Method for assisting in breeding high-southern-rust-resistance corn inbred line by utilizing leaf glandular hair character

Abstract

The invention discloses a method for assisted breeding of a high-southern-rust-resistance corn inbred line by using leaf glandular hair traits, and relates to the technical field of crop genetic breeding, and the method comprises the following specific steps: hybridizing the high-southern-rust-resistance corn inbred line with a to-be-improved southern-rust-susceptible corn inbred line or hybridizing and then backcrossing to select the line, selfing F1 generation and reserving seeds, and breeding the F1 generation and the F1 generation to obtain the high-southern-rust-resistance corn inbred line. Starting from the F2 generation or the BC1F1 generation, selecting plants or rows with large leaves and fewer hairs according to the form and the quantity of glandular hairs of the leaves, selecting single plants with good corn characters, and continuously selfing or backcrossing for N generations, so as to obtain the high-southern-rust-resistance corn selfing line with stable inheritance. According to the method disclosed by the invention, the corn inbred line with high southern rust resistance is bred according to the quantity and the sparse degree of the big hairs in the corn leaf glandular hairs, so that multiple limitations of inoculation identification and special habitat conditions can be overcome, the breeding process of the corn inbred line with high southern rust resistance is accelerated, accurate identification of resistant materials is realized, and a foundation is laid for cultivation of new varieties.

Description

Technical Field

[0001] The invention relates to the technical field of crop genetic breeding, and in particular to a method for utilizing leaf glandular hair traits to assist in breeding corn inbred lines with high resistance to southern rust. Background Art

[0002] Southern rust of corn is a typical air-borne disease that mainly occurs in the middle and late stages of corn growth. The main affected parts are leaves and leaf sheaths. In severe cases, the rust spots will infect the stems and bracts. The rust spots will hinder the photosynthesis of leaves, seriously affecting the yield of corn. In recent years, with the frequent occurrence of extreme weather, the scope and severity of the outbreak of southern rust of corn have increased year by year. At present, domestic rust-resistant corn germplasm resources are very limited. Most of the resources with high resistance to southern rust come from foreign tropical germplasm resources. Most tropical germplasm resources cannot be directly used in corn breeding in my country. They need to be backcrossed with local excellent germplasm many times to introduce the rust-resistant genes in tropical disease-resistant germplasm into local excellent materials in order to achieve the diversification of southern rust resistance genes in local inbred lines.

[0003] Breeding disease-resistant inbred lines is the key to breeding disease-resistant corn varieties. When predecessors directed the improvement and breeding of corn inbred lines or new varieties with high resistance to southern rust, they mainly used artificial inoculation or natural disease peak period to investigate the disease. The specific work was to focus on investigating the cob trefoil during the waxy stage of corn, record the overall disease level, and calculate the disease index. The statistical investigation work was cumbersome, the statistical workload was large, and the environmental requirements were strict.

[0004] There are three types of glandular hairs on corn leaves, namely, large hairs, spiny hairs and bicellular hairs. Large hairs gradually appear from the 6th leaf, and increase continuously in the 7th to 8th leaves, and the number reaches a stable level in the 9th to 13th leaves. At present, there is no report on whether the phenotypic identification of glandular hairs on corn leaves is related to the stress resistance of corn. The present invention finds for the first time that the number and sparseness of glandular hairs on corn leaves will cause differences in stress resistance between corn varieties, and are closely related to various resistances and various physiological activities of corn. Identifying and counting glandular hairs on corn is of great significance to the breeding of stress-resistant corn varieties. Summary of the invention

[0005] In order to overcome the deficiencies of the prior art, the object of the present invention is to provide a method for utilizing leaf glandular hair traits to assist in breeding corn inbred lines with high resistance to southern rust.

[0006] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0007] The present invention provides a method for breeding a corn inbred line with high resistance to southern rust by using leaf glandular hair traits. The method comprises the following specific steps: hybridizing a corn inbred line with high resistance to southern rust with a corn inbred line susceptible to southern rust to be improved or backcrossing the hybridized line to select a line; 1 Self-pollination and seed preservation in F2 or BC 1 F 1 From the beginning of the first generation, select plants or rows with fewer large leaf hairs based on the morphology and number of leaf glandular hairs, and also select individual plants with good corn traits. By continuous self-pollination or backcrossing for N generations, you can obtain a stable genetic inbred corn line with high resistance to southern rust.

[0008] As a further optimization scheme of the present invention, the corn inbred line with high resistance to southern rust is the corn inbred line Yanzi D1 (the national library number of the corn inbred line Yanzi D1 is 0L120004, and the query website is https: / / www.cgris.net / home ), the maize inbred line susceptible to southern rust is the maize inbred line Yanzi X22 (the plant variety right protection number of the maize inbred line Yanzi X22 is CNA20221000757, and the query website is http: / / 202.127.42.145 / bigdataNew / home / ManageOrg ), Yanzi D41 (the plant variety protection number of the corn inbred line Yanzi D41 is CNA20221002580, and the query website is http: / / 202.127.42.145 / bigdataNew / home / ManageOrg ).

[0009] As a further optimization scheme of the present invention, the N is 4-7.

[0010] As a further optimization scheme of the present invention, the selection criterion for leaves with fewer large hairs is that the leaves of the same part of the corymbose trefoil have significantly fewer large hairs than those of the susceptible inbred line. The specific manifestation of significantly fewer large hairs is that the number of large hairs on the corymbose trefoil leaves does not exceed 6 within a field of view under a 4x optical microscope.

[0011] As a further optimization scheme of the present invention, the corn phenotypic traits include plant type, leaf type, and disease resistance.

[0012] As a further optimization scheme of the present invention, the specific steps include:

[0013] (1) Crossbreeding corn inbred lines that are highly resistant to southern rust with those that are susceptible to southern rust;

[0014] (2) F 1 Self-pollination and seed preservation;

[0015] (3) F 2 Mixed sowing, select plants or rows with large leaves and less hair, and select single plants with good corn phenotypic traits, and self-pollinate to keep a single ear;

[0016] (4) Repeat the breeding steps of step (3) until F n After the first generation, the corn inbred lines with high resistance to southern rust were obtained by self-pollination and seed preservation.

[0017] As a further optimization scheme of the present invention, the specific steps include:

[0018] (1) Crossbreeding corn inbred lines that are highly resistant to southern rust with those that are susceptible to southern rust;

[0019] (2) F 1 The male parent was used as the substitute, and the maize inbred line susceptible to southern rust was used as the female parent for backcrossing;

[0020] (3) BC 1 F 1 For mixed sowing, select individual plants or rows with large leaves and less hair, and consider individual plants with good corn phenotypic traits, and keep a single ear after self-pollination;

[0021] (4) Repeat the breeding steps of step (3) for the offspring until BC 1 F n After the first generation, the corn inbred lines with high resistance to southern rust were obtained by self-pollination and seed preservation.

[0022] The principle of the present invention is that corn glandular hairs are a protective layer between the plant epidermis and the environment. The increase in the thickness of the plant epidermis can effectively reduce the invasion of pests and diseases. Corn glandular hairs can effectively reduce the heat load of the corn epidermis, reduce water loss in the plant body, and are conducive to adversity response. At the same time, glandular hairs can also synthesize, store and secrete important substances, cooperate with stomata, cutin and wax on the epidermis, alleviate freezing, ultraviolet damage and mechanical damage, and jointly complete various protective functions. The present invention first discovered that the number and sparseness of corn leaf glandular hairs are different from the stress resistance of corn varieties. Therefore, by identifying and counting corn glandular hairs, a new method for breeding corn stress-resistant varieties is provided.

[0023] The present invention has the following beneficial effects:

[0024] The invention uses a corn inbred line with high resistance to southern rust to be improved and a corn inbred line susceptible to southern rust to be hybridized and backcrossed to select a line. 2 or BC 1 F 1 Since the beginning of the first generation, we have selected corn inbred lines with high resistance to southern rust through the number and sparseness of glandular hairs on corn leaves. This has overcome the limitations of existing inoculation and identification methods for cultivating high resistance to southern rust and screening methods under special habitat conditions, accelerated the breeding process of corn inbred lines with high resistance to southern rust, achieved accurate identification of resistant materials, and laid the foundation for the cultivation of new varieties. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a comparison chart of the phenotypic traits of the highly resistant maize inbred line Yanzi D1 and the susceptible maize inbred line Yanzi X22;

[0026] Figure 2This is a comparison chart of the phenotypic traits of the highly resistant corn inbred line Yanzi D1 and the susceptible corn inbred line Yanzi D41.

[0027] Figure 3 AC are the maize inbred line Yanzi D1 with high resistance to southern rust, the maize inbred lines Yanzi X22 and Yanzi D41 susceptible to southern rust. The images were taken with a microscope (Olympus) (magnification 4 times);

[0028] Figure 4 A and B are the maize inbred line Yanzi X22 susceptible to southern rust and the F selected by the method of step 2.2.1. 8 The images of leaf glandular hairs of the first generation maize inbred lines were taken with a microscope (Olympus) (magnification 4 times);

[0029] Figure 5 A and B are the maize inbred line Yanzi D41 susceptible to southern rust and F selected by the method of step 2.2.2. 8 The images of leaf glandular hairs of the first generation maize inbred lines were taken with a microscope (Olympus) (magnification 4 times);

[0030] Figure 6 A and B are the maize inbred line Yanzi D41 susceptible to southern rust and BC selected by the method of step 2.2.3. 1 F 7 The images of leaf glandular hairs of the first generation maize inbred lines were taken with a microscope (Olympus) (magnification 4 times);

[0031] Figure 7 This is the planting map of the corn inbred line F8101 (the left is the corn inbred line F8101; the right is the corn inbred line Yanzi X22);

[0032] Figure 8 This is the planting map of the maize inbred line F8201 (the left one is the maize inbred line Yanzi D41; the right one is the maize inbred line F8201);

[0033] Fig. 9 BC 1 Planting map of F7101 (left is the corn inbred line BC 1 F7101; on the right is the maize inbred line tobacco D41). DETAILED DESCRIPTION

[0034] The present application is further described in detail below in conjunction with the accompanying drawings. It is necessary to point out here that the following specific implementation methods are only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application. Technical personnel in this field can make some non-essential improvements and adjustments to the present application based on the above application content.

[0035] 1. Materials

[0036] The methods used in this example are conventional methods known to those skilled in the art unless otherwise specified, and the reagents and other materials used are commercially available products unless otherwise specified.

[0037] 2. Methods

[0038] 2.1 Identification of leaf glandular trichome traits in maize inbred lines known to be susceptible or highly resistant to southern rust

[0039] The maize inbred line Yanzi D1 with high resistance to southern rust and the maize inbred lines Yanzi X22 and Yanzi D41 susceptible to southern rust were selected. The phenotypic traits of the maize inbred lines susceptible to and highly resistant to southern rust are shown in the figure below. Figure 1 , 2 As shown, ( Figure 1 They are the highly resistant maize inbred line Yanzi D1 and the susceptible maize inbred line Yanzi X22. Figure 2 The upper leaves of maize ears (Yanzi D1, a maize inbred line highly resistant to southern rust, and Yanzi D41, a maize inbred line susceptible to southern rust) were collected during the silking stage and observed under a microscope (Olympus). Electron microscopic images of glandular trichomes on the maize leaves were obtained, and the types, number density, etc. of the glandular trichomes were identified and counted.

[0040] The identification results are as follows Figure 3 As shown, Figure 3 A is an electron microscope image of leaf glandular hairs of the maize inbred line Yanzi D1. Figure 3 B is an electron microscope image of the glandular hairs on the leaves of the maize inbred line Yanzi X22. Figure 3 C is an electron microscope image of leaf glandular hairs of the maize inbred line Yanzi D41. From this, we can know that the maize inbred line Yanzi D1 has fewer leaf glandular hairs, while the maize inbred lines Yanzi X22 and Yanzi D41 have more leaf glandular hairs. Therefore, it is speculated that the glandular hair traits of maize leaves are related to the resistance of the maize inbred lines to southern rust.

[0041] 2.2 Using leaf glandular hairs to assist in breeding maize inbred lines with high resistance to southern rust

[0042] 2.2.1 A method for using leaf glandular hairs to assist in breeding corn inbred lines with high resistance to southern rust, the specific steps are as follows:

[0043] (1) The maize inbred line Yanzi D1, which is highly resistant to southern rust, was crossed with the maize inbred line Yanzi X22, which is susceptible to southern rust;

[0044] (2) F 1 Self-pollination and seed preservation;

[0045] (3) F 2 For mixed sowing, select individual plants with large leaves and less hair, and consider individual plants with good phenotypic traits such as plant shape, leaf shape, and disease resistance, and self-pollinate to keep a single ear;

[0046] (4) F 3 Planting is done by ear row, and single plants with large leaves and less hair are selected in the ear row. Single plants with good phenotypic traits such as plant type, leaf type, and disease resistance are also selected, and single ears are retained after self-pollination.

[0047] (5) F 4 Planting is done by ear row, and single plants with large leaves and less hair are selected in the ear row. Single plants with good phenotypic traits such as plant type, leaf type, and disease resistance are also selected, and single ears are retained after self-pollination.

[0048] (6) F 5 Planting is done by ear row, and the rows of plants with large leaves and less hair are selected in the ear row. Individual plants with good phenotypic traits such as plant type, leaf type, and disease resistance are selected, and a single ear is retained after self-pollination.

[0049] (7) F 6 Planting is done by ear row, and the rows of plants with large leaves and less hair are selected in the ear row. Individual plants with good phenotypic traits such as plant type, leaf type, and disease resistance are selected, and a single ear is retained after self-pollination.

[0050] (8) F 7 The first generation planted the seedlings in rows, and selected the rows with large leaves and less hair in the rows. The single plants with good phenotypic traits such as plant type, leaf type, and disease resistance were selected, and the seeds were self-pollinated to obtain F 8 Eleven maize inbred lines were generated and named as maize inbred line F8101;

[0051] Among them, the selection criteria for leaves with fewer large hairs are: the leaves of the same part of the Cloverleaf have significantly fewer large hairs than those of the susceptible inbred lines. The specific manifestation of significantly fewer large hairs is that the number of large hairs on the Cloverleaf leaves within a field of view under a 4x optical microscope is no more than 6.

[0052] The maize inbred lines Yanzi X22 and F 8 The upper leaves of the female ears of corn were collected at the silking stage and observed under a microscope (Olympus) to obtain the electron microscopic images of the glandular hairs on the corn leaves. Figure 4 As shown, Figure 4 A is an electron microscope image of leaf glandular hairs of the maize inbred line Yanzi X22. Figure 4 B is F 8 The electron microscope image of the leaf glandular hairs of the first generation maize inbred line F8101 proves that the F 8 The first generation maize inbred line F8101 has fewer glandular hairs on its leaves.

[0053] 2.2.2 A method for using leaf glandular hairs to assist in breeding corn inbred lines with high resistance to southern rust, the specific steps are as follows:

[0054] (1) The maize inbred line Yanzi D1, which is highly resistant to southern rust, was crossed with the maize inbred line Yanzi D41, which is susceptible to southern rust;

[0055] (2) F 1 Self-pollination and seed preservation;

[0056] (3) F 2 For mixed sowing, select individual plants with large leaves and less hair, and consider individual plants with good phenotypic traits such as plant shape, leaf shape, and disease resistance, and self-pollinate to keep a single ear;

[0057] (4) F 3 -F 7 The first generation was planted in rows according to the number of ears. Individual plants or rows with large leaves and less hair were selected from the rows. Individual plants with good phenotypic traits such as plant type, leaf type, and disease resistance were also selected. 7 The F 8 12 maize inbred lines were generated and named as maize inbred line F8201;

[0058] Among them, in F 3 、F 4 In the generation, select the individual plants with large leaves and less hair in the ear row; in the F 5-7 In the generation, select the rows of plants with large leaves and less hair;

[0059] Among them, the selection criteria for leaves with fewer large hairs are: the leaves of the same part of the Cloverleaf have significantly fewer large hairs than those of the susceptible inbred lines. The specific manifestation of significantly fewer large hairs is that the number of large hairs on the Cloverleaf leaves within a field of view under a 4x optical microscope is no more than 6.

[0060] The maize inbred lines Yanzi D41 and F 8 The upper leaves of the female ears of corn were collected at the silking stage and observed under a microscope (Olympus) to obtain the electron microscopic images of the glandular hairs on the corn leaves. Figure 5 As shown, Figure 5 A is an electron microscope image of leaf glandular hairs of the maize inbred line Yanzi D41. Figure 5 B is F 8 The electron microscope image of the leaf glandular hairs of the first generation maize inbred line F8201 proves that the F 8 The first generation maize inbred line F8201 has fewer glandular hairs on its leaves.

[0061] 2.2.3 A method for using leaf glandular hairs to assist in breeding corn inbred lines with high resistance to southern rust, the specific steps are as follows:

[0062] (1) The maize inbred line Yanzi D1, which is highly resistant to southern rust, was crossed with the maize inbred line Yanzi D41, which is susceptible to southern rust;

[0063] (2) F1 The male parent was used as the substitute, and the maize inbred line tobacco D41 was used as the female parent for backcrossing;

[0064] (3) BC 1 F 1 For mixed sowing, select individual plants with fewer large hairs on the leaves, and consider individual plants with good phenotypic traits such as plant shape, leaf shape, and disease resistance, and self-pollinate to keep a single ear;

[0065] (4) BC 1 F 2 -BC 1 F 6 The generations were planted in rows, and single plants or rows with fewer hairs on the leaves were selected, taking into account single plants with good phenotypic traits such as plant shape, leaf shape, and disease resistance. 1 F 6 Self-pollination to obtain BC 1 F 7 19 maize inbred lines were generated and named as maize inbred line BC 1 F 7 101;

[0066] Among them, in BC 1 F 2 , B.C. 1 F 3 In the generation, the plants with fewer hairs on the leaves were selected in the ear row; in the BC 1 F 4 -BC 1 F 6 In the generation, select the rows with fewer large hairs on the leaves;

[0067] Among them, the selection criteria for leaves with fewer large hairs are: the leaves of the same part of the Cloverleaf have significantly fewer large hairs than those of the susceptible inbred lines. The specific manifestation of significantly fewer large hairs is that the number of large hairs on the Cloverleaf leaves within a field of view under a 4x optical microscope is no more than 6.

[0068] The maize inbred lines Yanzi D41 and BC susceptible to southern rust were selected. 1 F 7 BC 1 F 7 101. The upper leaves of corn ears were collected during the silking period and observed under a microscope (Olympus) to obtain the electron microscope images of corn leaf glandular hairs. Figure 6 As shown, Figure 6 A shows that there are 12 large hairs on the leaves of D41. Figure 6 B shows BC 1 F 7 BC 1 F 7The number of large hairs on the leaves of 101 is 4, which proves that the BC 1 F 7 BC 1 F 7 101 is a maize inbred line with fewer glandular hairs on its leaves.

[0069] 2.3 Testing of southern rust resistance of developed maize inbred lines

[0070] In 2023, the maize inbred line F8101 bred by the above 2.2.1 method, the maize inbred line F8201 bred by the above 2.2.2 method, and the maize inbred line BC bred by the above 2.2.3 method will be used as the 1 F 7 101 was planted at the Fengyang Experimental Base of Anhui Academy of Agricultural Sciences (such as Figure 7-9 As shown), the southern rust resistance test was carried out and statistical identification was conducted based on the "Technical Specifications for Identification of Disease Resistance of Crops - Part 12: Corn Resistance to Southern Rust" (DB52 / T 1501.12-2020). The statistical data is shown in Table 1:

[0071] Table 1 Data of southern rust resistance test of selected maize inbred lines

[0072]

[0073] Experimental conclusion: According to the data in Table 1, all the segregated progeny are highly resistant to southern rust.

[0074] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for breeding corn inbred lines with high resistance to southern rust using leaf glandular hair traits, characterized in that: The specific steps include: hybridizing or backcrossing a corn inbred line with high resistance to southern rust with a corn inbred line susceptible to southern rust to be improved, self-pollinating the F1 generation for seed preservation, and starting from the F2 or BC1F1 generation, selecting plants or rows with fewer large leaf hairs based on the morphology and number of leaf glandular hairs, while also selecting individual plants with good corn traits, and continuously self-pollinating or backcrossing for N generations to obtain a corn inbred line with high resistance to southern rust with stable inheritance.

2. The method for breeding corn inbred lines with high resistance to southern rust using leaf glandular hairs according to claim 1, characterized in that: The corn inbred line with high resistance to southern rust is Yanzi D1, and the corn inbred lines susceptible to southern rust are Yanzi X22 and Yanzi D41.

3. The method for breeding corn inbred lines with high resistance to southern rust using leaf glandular hairs according to claim 1, characterized in that: The N is 4-7.

4. The method for breeding corn inbred lines with high resistance to southern rust using leaf glandular hairs according to claim 1, characterized in that: The selection criterion for leaves with fewer large hairs is that the leaves of the same part of the corymbose clover have significantly fewer large hairs than those of the susceptible inbred line. The specific manifestation of significantly fewer large hairs is that the number of large hairs on the corymbose clover leaves within a field of view under a 4x optical microscope is no more than 6.

5. The method of claim 1, wherein the method comprises: The corn phenotypic traits include plant type, leaf type, and disease resistance.

6. A method for breeding corn inbred lines with high resistance to southern rust using leaf glandular hairs according to any one of claims 1 to 5, characterized in that: The specific steps include: (1) Crossbreeding corn inbred lines that are highly resistant to southern rust with those that are susceptible to southern rust; (2) Self-pollination of the F1 generation to preserve seeds; (3) Mix the F2 generation and select plants or rows with large leaves and less hair, and select individual plants with good phenotypic traits of corn, and self-pollinate to keep a single ear; (4) Repeat the breeding steps of step (3) until F n After the first generation, the corn inbred lines with high resistance to southern rust were obtained by self-pollination and seed preservation.

7. A method for breeding corn inbred lines with high resistance to southern rust using leaf glandular hairs according to any one of claims 1 to 5, characterized in that: The specific steps include: (1) Crossbreeding corn inbred lines that are highly resistant to southern rust with those that are susceptible to southern rust; (2) Backcrossing with the F1 generation as the male parent and the corn inbred line susceptible to southern rust as the female parent; (3) BC1F1 generation mixed sowing, select individual plants or rows with large leaves and less hair, take into account individual plants with good corn phenotypic traits, and self-pollinate to keep a single ear; (4) Repeat the breeding procedure of step (3) for the offspring until BC1F is obtained. n After the first generation, the corn inbred lines with high resistance to southern rust were obtained by self-pollination and seed preservation.

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