Method for rapidly breeding indica rice restorer line with japonica rice consanguinity

Abstract

The invention provides a method for rapidly breeding a nonglutinous rice restorer line with japonica rice consanguinity. According to the method, a high-quality high-yield japonica rice three-line sterile line is used as a female parent, a plurality of high-quality disease-resistant indica rice varieties are used as male parents, and a large number of different combinations of F1 seeds are obtained through pairwise hybridization. The combination with high maturing rate is screened from the F2 generation, is planted and selected generation by generation, and is backcrossed with the indica rice variety for multiple times, and finally, the indica rice restorer line with japonica rice consanguinity is quickly obtained. According to the method, parent sources are expanded, genetic diversity is improved, manual castration operation is omitted, hybridization efficiency is improved, and the breeding period is remarkably shortened. The bred restorer line has the characteristics of high yield, disease resistance, high maturing rate and excellent agronomic traits, and is suitable for large-scale agricultural production and application.

Description

Technical Field

[0001] The invention relates to the technical field of rice breeding, in particular to a method for rapidly breeding an indica rice restorer line with japonica rice ancestry. Background Art

[0002] 1. Basic characteristics of japonica rice and indica rice and their ecological adaptability

[0003] Rice is one of the most important food crops in the world. It can be divided into two types, japonica rice and indica rice, according to its ecotype and growth characteristics. Japonica rice is mainly distributed in high-latitude areas such as Northeast China. It has the characteristics of short plants, compact plant type, large panicles and many grains, excellent rice quality, and strong cold resistance. Indica rice is mainly distributed in low-latitude areas such as southern China, Southeast Asia and South Asia. It has the characteristics of tall plant type, strong tillering ability, short growth period, wide adaptability, drought resistance and high temperature resistance. These two types of rice have their own advantages and disadvantages in ecological adaptability and production performance. Through hybrid breeding, their complementary advantages can be brought into play to cultivate new rice varieties with high yield, high quality and disease resistance.

[0004] 2. The significance and advantages of indica-japonica hybrid breeding

[0005] In rice breeding, utilizing hybrid vigor is an important means to increase yield and improve quality. Hybrid vigor refers to the phenomenon that hybrid offspring outperform their parents in growth rate, yield, disease resistance, etc. Due to the differences in ecotype and genetic background between japonica rice and indica rice, significant hybrid vigor can be produced through hybridization. Therefore, indica-japonica hybrid breeding has become a hot topic in rice breeding research in recent years. Through indica-japonica hybridization, the high-quality rice characteristics of japonica rice and the high-yield adaptability of indica rice can be combined in one variety to achieve the goal of cultivating new high-yield, high-quality, and disease-resistant varieties.

[0006] 3. Existing technical methods for hybrid breeding of indica and japonica rice

[0007] At present, there are two main ways to produce hybrid rice:

[0008] Combination of japonica sterile lines and indica-japonica intermediate restorer lines: This method uses the sterile lines of japonica rice to cross with the restorer lines of indica-japonica intermediate lines to obtain F1 hybrids. The sterile lines of japonica rice cannot produce pollen normally due to their own genetic defects, while the restorer lines of indica-japonica intermediate lines are wide-compatibility varieties obtained through hybrid breeding that have both japonica and indica genes. This method can obtain new hybrid rice varieties with high yield and disease resistance.

[0009] Combination of indica-japonica intermediate sterile lines with indica restorer lines: This method uses the sterile lines of indica-japonica intermediate types to cross with indica restorer lines to obtain F1 hybrids. Indica restorer lines can restore the pollen activity of sterile lines. Through this method, new hybrid rice varieties with both the high-yield characteristics of indica rice and the disease resistance of japonica rice can be cultivated.

[0010] IV. Deficiencies of Existing Technologies

[0011] Although the above two methods have achieved some success, there are still some shortcomings in practical applications:

[0012] Few parent varieties and low genetic diversity: The parent varieties currently used for indica-japonica hybridization are mainly some existing wide-compatibility restorer lines and sterile lines. The number of these varieties is limited, resulting in low genetic diversity. This is not conducive to the discovery and use of new favorable genes, limiting the potential of breeding.

[0013] The hybridization operation is complex and inefficient: The hybridization of two intermediate wide-compatibility restorer lines between indica and japonica requires artificial emasculation and pollination. This operation is complex, time-consuming and costly. At the same time, it is difficult to obtain a large number of F1 hybrid seeds in one hybridization, which limits the possibility of large-scale breeding.

[0014] 5. Method for Rapidly Breeding Indica Rice Restorer Lines with Japonica Rice Lineage

[0015] In view of the above problems, the present invention proposes a method for obtaining a large number of F1 seeds of different hybrid combinations by using high-quality and high-yield japonica rice three-line sterile lines as female parents and multiple high-quality disease-resistant indica rice varieties as male parents through pairwise hybridization. Through efficient screening and multiple backcrossing, a method for quickly breeding indica rice restorer lines with japonica rice ancestry is proposed. This method has the following significant advantages:

[0016] Expand the source of parents and improve genetic diversity: Using multiple high-quality disease-resistant indica rice varieties as male parents for hybridization can significantly expand the source of parents, improve the genetic diversity of offspring, and facilitate the discovery and utilization of more favorable genes.

[0017] Efficiently obtain F1 generation hybrid seeds: Using the three-line sterile line of japonica rice as the female parent can save the need for artificial detasseling of the female parent during hybridization, thereby improving the hybridization efficiency and being able to obtain a large number of F1 generation hybrid seeds at one time, which is suitable for large-scale breeding.

[0018] Screening for combinations with high fruit set rates: By recording the field fruit set rate of each hybrid combination in the F2 generation population, eliminating combinations with low fruit set rates, and selecting combinations with high fruit set rates for subsequent breeding, the fruit set rate of the offspring can be quickly improved.

[0019] Multiple backcrossing to stabilize the genetic background: By selecting excellent panicle lines as the male parent in the F4 generation population and conducting multiple backcrossings with the corresponding indica rice varieties, the sterile line genes of japonica rice can be introduced into the indica rice genome, stabilizing the genetic background of the offspring and improving the success rate of breeding.

[0020] The selected restorer line has the characteristics of high yield, disease resistance and stability: through strict screening and multiple backcrossing, the indica-japonica intermediate restorer line finally bred not only has part of the genome of the japonica rice three-line sterile line, but also retains the high yield and disease resistance characteristics of indica rice varieties, and can show superior agronomic traits in actual production.

[0021] 6. Technical principles and innovations

[0022] The technical principle of the present invention is to utilize the high-yield and high-quality potential of the three-line sterile japonica rice line and the genetic diversity of multiple high-quality disease-resistant indica rice varieties, and through paired hybridization and multiple backcrossing, quickly select and breed an indica-japonica intermediate restorer line that has both japonica rice ancestry and indica rice high-yield characteristics. Its innovative points are:

[0023] Using high-quality japonica three-line sterile line as the female parent: Due to its special gene defect, the japonica three-line sterile line cannot produce pollen normally, but it can hybridize with indica rice varieties to produce hybrid seeds. This characteristic gives it a unique advantage in hybrid breeding.

[0024] Pairwise hybridization to obtain a variety of combinations of F1 generation seeds: Through pairwise hybridization, a large number of different combinations of F1 generation seeds can be obtained, which significantly expands the source of parents and improves the genetic diversity of future generations.

[0025] Efficient screening and multiple backcrossing: During the breeding process, through efficient screening and multiple backcrossing, combinations with low fruit set rates can be quickly eliminated, and combinations with high fruit set rates and excellent agronomic traits can be selected, shortening the breeding cycle and improving breeding efficiency.

[0026] VII. Practical Application and Promotion Value

[0027] The method of the present invention is not only applicable to scientific research institutions and breeding companies, but also to large-scale agricultural production. In practical applications, by rationally utilizing japonica rice three-line sterile lines and multiple high-quality disease-resistant indica rice varieties, combined with multiple hybridization and backcrossing methods, indica rice restorer lines with japonica rice ancestry can be quickly bred. These restorer lines not only have a high fruit setting rate and excellent agronomic traits, but also can show superior disease resistance and high yield performance in production. Through the above specific embodiments, the method of the present invention is not only feasible, but also has significant promotion value in practical applications.

[0028] The method of the present invention can significantly improve the efficiency of rice breeding, shorten the breeding cycle, and reduce breeding costs. At the same time, the selected indica-japonica intermediate restorer line shows excellent characteristics of high yield, disease resistance, and stability in actual production, which can bring significant economic and social benefits to agricultural production. Therefore, the method of the present invention has broad application prospects and important promotion value in the field of rice breeding. Summary of the invention

[0029] Based on the existing technical problems, the present invention proposes a method for rapidly breeding an indica rice restorer line with japonica rice ancestry, comprising the following steps:

[0030] The three-line sterile line of japonica rice was used as the female parent;

[0031] Using multiple high-quality disease-resistant indica rice varieties as male parents;

[0032] F1 generation seeds are obtained by pairwise hybridization;

[0033] Plant F1 plants, investigate the fruit set rate, eliminate combinations with a fruit set rate below 30%, and harvest F2 generation seeds with a high fruit set rate;

[0034] Plant the F2 population and select the ears with a fruit set rate greater than 60%;

[0035] The F3 generation population is planted as a single ear, and the ear line with good agronomic traits is selected as the male parent and backcrossed with the indica rice variety during the flowering period to obtain BC1F1 generation seeds; the F4 generation seeds with good fruit set are harvested when mature.

[0036] Plant BC1F1 generation seeds, select combinations with good agronomic traits and high fruit set rate, and obtain self-pollinated seeds;

[0037] Planting BC1F2 generation seeds and continuing backcrossing with the corresponding F4 generation ear line male parent to obtain BC2F1 generation seeds;

[0038] Plant BC2F1 generation seeds, select combinations with good agronomic traits and high fruit set rate, and obtain self-pollinated seeds;

[0039] Continuously self-pollinate and strictly select single ears with high fruiting rate and good agronomic traits in the offspring population, and plant the ear lines;

[0040] In the BC2F8 generation, excellent panicle lines were selected for variety comparison tests, and at the same time, they were hybridized with the three-line sterile lines of japonica rice to test their resilience. The excellent lines were screened as the intermediate restorer line seedlings of indica and japonica.

[0041] As a preferred technical solution: the japonica rice three-line sterile line is 20A.

[0042] The method according to claim 1 is characterized in that the high-quality disease-resistant indica rice variety is dwarf rice.

[0043] As a preferred technical solution: in the step of paired hybridization, each male indica rice variety is hybridized with a japonica rice three-line sterile line to obtain a variety of different combinations of F1 generation seeds.

[0044] As a preferred technical solution: in the step of planting the F1 generation plants, the fruit setting rate of each hybrid combination is recorded, and combinations with a fruit setting rate lower than 50% are eliminated.

[0045] 5. The method for rapidly breeding indica rice restorer lines with japonica rice ancestry according to claim 1, characterized in that the screening criteria for the F2 generation population include fruit set rate, disease resistance and growth potential to ensure that the offspring have excellent agronomic traits.

[0046] As a preferred technical solution: the planting density of the F3 generation population is 30 to 50 holes for each single ear. Moderate density is beneficial to the fruit setting rate and growth potential of the single ear.

[0047] As a preferred technical solution: in the backcrossing step of the F3 generation population, each excellent panicle line is backcrossed with an indica rice variety to ensure the stability and diversity of the genetic background.

[0048] As a preferred technical solution: the screening criteria for the BC1F1 generation seeds include fruit set rate, disease resistance and agronomic traits, and the fruit set rate must be higher than 75% to ensure the excellent performance of the offspring.

[0049] As a preferred technical solution: in the planting and screening steps of the BC1F2 generation seeds, molecular marker-assisted selection technology is combined to improve the screening efficiency and accuracy.

[0050] As a preferred technical solution: the screening criteria for the BC2F1 generation seeds include disease resistance, fruit set rate and agronomic traits, and the fruit set rate must be higher than 80% to ensure the excellent performance and stability of the offspring; the selection criteria for the excellent panicle lines of the BC2F8 generation include the compatibility recovery rate with the japonica rice three-line sterile line must reach more than 90%, and the fruit set rate must be higher than 85%, to ensure that the finally selected indica-japonica intermediate restorer line has good compatibility and fruit set rate.

[0051] Beneficial effects:

[0052] The present invention uses japonica rice three-line sterile line as the female parent and multiple high-quality disease-resistant indica rice varieties as the male parent, and obtains multiple F1 generation seeds through paired hybridization, which significantly expands the source of parents. This method not only improves the genetic diversity of the offspring, is conducive to the discovery and utilization of more favorable genes, but also can make full use of the excellent characteristics of different varieties in the hybridization process, realize gene recombination, improve breeding efficiency, and finally select and breed indica rice restorer lines with japonica rice ancestry.

[0053] The present invention utilizes the high-efficiency fertility recovery ability of the three-line sterile line of japonica rice, eliminates the cumbersome operation of artificial emasculation of the female parent during hybridization, and significantly improves the hybridization efficiency. In addition, the field fruiting rate of each hybrid combination is recorded in the F2 generation population, the combination with low fruiting rate is eliminated, and the combination with high fruiting rate is selected for subsequent breeding, which effectively improves the fruiting rate of the offspring. Multiple backcrossing and strict screening ensure that the selected restorer line has a high fruiting rate and excellent agronomic traits.

[0054] The present invention can select and breed excellent indica-japonica intermediate restorer lines in a relatively short time by means of paired hybridization and multiple backcrossing, efficient screening and elimination of combinations with low fruiting rates. Compared with traditional breeding methods, the present invention significantly shortens the breeding cycle and reduces breeding costs. At the same time, the selected restorer lines not only have high yield and disease resistance characteristics, but also show excellent stability and adaptability in actual production, bringing significant economic and social benefits to agricultural production. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 The present invention provides a method for rapidly breeding an indica rice restorer line with japonica rice ancestry and a flow chart of the method. DETAILED DESCRIPTION

[0056] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0057] Example 1: Hybrid breeding of japonica rice three-line sterile line 20A and dwarf silk seedling

[0058] Step 1: Selection of hybrid combinations

[0059] Female parent selection: Select japonica rice three-line sterile line 20A.

[0060] Male parent selection: Choose high-quality disease-resistant indica rice variety Dwarf Silk Seedling.

[0061] Step 2: Obtaining F1 generation seeds

[0062] The japonica rice three-line sterile line 20A was used as the female parent and hybridized with the dwarf rice seedling.

[0063] After hybridization, F1 seeds are harvested.

[0064] Step 3: Planting and screening of F1 plants

[0065] The F1 generation seeds were planted and the fruit set rate of each hybrid offspring individual was recorded.

[0066] Eliminate individual plants with a fruit set rate below 30%, retain the plants with a high fruit set rate, and harvest single ear seeds of the F2 generation.

[0067] Step 4: Screening of the F2 population

[0068] The F2 population was planted as single ear, and the fruit set rate, disease resistance and growth potential of each ear were recorded.

[0069] Single ears with a fruit set rate higher than 60% were selected and F3 seeds were harvested from the single ears.

[0070] Step 5: Planting, screening and backcrossing of F3 population

[0071] Each ear is planted in 30 to 50 holes, and the agronomic traits are recorded. The single ear strains with high pollen fertility and good traits are selected as the male parent, and backcrossed with the dwarf silk seedlings. When mature, the single ear is harvested as the F4 generation seed.

[0072] Step 6: Screening and secondary backcrossing of BC1F1 population

[0073] Plant BC1F1 generation seeds, select strains with good agronomic traits, and backcross the artificially emasculated female parent with the corresponding F4 generation ear line as the male parent for a second time to obtain BC2F1 generation seeds.

[0074] Step 7: Screening of BC2F1 Generation

[0075] Plant BC2F1 generation seeds, select combinations with good agronomic traits and high fruit set rate, and obtain self-pollinated seeds.

[0076] Step 8: Rigorous selection of selfing generations

[0077] Continuously self-pollinate and strictly select single ears with high fruit set rate and good agronomic traits in the offspring population, and plant the ear lines.

[0078] Step 9: Selection of superior spikelets in the BC2F8 generation

[0079] Excellent ear lines were selected for variety comparison test and hybridized with 20A to test the resilience.

[0080] The excellent strains screened are the intermediate indica and japonica restorer line varieties.

[0081] Example 2: Hybrid breeding of three-line sterile japonica rice and high-quality disease-resistant indica rice variety Yeyue Si Miao

[0082] Step 1: Selection of hybrid combinations

[0083] Female parent selection: Select the three-line sterile line of japonica rice.

[0084] Male parent selection: Choose high-quality disease-resistant indica rice variety Yeyue Si Miao.

[0085] Step 2: Obtaining F1 generation seeds

[0086] The three-line sterile line of japonica rice was used as the female parent and hybridized with Yeyue Si Miao.

[0087] After hybridization, F1 seeds are harvested.

[0088] Step 3: Planting and screening of F1 plants

[0089] The F1 seeds were planted and the fruit set rate of each hybrid combination was recorded.

[0090] Eliminate individual plants with a fruit set rate below 40%, retain plants with a high fruit set rate, and harvest F2 generation seeds from a single ear.

[0091] Step 4: Screening of the F2 population

[0092] The F2 generation population was planted individually, and the fruit set rate, disease resistance and growth potential of each individual ear population were recorded.

[0093] Select single ears with a fruit set rate higher than 75% and harvest F3 seeds.

[0094] Step 5: Planting, screening and backcrossing of F3 population

[0095] Plant 40 to 60 holes for each ear, and record pollen fertility and agronomic traits. Select strains with good agronomic traits as male parents and backcross with wild Yuesi seedlings. Different strains are used as male parents and backcrossed with wild Yuesi seedlings to obtain BC1F1 generation seeds. When mature, select single ears with high fruit set rate of the corresponding strains and harvest F4 generation seeds.

[0096] Step 6: Screening and secondary backcrossing of BC1F1 population

[0097] Plant BC1F1 generation seeds, select strains with good agronomic traits, and backcross the female parent with the corresponding F4 generation strain male parent to obtain BC2F1 generation seeds.

[0098] Step 7: Screening of BC2F1 Generation

[0099] Plant BC2F1 generation seeds, select combinations with good agronomic traits and high fruit set rate, and obtain self-pollinated seeds.

[0100] Step 8: Rigorous selection of selfing generations

[0101] Continuously self-pollinate and strictly select single ears with high fruit set rate and good agronomic traits in the offspring population, and plant the ear lines.

[0102] Step 9: Selection of superior spikelets in the BC2F8 generation

[0103] Excellent panicle lines were selected for variety comparison test and hybridized with three-line sterile lines of japonica rice to test their resilience.

[0104] The excellent strains screened are the intermediate indica and japonica restorer line varieties.

[0105] Example 3: Hybrid breeding for large-scale production

[0106] Step 1: Large-scale hybrid selection

[0107] Female parent selection: Select the three-line sterile japonica rice line that is widely used in production.

[0108] Male parent selection: Select high-quality disease-resistant indica rice varieties that are planted on a large scale in production.

[0109] Step 2: Obtaining large-scale F1 seeds

[0110] The three-line sterile line of japonica rice was used as the female parent for large-scale hybridization with multiple indica rice varieties.

[0111] After hybridization, a large amount of F1 seeds are harvested.

[0112] Step 3: Planting and screening of F1 plants

[0113] The F1 seeds were planted in the field and the fruit set rate of each hybrid combination was recorded.

[0114] Eliminate the combinations with a fruit set rate lower than 45%, retain the combinations with a high fruit set rate, and harvest the F2 generation seeds from a single ear.

[0115] Step 4: Screening of the F2 population

[0116] The F2 population was planted individually in the field, and the fruit set rate, disease resistance and growth potential of each ear were recorded.

[0117] Select single ears with a fruit set rate higher than 70% and harvest F3 seeds.

[0118] Step 5: Planting, screening and backcrossing of F3 population

[0119] Each ear and plant were planted in 50 holes in the field, and the pollen fertility and agronomic traits of each plant were recorded.

[0120] Continue to select single plants with high pollen fertility as male parents and backcross with indica rice varieties. Different strains are used as male parents and backcrossed with indica rice varieties to obtain a large number of BC1F1 generation seeds. When mature, harvest the F4 generation seeds of the corresponding strains.

[0121] Step 6: Screening and secondary backcrossing of BC1F1 population

[0122] BC1F1 seeds were planted in the field, strains with good agronomic traits were selected, and the female parent was artificially emasculated and backcrossed with the corresponding F4 generation male parent to obtain a large number of BC2F1 seeds.

[0123] Step 7: Screening of BC2F1 Generation

[0124] BC2F1 seeds are planted in the field, and combinations with good agronomic traits and high fruit set rates are screened to obtain a large number of self-pollinated seeds.

[0125] Step 10: Rigorous selection of selfing generations

[0126] Continuously self-pollinate and strictly select single ears with high fruit set rate and good agronomic traits in the offspring population, and plant the ear lines.

[0127] Step 11: Selection of superior spikelets in the BC2F8 generation

[0128] Excellent panicle lines were selected for variety comparison test and hybridized with three-line sterile lines of japonica rice to test their resilience.

[0129] The excellent strains screened are the intermediate indica and japonica restorer line varieties.

[0130] Example 4: Breeding of intermediate restorer lines between indica and japonica rice by three-way cross breeding

[0131] Step 1: Selection of hybrid combinations using the three-way cross method

[0132] Mother plant selection: Choose high-quality indica or japonica rice varieties.

[0133] Selection of male parent: The F3 generation material of the japonica rice three-line sterile line and the indica rice restorer line, such as the pollen of the F3 generation individual plants of the hybrid combination of 20A×Dwarf Silk Seedling, should have a pollen fertility test of greater than 70%.

[0134] Step 2: Obtaining F1 generation seeds

[0135] Select high-quality indica rice varieties (such as Wushan Meihe, Jinluo No. 9, Taiwan Xiangzhan, etc.) and high-quality japonica rice varieties (such as 5B) as female parents and hybridize with [(20A×Aijiaosi Miao) F3 generation pollen].

[0136] After hybridization, the F1 generation seeds of the corresponding combination are harvested.

[0137] Step 3: Planting and screening of F1 plants

[0138] The F1 seeds were planted in the field, and the field traits and fruit set rate of each hybrid combination were recorded.

[0139] Keep the combination with high fruit set rate and harvest F2 seeds from single ear.

[0140] Table 1 Field performance and fruiting rate of some F1 generations

[0141] Hybrid combination Field traits Fruiting rate Wushan Meihe×(20A×Dwarf Silk Seedling) Tall plant with slender leaves 78.3％ Wushan Meihe×(20A×Wild Cantonese Silk Seedling) Slender leaves 80.2％ Huang He×(20A×Wild Cantonese Silk Seedling) Slender leaves 81.3％ China Airlines soft silk × (20A × wild Guangdong silk seedlings) Long leaves and large spikes 83.4％ China Airlines soft silk × (20A × short-legged silk seedlings) Thick stems, long leaves, oval grains 87.5％ 5B×(20A×Dwarf Silk Seedling) Tall plant, short round seeds, awned 64.8％

[0142] Step 4: Screening of the F2 population

[0143] The F2 population was planted individually in the field, and the fruit set rate, disease resistance and growth potential of the offspring of each individual ear line were recorded.

[0144] Select single ears with a fruit set rate higher than 70% and harvest F3 seeds.

[0145] Step 5: Planting and screening of the F3 population

[0146] Each ear was planted in 50 holes in the field, and the fruit setting rate and agronomic traits were recorded.

[0147] Continue to select single ears with high fruit set rate and harvest F4 generation seeds.

[0148] Step 6: Rigorous selection of selfing generations

[0149] Continue self-pollination and strictly select single ears with high fruit set rate and good agronomic traits in the offspring population, and plant the ear lines. At the same time, use molecular markers for auxiliary selection.

[0150] Step 7: Selection of superior spikelets of the F8 generation

[0151] Excellent panicle lines were selected for variety comparison test and hybridized with three-line sterile lines of japonica rice to test their resilience.

[0152] The excellent strains screened are the intermediate indica and japonica restorer line varieties.

[0153] Summary: The present invention utilizes japonica rice three-line sterile lines and high-quality disease-resistant indica rice varieties in a reasonable manner, combined with multiple hybridization and backcrossing methods, to efficiently breed indica rice restorer lines with japonica rice ancestry. These restorer lines not only have a high fruit set rate and excellent agronomic traits, but also can show superior disease resistance and high yield performance in production. Through the above specific embodiments, the method of the present invention is not only feasible, but also has significant promotion value in practical applications.

[0154] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0155] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for rapidly breeding a japonica rice restorer line, characterized in that: The following steps are involved: The three-line sterile line of japonica rice was used as the female parent; Using multiple high-quality disease-resistant indica rice varieties as male parents; F1 generation seeds are obtained by pairwise hybridization; Plant F1 plants, investigate the fruit set rate, eliminate combinations with a fruit set rate below 30%, and harvest F2 generation seeds with a high fruit set rate; Plant the F2 population and select the ears with a fruit set rate greater than 60%; The F3 generation population is planted as a single ear, and the ear line with good agronomic traits is selected as the male parent and backcrossed with the indica rice variety during the flowering period to obtain BC1F1 generation seeds; the F4 generation seeds with good fruit set are harvested when mature. Plant BC1F1 generation seeds, select combinations with good agronomic traits and high fruit set rate, and obtain self-pollinated seeds; Planting BC1F2 generation seeds and continuing backcrossing with the corresponding F4 generation ear line male parent to obtain BC2F1 generation seeds; Plant BC2F1 generation seeds, select combinations with good agronomic traits and high fruit set rate, and obtain self-pollinated seeds; Continuously self-pollinate and strictly select single ears with high fruiting rate and good agronomic traits in the offspring population, and plant the ear lines; In the BC2F8 generation, excellent panicle lines were selected for variety comparison tests, and at the same time, they were hybridized with the three-line sterile lines of japonica rice to test their resilience. The excellent lines were screened as the intermediate restorer line seedlings of indica and japonica.

2. The method for rapidly breeding a japonica rice restorer line according to claim 1, characterized in that: The japonica rice three-line sterile line is 20A. The method according to claim 1 is characterized in that the high-quality disease-resistant indica rice variety is dwarf rice.

3. The method for rapidly breeding a japonica rice restorer line according to claim 1, characterized in that: In the step of pairwise hybridization, each male indica rice variety is hybridized with a japonica rice three-line sterile line to obtain a variety of different combinations of F1 generation seeds.

4. The method for rapidly breeding a japonica rice restorer line according to claim 1, characterized in that: In the step of planting the F1 generation plants, the fruit setting rate of each hybrid combination is recorded, and combinations with a fruit setting rate lower than 30% are eliminated.

5. The method for rapidly breeding a japonica rice restorer line according to claim 1, characterized in that: The screening criteria for the F2 generation population include fruit set rate, disease resistance and growth potential, and single ears with a fruit set rate greater than 60% are selected to ensure that the offspring have excellent agronomic traits.

6. The method for rapidly breeding a japonica rice restorer line according to claim 1, characterized in that: The planting density of the F3 generation population is 30 to 50 holes for each single ear, and a moderate density is beneficial to the fruit setting rate and growth potential of the single ear.

7. The method for rapidly breeding a japonica rice restorer line according to claim 1, characterized in that: In the backcrossing step of the F4 generation population, each superior panicle line is backcrossed with an indica rice variety to ensure the stability and diversity of the genetic background.

8. The method for rapidly breeding a japonica rice restorer line according to claim 1, characterized in that: The screening criteria for the BC1F1 generation seeds include fruit set rate, disease resistance and agronomic traits, and the fruit set rate must be higher than 75% to ensure the excellent performance of the offspring.

9. The method for rapidly breeding a japonica rice restorer line according to claim 1, characterized in that: The steps of planting and screening the BC1F2 generation seeds are combined with molecular marker-assisted selection technology to improve screening efficiency and accuracy.

10. The method for rapidly breeding a japonica rice restorer line according to claim 1, characterized in that: The screening criteria for the BC2F1 generation seeds include disease resistance, fruit set rate and agronomic traits, and the fruit set rate must be higher than 80% to ensure the excellent performance and stability of the offspring; the selection criteria for the excellent panicle lines of the BC2F8 generation include the compatibility recovery rate with the japonica rice three-line sterile line must reach more than 90%, and the fruit set rate must be higher than 85%, to ensure that the finally selected indica-japonica intermediate restorer line has good compatibility and fruit set rate.

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