A breeding method of a new variety of south high-quality long-grain japonica rice

Abstract

The application discloses a breeding method of a new south high-quality long-grain japonica rice variety, and the method comprises the following steps: (1) selecting a south high-quality long-grain indica rice variety as a male parent, a large-eared japonica rice variety as a female parent, carrying out hybridization, and backcrossing F1 generation seeds with japonica rice; (2) continuously planting BC1F1 seeds for three generations, and selecting, in a field, a large-eared japonica rice variety with a compact plant type, a good shape and color of a sword leaf, a small chalkiness, and a long-grain type to carry out generation multiplication; (3) carrying out molecular marker detection on a single plant of BC1F4 generation, detecting two genes Gn1a and GS3, screening a plant with a Gn1a gene sequence as shown in SEQ ID NO. 4, and detecting the breeding candidate plant BC1F5 generation again to obtain a plant with a target gene in homozygosis. A series of south high-quality long-grain large-eared japonica rice new varieties are bred by adopting the method, a length-width ratio reaches 3-4, and the requirement of a south high-end high-quality japonica rice is basically met.

Description

TECHNICAL FIELD

[0001] The application relates to a breeding method of a new japonica rice variety, in particular to a breeding method of a new high-quality long-grain japonica rice variety in the south. BACKGROUND

[0002] The indica and japonica rice has its own characteristics, and China has always had the planting tradition of 'indica in the south and japonica in the north'. For a long time, the domestication and adaptation of rice in China have formed a planting pattern of 'indica in the south and japonica in the north' with the Qinling-Huaihe River as the boundary. Relatively speaking, the indica rice in the south has a fluffy and fragrant taste, and the japonica rice in the north has a smooth taste and has more chewability.

[0003] With the improvement of people's living standards and the demand for material diversity, and the smoothness and other characteristics of japonica rice that indica rice does not have are beginning to be adapted by some people in the south. 'Japonica rice moving to the south' has become an important goal of rice breeding and improvement. Moreover, the cultivation of japonica rice with indica characteristics can integrate the early growth and quality characteristics of indica rice and the cold tolerance and chewability of japonica rice, which is a direction of high-end new rice cultivation.

[0004] The length-width ratio of general japonica rice is about 1.6, the length-width ratio of partial long-grain japonica rice is about 2.5, and the length-width ratio of high-end quality indica rice in the south is about 4.0. At present, the round-grain japonica rice is difficult to meet the demand of the south market, and the japonica rice has the chewability and smoothness that indica rice does not have, and is gradually accepted by some markets in the south. Cultivating a new japonica rice variety suitable for the south can enrich the rice resources in the south.

[0005] There are some japonica (waxy) rice varieties in Jiangxi, especially in the northern part of Jiangxi, but they have not been improved for a long time. In order to meet the requirements of modern breeding level, excellent japonica rice varieties need to be introduced for trial and improvement. After more than three years of introduction and trial, the japonica rice in the northeast (high latitude) is mainly sensitive to temperature, and the growth period is too short and the yield is very low after being introduced into Jiangxi. The japonica rice in the surrounding areas such as Jiangsu, Zhejiang and Anhui is mainly strong to light, and there is no japonica rice variety with high yield, disease resistance and suitable for the south. SUMMARY

[0006] The application aims to provide a breeding method of a new high-quality long-grain japonica rice variety in the south, which solves the problems of indica-japonica separation, slow stability and improves the directional selection efficiency, and a new plant type combines the advantages of indica and japonica rice.

[0007] In order to achieve the above-mentioned purpose, the application provides a breeding method of a new high-quality long-grain japonica rice variety in the south, which comprises the following steps:

[0008] (1) selecting a high-quality long-grain indica rice variety as a male parent and a large-ear japonica rice variety as a female parent to carry out hybridization, and carrying out backcrossing of F1 generation seeds and japonica rice;

[0009] (2) BC1F1 seed is continuously planted for 3 generations, and a large-spike and semi-glutinous plant line with compact plant type, good shape of sword leaf, good color change, small chalkiness and long grain type is selected in the field for further generation; wherein the compact plant type is that the tillering angle is less than 10 DEG C, the straight sword leaf is that the angle of the sword leaf is less than 30 DEG C, the small chalkiness is that the chalkiness is less than 5%, and the long grain type is that the grain length-width ratio is greater than 3.0;

[0010] (3) BC1F4 single plant screening, screening of the plant with grain length-width ratio greater than 3.0 and Gn1a gene as shown in SEQ ID NO. 4 sequence, or screening of the plant with Gn1a gene as shown in SEQ ID NO. 4 sequence and GS3 gene as shown in SEQ ID NO. 7 sequence, and repeating the process of BC1F4 single plant screening for the breeding candidate plant line BC1F5 generation, to obtain the plant with target gene homozygosity.

[0011] Preferably, in step (2), no less than 200 plant lines per generation.

[0012] Preferably, the nucleotide sequence of the functional marker primer for the Gn1a gene is shown in SEQ ID NO. 1 and SEQ ID NO. 2.

[0013] Preferably, the nucleotide sequence of the functional marker primer for the GS3 gene is shown in SEQ ID NO. 5 and SEQ ID NO. 6.

[0014] Preferably, for the Gn1a gene molecular marker detection, a small difference fragment product is detected by medium concentration agarose electrophoresis: 3.5% agarose gel, 1 muL of loading amount, 1xTBE electrophoresis buffer, 85v voltage, electrophoresis for 2h, and photographing.

[0015] Preferably, the male parent is high-quality long-grain indica rice Xiangya Xiangzhan, and the female parent is large-spike Wujujing No. 33.

[0016] The breeding method of the new variety of high-quality long-grain japonica rice in the south of the present application has the following advantages:

[0017] The present application combines traditional breeding methods and molecular breeding techniques to solve the problems of large separation, slow stability and the like in indica-japonica cross, and the inventors find through experiments that indica-indica cross and japonica-japonica cross F2 generation can be detected, indica-japonica cross is not detected in F4 generation, and F14 generation can achieve basic stability, which is large in workload, the present application detects target genes in BC1F4 generation, the offspring is stable and fast, the directional selection efficiency is improved, and the new plant type combines the advantages of indica and japonica rice.

[0018] The application takes a high-quality long-grain indica rice variety as the father parent, a large-panicle japonica rice variety as the mother parent, carries out hybridization, backcrosses F1 generation seeds with japonica rice, expands a low generation field to more than 200 populations, carries out field selection on the large-panicle japonica type plant lines with compact plant type, good shape and color of sword leaves, small chalkiness, long-grain type, carries out molecular marker detection on the BC1F4 generation single plants, detects two genes of Gn1a and GS3, and carries out detection again on the BC1F5 generation plant lines of breeding candidates, obtains target gene homozygous plants, and breeds a series of new japonica rice lines with long-grain and large-panicle in the south, the length-width ratio reaches 3-4, the rice quality is excellent, and the requirements of high-end japonica rice in the south are basically reached. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is the molecular detection electrophoretogram of application example 1 of the application.

[0020] Figure 2 It is the phenotype photo of long-grain and large-panicle indica-type japonica rice of the application.

[0021] Figure 3 It is the sequence difference diagram of the amplification product of the Gn1a gene functional marker of the application.

[0022] Figure 4 It is the mutation of the second exon C-A (long-grain, length-width ratio) of the GS3 gene of the application. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the application will be clearly and completely described below. Apparently, the described embodiments are only some of the embodiments of the application, not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.

[0024] Embodiment 1

[0025] A breeding method of a new japonica rice variety with high quality and long grain in the south comprises the following steps:

[0026] (1) a high-quality long-grain indica rice variety is selected as the father parent, a large-panicle japonica rice variety is selected as the mother parent, hybridization is carried out, and F1 generation seeds are backcrossed with japonica rice;

[0027] (2) BC1F1 seeds are continuously planted for three generations, each generation is not less than 200 plant lines, field selection is carried out on the large-panicle japonica type plant lines with compact plant type (tiller angle is less than 10℃), straight sword leaves (sword leaf angle is less than 30℃), good color in the later period, chalkiness less than 5%, and long-grain type (length-width ratio is greater than 3.0), and the plant lines are further bred;

[0028] (3) Screening of single plant of BC1F4 generation, screening of plants with grain length-width ratio greater than 3.0 and Gn1a gene as shown in SEQ ID NO. 4, or screening of plants with Gn1a gene as shown in SEQ ID NO. 4 and GS3 gene as shown in SEQ ID NO. 7, and repeating the process of screening of single plant of BC1F4 generation to BC1F5 generation of breeding candidate strains to obtain plants with target gene homozygosity.

[0029] The developed functional marker is used for detection, wherein the large panicle is caused by 16bp deletion in the 5' non-coding region of the Gn1a gene (SEQ ID NO. 3) and 1bp replacement and 6bp (large panicle) deletion in the first exon, and the length of the large panicle amplification product is 673bp (SEQ ID NO. 4). The functional marker primer of the Gn1a gene is shown in Table 1. The variation of the second exon C-A of the GS3 gene (SEQ ID NO. 8) explains 33.4% of the phenotypic variation (long grain type of GS3 gene), and some internal repeat polymorphisms also contribute to the long grain, and the functional marker is complex, and the application is more economical and rapid by amplifying the variation of the second exon C-A and sequencing, and cutting the sequence of the repeat polymorphism. In addition, the effect of the grain length gene of GS3 is the largest, and the effect is visible to the naked eye, that is, it can be judged by grain type, so it can also be directly judged by phenotype without functional marker detection. Figure 4 The a is the long grain type of GS3 gene, and there are some internal repeat polymorphisms which contribute to the long grain, and the functional marker is complex, and the application is more economical and rapid by amplifying the variation of the second exon C-A and sequencing, and cutting the sequence of the repeat polymorphism. In addition, the effect of the grain length gene of GS3 is the largest, and the effect is visible to the naked eye, that is, it can be judged by grain type, so it can also be directly judged by phenotype without functional marker detection.

[0030] Table 1: Information of molecular marker primers

[0031]

[0032] The agarose electrophoresis rapid detection method of small difference fragments: 3.5% agarose gel, 1ul loading amount, 1xTBE electrophoresis buffer, 85v voltage, electrophoresis for 2h, and taking pictures.

[0033] High-end high-quality indica rice in the south needs grain length-width ratio of about 4.0, and general japonica rice has a length-width ratio of about 1.6, and the length-width ratio of partial long grain type japonica rice is about 2.5, which is difficult to meet the demand of the market in the south, and japonica rice has the characteristics of chewing smoothness which indica rice does not have, and is gradually accepted by part of the market in the south, and cultivating new japonica rice varieties with long grain and large panicle suitable for the south can enrich the seed source in the south. A series of new japonica rice strains with long grain and large panicle suitable for the south are bred in the application, and the length-width ratio reaches 3-4, which basically meets the requirements of high-end high-quality japonica rice in the south. The application provides a new idea for creating new japonica rice strains with japonica indica, shaping the ear structure of japonica rice, and improving the quality and grain type, and enriches the seed source for the development of seed industry in Jiangxi and even the whole south.

[0034] Application example 1

[0035] The high-quality long-grain indica rice Xiangya Xiangzhan was used as the father, and the large-spike Wujiu japonica 33 was used as the mother. According to the breeding method in Example 1, the specific process is shown in Table 2, and the molecular detection electrophoretogram is shown in Figure 1 (Gn1a functional marker electrophoretogram, 2000 marker, electrophoretic band difference 16+6=22bp), through 10 generations of directional selection, long-grain large-spike indica japonica hybrid rice Ganwan japonica 160-2 (LY160-2), Lzhong 22, LY129-4 and LY135-1 were obtained. See Figure 2 , are the phenotypes of Ganwan japonica 160-2, and (D)~(F) are the phenotypes of Lzhong 22. In the figure, the plant bar=20cm, the ear bar=5cm, and the characteristics of the long-grain large-spike indica japonica hybrid rice are shown in Table 3.

[0036] Table 2 is the breeding process of long-grain large-spike indica japonica hybrid rice

[0037]

[0038] Table 3 is the characteristics of long-grain large-spike indica japonica hybrid rice

[0039]

[0040]

[0041] Although the content of the present application has been described in detail by the above preferred embodiments, it should be recognized that the above description should not be considered as a limitation of the present application. After reading the above content, various modifications and alternatives of the present application will be apparent to those skilled in the art. Therefore, the protection scope of the present application should be defined by the appended claims.

Claims

1. A breeding method of a new variety of high-quality long-grain japonica rice in the south, characterized by, The method comprises: (1) selecting a high-quality long-grain indica rice variety as a male parent, a large-spike japonica rice variety as a female parent, carrying out hybridization, and backcrossing F1 generation seeds with japonica rice; the male parent is high-quality long-grain indica rice Xiangya Xiangzhan, and the female parent is large-spike Wuyu Jinqian No. 33; (2) continuously planting BC1F1 seeds for three generations, and selecting, in the field, large-spike japonica type plant lines with compact plant type, good shape and color of a sword leaf, small chalkiness, and long-grain type to carry out generation multiplication; wherein the compact plant type is a tiller angle less than 10℃; the straight sword leaf is a sword leaf angle less than 30℃; the small chalkiness is less than 5%; and the long-grain type is a grain length-width ratio greater than 3.0; (3) screening single plant of BC1F4 generation, screening grain length-width ratio greater than 3.0 and Gn1a plant with gene as shown in SEQ ID NO. 4, or screening Gn1a plant with gene as shown in SEQ ID NO. 4 and GS3 plant with gene as shown in SEQ ID NO. 7, and repeating the process of screening single plant of BC1F4 generation for breeding candidate plant of BC1F5 generation, to obtain plant with target gene homozygous.

2. The breeding method according to claim 1, characterized by, In step (2), no less than 200 plant lines per generation.

3. The selection method according to claim 1, wherein Aim to Gn1a The nucleotide sequences of the functional marker primers of the genes are shown in SEQ ID NO. 1 and SEQ ID NO.

2.

4. The method of breeding according to claim 1, wherein against GS3 The nucleotide sequences of the functional marker primers for the gene are shown in SEQ ID NO.5 and SEQ ID NO.

6.

5. The selection method according to claim 1, wherein In step (3), for Gn1a For the detection of genetic molecular markers, the products of small difference fragments are detected by agarose electrophoresis with medium concentration: 3.5% agarose gel is electrophoresed in 1xTBE electrophoresis buffer, the loading amount is 1 μL, the voltage is 85v, the electrophoresis time is 2h, and the photograph is taken.

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