System and method for identifying field leaf disease resistance of large-batch sugarcane germplasm

Abstract

The invention belongs to the field of crop germplasm resource identification and evaluation and genetic breeding, and particularly discloses a field leaf disease resistance identification system and method for large-scale sugarcane germplasm. Carrying out susceptibility grade division on a sugarcane sample to be detected; according to the susceptibility level of the to-be-detected sugarcane sample, obtaining the disease index of the sugarcane plant; and according to the disease index and a preset resistance evaluation system, obtaining the disease resistance level and the comprehensive disease resistance level of the sugarcane leaves. The method can quickly complete field disease resistance identification of leaf diseases of a large batch of sugarcane germplasm resources. Most importantly, the evaluation of the disease resistance of the sugarcane leaves integrates various leaf diseases, can reflect the comprehensive disease resistance of the sugarcane infected by the various leaf diseases, and better meets the actual requirements of breeders in sugarcane breeding.

Description

Technical Field

[0001] The invention belongs to the field of crop germplasm resource identification and evaluation and genetic breeding, and in particular relates to a field leaf disease resistance identification system and method for large quantities of sugarcane germplasm. Background Art

[0002] Sugarcane is the most important sugar crop in my country, and sugarcane sugar accounts for more than 80% of my country's edible sugar. However, in sugarcane production, due to the influence of climate and environmental factors, sugarcane leaf diseases frequently occur, especially in areas with heavy rainfall in summer. After the rainy season, sugarcane leaf diseases begin to occur in large numbers, forming various lesions on the leaves, affecting the photosynthetic efficiency of the plants, resulting in reduced sugarcane yield and quality in the later period, which seriously threatens the high-quality and sustainable development of my country's sugar industry. Screening disease-resistant sugarcane germplasm for hybridization is currently the most important and effective way to cultivate new disease-resistant varieties and ensure the high-quality and sustainable development of my country's sugar industry.

[0003] However, due to the rich types and large number of sugarcane germplasm resources, the screening of disease-resistant germplasm faces many difficulties. In addition, sugarcane leaf diseases include rust, yellow spot (spot) disease, brown streak disease, brown spot disease, ring spot disease, eye spot disease, tip rot, etc., with many types. At the same time, the occurrence of these leaf diseases is often not independent, but mostly mixed infection, that is, a sugarcane can be infected with multiple leaf diseases at the same time and show different lesions and symptoms on the leaves, which further brings great challenges to the identification and evaluation of leaf disease resistance of large quantities of sugarcane germplasm.

[0004] The currently established methods for identifying and evaluating the resistance of sugarcane to leaf diseases are all targeted at a single disease, and are graded and evaluated based on the ratio of the lesion area to the leaf area, such as resistance to brown streak disease and yellow spot disease. If the existing technology is used to carry out field disease resistance identification and evaluation of large quantities of sugarcane germplasm resources, there are three major defects: (1) There is a lack of description of the susceptibility of the main functional leaves of the plant; the range of the lesion area is narrow, which is difficult to judge during the investigation. At the same time, it is difficult to distinguish only by lesion area; in addition, grading only by lesion area cannot reflect the development law of the disease on the leaf. Usually, leaf diseases first occur and show symptoms on older leaves, and then spread to newly grown leaves; (2) It can only identify the resistance of sugarcane germplasm to a single disease, but cannot reflect the overall occurrence of sugarcane leaf lesions, and cannot effectively evaluate the comprehensive disease resistance of sugarcane. In sugarcane breeding, what breeders actually need to master is the comprehensive resistance level of sugarcane germplasm to multiple diseases, which is the overall disease resistance of sugarcane when infected by multiple leaf diseases. Therefore, germplasm that is only resistant to a single disease cannot meet the actual needs of breeding; (3) If the disease resistance of sugarcane germplasm is graded and evaluated one by one according to the identification technical plan of each disease, the workload required is large and time-consuming, and it is not suitable for large quantities of sugarcane germplasm resources. Summary of the invention

[0005] The present invention aims to establish a field disease resistance identification technology applicable to large quantities of sugarcane germplasm resources, and is also applicable to the disease resistance identification of sugarcane to a single leaf disease and to the disease resistance identification of sugarcane germplasm with complex infection of multiple leaf diseases.

[0006] To this end, the present invention proposes a field leaf disease resistance identification system for large quantities of sugarcane germplasm, including a plant grading unit, a disease calculation unit and a resistance evaluation unit;

[0007] The plant classification unit is used to classify the disease susceptibility level of the sugarcane samples to be tested according to the preset sugarcane leaf disease categories, and the preset sugarcane leaf disease susceptibility classification and symptom descriptions;

[0008] The disease calculation unit is used to obtain the disease index of the sugarcane plant according to the disease susceptibility level of the sugarcane sample to be detected;

[0009] The resistance evaluation unit is used to obtain the disease resistance grade and comprehensive disease resistance level of the sugarcane plant leaves according to the disease index and a preset resistance evaluation system.

[0010] Preferably, the preset sugarcane leaf disease grading and symptom description divides the disease susceptibility levels according to the degree of occurrence of sugarcane leaf lesions and the infected leaves.

[0011] Preferably, in the condition calculation unit, the method for calculating the condition index includes:

[0012] Disease index = Σ(number of plants of each disease level × the level of that level) / (total number of plants surveyed × the highest level) × 100.

[0013] The present invention also proposes a method for identifying resistance to leaf diseases of large quantities of sugarcane germplasm in the field, comprising the following steps:

[0014] According to the preset sugarcane leaf disease categories, preset sugarcane leaf disease grading and symptom descriptions, the sugarcane samples to be tested are classified into disease susceptibility levels;

[0015] Obtaining a disease index of the sugarcane plant according to the disease susceptibility level of the sugarcane sample to be tested;

[0016] According to the disease index and the preset resistance evaluation system, the disease resistance grade and comprehensive disease resistance level of the sugarcane plant leaves are obtained.

[0017] Preferably, the preset sugarcane leaf disease grading and symptom description divides the disease susceptibility levels according to the degree of occurrence of sugarcane leaf lesions and the infected leaves.

[0018] Preferably, the method for calculating the disease index includes:

[0019] Disease index = Σ(number of plants of each disease level × the level of that level) / (total number of plants surveyed × the highest level) × 100.

[0020] The beneficial effects of the present invention are as follows:

[0021] The present invention discloses a field leaf disease resistance identification system and method for large quantities of sugarcane germplasm, which can quickly complete the field disease resistance identification of leaf diseases of large quantities of sugarcane germplasm resources. Most importantly, the evaluation of sugarcane leaf disease resistance in the present invention integrates a variety of leaf diseases, which can truly reflect the comprehensive disease resistance of sugarcane leaves when infected by a variety of leaf diseases, and better meet the actual needs of breeders in sugarcane breeding. The present invention has a wide range of applications and is applicable to all types of sugarcane germplasm materials, including varieties, wild resources, innovative germplasms, etc., and is applicable to both newly planted sugarcane and ratoon sugarcane. DETAILED DESCRIPTION

[0022] 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.

[0023] As climate and environmental conditions change, sugarcane diseases occur frequently, seriously affecting sugarcane yield and quality. Therefore, cultivating new disease-resistant varieties is one of the important goals of sugarcane breeding. To cultivate new disease-resistant varieties, it is necessary to establish a simple and reliable method for identifying and evaluating sugarcane disease resistance, and select disease-resistant germplasm from a large number of germplasm resources for hybrid breeding.

[0024] Embodiment 1

[0025] A field leaf disease resistance identification system for large quantities of sugarcane germplasm mainly includes three functional units: a plant grading unit, a disease calculation unit and a resistance evaluation unit.

[0026] Specifically, the plant classification unit is used to classify the disease susceptibility level of the main functional leaves of the sugarcane sample to be tested according to the preset sugarcane leaf disease category, the preset sugarcane leaf disease susceptibility classification and symptom description. The disease calculation unit is used to obtain the disease index of the sugarcane plant according to the disease susceptibility level of the sugarcane leaf sample to be tested. The resistance evaluation unit is used to obtain the disease resistance level and comprehensive disease resistance level of the sugarcane plant leaf according to the disease index and the preset resistance evaluation system.

[0027] Specifically, the preset sugarcane leaf disease grading and symptom description divides the disease susceptibility level according to the degree of occurrence of sugarcane leaf lesions and the infected leaves.

[0028] Specifically, in the condition calculation unit, the calculation method of the condition index includes:

[0029] Disease index = Σ(number of plants of each disease level × the level of that level) / (total number of plants surveyed × the highest level) × 100.

[0030] Embodiment 2

[0031] A method for identifying resistance to leaf diseases of large quantities of sugarcane germplasm in the field mainly comprises the following steps:

[0032] First, according to the preset sugarcane leaf disease categories, preset sugarcane leaf disease grading and symptom descriptions, the main functional leaves of the sugarcane samples to be tested are divided into disease susceptibility levels. Specifically, the disease susceptibility levels are divided according to the occurrence degree of sugarcane leaf lesions and the infected leaves.

[0033] Then, according to the disease susceptibility level of the sugarcane sample to be tested, the disease index of the sugarcane plant is obtained. Specifically, the disease index = Σ(number of plants of each disease level × the level of the level) / (total number of plants surveyed × the highest level) × 100.

[0034] Finally, based on the disease index and the preset resistance evaluation system, the disease resistance level and comprehensive disease resistance level of the sugarcane plant leaves were obtained.

[0035] Embodiment 3

[0036] This embodiment uses a specific example to specifically illustrate the identification method of the present invention.

[0037] For the planting of materials (samples) to be evaluated, healthy sugarcane seed stems are taken for conventional field planting. The sugarcane planting time is usually February each year, with a row length of 1.5m to 4m and a row width of 1.1 to 1.5m.

[0038] The first step is to classify the disease susceptibility level of the main functional leaves of the sugarcane sample to be tested according to the preset sugarcane leaf disease categories, the preset sugarcane leaf disease susceptibility classification and symptom description. Specifically, the disease susceptibility level is classified according to the occurrence degree of sugarcane leaf lesions and the infected leaves.

[0039] Specifically, from August to October, that is, 6 to 8 months after planting (sugarcane is in a rapid growth period at this time, most leaf diseases are prevalent at this time, and at the same time, the height of sugarcane plants is suitable and easy to observe). The occurrence of sugarcane leaf diseases is investigated. In this embodiment, five disease categories are selected, namely yellow spot disease, brown spot disease, brown streak disease, rust disease, and ring spot disease. However, in actual operation, the above five diseases are not limited, but the disease categories can be adjusted according to actual needs. However, the subsequent disease classification and symptom description can refer to the present invention. 5 to 10 plants are investigated for each material, and +1 to +5 leaves are investigated for each plant (because +1 to +5 leaves have a greater impact on the photosynthesis of the plant). The experiment is repeated 3 times. According to the sugarcane leaf susceptibility classification and symptom description in Table 1, the investigated plants are classified and graded for susceptibility levels.

[0040] Table 1 Disease classification and symptom description of sugarcane leaves

[0041]

[0042] The second step is to calculate the disease index of the sugarcane plants based on the leaf disease susceptibility level assessment results of the sugarcane samples to be tested.

[0043] Specific operation: Based on the disease grading data of the 5 sugarcane plants obtained above, the disease index of the sugarcane germplasm is calculated according to the following formula:

[0044] Disease index = Σ(number of plants at each disease level × the level of that level) / (total number of plants surveyed × the highest level) × 100

[0045] The third step is to obtain the disease resistance level and comprehensive disease resistance level of the sugarcane plant leaves according to the disease index and grade assessment results and the preset resistance evaluation system.

[0046] Specifically, the average disease index of three replicate sugarcane plants was calculated, and the disease resistance level and comprehensive disease resistance level of sugarcane plant leaves were divided according to the classification and comprehensive disease resistance identification of sugarcane germplasm leaves in Table 2.

[0047] Table 2 Classification and comprehensive disease resistance identification of sugarcane germplasm leaves

[0048] Leaf disease resistance level Disease index (%) Comprehensive disease resistance 0 0 immunity 1 ≤10.0 High resistance 2 10.1～15.0 Disease resistance 3 15.1～20.0 Zhongkang 4 20.1～25.0 Medium 5 25.1～30.0 Infection 6 >30.0 High Sensitivity

[0049] According to the method, the field disease resistance identification of leaf diseases of large quantities of sugarcane germplasm resources can be completed quickly. Most importantly, the evaluation of the disease resistance of sugarcane leaves in the invention integrates a variety of leaf diseases, which can truly reflect the comprehensive disease resistance of sugarcane leaves after being infected by a variety of leaf diseases, and better meet the actual needs of breeders in sugarcane breeding. The invention has a wide range of applications and is applicable to all types of sugarcane germplasm materials, including varieties, wild resources, innovative germplasms, etc., and is applicable to both newly planted sugarcane and perennial sugarcane.

[0050] Embodiment 4

[0051] This embodiment uses a specific example to specifically illustrate the technical effect of the method of the present invention.

[0052] 1. Test materials

[0053] 171 Yunrui sugarcane innovative germplasms and 3 sugarcane cultivars (as controls).

[0054] 2. Experimental design and climate data of the experimental site

[0055] The field experiment was a randomized block with 3 replicates, 1 row / germplasm / replicate, 1.5m long and 1.1m wide. The experimental site is located in Longchuan County, Dehong Prefecture, Yunnan Province (24.0°N, 90°E), with a subtropical monsoon climate, an average annual temperature of 18.9℃, 2316h of sunshine per year, an average annual rainfall of 1595mm, an average annual rainfall day of 166d, and an average annual relative humidity of 79%. The high temperature and heavy rainfall from July to October are conducive to the occurrence and spread of sugarcane leaf diseases.

[0056] 3. Leaf disease investigation

[0057] The leaf diseases (yellow spot, brown spot, brown streak, rust, ring spot, etc.) of the test materials were investigated 6 months after planting. The sugarcane plants were not too tall at this stage, so it was easy to observe the disease spots. Five plants were investigated for each material, and the leaf spots on leaves +1 to +5 were observed for each plant. The disease susceptibility of individual plants was graded according to Table 1 above, and then the disease index of the sugarcane germplasm material was calculated according to the disease index (DSI) calculation formula.

[0058] DSI = Σ(number of plants at each disease level × the level of the level) / (total number of plants surveyed × the highest level) × 100

[0059] Among them, Σ represents the sum; the total number of plants investigated in this experiment is 5; the highest level is 6. Finally, the disease resistance level is divided and the comprehensive disease resistance level is identified based on the calculated disease index and Table 2 above.

[0060] 4. Test results

[0061] According to the method of the present invention, the leaf comprehensive disease resistance of 171 Yunrui innovative germplasms and 3 cultivars (control) totaling 174 sugarcane germplasm materials was evaluated. Among them, 16 materials with leaf comprehensive disease resistance of level 1 were highly resistant germplasms; 23 materials with disease resistance of level 2 were disease-resistant germplasms; 39 materials with disease resistance of level 3 were medium-resistant germplasms; 30 materials with disease resistance of level 4 were medium-susceptible germplasms; 22 materials with disease resistance of level 5 were susceptible germplasms; and 45 materials with disease resistance of level 6 were highly susceptible germplasms. The specific results are shown in Table 3.

[0062] Table 3 Comprehensive disease resistance evaluation results of 174 sugarcane germplasms

[0063]

[0064]

[0065]

[0066]

[0067] The embodiments described above are only descriptions of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A field leaf disease resistance identification system for large quantities of sugarcane germplasm, characterized in that: It includes plant grading unit, disease calculation unit and resistance evaluation unit; The plant classification unit is used to classify the disease susceptibility level of the sugarcane samples to be tested according to the preset sugarcane leaf disease categories, and the preset sugarcane leaf disease susceptibility classification and symptom descriptions; The disease calculation unit is used to obtain the disease index of the sugarcane plant according to the disease susceptibility level of the sugarcane sample to be detected; The resistance evaluation unit is used to obtain the disease resistance grade and comprehensive disease resistance level of the sugarcane plant leaves according to the disease index and a preset resistance evaluation system.

2. The identification system according to claim 1, characterized in that: The preset sugarcane leaf disease susceptibility classification and symptom description divides the disease susceptibility level according to the occurrence degree of sugarcane leaf lesions and the infected leaves.

3. The identification system according to claim 1, characterized in that: In the condition calculation unit, the method for calculating the condition index includes: Disease index = Σ(number of plants of each disease level × the level of that level) / (total number of plants surveyed × the highest level) × 100.

4. A method for identifying resistance to leaf diseases in large quantities of sugarcane germplasm in the field, characterized in that: The steps include: According to the preset sugarcane leaf disease categories, preset sugarcane leaf disease grading and symptom descriptions, the sugarcane samples to be tested are classified into disease susceptibility levels; Obtaining a disease index of the sugarcane plant according to the disease susceptibility level of the sugarcane sample to be tested; According to the disease index and the preset resistance evaluation system, the disease resistance grade and comprehensive disease resistance level of the sugarcane plant leaves are obtained.

5. The identification method according to claim 4, characterized in that: The preset sugarcane leaf disease susceptibility classification and symptom description divides the disease susceptibility level according to the occurrence degree of sugarcane leaf lesions and the infected leaves.

6. The identification method according to claim 4, characterized in that: The calculation method of the disease index includes: Disease index = Σ(number of plants of each disease level × the level of that level) / (total number of plants surveyed × the highest level) × 100.

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