Application of HAES826 in breeding new macadamia cultivars with self-compatibility and high quality fruits

Abstract

The application discloses an application of a macadamia germplasm HAES826 in breeding of a new macadamia variety with self-compatibility and high-quality fruits, and belongs to the technical field of plant breeding. The application discloses that the macadamia germplasm HAES826 has excellent traits of self-compatibility and low fruit quality degradation rate of offspring, and can be used as a core breeding parent to obtain self-compatible and high-quality varieties through hybrid breeding or pure line breeding. The bagging selfing fruit setting rate of the macadamia germplasm HAES826 is greater than or equal to 0.5%, and the selfing fruit weight, total amount of unsaturated fatty acids and total amount of essential amino acids of the selfing fruits have a selfing degradation rate of less than 20%, 10% and 10%, respectively. The application can solve the problem that self-compatibility and high-quality traits are difficult to be considered in macadamia breeding, significantly shorten the breeding cycle, and cultivate varieties with reduced orchard pollination management cost, stable yield and high quality, and outstanding industrial application value.

Description

Technical Field

[0001] This invention belongs to the field of plant breeding technology, and in particular relates to the application of HAES826 in the selection and breeding of new macadamia nut varieties that are self-compatible and have high-quality fruits. Background Technology

[0002] The macadamia spp. industry has long faced problems such as low fruit set rate and large yield fluctuations due to self-incompatibility, which have hindered the stable development of the industry. Traditional solutions include setting up pollinator trees or screening for self-compatible germplasm. However, setting up pollinator trees increases the complexity of orchard management, and the effect is greatly affected by environmental factors; while the self-compatible germplasm screened by existing technologies often produces offspring with severe "self-degeneration," resulting in smaller fruits and reduced quality, making them unsuitable for direct use as superior parents and leading to low breeding efficiency.

[0003] Through systematic preliminary research, the inventors established a comprehensive evaluation method to accurately identify valuable germplasm that is not only self-compatible but also exhibits minimal decline in the quality of its self-pollinated offspring's fruit (such as single fruit weight, unsaturated fatty acid content, and essential amino acid content). Among these, germplasm HAES826 stands out. Currently, existing technologies only disclose HAES826 as a common macadamia nut variety or germplasm resource, but do not reveal its special value as a core breeding parent with self-compatibility and stable quality traits, nor its specific application methods. Applying this novel characteristic of HAES826 to targeted breeding is of great significance for rapidly cultivating new macadamia nut varieties that require no complex pollination management, have high and stable yields, and possess excellent commercial quality. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide the application of HAES826 in the breeding of new macadamia varieties that are self-compatible and have high-quality fruit. HAES826 is used as a parent to breed new macadamia varieties that are self-compatible and have high-quality fruit. This invention also provides a specific method for breeding new varieties using HAES826, so as to efficiently utilize this excellent germplasm and solve the breeding problem in the industry where self-compatibility and excellent fruit quality are difficult to achieve simultaneously.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: Application of macadamia germplasm HAES826 in the breeding of new macadamia varieties with self-compatibility and high-quality fruit.

[0006] Preferably, the HAES826 is directly bred into a self-compatible homozygous strain through continuous self-pollination screening combined with asexual reproduction.

[0007] Preferably, HAES826 is used as one of the hybrid parents and crossed with another macadamia nut variety with complementary target traits to cultivate a new hybrid variety that is self-compatible and produces high-quality fruit.

[0008] More preferably, the criteria for determining self-compatibility are: a self-pollination fruit set rate ≥ 0.5% for bagged fruits; and the criteria for determining high-quality fruits are: a self-pollination degradation rate of < 20% for single fruit weight, a self-pollination degradation rate of < 10% for total unsaturated fatty acids, and a self-pollination degradation rate of < 10% for total essential amino acids. The formula for calculating the self-pollination depression rate is: Self-pollination depression rate = [(Trait value of naturally pollinated fruit on the same plant - Trait value of self-pollinated fruit) / Trait value of naturally pollinated fruit on the same plant] × 100%.

[0009] This invention also provides a method for cultivating a new macadamia nut variety that is self-compatible and produces high-quality fruit. The method uses macadamia nut germplasm HAES826 as one of the parents and cross-pollinates it with another macadamia nut variety that has complementary target traits. The hybrid offspring are then jointly screened based on the self-pollination fruit setting rate and fruit quality. The superior single plants obtained from the screening are then asexually propagated to obtain a stable new line.

[0010] Preferably, it includes the following steps: (1) Parent selection: Using HAES826 as the female parent or male parent, select another macadamia nut variety with complementary target traits as the paired parent; (2) Artificial hybridization: During the full bloom period, the female parent is emasculated, bagged, and artificially pollinated to harvest hybrid seeds; (3) Seedling cultivation: Sow hybrid seeds and cultivate F1 generation seedlings; (4) Separation population construction and screening: Separation populations were constructed using self-crossing or backcrossing routes, and individual plants with self-compatibility and high-quality fruit were screened from them; (5) Strain breeding: Asexual reproduction of the selected superior single plants to obtain stable new strains.

[0011] More preferably, in step (4): the self-pollination segregation route is: bagging F1 generation plants for self-pollination to obtain F2 generation segregation population, and selecting target individual plants from F2 generation; the backcrossing route is: backcrossing F1 generation plants with one of the parents to obtain backcross offspring population, and selecting target individual plants from backcross offspring.

[0012] More preferably, the screening in step (4) adopts a graded screening method: first, a preliminary screening is carried out based on the self-pollination fruit setting rate ≥ 0.3%, and then a secondary screening is carried out based on the self-pollination fruit setting rate ≥ 0.5% and the fruit quality meeting the standards.

[0013] More preferably, the other macadamia nut variety with complementary target traits is Guire No. 1.

[0014] Preferably, the criteria for determining self-compatibility are: a self-pollination fruit set rate ≥ 0.5% for bagged fruits; and the criteria for determining high-quality fruits are: a self-pollination degradation rate of < 20% for single fruit weight, a self-pollination degradation rate of < 10% for total unsaturated fatty acids, and a self-pollination degradation rate of < 10% for total essential amino acids. The formula for calculating the self-pollination depression rate is: Self-pollination depression rate = [(Trait value of naturally pollinated fruit on the same plant - Trait value of self-pollinated fruit) / Trait value of naturally pollinated fruit on the same plant] × 100%.

[0015] Compared with the prior art, the present invention has the following beneficial effects: This invention is the first to clearly reveal that HAES826 is not only a self-compatible germplasm, but also a valuable breeding material with low fruit quality degradation rates in its self-pollinated offspring (single fruit weight degradation rate less than 20%, total unsaturated fatty acid degradation rate less than 10%, and total essential amino acid degradation rate less than 10%). Using HAES826 as a parent for hybridization breeding can directionally introduce its superior characteristics of "self-compatibility and low quality degradation rate" into offspring, efficiently combining multiple excellent traits and significantly shortening the breeding cycle.

[0016] The new macadamia nut variety bred using the breeding method of this invention can inherit the self-compatibility characteristics of HAES826, reduce dependence on pollinator trees, and achieve stable yield; at the same time, it maintains excellent commercial quality, solving the contradiction of "ensuring yield but not quality" in traditional self-compatibility breeding. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating the hybridization breeding process using HAES826 according to the present invention. Detailed Implementation

[0018] The macadamia nut germplasm HAES826 of this invention is disclosed in "Preliminary Construction of Core Germplasm of Macadamia Nuts" (Wu Chao, Li Zhiqiang, Tao Liang, et al. Preliminary Construction of Core Germplasm of Macadamia Nuts [J]. Tropical Agricultural Science and Technology, 2025, 48 (2):1-7. DOI:10.16005 / j.cnki.tast.2025.02.001.); the Gui Re 1 variety of this invention was independently bred by the Guangxi South Subtropical Agricultural Research Institute and has been planted on a large scale. The above germplasm or varieties can be legally obtained by those skilled in the art through public channels.

[0019] The self-pollination fruit set rate of this invention refers to the proportion of inflorescences that ultimately set fruit after self-pollination under bagging isolation conditions, out of the total number of inflorescences treated, and is used to quantify the self-compatibility of germplasm.

[0020] The calculation formula is: Self-pollination fruit set rate (%) = Number of effective fruit-setting inflorescences / Total number of inflorescences treated with bagging × 100%.

[0021] The statistical analysis was conducted after the physiological fruit drop period (approximately 8 weeks after flowering), with at least 100 inflorescences per plant and at least 3 biological replicates per germplasm.

[0022] The self-pollination degradation rate of this invention is used to quantitatively evaluate the degree of phenotypic decline of self-pollinated fruits compared to naturally cross-pollinated fruits, with naturally pollinated fruits from the same plant serving as the control benchmark.

[0023] The calculation formula is: Self-pollination depression rate (%) = [(naturally pollinated fruit trait value - self-pollinated fruit trait value) / naturally pollinated fruit trait value] × 100%.

[0024] If the trait value of self-pollinated fruit is higher than that of naturally pollinated fruit, the calculated result is negative, which is considered as no self-pollination depression of that trait.

[0025] The fruit phenotypic characteristics of this invention are determined using the following methods: Single fruit weight: 30 mature fruits with shells were randomly selected, and the weight of each fruit was measured using an electronic balance. The average value was taken.

[0026] Longitudinal and transverse diameters of kernels: Measure the maximum longitudinal and transverse diameters of kernels using vernier calipers and take the average value.

[0027] Shell thickness: Measure the thickness of the waist of the shell with vernier calipers and take the average value.

[0028] The present invention uses near-infrared spectroscopy for rapid and non-destructive determination of fruit nutritional quality traits, and simultaneously verifies the detection results of gas chromatography (fatty acid components) and automatic amino acid analysis (amino acid components), and takes the average value of parallel samples.

[0029] The measured indicators include: total crude fat, total unsaturated fatty acids, palmitic acid, oleic acid, linoleic acid content, and total essential amino acids (including 7 types: threonine, valine, methionine, isoleucine, leucine, phenylalanine, and lysine).

[0030] The self-pollination fruit set rate threshold of 0.5% in this invention is set based on the critical value for economic yield in macadamia field production. Field production data shows that when the self-pollination fruit set rate of a variety reaches 0.5% or higher, a basic economic yield can be achieved without relying on pollinator trees, demonstrating its production and application value as a self-compatible variety. This threshold also matches the measured self-pollination fruit set rate range (0.6%~1.3%) of HAES826, which is consistent with the biological characteristics of self-compatible macadamia germplasm.

[0031] The fruit quality degradation rate threshold of this invention is set based on the commercial fruit grade and core nutritional standards: Single fruit weight decline rate <20%: When the single fruit weight declines by more than 20%, the fruit size will drop below the mainstream commercial grade, and the economic value will decrease significantly. Total unsaturated fatty acid decline rate <10%, total essential amino acid decline rate <10%: Unsaturated fatty acids and essential amino acids are the core nutritional selling points of macadamia nuts. A decline of more than 10% will result in the loss of core quality advantages and will not meet the positioning of high-quality commercial fruit.

[0032] The above thresholds are all appropriately relaxed based on the measured degradation rate data of HAES826, taking into account both the rigor of the screening and the practicality of breeding practice.

[0033] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0034] Example 1 Verification of the self-fertilization characteristics of HAES826 as a parent This embodiment is used to confirm the core "self-compatibility" and "quality stability" of germplasm HAES826 as a breeding parent.

[0035] Self-pollination fruit set rate determination: Ten healthy, disease-free, mature HAES826 plants were selected. During the peak flowering period, 200 inflorescences from each plant were bagged for isolation. After the fruit matured, the average number of self-pollinated fruits within the bagged inflorescences of each plant was counted, and the self-pollination fruit set rate was calculated.

[0036] Results: The self-pollination fruit set rate of 10 HAES826 plants ranged from 0.6% to 1.3%, with an average of 0.8 ± 0.2%, which was much higher than that of ordinary self-incompatible varieties (<0.1%), proving that it has stable self-compatibility characteristics.

[0037] Quality self-pollination degradation rate determination: The self-pollinated fruits were harvested and compared with the quality of unbagged outcrossed fruits (naturally pollinated fruits) from the same plant. Single fruit weight degradation rate: The average single fruit weight of self-pollinated fruits was 6.5g, and that of outcrossed fruits was 7.1g, with a degradation rate of 8.5%. Total unsaturated fatty acid degradation rate: The average for self-pollinated fruits was 78.5%, and that for outcrossed fruits was 80.2%, with a degradation rate of 2.1%. Total essential amino acid degradation rate: The average for self-pollinated fruits was 31.5%, and that for outcrossed fruits was 33.0%, with a degradation rate of 4.5%.

[0038] Conclusion: Although the self-pollinated fruits of HAES826 showed a decline in single fruit weight, fatty acids, and amino acids, the decline rate was lower than the set thresholds (single fruit weight self-pollution decline rate <20%, total unsaturated fatty acid self-pollution decline rate <10%, total essential amino acid self-pollution decline rate <10%), and they are considered acceptable high-quality breeding parents.

[0039] Example 2 Hybrid breeding and application using HAES826 as parents This embodiment demonstrates a specific operational approach for cultivating a self-compatible new variety with high-quality fruit using HAES826, such as... Figure 1 As shown.

[0040] Parental selection: HAES826 was used as the female parent and the main cultivated variety Guire No. 1 (with weak self-compatibility, large fruit, and high yield) was used as the male parent.

[0041] Artificial hybridization and F1 generation breeding: After emasculating HAES826, it was pollinated with Guire 1 pollen, bagged, and the hybrid seeds were harvested. After sowing, 200 F1 generation seedlings were cultivated.

[0042] F2 generation self-pollination and screening: The F1 generation population was bagged and self-pollinated, and preliminary screening was conducted based on a self-pollination fruit set rate ≥0.3%. The selected F1 generation self-pollinated fruits (F2 generation) were sown to obtain approximately 500 F2 generation segregating plants. All F2 generation plants were bagged and self-pollinated, and a second screening was conducted based on a self-pollination fruit set rate ≥0.5%, selecting 22 plants for the next round of testing.

[0043] Fruit quality screening: The self-pollinated fruits of the above 22 compatible plants were measured. Among them, the self-pollinated single fruit weight of 8 plants reached or exceeded 6.5g (deterioration rate <20%), the total unsaturated fatty acid content was higher than 78% (total unsaturated fatty acid degradation rate <10%), and the total essential amino acid content was higher than 30% (total essential amino acid degradation rate <10%). The 3 plants with the best overall traits were selected, and their specific traits are shown in Table 1: Table 1. Comprehensive traits of three superior offspring selection lines

[0044] The data in the table above shows that the self-pollination fruit setting rate of the three selected lines all reached 0.9%~1.2%, and the degradation rate of each quality was lower than the set threshold. Among them, GHR826-15 had the best overall performance, with an average single fruit weight of 7.2g, a self-pollination fruit setting rate of 1.2%, and an unsaturated fatty acid content of 79.5%.

[0045] Example 3 Direct breeding of self-compatible strains This embodiment demonstrates the pathway for directly cultivating self-compatible lines from HAES826 through a combination of self-pollination selection and asexual reproduction.

[0046] Twenty mature HAES826 plants were selected and self-pollinated under bagging during their peak flowering period to harvest self-pollinated seeds (S1 generation). The S1 generation seeds were sown, and the resulting S1 generation plants were self-pollinated again under bagging. Individual plants with a self-pollination fruit set rate ≥0.5% were selected. After two generations of self-pollination and selection, the selected individual plants were propagated by cuttings or grafting to obtain asexual strains.

[0047] The test results showed that the self-pollination fruit setting rate of the obtained clonal lines remained stable between 0.5% and 1.0%, and the quality degradation rate was not significantly different from that of the original HAES826. It can be used as a parent for breeding new macadamia nut varieties that are self-compatible and have high-quality fruits.

[0048] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. Application of macadamia germplasm HAES826 in the breeding of new macadamia varieties with self-compatibility and high-quality fruit.

2. The application according to claim 1, characterized in that, The HAES826 strain was directly bred into a self-compatible homozygous line through continuous self-pollination screening combined with asexual reproduction.

3. The application according to claim 1, characterized in that, Using HAES826 as one of the hybrid parents, it was crossed with another macadamia nut variety with complementary target traits to cultivate a new hybrid variety that is self-compatible and produces high-quality fruit.

4. The application according to any one of claims 1 to 3, characterized in that, The criteria for determining self-compatibility are: a fruit set rate of ≥0.5% for bagged self-pollination; and the criteria for determining high-quality fruit are: a self-pollination degradation rate of <20% for single fruit weight, a self-pollination degradation rate of <10% for total unsaturated fatty acids, and a self-pollination degradation rate of <10% for total essential amino acids. The formula for calculating the self-pollination depression rate is: Self-pollination depression rate = [(Trait value of naturally pollinated fruit on the same plant - Trait value of self-pollinated fruit) / Trait value of naturally pollinated fruit on the same plant] × 100%.

5. A method for breeding a new macadamia nut variety that is self-compatible and produces high-quality fruit, characterized in that, Using macadamia germplasm HAES826 as one of the parents, it was cross-pollinated with another macadamia cultivar with complementary target traits. The hybrid offspring were jointly screened based on the self-pollination fruit setting rate and fruit quality. The superior single plants obtained from the screening were then propagated asexually to obtain stable new lines.

6. The method according to claim 5, characterized in that, Includes the following steps: (1) Parent selection: Using HAES826 as the female parent or male parent, select another macadamia nut variety with complementary target traits as the paired parent; (2) Artificial hybridization: During the full bloom period, the female parent is emasculated, bagged, and artificially pollinated to harvest hybrid seeds; (3) Seedling cultivation: Sow hybrid seeds and cultivate F1 generation seedlings; (4) Segregation population construction and screening: Segregation populations were constructed using self-crossing or backcrossing routes, and individual plants with self-compatibility and high-quality fruit were screened from them; (5) Strain breeding: Asexual reproduction of the selected superior single plants to obtain stable new strains.

7. The method according to claim 6, characterized in that, In step (4): the self-pollination segregation route is: bagging F1 generation plants for self-pollination to obtain F2 generation segregation population, and selecting target individual plants from F2 generation; the backcrossing route is: backcrossing F1 generation plants with one of the parents to obtain backcross offspring population, and selecting target individual plants from backcross offspring.

8. The method according to claim 6, characterized in that, The screening in step (4) adopts a graded screening method: first, the self-pollination fruit setting rate ≥0.3% is used as the standard for preliminary screening, and then the self-pollination fruit setting rate ≥0.5% and the fruit quality meets the standard for secondary screening.

9. The method according to any one of claims 5 to 8, characterized in that, Another macadamia nut variety with complementary target traits is Guire No.

1.

10. The method according to claim 5, characterized in that, The criteria for determining self-compatibility are: a fruit set rate of ≥0.5% for bagged self-pollination; and the criteria for determining high-quality fruit are: a self-pollination degradation rate of <20% for single fruit weight, a self-pollination degradation rate of <10% for total unsaturated fatty acids, and a self-pollination degradation rate of <10% for total essential amino acids. The formula for calculating the self-pollination depression rate is: Self-pollination depression rate = [(Trait value of naturally pollinated fruit on the same plant - Trait value of self-pollinated fruit) / Trait value of naturally pollinated fruit on the same plant] × 100%.

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