Method for breeding new high-quality late-mature and storage-resistant pear variety

Abstract

The application discloses a high-quality late-mature and storage-resistant pear new variety cultivation method. The method provided by the application comprises the following steps: screening a variation branch from an existing pear germplasm; then, the variation branch is propagated through grafting to obtain a new pear germplasm; the screening method of the variation branch is as follows: (1) 35 days after the flowering period, a plurality of fruits are extracted from each branch, and if the fruit transcription level relative values of all the fruits extracted from a branch are all greater than or equal to 2, the branch is marked as a target branch; (2) in the fruiting period, a plurality of mature fruits are obtained from the marked target branch, and the stone cell content and the pulp solid content of the fruits are detected respectively; if the fruit stone cell content relative values of all the fruits extracted from a branch are all less than or equal to 80% and the pulp solid content relative values are all greater than or equal to 110%, the branch is a variation branch. The inventors of the application create two pear new varieties 'Shannong Su pear' and 'Shannong Su pear No. 1', and provide the high-quality late-mature and storage-resistant pear new variety cultivation method.

Description

Breeding Methods for High-Quality, Late-Maturing, Storage-Resistant Pear Varieties Technical Field

[0001] This invention relates to a method for cultivating a new high-quality, late-maturing, and storage-resistant pear variety. Background Technology

[0002] Pears are the second largest deciduous fruit tree species in my country and a major fruit supplied year-round, accounting for more than 60% of the world's cultivation area and output. Pears are a healthy fruit that can quench thirst, relieve dryness, stop coughs, and resolve phlegm, making them both food and medicine. Among northern deciduous fruit trees such as apples, pears, peaches, grapes, dates, and apricots, pears are one of the tree species with the strongest salt and alkali resistance, making them the preferred fruit tree species for high-quality development and efficient utilization of saline-alkali land in the Yellow River Basin.

[0003] In the 1980s, the ratio of early, mid, and late-maturing pear varieties in my country was 7:23:70, indicating an overemphasis on late-maturing varieties and a relative lack of high-quality early-maturing varieties. Therefore, developing new high-quality early and mid-maturing pear varieties became a crucial goal in my country's pear breeding program. Through the combined efforts of 40 breeding institutions and generations of resource breeding experts, significant breakthroughs were achieved. Pear varieties such as 'Apple Pear', 'Twentieth Century', 'Ya Pear', 'Chi Pear', 'Dangshan Crisp Pear', 'Korla Fragrant Pear', 'New Century', 'Early Crisp Pear', and 'Snowflake Pear' were identified as key parents for improving pear quality and maturity. Among the 265 varieties with clearly defined fruit maturity periods, early, mid, and late-maturing pear varieties accounted for 25%, 44%, and 31%, respectively, representing a historic shift in the variety structure and completely resolving the problem of an overemphasis on late-maturing varieties and a relative lack of high-quality early and mid-maturing varieties.

[0004] Despite significant progress in the breeding of high-quality, early-maturing pear varieties in my country, making outstanding contributions to the optimization and adjustment of the pear industry's varietal structure, the main pear varieties currently cultivated in my country are still traditional local famous varieties such as 'Dangshan Crisp Pear' and 'Ya Pear,' which suffer from the problem of "late-maturing but not high-quality." This not only limits the profit margins for growers and distributors but also fails to meet the demands of high-end consumers, representing a bottleneck restricting the high-quality and efficient development of my country's pear industry. Therefore, further adopting a technical approach combining hybridization breeding and bud mutation selection to breed high-quality, late-maturing, and storage-resistant pear varieties is of great significance for promoting the high-quality and efficient development of my country's pear industry. Summary of the Invention

[0005] The purpose of this invention is to provide a breeding method for a new high-quality, late-maturing, and storage-resistant pear variety.

[0006] This invention provides a pear breeding method, comprising the following steps:

[0007] Mutant branches are selected from existing pear germplasm; then, the mutant branches are propagated through grafting to obtain new pear germplasm.

[0008] The method for screening mutant branches includes the following steps:

[0009] (1) 35 days after the full bloom, several fruits were taken from each branch, and the relative transcription level of specific DNA molecules in the pulp of each fruit was tested. The average relative transcription level of all fruits was used as reference 1, and the relative value of each fruit was calculated, which is the relative value of the fruit transcription level. If the relative value of the fruit transcription level of all fruits taken from a certain branch is ≥2, the branch is marked as the target branch.

[0010] (2) During the peak fruiting period, several mature fruits were obtained from the target branches marked in step (1), and the content of stone cells in the pulp and the content of solids in the pulp were tested respectively. The average value of the stone cell content in the pulp of all fruits was used as reference 1 to obtain the relative value of each fruit, which is the relative value of the stone cell content of the fruit. The average value of the solids in the pulp of all fruits was used as reference 1 to obtain the relative value of each fruit, which is the relative value of the solids in the pulp. If the relative value of the stone cell content of all fruits extracted from a certain branch is ≤80% and the relative value of the solids in the pulp is ≥110%, the branch is the target branch, i.e., the variant branch.

[0011] The specific DNA molecule is shown as Sequence 1 in the sequence listing.

[0012] Specifically, the branches referred to are the main branches.

[0013] Specifically, the specific DNA molecule is shown at positions 939-1112 in sequence 1 of the sequence listing.

[0014] The specific steps for detecting the relative transcription level of specific DNA molecules in fruit pulp are as follows: extract total RNA from the fruit pulp and reverse transcribe it to obtain cDNA; use the cDNA as a template and detect the relative transcription level of specific DNA molecules by real-time PCR.

[0015] The specific steps for detecting the relative transcription level of specific DNA molecules in fruit pulp are as follows: extract total RNA from the fruit pulp and reverse transcribe it to obtain cDNA. Using cDNA as a template and the Actin gene as an internal reference gene, the relative transcription level of specific DNA molecules is detected by real-time PCR.

[0016] Specifically, quantitative real-time PCR was performed using the iCycler iQ5 system and SYBR Green PCR Master Mix, and the relative transcriptional level data of specific DNA molecules were output using Bio-Rad CFX Manager 3.1 software.

[0017] In quantitative real-time PCR, the primer pair used to amplify specific DNA molecules consists of single-stranded DNA molecules shown in Sequence 2 of the sequence listing and single-stranded DNA molecules shown in Sequence 3 of the sequence listing.

[0018] In quantitative real-time PCR, the primer pair used to amplify the internal reference gene consists of a single-stranded DNA molecule as shown in Sequence 4 of the sequence listing and a single-stranded DNA molecule as shown in Sequence 5 of the sequence listing.

[0019] Specifically, the existing pear variety is the 'Shannongsu' pear.

[0020] Specifically, the existing pear germplasm is the grafted tree of 'Shannongsu' pear, that is, the rootstock is Pyrus pyrifolia and the scion is 'Shannongsu' pear.

[0021] The breeding objective is to obtain pear germplasm with reduced stone cell content and increased pulp solids content.

[0022] This invention also protects the application of 'Shannong Crisp Pear No. 1' in pear breeding; the breeding objective is to obtain pear germplasm with reduced stone cell content and increased pulp solids content.

[0023] This invention also protects the application of 'Shannong Crisp Pear No. 1' in the preparation of pears with reduced stone cell content and increased pulp solids content.

[0024] This invention also protects a method for preparing pear germplasm with reduced stone cell content and increased pulp solids content, comprising the following steps: asexually propagating 'Shannong Crisp Pear No. 1' to obtain pear germplasm with reduced stone cell content and increased pulp solids content.

[0025] Specifically, the asexual reproduction mentioned is grafting.

[0026] Specifically, the asexual reproduction mentioned is tissue culture.

[0027] Specifically, the solid content mentioned above refers to the soluble solid content.

[0028] This invention also protects a method for preparing pear products, comprising the following steps: using mature fruits of the 'Shannong Crisp Pear No. 1' plant as raw materials to prepare pear products.

[0029] Specifically, the pear processed product is pear juice.

[0030] The full name of any of the above-mentioned 'Shannong Crisp Pear No. 1' is White Pear (Pyrus bretschneideri) Shannong Crisp Pear No. 1. White Pear Shannong Crisp Pear No. 1 was deposited on April 10, 2023, at the China General Microbiological Culture Collection Center (CGMCC, address: No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences), with accession number CGMCC NO. 45558.

[0031] The inventors of this invention have created two new pear varieties, 'Shannong Crisp Pear' and 'Shannong Crisp Pear No. 1', and provided a breeding method for high-quality, late-maturing, and storage-resistant pear varieties. Attached Figure Description

[0032] Figure 1 shows the relative transcription levels of specific DNA molecules in 'Shannong Crisp Pear No. 1' and other germplasms.

[0033] Figure 2 shows exemplary photographs of sclereid histochemical localization of 'Shannong Crisp Pear No. 1' and other germplasms.

[0034] Figure 3 shows the results of detecting the stone cell content in the pulp of 'Shannong Crisp Pear No. 1' and other germplasms.

[0035] Figure 4 shows the results of sugar content determination for 'Shannong Crisp Pear No. 1' and other germplasms. Detailed Implementation

[0036] The present invention will now be described in further detail with reference to specific embodiments. The given embodiments are merely illustrative of the invention and not intended to limit its scope. The embodiments provided below can serve as a guide for further improvements by those skilled in the art and do not constitute a limitation on the invention in any way.

[0037] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following embodiments are commercially available. Unless otherwise specified, the quantitative experiments in the following embodiments are all performed in triplicate, and the results are averaged.

[0038] The 'Dangshan Su' pear is recorded in the following literature (i.e., Dangshan Su pear in the literature): Wang Bin, Zhang Nan et al. Effects of bagging on stone cell development and lignin metabolism in Dangshan Su pear fruit, Journal of Horticulture, 2013, 40(03): 531-539.

[0039] The 'Xinli No. 7' pear is recorded in the following literature (i.e., Xinli No. 7 in the literature): Zhang Shoushi, Qiao Baoying et al., Introduction performance and cultivation techniques of Xinli No. 7 in Zhengzhou, Deciduous Fruit Trees, 2020, 52(03):31-32.

[0040] The parental combination of 'Xinli No. 7' pear is Korla fragrant pear (Xinjiang pear, P. sinkiangensis Yu) × Zaosu pear. The parent of Zaosu pear is apple pear (P. pyrifolia Burm.) × Shenzhibu. It has been verified that Shenzhibu is a hybrid offspring of European pear (P. communis L.) and white pear (P. bretschneideri Rehd.). Therefore, 'Xinli No. 7' pear contains the bloodline of four species of the genus Pyrus: Xinjiang pear, sand pear, European pear, and white pear. For the tracing of the parental lineage of 'Xinli No. 7' pear, see the literature: Chen Xuesen et al., Genetic Improvement and Enhancement Practice of Fruit Quality in Major Fruit Trees, Chinese Agricultural Science, 2015, 48(17):3524-3540.

[0041] The method for detecting the stone cell content in fruit pulp is as follows:

[0042] (1) Take the fruit, remove the peel, and use the quartering method to take 50g of pulp;

[0043] (2) Place the pulp obtained in step (1) in a -20℃ freezer for 24 hours, then thaw at room temperature, then homogenize at 22000r / min for 3 minutes, then transfer to a 1000ml beaker, stir evenly, let stand for 5 minutes and then discard the upper liquid phase, retain the precipitate, and wash repeatedly 5 times.

[0044] (3) After completing step (2), filter with 100-mesh nylon cloth, collect the precipitate, dry at 60°C to constant weight, weigh, and that is the dry weight of the stone cells.

[0045] Percentage of stone cells (%) = Dry weight of stone cells (g) / Fresh weight of pulp (g) × 100%.

[0046] The method for detecting soluble solids content is as follows:

[0047] Take the fruit, remove the peel, extract the pulp from the edible part in the middle of the fruit, and squeeze out the juice; use an HMS35 digital refractometer to detect the soluble solids content of the juice, and the result is a percentage (%).

[0048] Example 1: Creation of a new germplasm for 'Shannongsu' pear

[0049] 1. Hybridization (conducted in Tarim Basin, Xinjiang)

[0050] In April 2003, pollen from 'Dangshan Su' pears was used to pollinate emasculated 'Xinli No. 7' pears, and F1 hybrid seeds were harvested. After washing the F1 hybrid seeds, they were placed in the crisper compartment of a refrigerator at 1-3℃ for about 60 days for stratification treatment (the purpose was to break the seed dormancy by meeting the chilling requirements).

[0051] 2. Greenhouse seedling cultivation (conducted in Tai'an, Shandong)

[0052] In December 2003, the F1 hybrid seeds obtained in step 1 were sown in nutrient pots containing seedling substrate (3-5 seeds per pot) and cultured until the seedlings reached a height of 8-15cm and the root collar was lignified (usually 2-3 months after sowing). Then, the seedlings were transplanted into new nutrient pots containing seedling substrate (1 seedling per pot) for further cultivation. The cultivation conditions in this step were: 25℃, 12 hours of light per day (light intensity 3000 lx), and 40-50ml of nutrient solution (the stock solution of macro-elements in MS basic medium diluted with water to 10 times the volume) every 7-10 days from the start of seed germination, for each nutrient pot.

[0053] 3. Transplanting of hybrid seedlings (conducted in Tai'an, Shandong)

[0054] In February 2004, 6000 kg of organic fertilizer (fully decomposed dairy cow manure was used in this example) was applied per mu in the seed selection nursery (field) where the seedlings were to be planted, and the nursery was watered to settle the soil. In April 2004, 860 seedlings obtained in step 2 were planted in the seed selection nursery. In April 2004, 6000 kg of organic fertilizer (fully decomposed dairy cow manure was used in this example) was applied per mu in the seed selection nursery where the seedlings were planted, and the nursery was watered in time.

[0055] 4. In 2009, plants with excellent comprehensive traits were selected from hybrid seedlings.

[0056] A single plant is called a strain, and new strains can be obtained by grafting branches from it.

[0057] The best-performing plant will be temporarily named 'Shan Nong Su' pear.

[0058] After undergoing a selection process including variety comparison trials and regional cultivation trials, the 'Shannongsu' pear was approved by the Shandong Provincial Crop Variety Approval Committee in 2015 and officially named 'Shannongsu' pear.

[0059] Characteristics of 'Shannong Crisp' pear: Large fruit size, spindle-shaped, 11cm in length and 10cm in width, with an average single fruit weight of 460g; the fruit is green when unbagged and yellow when bagged, with medium-sized lenticels; the fruit stalk is obliquely oriented and 3.5cm long; the core is small and the seeds are oval; the flesh is fine, crisp, and of excellent quality; it has a low stone cell content, does not turn brown 72 hours after being cut, and is resistant to oxidation; the fruit development period is about 180 days, and it is very late-maturing, ripening in early October in Tai'an.

[0060] 'Shannong Su' pear is China's first high-quality, storage-resistant, extremely late-maturing, and antioxidant-resistant pear variety. While maintaining the excellent traits of its parent varieties, it has a lower stone cell content. It has become a replacement variety, solving the problem of "late maturing and not high quality" in major varieties such as Dangshan Su pear. It has been widely welcomed by the market and consumers, making a significant contribution to the development of China's pear industry.

[0061] The 'Shannongsu' pear is recorded in the following literature (i.e., the Shannongsu pear mentioned in the literature): Feng Shouqian, Wang Deyun, Wang Nan, Jiang Shenghui, Xu Haifeng, Liu Jingxuan, Chen Xiaoliu, Wu Shujing, Mao Zhiquan, Chen Xuesen. New late-maturing pear variety 'Shannongsu', Journal of Horticulture, 2016, 43(S2): 2685-2686.

[0062] Example 2: Establishment of methods for the discovery and detection of molecular markers

[0063] Extensive research by the inventors revealed a correlation between bud mutations and differences in the transcriptional level of specific DNA molecules related to the stone cell content in 'Shannongsu' pear fruits. The specific DNA molecules are shown in Sequence 1 of the sequence listing. Detection revealed that the genomic DNA of 'Dangshansu' pear, 'Xinli No. 7' pear, and 'Shannongsu' pear all contained the specific DNA molecules shown in Sequence 1 of the sequence listing.

[0064] The method for detecting the relative transcription level of specific DNA molecules in fruit pulp is as follows:

[0065] 1. Collect the pulp and extract total RNA.

[0066] Total RNA was extracted using the RNAprepPure Polysaccharide and Polyphenol Plant Total RNA Extraction Kit (TIANGEN BIOTECH, BEIJING, Cat.#DP441; operated according to the instructions).

[0067] 2. Take the total RNA obtained in step 1 and perform reverse transcription to obtain cDNA.

[0068] Reverse transcription was performed using the HIScript II QRT super mix for qPCR gDNA wiper Kit (vazyme, Nanjing, China, R223-01; operated according to the instructions).

[0069] 3. Using cDNA as a template and the Actin gene as an internal reference gene, the relative transcription level of specific DNA molecules was detected by real-time PCR.

[0070] Quantitative real-time PCR was performed using the iCycler iQ5 system (Bio-Rad, Hercules, CA, USA) and SYBR Green PCR MasterMix (transgene). Relative transcriptional levels of specific DNA molecules were output using Bio-Rad CFX Manager 3.1 software.

[0071] The primers used to amplify specific DNA molecules are as follows:

[0072] PbMYB308-qPCR-F (Sequence 2 in the sequence listing): AGTGACGGTTTGAAGAGT;

[0073] PbMYB308-qPCR-R (Sequence 3 in the sequence listing): GCTTTGTAATCCAAGACC.

[0074] The primers used to amplify the internal reference gene are as follows:

[0075] PbActin-qPCR-F (Sequence 4 in the sequence listing): CCATCCAGGCTGTTCTCTC;

[0076] PbActin-qPCR-R (Sequence 5 in the sequence listing): GCAAGGTCCAGACGAAGG.

[0077] Example 3: New germplasm was obtained from 'Shannongsu' pear through bud mutation selection.

[0078] Years of breeding practice have shown that the organic combination of hybridization breeding and bud mutation selection is an effective technical approach to solving variety problems in the fruit tree industry. Therefore, bud mutation selection was carried out on the fruit characteristics of the 'Shannongsu' pear.

[0079] 1. Screening for variant branches

[0080] The target for bud mutation selection: an orchard in Guanxian County, Shandong Province, with 240 'Shannongsu' pear trees planted in the orchard; all the trees were grafted (the rootstock was all Pyrus pyrifolia and the scion was all 'Shannongsu' pear); the grafting was completed 3 years ago.

[0081] In 2018, select branches according to the following procedure (here, branches refer to main branches, which are large branches that grow directly from the central trunk of the fruit tree):

[0082] (1) Thirty-five days after full bloom, three fruits were taken from each branch, and the relative transcription level of specific DNA molecules in the pulp of each fruit was tested (see Example 2 for the method). The average relative transcription level of all fruits was used as reference 1, and the relative value of each fruit was calculated, which is the relative transcription level of the fruit. If the relative transcription level of all fruits taken from a certain branch is ≥2, the branch is designated as the target branch (marked).

[0083] (2) During the peak fruiting period, mature fruits are obtained from the target branches marked in step (1) (3 fruits are taken from each branch), and the content of stone cells and the content of solids in the pulp are tested respectively. The average value of the stone cell content in the pulp of all fruits is used as reference 1 to obtain the relative value of each fruit, which is the relative value of the stone cell content of the fruit. The average value of the solids in the pulp of all fruits is used as reference 1 to obtain the relative value of each fruit, which is the relative value of the solids in the pulp. If the relative value of the stone cell content of all fruits taken from a certain branch is ≤80% and the relative value of the solids in the pulp is ≥110%, the branch is the target branch, i.e., the variant branch.

[0084] In 2018, four mutant branches were selected (named mutant branch 1, mutant branch 2, mutant branch 3 and mutant branch 4, respectively) and marked on the fruit trees.

[0085] II. Grafting

[0086] Location: Orchard in Guanxian County, Shandong Province.

[0087] Rootstock: 3-year-old wild pear rootstock.

[0088] In 2019, branches were cut from the mutant branches as scions (each scion had 1-2 buds) and grafted onto the rootstocks, with one scion grafted onto each rootstock. Ten rootstocks were grafted onto each mutant branch.

[0089] In 2019, branches were taken from 'Shannongsu' pear trees as scions (each scion had 1-2 buds) and grafted onto rootstocks, with one scion grafted onto each rootstock. Ten rootstocks were grafted.

[0090] In 2019, branches were taken from 'Dangshan Su' pear trees as scions (each scion had 1-2 buds) and grafted onto rootstocks, with one scion grafted onto each rootstock. Ten rootstocks were grafted.

[0091] In 2019, branches were taken from the 'Xinli No. 7' pear tree as scions (each scion had 1-2 buds) and grafted onto the rootstock, with one scion grafted onto each rootstock. Ten rootstocks were grafted.

[0092] III. Comparison of Fruit Performance

[0093] Object: The grafted tree obtained in step two.

[0094] Time: 2022.

[0095] Thirty-five days after full bloom, fruits were collected from the trees (10 fruits randomly selected from each tree), and the relative transcription level of specific DNA molecules in the pulp was detected (method described in Example 2). During the peak fruiting period, mature fruits were collected from the trees (10 fruits randomly selected from each tree), and the content of stone cells and solids in the pulp was detected. The results are shown in Table 1.

[0096] Table 1

[0097]

[0098] The stone cell content of the four bud mutation lines obtained by grafting the mutant branches was significantly lower than that of the control varieties such as 'Shannongsu' pear and 'Dangshansu' pear, while the soluble solids content was significantly higher than that of the control varieties such as 'Shannongsu' pear and 'Dangshansu' pear, and the specific DNA transcription level was significantly higher than that of the control varieties such as 'Shannongsu' pear and 'Dangshansu' pear (the results are shown in Figure 1).

[0099] The bud mutation obtained by grafting mutant branch 1 produced the best fruit performance and was named 'Shannong Crisp Pear No. 1'. The fruit characteristics of 'Shannong Crisp Pear No. 1' are: well-shaped fruit, fine flesh, high soluble solids content, and superior fresh-eating quality. 'Shannong Crisp Pear No. 1' belongs to the white pear family (Pyrus bretschneideri).

[0100] Shannong Crisp Pear No. 1 was deposited on April 10, 2023, at the China General Microbiological Culture Collection Center (CGMCC, address: No. 3, No. 1 Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences), with accession number CGMCC NO. 45558.

[0101] Example 4: Detection of sclereid content and gene transcription level

[0102] The tested fruits were: mature fruits of 'Dangshan Su' plant (the grafted plant in Example 3), mature fruits of 'Shannong Su' plant (the grafted plant in Example 3), mature fruits of 'Shannong Su Pear No. 1' (the grafted plant in Example 3), mature fruits of commercially available long-stemmed pears, and mature fruits of commercially available Korla fragrant pears.

[0103] The pulp of the tested fruit was used for histochemical localization of sclereids. The method for histochemical localization of sclereids was as follows: the fruit was taken and transversely sectioned. The section was then treated with a 30% HCl aqueous solution for 1 minute, followed by staining with a 12% phloroglucinol ethanol solution for 7 minutes (the staining target was lignified cells; lignified cells would be stained red, while non-lignified cells would not be stained). The sections were then thoroughly washed with water, and photographed. An example photograph is shown in Figure 2.

[0104] The pulp of the tested fruit was collected, and the content of stone cells and solids in the pulp was measured. The results of the stone cell content are shown in Figure 3. The results of the pulp solids content are shown in Figure 4.

[0105] The pulp stone cell content of the 'Shannong Crisp Pear No. 1' germplasm is significantly lower than that of other germplasms, and the pulp solid content of the 'Shannong Crisp Pear No. 1' germplasm is significantly higher than that of other germplasms.

[0106] The present invention has been described in detail above. For those skilled in the art, the invention can be practiced in a wide range of ways with equivalent parameters, concentrations, and conditions without departing from its spirit and scope, and without requiring unnecessary experiments. Although specific embodiments have been given, it should be understood that further modifications can be made to the invention. In summary, according to the principles of the invention, this application is intended to include any changes, uses, or improvements to the invention, including changes made using conventional techniques known in the art that depart from the scope disclosed herein. Some of the essential features can be applied within the scope of the following appended claims.

Claims

1. A pear breeding method, comprising the following steps: screening mutant branches from existing pear germplasm; then propagating the mutant branches by grafting to obtain new pear germplasm; the method for screening mutant branches comprises the following steps: (1) 35 days after the full bloom, extracting several fruits from each branch, and detecting the relative transcription level of specific DNA molecules in the pulp of each fruit; using the average relative transcription level of all fruits as reference 1, calculating the relative value of each fruit, which is the relative value of the fruit transcription level; if the relative value of the fruit transcription level of all fruits extracted from a certain branch is ≥2, the branch is marked as the target branch; (2) during the full fruiting period, from step (1) Several mature fruits were obtained from the marked target branches, and the content of stone cells in the pulp and the content of solids in the pulp were detected respectively. The average value of the stone cell content in the pulp of all fruits was used as reference 1 to obtain the relative value of each fruit, which is the relative value of the stone cell content in the fruit. The average value of the solids in the pulp of all fruits was used as reference 1 to obtain the relative value of each fruit, which is the relative value of the solids in the pulp. If the relative value of the stone cell content in all fruits extracted from a certain branch is ≤80% and the relative value of the solids in the pulp is ≥110%, the branch is the target branch, i.e., the variant branch. The specific DNA molecule is shown as sequence 1 in the sequence listing.

2. The method as described in claim 1, characterized in that: The existing pear variety is the 'Shannongsu' pear.

3. The method as described in claim 1 or 2, characterized in that: The breeding objective is to obtain pear germplasm with reduced stone cell content and increased pulp solids content.

4. The application of the white pear (Pyrus bretschneideri) Shannong Su Pear No. 1 obtained by the pear breeding method of claim 1 in pear breeding; the breeding objective is to obtain pear germplasm with reduced stone cell content and increased pulp solids content; the white pear (Pyrus bretschneideri) Shannong Su Pear No. 1 has the preservation registration number CGMCC NO.45558.

5. The application of the white pear (Pyrus bretschneideri) Shannong Su Pear No. 1 obtained by the pear breeding method of claim 1 in the preparation of pear fruits with reduced stone cell content and increased pulp solid content; the white pear (Pyrus bretschneideri) Shannong Su Pear No. 1 has the preservation registration number CGMCC NO.45558.

6. A method for preparing pear germplasm with reduced stone cell content and increased pulp solids content, comprising the following steps: asexually propagating the white pear (Pyrus bretschneideri) Shannong Su Pear No. 1 obtained by the pear breeding method of claim 1 to obtain pear germplasm with reduced stone cell content and increased pulp solids content; wherein the white pear (Pyrus bretschneideri) Shannong Su Pear No. 1 has the preservation registration number CGMCC NO.45558.

7. The method as described in claim 6, characterized in that: The asexual reproduction mentioned is grafting.

8. The method as described in claim 6, characterized in that: The asexual reproduction mentioned is tissue culture.

9. A method for preparing pear processed products, comprising the following steps: using the mature fruit of the white pear (Pyrus bretschneideri) Shannong Su Pear No. 1 plant obtained by the pear breeding method of claim 1 as raw material to prepare pear processed products; wherein the white pear (Pyrus bretschneideri) Shannong Su Pear No. 1 has the preservation registration number CGMCC NO.45558.

10. The method as described in claim 9, characterized in that: The pear processed product is pear juice.

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