Breeding method of low glycemic index purple rice

Abstract

The present application relates to rice breeding technical field, and relates to a low glycemic index purple rice breeding method. The method comprises the following steps: taking RG4 as the father and taking Zheda Zi 1S as the mother to obtain F1 generation seeds by hybridization; planting the F1 generation seeds, taking the F1 generation as the father and taking Zheda Zi 1S as the mother to obtain BC1F1 generation seeds by backcrossing; planting the backcrossed BC1F1 generation seeds, and obtaining BC1F2 generation seeds by selfing; planting the BC1F2 generation seeds, harvesting normal seed setting fertile excellent single plants, shelling and selecting purple rice, processing into whole white non-waxy rice with endosperm, and then detecting and selecting high resistance starch content strains; planting the BC1F3 generation seeds, selecting and reserving the strains with stable purple rice traits, and determining and selecting strains with whole white endosperm and high resistance starch content; planting the BC1F4 generation seeds, determining and selecting low GI strains; planting the BC1F5 generation seeds, selecting and reserving strains with high alkali solubility value and easy cooking by taking good cooking as the screening index, and breeding low GI purple rice. The rice obtained by the method particularly meets the individual nutritional needs of diabetic patients.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rice breeding, and particularly relates to a breeding method of low glycemic index purple rice. BACKGROUND

[0002] Rice is the staple food of more than 50% of the world's population and is one of the most important crops in the world. In polished rice with a water content of 14%, starch accounts for 70-80% of its content. Starch is divided into rapidly digestible starch, slowly digestible starch and resistant starch (Resistant starch, RS) according to its digestion characteristics. Resistant starch refers to "starch and its degradation products that are not absorbed in the small intestine of healthy people", which is negatively correlated with the glycemic index (Glycemic Index, GI), and among them, especially resistant starch type 3 (RS3), which is resistant starch formed by retrogradation after cooking and processing.

[0003] Purple rice is rich in nutrients, including protein, fat, amino acids, vitamins, trace elements, natural pigments and various physiological active substances. It is both food and medicine and has high value. In addition to porridge, it is often made into various nutritional foods and wine, and has been praised as "medicinal rice", "tribute rice", "longevity rice" and other names since ancient times.

[0004] Therefore, cultivating new varieties of low glycemic index purple rice is suitable for diabetics to eat and also facilitates nutritional fortification, especially meeting the individual needs of diabetics. SUMMARY

[0005] The present application provides a breeding method of low glycemic index purple rice. The rice obtained by the method has the characteristics of high resistant starch, low glycemic index and nutritious purple rice, and can be used to develop nutritional and low glycemic index special diet food, and also can be used as a staple food for diabetics.

[0006] In order to achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0007] The present application provides a breeding method of low glycemic index purple rice, comprising:

[0008] (1) using RG4 as the male parent and Zhe Da Zi 1S as the female parent, hybridizing to obtain F1 generation seeds;

[0009] (2) planting the F1 generation seeds, using the F1 generation as the male parent and Zhe Da Zi 1S as the female parent, backcrossing to obtain BC1F1 generation seeds;

[0010] (3) planting the backcrossed BC1F1 generation seeds, selfing to obtain BC1F2 generation seeds;

[0011] (4) Planting BC1F2 generation seeds, harvesting normal seed setting and fertile excellent single plants, shelling and selecting purple rice, processing into milled rice, selecting whole white non-waxy endosperm rice, and then detecting and selecting high resistant starch content lines to obtain BC1F3 generation seeds;

[0012] (5) Planting BC1F3 generation seeds, selecting lines with stable purple rice traits, determining and selecting lines with whole white endosperm and high resistant starch content, to obtain BC1F4 generation seeds;

[0013] (6) Planting BC1F4 generation seeds, determining and selecting lines with low glycemic index, to obtain BC1F5 generation seeds;

[0014] (7) Planting BC1F5 generation seeds, determining and selecting lines with high alkali solubility, to obtain low glycemic index purple rice.

[0015] Among them, RG4 is a new rice line bred by Zhejiang University, with RS3 content as high as 11.4%, which can be purchased from Zhejiang University Institute of Nuclear Agricultural Sciences or Zhejiang Jeneron Biotechnology Co., Ltd. The variety has been disclosed in the literature, see: Yi Ding et al., Physiochemical properties of rice with contrasting resistant starch content. Journal of Cereal Science, 2019, 89: 102815.

[0016] Among them, Zhebig1S is a purple rice indica warm sterile line bred by Zhejiang University, which can be purchased from Zhejiang University Institute of Nuclear Agricultural Sciences or Zhejiang Jeneron Biotechnology Co., Ltd. The variety has been approved by Zhejiang Provincial Crop Variety Approval Committee in 2021, with the approval number of Zhejiang Rice [sterile line] 2021008; has applied for plant new variety right protection (announcement number CNA035177E), see the variety right application announcement (general No. 129) (1) on January 1, 2021. Zhebig1S line is a new rice line bred by hybridization of high-quality medium indica 93-11 (Yangdao No. 6) sterile line Zhebig01S and 93-11 purple rice mutant, which well retains the excellent characteristics of high-quality medium indica 93-11 (Yangdao No. 6). 93-11 (Yangdao No. 6) can be obtained from Jiangsu Lixiahe Agricultural Academy of Sciences or National Rice Germplasm Bank.

[0017] The "endosperm non-waxy rice full white" in the present application refers to the endosperm appearance of non-waxy rice being white, which is a unique characteristic of RG4. The present applicant uses this characteristic of RG4 to quickly lock the strain with high resistant starch content in the early screening, that is, the operation in step (4) in the present breeding method. Specifically, the part BC1F2 generation seeds with the endosperm appearance being all white are selected. At this time, the "endosperm non-waxy rice full white" corresponds to "seed endosperm appearance all white".

[0018] And then in step (5), all the BC1F3 generation seeds with the endosperm appearance being all white are selected by checking the endosperm appearance.

[0019] Preferably, in the step (4), the high resistant starch content is evaluated by the RS3 content ≥ 10%.

[0020] Preferably, in the step (5), the high resistant starch content is evaluated by the RS3 content ≥ 10%.

[0021] Preferably, in the step (6), the low glycemic index is evaluated by the glycemic index ≤ 50.

[0022] Preferably, in the step (7), the high alkali dissolution value is evaluated by the alkali dissolution value ≥ 6.0.

[0023] Therefore, the present application has the following beneficial effects:

[0024] (1) The low glycemic index purple rice of the present application is selected by taking resistant starch as an indirect screening index, which is more labor-saving and cost-saving. The low glycemic index purple rice obtained has the characteristics of high resistant starch, low glycemic index and nutritious purple rice, and can be used to develop a nutrition-enhanced low glycemic index special diet food and as a staple food for diabetes.

[0025] (2) The present application uses Zhejiangzi 1S as the female parent and adopts the strategy of hybridization and backcrossing, which has the advantages of high efficiency and labor-saving, without artificial detasseling and intuitive identification of purple rice markers. More importantly, the Zhejiangzi 1S retains the excellent characteristics of high-quality medium indica 93-11 (Yangdao 6), and is similar to using 93-11 (Yangdao 6) as a chassis variety. Therefore, the breeding method of the present application has high expectations and functions to consider yield.

[0026] (3) The present application uses RG4 as the male parent, which has the characteristics of high resistant starch dominant inheritance, and the endosperm chalkiness trait is intuitively screened, which quickly reduces the breeding population and develops a series of high-efficiency selection breeding strategies with high efficiency.

[0027] (4) The low glycemic index purple rice bred by the application is rich in fat and iron elements, has good flavor, and is suitable for use as raw material of nutritional products or beauty and skin care food. DETAILED DESCRIPTION

[0028] The application will be further described in conjunction with specific embodiments. Those skilled in the art will be able to implement the application based on these descriptions. In addition, the embodiments of the application involved in the following description are generally only a part of the embodiments of the application, not all the embodiments. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments in the application without creative labor should be within the scope of protection of the application.

[0029] Example 1 Genetic characteristics of purple rice traits of ZheDaZi 1S

[0030] The reciprocal cross between ZheDaZi 1S and common high amylose starch RG4 was carried out, and the results in Table 1 show that the purple rice trait is inherited as endosperm trait, and the offspring shows purple rice regardless of being the female parent or the male parent.

[0031] Table 1 Genetic characteristics analysis of purple rice traits of ZheDaZi 1S

[0032] Variety Zhe Da Zi 1S (purple rice) RG4 (common) Zhe Da Zi 1S (purple rice) — Purple rice RG4 (common) Purple rice —

[0033] Example 2 Genetic study of RG4 carrying high amylose starch and endosperm non-waxy rice

[0034] Investigation of 361 single plants of F2 population of the cross between ZheDaZi 1S (low amylose starch, transparent endosperm) and RG4 (high amylose starch, endosperm non-waxy rice) shows that the endosperm non-waxy rice and the high amylose starch content are extremely significantly correlated, and are inherited in a semi-dominant manner. Therefore, the endosperm non-waxy rice can be used as a primary selection marker trait of high amylose starch content.

[0035] Example 3 Breeding of low glycemic index purple rice rice with ZheDaZi 1S and RG4 as parents

[0036] (1) In spring 2020 in Lingshui, Hainan, 28 seeds of F1 (ZheDaZi 1S / RG4) were obtained by crossing with ZheDaZi 1S as the female parent and high amylose starch rice RG4 as the male parent;

[0037] (2) In summer and autumn 2020 in Hangzhou, Zhejiang, 21 plants of BC1F1 (ZheDaZi 1S / / ZheDaZi 1S / RG4) were obtained by backcrossing with ZheDaZi 1S as the female parent, with 28 plants of F1 (ZheDaZi 1S / RG4) as the parent plants;

[0038] (3) In the spring of 2021, 12 plants of the backcross BC1F1 (Zhedazipu 1S / / Zhedazipu 1S / RG4) generation were planted in Lingshui, Hainan, selfed, and 2136 seeds of the BC1F2 generation were obtained;

[0039] (4) In the summer and autumn of 2021, 682 plants of the BC1F2 generation were planted in Hangzhou, Zhejiang, and 235 plants of purebred purple rice were obtained by shelling and selecting normal seed-setting fertile excellent single plants. 73 plants of all-white endosperm non-waxy rice were selected by processing part of the 235 plants of purebred purple rice into milled rice. 59 single plants with high resistance starch content ≥10% were selected by re-detecting, and seeds of the BC1F3 generation were obtained;

[0040] (5) In the spring of 2022, 29 single plants with stable purple rice traits in the plant line and all-white endosperm and high resistance starch content were selected and reserved in the BC1F3 generation, and seeds of the BC1F4 generation were obtained in Lingshui, Hainan;

[0041] (6) In the summer and autumn of 2022, 9 excellent lines with a blood glucose generation index ≤50 were selected and reserved in the BC1F4 generation in Hangzhou, Zhejiang, and seeds of the BC1F5 generation were obtained by taking the blood glucose generation index as a screening index;

[0042] (7) In the spring of 2023, 1 excellent variety with an alkali solubility value ≥6.0 and easy cooking was selected and reserved in the BC1F5 generation in Lingshui, Hainan, that is, the low blood glucose generation index purple rice- low sugar purple valley was obtained as a finalized product.

[0043] The main indexes of the low sugar purple valley selected and bred in this embodiment are the successful aggregation of purple rice, low blood glucose generation index and high RS3, which effectively aggregates the excellent traits of two parents, which is exactly what the majority of diabetic patients need. The yield is significantly increased compared to RG4, and is similar to the original parent high-quality medium indica 93-11 (Yangdao No. 6), and the function takes into account the yield. Therefore, Zhedazipu 1S well retains the excellent characteristics of high-quality medium indica 93-11 (Yangdao No. 6), and taking it as a backcross parent is similar to taking 93-11 (Yangdao No. 6) as a chassis variety, which ensures that the present application has a high expectation.

[0044] After the finalized product was screened, various nutritional indexes were measured, and the indexes of the finalized product and its parents are shown in Tables 2 and 3.

[0045] The determination methods of each index in Table 2 and Table 3 are as follows: rough rice color, yield, thousand-grain weight: National Rice Variety Test Observation Record Project, Method and Standard (Trial); resistant starch: AOAC 2002.02; GI value determination method: People's Republic of China National Health Commission WS / T 652-2019 "Food Glycemic Index Determination Method"; rice quality (amylose, gel consistency, alkali value): NY / T593-2013; protein: GB / T 24897-2010; lipid: GB / T 5009.6-2003; calcium: GB / T 5009.92-2003; iron: GB / T 5009.90-2003; zinc: GB / T 5009.14-2003.

[0046] Table 2 Comparison of yield and main nutritional components of parent and shaped product Table 1

[0047]

[0048] Note: * and ** respectively represent 5% and 1% significant difference compared with the parent Zhe Da Zi 1S (93-11).

[0049] Table 3 Comparison of yield and main nutritional components of parent and shaped product Table 2

[0050]

[0051] Note: * and ** respectively represent 5% and 1% significant difference compared with the parent Zhe Da Zi 1S (93-11).

[0052] From the data in Table 2 and Table 3, in the shaped product "low-sugar purple valley", the special nutritional components are as follows: first, the protein nutrition is higher (9.1%), which is significantly higher than that of the parent Zhe Da Zi 1S (7.9%) and the parent RG4 (8.2%), which may be directly related to the decrease in thousand-grain weight of the grain. Second, the high iron content (1.9 mg / 100 g) is significantly higher than that of the parent Zhe Da Zi 1S (1.5 mg / 100 g) and the parent RG4 (1.1 mg / 100 g). Iron nutrition prevents anemia, which is particularly important for blood toning and is the focus of micronutrient biofortification. "Low-sugar purple valley" is higher than the parent varieties, with higher micronutrient quality. The increase in iron content may be related to the fact that "low-sugar purple valley" is purple rice and small-grained. Third, it is rich in crude fat (1.9%), which is significantly higher than that of the parent Zhe Da Zi 1S (0.5%) and the parent RG4 (1.5%). Fat is an important substance that affects the taste and aromatic flavor of rice and is the cause of the attractive luster of rice. The fat in rice includes non-starch fat and starch-bound fat. "Low-sugar purple valley" has high amylose and high RS3 characteristics, which makes it easier to form amylose and fat complexes, which may be the cause of the significantly higher crude fat.

[0053] The data results in Table 2 and Table 3 can illustrate that the varieties selected and bred by the present application have high resistant starch, low glycemic index, purple rice, and rich crude fat and protein nutrition, and have better functional quality, nutritional characteristics and good eating flavor. This is what the current health needs, and is suitable for special diabetic population to eat. The iron micronutrient biofortification is a global public nutrition problem, and the crude fat is beneficial to improve the flavor of rice.

[0054] Therefore, the "low-sugar purple valley" selected and bred by the present application has the nutritional advantages of rich fat and iron, good flavor and blood nourishing.

Claims

1. A method for breeding low glycemic index purple rice, characterized in that, Comprise: (1) take RG4 as the father, take Zhe Da Zi 1S as the mother, crossbreed to obtain F1 generation seed; (2) plant F1 generation seed, take F1 generation as the father, take Zhe Da Zi 1S as the mother, backcross to obtain BC1F1 generation seed; (3) plant backcross BC1F1 generation seed, self-cross to obtain BC1F2 generation seed; (4) plant BC1F2 generation seed, harvest normal seed setting fertile excellent single plant, shell selects and leaves purple rice, processes into fine rice selects and leaves endosperm non-waxy rice whole white, detects again selects and leaves high resistant starch content strain, obtains BC1F3 generation seed, the high resistant starch content is with RS3 content ≥10% as the evaluation criterion; (5) plant BC1F3 generation seed, selects and leaves purple rice trait stable strain, measures and selects and leaves endosperm whole white and high resistant starch content strain, obtains BC1F4 generation seed, the high resistant starch content is with RS3 content ≥10% as the evaluation criterion; (6) plant BC1F4 generation seed, measures and selects and leaves low glycemic index strain, obtains BC1F5 generation seed, the low glycemic index is with glycemic index ≤50 as the evaluation criterion; (7) plant BC1F5 generation seed, measures and selects and leaves high alkali digestion value strain, selects and breeds to obtain low glycemic index purple rice rice, the high alkali digestion value is with alkali digestion value ≥6.0 as the evaluation criterion.

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