A method for breeding a rice resistant to southern rice black-streaked dwarf disease

Abstract

The application relates to a breeding method of a plant variety, in particular to a breeding method of a rice resistant to southern rice black-streaked dwarf virus. The method crosses a Haikeng rice No. 7 material with a material needing to be improved in southern rice black-streaked dwarf virus resistance to obtain an F1 generation material, and obtains a rice resistant to southern rice black-streaked dwarf virus; wherein the Haikeng rice No. 7 material is a material with a public notice number of CNA080658E in the Agricultural Plant New Variety Protection Bulletin, and the method of the application reduces the 100% incidence of black-streaked dwarf virus to 3.4%-6.7%.

Description

Technical Field

[0001] This invention relates to a method for breeding plant varieties, specifically a method for breeding rice resistant to Southern Rice Black-Streaked Dwarf Disease. Background Technology

[0002] Southern rice black-streaked dwarf virus (SMRV) is a rice disease caused by the Southern Rice Black-streaked Dwarf Virus. The main symptoms include stunted growth, increased tillering, short, broad, stiff, dark green leaves, and short, waxy-white, later brownish, wart-like growths initially appearing on the veins and stems on the underside of the leaves. Symptoms include failure to produce panicles or small panicles, poor grain filling, incomplete heading during the panicle stage, and wrinkling at the base of the flag leaf. Symptoms vary slightly depending on the growth stage. The disease is characterized by its high susceptibility, rapid spread, and insidious damage; once an outbreak occurs, it can lead to reduced rice yields or even total crop failure.

[0003] Southern rice black-streaked dwarf disease is mainly caused by the white-backed planthopper, and there is currently no specific pesticide for its control; prevention is the primary approach in production. Addressing the past practice of farmers prioritizing pesticide application over prevention in controlling Southern rice black-streaked dwarf disease, agricultural technicians have proposed a comprehensive control plan that replaces pesticide treatment with production-based repellency. The severity of Southern rice black-streaked dwarf disease is closely related to rice variety resistance, the initial population and virus-carrying rate of the white-backed planthopper, cropping system, and the degree of overlap between the white-backed planthopper migration period and the rice's sensitive period. Generally, when all of these favorable conditions are present simultaneously, the disease will inevitably be severe. The disease incidence rate is essentially equal to the loss rate; once a large-scale outbreak occurs, yield reductions of over 90% or even total crop failure can occur. Existing technologies, lacking stable sources of resistance, mostly rely on controlling insect pests to prevent the spread of damage. The incidence rate of existing superior resistant materials to Southern Rice Black-Streaked Dwarf Disease is 6.25%~28.51%. Although they possess resistance to Southern Rice Black-Streaked Dwarf Disease, their incidence rate remains high. Furthermore, it is unknown whether the resistance genes of these materials are stably inherited by offspring when used for breeding. Therefore, there is a need to provide breeding methods for rice that can reduce the loss rate of Southern Rice Black-Streaked Dwarf Disease through breeding techniques. Summary of the Invention

[0004] To reduce the loss rate of Southern Rice Black-Streaked Dwarf Disease, this invention provides a method for breeding rice resistant to Southern Rice Black-Streaked Dwarf Disease.

[0005] A method for breeding rice resistant to Southern Rice Black-Streaked Dwarf Disease involves crossing the Haiken Rice 7 material with materials that require improved resistance to Southern Rice Black-Streaked Dwarf Disease to obtain F1 generation materials, thus obtaining rice resistant to Southern Rice Black-Streaked Dwarf Disease. Among them, the material of Haiken Rice No. 7 is the material with announcement number CNA080658E in the Bulletin on the Protection of New Varieties of Agricultural Plants; Targeted generation selection of F1 generation materials yielded rice varieties with stable genetic resistance to Southern Rice Black-Streaked Dwarf Disease. In the targeted generation selection, the selection is made with the yield characteristics of F1 generation materials as the target.

[0006] Preferably, the yield traits refer to tillering and grain filling rate.

[0007] Preferably, during the directional generation selection, plants with tillering characteristics superior to the average tillering characteristics of the F1 generation material are selected.

[0008] Preferably, during the directional generation selection, plants with a grain setting rate higher than the average grain setting rate of the F1 generation are selected.

[0009] Preferably, during the targeted generation selection, plants from the F1 generation that exhibit disease and pest resistance and do not show symptoms in the field are selected.

[0010] Preferably, the stable rice variety resistant to Southern Rice Black-Streaked Dwarf Disease is one that simultaneously meets the conditions of plant type performance, grain filling performance, and disease and pest resistance performance.

[0011] Preferably, during the targeted generation selection, plants infected with Southern Rice Black-Streaked Dwarf Disease (SMR) are planted in the same area as F1 generation materials to provide pathogens.

[0012] Preferably, the material for improving the resistance of southern rice to black-streaked dwarf disease is 19 Xiang.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a stable resistance source, namely Haiken Rice No. 7. Based on the provided stable resistance source, this invention provides a method for breeding rice resistant to Southern Rice Black-Streaked Dwarf Disease (SMR). This method breaks through the existing technology that can only avoid damage by controlling pests. Specifically, it uses Haiken Rice No. 7, which is resistant to SMR, as the resistance source material. The incidence of SMR in Haiken Rice No. 7 is 0%. By crossing the resistance source material with materials that need to improve resistance to SMR, SMR-resistant plants are separated from the offspring, proving that the resistance to SMR can be stably inherited. After directional generation selection, rice with stable resistance to SMR is obtained, reducing the incidence of SMR from 100% to 3.4%~6.7%, providing a method for stable resistance to SMR.

[0014] The method of this invention can improve the technical level of resistance breeding, avoid the production losses caused by the large-scale outbreak of rice black-streaked dwarf disease in southern China, and also reduce the amount of pesticides used to control rice planthoppers. Attached Figure Description

[0015] Figure 1 Flowchart of rice breeding process to resist Southern Rice Black-Streaked Dwarf Disease.

[0016] Figure 2 This is a comparison between 19xiang and Haiken Rice No. 7, where A is 19xiang and B is Haiken Rice No. 7.

[0017] Figure 3 This is a comparison between Haiken Rice No. 7 and diseased materials from the same batch. In this comparison, A represents Haiken Rice No. 7, and B represents diseased materials from the same batch.

[0018] Figure 4 The two types of rice are F1 generation seeds and rice resistant to Southern Rice Black-Streaked Dwarf Disease. Among them, A is F1 generation seeds obtained through glume cutting hybridization, and B is a resistant single column selected by field screening of plant susceptibility to Southern Rice Black-Streaked Dwarf Disease.

[0019] Figure 5 The results show the performance of F1 generation materials in the later stages of planting. Among them, A represents the performance of 19xiang, which is basically in a diseased state, with severe dwarfing and unable to produce normal ears. B represents the offspring of 19xiang and Haiken Rice No. 7, which has normal growth, normal plant height, and no dwarfing phenomenon. Detailed Implementation

[0020] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. Unless otherwise specified, the experimental methods described in the embodiments of the present invention are conventional methods.

[0021] In this invention, 19xiang is the name of rice.

[0022] Example 1 The breeding method of Haiken Rice No. 7 includes the following steps: Starting in 2009, Zhongzhonghui 629 was used to perform recurrent hybridization with BL122 and Cbb23, which was repeated 6 times until 2012. The materials containing Pi2 gene and Xa23 were obtained respectively. Specifically, Zhongzhonghui 629 was hybridized with the bacterial blight resistant material CBB23 and then recurrently hybridized with Zhongzhonghui 629 to obtain 629-1. 629-2 was obtained by crossing Zhongzhonghui 629 with the blast-resistant rice material BL122 and then recursively crossing it with Zhongzhonghui 629. In 2013, a single plant that successfully fused with the polymer through hybridization was tentatively named R6294.

[0023] In 2019, early rice was hybridized using Longhui 1031 as the female parent and R6294 as the male parent. Subsequent generations were added through directional selection, reaching F8 by 2022. The offspring exhibited good plant and leaf morphology, strong tillering, and good resistance. A stable and consistent single plant, C135-7, was selected for variety comparison trials. In the 2023 late-season variety comparison, it showed an 8% yield increase compared to the control variety (25% of the total yield was indica rice), and also demonstrated significantly improved field resistance. Therefore, a trial planting was arranged, and it was named Haiken Rice No. 7.

[0024] In late-season planting in Sanya, Hainan, the Haiken Rice No. 7 variety has a full growth period of 110 days, with an average yield of 508.3 kg / mu (approximately 33.3 kg / ha), an 8.0% increase compared to the control variety, Special Indica Rice 25. The plant height is 112 cm, with a well-proportioned panicle-grain structure, 155,000 effective panicles per mu (approximately 7.33 hectares), a panicle length of 27.4 cm, 152.7 grains per panicle, a seed setting rate of 88.1%, and a thousand-grain weight of 20.3 g. No rice blast was observed in the field, and bacterial blight was mild. This variety exhibits uniform plant growth, a moderately compact plant type, relatively thick and strong stems, good toughness, a moderate tillering rate, upright leaves, light green leaf sheaths, and yellow lemma tips. This variety demonstrates high yield, good appearance and grain quality, and resistance to rice blast, and is recommended for participation in the 2024 Hainan Province late-season regional trials.

[0025] Among them, the entire growth period of Haiken Rice No. 7 is 110 days, which is comparable to that of Special Indica Rice 25. The average yield of Haiken Rice No. 7 is 508.3 kg per mu, which is 8.0% higher than that of the control Special Indica Rice 25. Moreover, the incidence of Southern Rice Black-Streaked Dwarf Disease is 0%.

[0026] The announcement number for Haiken Rice No. 7 in the "Agricultural Plant Variety Protection Bulletin" is CNA080658E.

[0027] Example 2 A method for breeding rice resistant to Southern Rice Black-Streaked Dwarf Disease, flowchart as follows: Figure 1 As shown, it includes the following steps: The Haiken Rice No. 7 material was hybridized with materials that needed improvement and had no resistance to Southern Rice Black-Streaked Dwarf Disease to obtain F1 generation materials and hybrid combinations. The F1 generation materials were then identified or further generations were added and targeted screening was conducted to obtain new rice materials and combinations resistant to Southern Rice Black-Streaked Dwarf Disease.

[0028] In this embodiment, the material that needs to be improved and is not resistant to Southern Rice Black-Streaked Dwarf Disease is 19xiang. The material Haiken Rice 7 is crossed with 19xiang to obtain the F1 generation material 19xiang × Haiken Rice 7, which is the rice resistant to Southern Rice Black-Streaked Dwarf Disease.

[0029] Example 3 By performing targeted generation selection on the F1 generation material obtained in Example 2, stable rice resistant to Southern Rice Black-Streaked Dwarf Disease was obtained.

[0030] During the targeted generation selection, plants infected with Southern Rice Black-Streaked Dwarf Disease were planted in the same area as F1 generation materials to provide pathogens. Among the F1 generation materials, plants with better tillering than the average tillering of F1 generation materials, higher seed setting rate than the average seed setting rate of F1 generation materials, and no disease or pest resistance in the field were selected.

[0031] Effect verification 1. The F1 generation material obtained in Example 2 was tested for resistance to black-streaked dwarf disease. The test results are as follows: (1) Create areas suitable for the occurrence of rice black-streaked dwarf disease in southern China. Taking advantage of the natural basin topography of the Nanbin Farm outpost base in Yazhou District, Sanya City, and the high incidence of white-backed planthoppers and thrips in the surrounding fruits and vegetables, it was selected as the experimental site.

[0032] Rice plants infected with Southern Rice Black-Streaked Dwarf Virus (SMR) were collected and transplanted for preservation. Taking advantage of the fact that rice can still grow normally in Sanya, Hainan during winter, the infected plants were divided and planted around the experimental site to maintain a stable supply of the pathogen. Control measures were applied to the infected rice stubble only to stem borers, not rice planthoppers.

[0033] (2) The 19xiang × Haiken Rice No. 7 obtained in Example 2 was transplanted together with its parents, that is, 19xiang × Haiken Rice No. 7, 19xiang, and Haiken Rice No. 7 were transplanted, with 60 plants for each material. After the initial heading stage, i.e., early July, when the dwarf disease of each material was fully developed, the survey was started to obtain the percentage of diseased plants in the population.

[0034] result According to the field survey results of the hybrid offspring obtained in July 2024, such as Figures 2-5 The resistance of 19xiang rice × Haiken Rice 7 F1 generation material was significantly improved with an incidence rate of 6.7%, while the incidence rate of 19xiang rice planted in the same plot during the same season was 100%.

[0035] 2. After verifying the effectiveness of the resistance to Southern Rice Black-Streaked Dwarf Disease in the known variety 19, the inventors also verified it in materials without resistance to Southern Rice Black-Streaked Dwarf Disease that were preserved in the laboratory.

[0036] The materials without resistance to Southern Rice Black-Streaked Dwarf Disease are Haixiang 319, 201A, and Jia 201A.

[0037] Hai Xiang 319 is a conventional rice variety bred by pedigree method through the crossbreeding of Han Xiang-S and F309. Han Xiang-S is a two-line sterile line bred by Hainan Nongle Nanfan Seed Industry Co., Ltd., with the parent variety originating from the Jiu Jiu Xiang mutant. F309 is an intermediate progeny material of 93-11 / CBB23 used by Hainan University.

[0038] 201A was obtained by crossing 9311 with intermediate material one, which was obtained by crossing HD9802S with R6, wherein R6 is a resource containing the Pigm rice blast resistance gene.

[0039] Jia 201A was obtained by hybridization of Guang 8B and intermediate material two, which was obtained by hybridization of Yun 9S and Luojia 9, wherein Luojia 9 is a material containing Bph9 in 9311 background.

[0040] The material Haiken Rice 7 was hybridized with Haixiang 319 to obtain the F1 generation material Haixiang 319 × Haiken Rice 7.

[0041] The material Haikeng Rice 7 was hybridized with 201A to obtain the F1 generation material 201A×Haikeng Rice 7.

[0042] The Haikeng Rice 7 material was hybridized with Jia 201A to obtain the F1 generation material Jia 201A × Haikeng Rice 7.

[0043] Resistance to rice black-streaked dwarf disease was tested on Haixiang 319 × Haiken Rice 7, 201A × Haiken Rice 7, and Jia 201A × Haiken Rice 7, respectively. The results are as follows: (1) Create areas suitable for the occurrence of rice black-streaked dwarf disease in southern China. Taking advantage of the natural basin topography of the Nanbin Farm outpost base in Yazhou District, Sanya City, and the high incidence of white-backed planthoppers and thrips in the surrounding fruits and vegetables, it was selected as the experimental site.

[0044] Rice plants infected with Southern Rice Black-Streaked Dwarf Virus (SMR) were collected and transplanted for preservation. Taking advantage of the fact that rice can still grow normally in Sanya, Hainan during winter, the infected plants were divided and planted around the experimental site to maintain a stable supply of the pathogen. Control measures were applied to the infected rice stubble only to stem borers, not rice planthoppers.

[0045] (2) Haixiang 319 × Haiken Rice No. 7, 201A × Haiken Rice No. 7 and Jia 201A × Haiken Rice No. 7 were transplanted together with their parent plants. That is, Haixiang 319 × Haiken Rice No. 7, Haixiang 319, Jia 201A × Haiken Rice No. 7, Jia 201A, 201A × Haiken Rice No. 7, 201A and Haiken Rice No. 7 were transplanted. 60 plants were transplanted for each material. After the initial heading stage, i.e. early July, when the dwarf disease of each material was fully developed, the survey was started to obtain the percentage of diseased plants in the population.

[0046] result According to field survey results of hybrid offspring obtained in July 2024, the incidence of dwarf virus in the field of Jia 201A was 100%, while the incidence of Jia 201A × Haiken Rice 7 was 3.4%. The incidence of dwarf virus in the field of 201A was also 100%, while the incidence of 201A × Haiken Rice 7 was 5.0%, indicating a significant improvement in the resistance of the hybrid offspring.

[0047] The incidence of rice dwarf disease in the Jia 201A × Haixiang 319 and 201A × 19xiang combinations sown at the same time reached 100%, which also indicates that Jia 201A, Haixiang 319, 201A and 19xiang are all materials without resistance to Southern Rice Black-Streaked Dwarf Disease.

[0048] In summary, this invention utilizes the persistent and severe outbreaks of Southern Black-Streaked Dwarf Disease (SMD) in rice at the Nanbin Farm outpost base in Yazhou District, Sanya City in recent years. In 2023 and 2024, almost all rice varieties suffered total crop failure due to SMD. In this testing area, an investigation into the resistance of various rice varieties to SMD revealed a resistant variety, named Haiken Rice No. 7. After two years of cultivation, the resistance to SMD was outstanding. While other rice varieties showed 100% infection rates and crop failure, Haiken Rice No. 7 still managed to head and grain normally.

[0049] After a year of hybridization and selection, it was found that its offspring separated offspring resistant to southern black-streaked dwarf disease, proving that its resistance to southern black-streaked dwarf disease can be stably inherited. This provides a stable and reliable traditional breeding method for further solving the resistance problem of southern black-streaked dwarf disease in rice.

[0050] First, the already selected Haiken Rice No. 7 material was hybridized with materials requiring improved resistance to rice black-streaked dwarf disease. During the generational selection process, based on the occurrence characteristics of the white-backed planthopper, the peak infestation period in the Yacheng area begins around March 20th each year, when the planthopper population density is high. If the terrain is suitable, such as the low-lying terrain currently used in the experiment, it easily leads to a large-scale reproduction of the white-backed planthopper. If the planthopper population carries the virus, it will cause a large-scale outbreak of Southern Rice Black-Streaked Dwarf Disease. This invention satisfies the terrain characteristics, the occurrence characteristics of the planthopper population, and the susceptibility characteristics of rice, namely, satisfying the climate and season suitable for the large-scale reproduction of white-backed planthoppers, the presence of virus-carrying plants in the field, and the rice growing season being a period of high susceptibility. By simultaneously meeting these three conditions, an area suitable for the occurrence of Southern Rice Black-Streaked Dwarf Disease was created for field identification of whether the offspring can resist the dwarf disease. During the peak period of dwarf disease incidence from March to July each year, screening for dwarf disease resistance is conducted. At other times, targeted selection is carried out on yield traits. In high-generation materials, rice quality testing is used to select superior varieties with strong resistance, high yield, and good rice quality.

[0051] Although the incidence of Southern Rice Black-Streaked Dwarf Disease (SMR) has been increasing year by year, there is no representative region or area that can achieve continuous occurrence of this disease annually. To address the need for continuous outbreaks, in addition to finding suitable terrain for pest occurrence, a rich source of pests is also required. The experimental site selected is somewhat basin-like with poor air circulation, and the surrounding area has large areas of banana plantations and vegetable fields such as cowpeas and eggplants where thrips and white-backed planthoppers are severely infested, meeting the conditions for abundant pest sources and easy reproduction and spread of virus-carrying pests. This year, due to the peak incidence of the disease, almost the entire field was affected by SMR. This invention preserves and cultivates severely infected virus-carrying rice stubble, maintaining the conditions for pathogen occurrence, while also ensuring the reliability of resistant material breeding.

[0052] Because the resistance materials for Southern Black-streaked Dwarf Disease currently publicly released do not show ideal resistance performance, that is, there is no resistance source material with good resistance performance. However, the Haiken Rice No. 7 of this invention has a disease incidence of 0% against Southern Black-streaked Dwarf Disease, and has obtained a stable resistance material, truly achieving a breakthrough in breeding technology for resistance to Southern Black-streaked Dwarf Disease.

[0053] It should be noted that when numerical ranges are mentioned in the claims of this invention, it should be understood that the two endpoints of each numerical range and any value between the two endpoints can be selected. To avoid redundancy, the present invention describes preferred embodiments.

[0054] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0055] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for breeding rice resistant to Southern Rice Black-Streaked Dwarf Disease, characterized in that, The material Haiken Rice No. 7 was crossed with a material that needed to improve resistance to Southern Rice Black-Streaked Dwarf Disease to obtain F1 generation material, which is the rice resistant to Southern Rice Black-Streaked Dwarf Disease; the material that needed to improve resistance to Southern Rice Black-Streaked Dwarf Disease is 19 Xiang. Targeted generation selection of F1 generation materials yielded rice varieties with stable genetic resistance to Southern Rice Black-Streaked Dwarf Disease. In the targeted generation selection, the selection is based on the yield characteristics of the F1 generation material; The yield traits refer to tillering and grain filling rate; During the targeted generation selection, plants with tillering characteristics superior to the average tillering characteristics of the F1 generation materials were selected. During the targeted generation selection, plants with a grain setting rate higher than the average grain setting rate of the F1 generation material are selected. During the targeted generation selection, plants from the F1 generation that exhibit disease and pest resistance and do not show symptoms in the field are selected. The rice species that are stably resistant to Southern Rice Black-Streaked Dwarf Disease are those that simultaneously meet the conditions of plant type performance, grain filling performance, and disease and pest resistance performance.

2. The breeding method according to claim 1, characterized in that, During the targeted generation selection, plants infected with Southern Rice Black-Streaked Dwarf Virus (SMR) were planted in the same area as F1 generation materials to provide pathogens.

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