excellent economic traits.

2. The rapid breeding method for a sex-limited egg-colored silkworm variety according to claim 1, characterized in that: The individual selection in step S8 includes individual weighing to select total cocoon weight, cocoon layer weight, cocoon layer ratio, and utilization rate. The 20 intelligent live pupa reeling machine selects individual filaments for length, unwinding, fineness, and knotting during live pupa reeling.

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