New dragon fruit sterile line variety breeding method

Abstract

The invention discloses a new dragon fruit sterile line variety breeding method, and belongs to the technical field of plant breeding. The method comprises the following steps: pollinating and hybridizing a target female parent by using pitaya pollen with complex ploidy, and harvesting fruits; sowing the seeds and raising seedlings to obtain seedlings; measuring chromosome ploidy of seedling cotyledons, and screening triploid, pentaploid, 3n + x, 4n + x and 5n + x pitaya offspring; the screened seedlings are strengthened and then grafted to mature old rootstocks; and when the group blooms, obtaining a pollen-dead strain, namely the male sterile line of the pitaya. According to the method, dragon fruit pollen with complex ploidy is selected for hybridization, a dragon fruit male sterile line is bred through specific hybridization screening and other steps, and a new line with excellent characters is further obtained through pollen matching. According to the breeding method, the breeding period can be effectively shortened, the breeding efficiency is improved, and the bred new dragon fruit variety has special color and taste and is high in fruit sweetness.

Description

Technical Field

[0001] The present invention relates to the technical field of plant breeding, and in particular to a method for breeding new varieties of pitaya sterile lines. Background Art

[0002] Pitaya, also known as red dragon fruit, dragon fruit, etc., is a species of the genus Hylocereus in the Cactaceae family ( Hylocereus ) or the genus Snakehead ( Seleniereus The dragon fruit plant, known for its sweet, nutritious, and health-promoting fruits, is widely popular worldwide and enjoys high market demand. With the continuous development of the dragon fruit industry, the requirements for dragon fruit varieties are also becoming increasingly higher. Cultivating high-quality new dragon fruit varieties has become a key to the industry's development.

[0003] Currently, pitaya breeding is primarily based on conventional hybridization. Conventional hybridization requires multiple generations of hybridization, selfing, and screening, typically requiring a significant period of time to produce new varieties with stable traits. Male sterile pitaya lines are crucial in hybridization, simplifying the hybrid seed production process, shortening the production cycle, and reducing production costs. However, the frequency of male sterile pitaya plants is extremely low under natural conditions, making screening them using conventional methods extremely difficult. Previous studies have observed and screened large numbers of pitaya plants, often only finding a very small number of male sterile plants. These sterile plants may not possess desirable traits and cannot be directly used for breeding new varieties. Currently, there are no reports on the successful cultivation and application of male sterile pitaya. Therefore, developing a method for breeding new pitaya varieties with male sterile lines is crucial for promoting the development of the pitaya industry. Summary of the Invention

[0004] Based on the deficiencies of the existing technology, the present invention aims to provide a method for breeding new pitaya sterile lines to solve the problem of difficulty in breeding existing pitaya male sterile lines, thereby quickly and efficiently breeding new pitaya varieties with excellent traits.

[0005] The technical solution of the present invention mainly includes the following contents: A method for breeding new varieties of pitaya sterile lines comprises the following steps: (1) Using pitaya pollen with complex ploidy to pollinate the target female parent and harvest the fruit; (2) sowing the seeds and raising seedlings to obtain dragon fruit seedlings with changed fertility; (3) Measure the chromosome ploidy of the cotyledons of pitaya seedlings, and screen out pitaya offspring with triploid, pentaploid, 3n+x, 4n+x, and 5n+x; "n" represents a chromosome set, which contains a complete set of non-homologous chromosomes necessary for the growth, development, and inheritance of the species. "3n", "4n", and "5n" represent triploid, tetraploid, and pentaploid respectively, that is, there are 3, 4, and 5 chromosome sets in the somatic cells respectively. "x" represents the additional number of chromosomes, x ≠ 0 and x < n; taking "3n + x" as an example, the total number of chromosomes in the cells of this pitaya is increased by x chromosomes based on the triploid (3n), and its chromosome composition is not a standard integer multiple, but a non-integer variation in the number of chromosomes. (4) After strengthening the selected polyploid seedlings, graft them onto mature old rootstocks to promote the rapid maturation of the branches and achieve high-quality growth of the scions; when the population flowers, detect the pollen viability and pollen quantity, and obtain the plant lines with pollen death, that is, the male sterile lines of pitaya.

[0006] Further, in step (2), the seeds can be disinfected and then inoculated on the MS solid medium to promote seed germination. After the seedling growth is completed, transplant them to the nursery for cultivation to obtain pitaya seedlings.

[0007] Further, pollinate the male sterile lines of pitaya with the pollen of diploid pitaya to make it bear fruit, and obtain a pitaya strain with high yield, high sweetness, characteristic color and taste. Preferably, the pitaya strain can be self-crossed for multiple generations to stabilize the traits of the plants and obtain pure homozygotes, providing high-quality pure parental lines for further cross-breeding.

[0008] Further, the target female parents include diploid, diploid pitaya, etc.

[0009] Further, the diploid pitaya includes "Dahong" pitaya and "Wucihong" pitaya.

[0010] Further, the target female parents include pitaya varieties such as "Dahong" pitaya, "Wucihong" pitaya, "Meilong" pitaya, "Guilonghong" pitaya, and Brazilian red-skin pitaya.

[0011] Further, the pollen of pitaya with complex ploidy shows a complex polyploid system, and the pollen ploidy simultaneously shows multiple ploidies such as haploid, diploid, and tetraploid.

[0012] Furthermore, the complex ploidy pitaya includes the "Bird's Nest" dragon fruit. "Bird's Nest" is a tetraploid plant produced by the hybridization of the genera of Hylocereus and Hylocereus, combining some characteristics of both genera. The more common "Bird's Nest" has yellow skin and white flesh. The aforementioned Brazilian red-skinned bird's nest fruit is a pitaya variety originating from Brazil, marketed as "Brazilian red-skinned bird's nest fruit," which has red skin and white flesh.

[0013] Furthermore, the pitaya with complex ploidy also includes other pitaya varieties such as "Black Dragon" pitaya, "Thornless Red" pitaya.

[0014] Furthermore, the rootstocks include "Jindu" pitaya, "Dahong" pitaya, etc.

[0015] Beneficial effects of the present invention: The present invention can accurately screen out male sterile lines of pitaya, solves the problem of difficulty in screening male sterile lines in traditional methods, and provides effective materials for utilizing hybrid advantages of pitaya.

[0016] By rationally selecting parents, using pitaya pollen with complex ploidy to pollinate the target female parent for hybridization, and conducting rational screening and evaluation during the breeding process, the present invention can breed new pitaya sterile lines with excellent comprehensive traits. Pollination of male sterile plants can produce new pitaya lines with high sweetness, high yield, and distinctive color and taste. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 : Polyploid seedlings are grafted onto mature old rootstocks.

[0018] Figure 2 : Pollen viability detected by TTC staining. Left: Viable pollen. Right: Dead pollen, inactive pollen, and a large number of empty pollen shells.

[0019] Figure 3 : Select strains with dead pollen and pollinate pollen with diploid chromosome ploidy.

[0020] Figure 4 Seedlings derived from the hybridization of "Bird's Nest Fruit" and "Thornless Red" dragon fruits. The horizontal axis (PB450 - A) represents fluorescence intensity, which measures intracellular DNA content. A larger horizontal axis value indicates a higher cellular DNA content. The vertical axis (Count) represents the number of cells, i.e., the number of cells with a corresponding fluorescence intensity (DNA content).

[0021] Figure 5 : Results of chromosome ploidy detection of cotyledons of pitaya seedlings.

[0022] Figure 6 : Fruits obtained after pollination of sterile line F2-88. DETAILED DESCRIPTION

[0023] In order to better understand the technical content of the present invention, the present invention is further described below in conjunction with specific embodiments and drawings.

[0024] Example 1 (1) Use the pollen of the more complex "Bird's Nest Fruit" to pollinate the target female parent ("Big Red" Pitaya) and harvest the fruit.

[0025] There are a large number of seeds with incomplete embryo development in the fruit, mainly red seeds: seeds with incomplete embryo development, black seeds: seeds with complete embryo, and white seeds: no seed coat and incomplete embryo development.

[0026] (2) After the seeds are disinfected, they are inoculated on MS solid culture medium to promote seed germination. After the seedlings have grown, they are transplanted to the nursery room for cultivation to obtain dragon fruit seedlings.

[0027] (3) The chromosome ploidy of the cotyledons of pitaya seedlings was measured by flow cytometry, and triploid, pentaploid, 3n+x, 4n+x, and 5n+x pitaya offspring were screened out.

[0028] (4) After the selected polyploid seedlings are strengthened, they are grafted onto the mature old rootstock of "Jindu" dragon fruit ( Figure 1 ), promote rapid aging of branches and achieve high-quality growth of scions. When the group blooms, the pollen activity and pollen quantity are detected by TTC staining, and it is found that the pollen quality of different strains is different ( Figure 2 ), pollen activity 0%-98%. Select the strains with dead pollen and pollinate with the pollen of diploid pitaya "Dahong" ( Figure 3 ), to promote its results.

[0029] (5) After fruiting, the quality of the fruits of each strain was measured, and strains with a central sweetness greater than 22% Brix and a yield of more than 8,000 jin / mu were obtained.

[0030] Example 2 (1) Use the pollen of “Bird’s Nest Fruit” with more complex ploidy to pollinate “Thornless Red” dragon fruit and harvest the fruit.

[0031] There are a large number of seeds with incomplete embryo development in the fruit, mainly red seeds: seeds with incomplete embryo development, black seeds: seeds with complete embryo, and white seeds: no seed coat and incomplete embryo development.

[0032] (2) After the seeds are disinfected, they are inoculated on MS solid culture medium to promote seed germination. After the seedlings have grown, they are transplanted to the nursery room for cultivation, and about 3,000 dragon fruit seedlings are obtained ( Figure 4 ); (3) The chromosome ploidy of the cotyledons of pitaya seedlings was measured by flow cytometry, and triploid, pentaploid, 3n+x, 4n+x, and 5n+x pitaya offspring were screened out. Figure 5 The results of chromosome ploidy detection of some cotyledons of pitaya seedlings are shown.

[0033] (4) The selected offspring seedlings were grafted onto sufficiently mature "Jindu" dragon fruit rootstocks to promote rapid aging of the seedlings and achieve high-quality growth of the scion. When the group bloomed, the pollen activity and pollen quantity were detected using the TTC staining method. The lines with dead pollen were selected and pollinated with pollen from the diploid dragon fruit "Wuxihong" to promote fruiting.

[0034] (5) After fruiting, the quality of the fruits of each strain was measured, and strains with a central sweetness greater than 22% Brix and a yield of more than 8,000 jin / mu were obtained.

[0035] Example 3 (1) Use the pollen of the more complex "Bird's Nest Fruit" to pollinate the target female parent ("Big Red" Pitaya) and harvest the fruit.

[0036] There are a large number of seeds with incomplete embryo development in the fruit, mainly red seeds: seeds with incomplete embryo development, black seeds: seeds with complete embryo, and white seeds: no seed coat and incomplete embryo development.

[0037] (2) After the seeds are disinfected, they are inoculated on MS solid culture medium to promote seed germination. After the seedlings have grown, they are transplanted to the nursery room for cultivation to obtain dragon fruit seedlings.

[0038] (3) The chromosome ploidy of the cotyledons of pitaya seedlings was measured by flow cytometry, and triploid, pentaploid, 3n+x, 4n+x, and 5n+x pitaya offspring were screened out.

[0039] (4) After the selected polyploid seedlings are strengthened, they are grafted onto mature rootstocks of the "Dahong" pitaya to promote rapid aging of the branches. When the group blooms, the pollen activity and pollen quantity are detected using the TTC staining method. The lines with dead pollen are selected and pollinated with pollen from the diploid pitaya "Wushihong" to promote fruiting.

[0040] (5) After fruiting, the quality of the fruits of each strain was measured, and strains with a central sweetness greater than 22% Brix and a yield of more than 8,000 jin / mu were obtained.

[0041] Example 4 (1) Use the pollen of the more complex "Black Dragon" pitaya to pollinate the target female parent ("Meilong No. 1" pitaya) and harvest the fruit.

[0042] There are a large number of seeds with incomplete embryo development in the fruit, mainly red seeds: seeds with incomplete embryo development, black seeds: seeds with complete embryo, and white seeds: no seed coat and incomplete embryo development.

[0043] (2) After the seeds are disinfected, they are inoculated on MS solid culture medium to promote seed germination. After the seedlings have grown, they are transplanted to the nursery room for cultivation to obtain dragon fruit seedlings.

[0044] (3) The chromosome ploidy of the cotyledons of pitaya seedlings was measured by flow cytometry, and triploid, pentaploid, 3n+x, 4n+x, and 5n+x pitaya offspring were screened out.

[0045] (4) After the selected polyploid seedlings are strengthened, they are grafted onto mature rootstocks of the "Dahong" pitaya to promote rapid aging of the branches. When the group blooms, the pollen activity and pollen quantity are detected using the TTC staining method. The lines with dead pollen are selected and pollinated with pollen from the diploid pitaya "Wushihong" to promote fruiting.

[0046] (5) After fruiting, the quality of the fruits of each strain was measured, and the strain with a central sweetness greater than 22% Brix, a distinctive color and taste, and a yield of more than 8,300 jin / mu was obtained.

[0047] Example 5 (1) Use the pollen of the more complex “thornless red” pitaya to pollinate the target female parent (Brazilian red-skinned bird’s nest fruit) and harvest the fruit.

[0048] There are a large number of seeds with incomplete embryo development in the fruit, mainly red seeds: seeds with incomplete embryo development, black seeds: seeds with complete embryo, and white seeds: no seed coat and incomplete embryo development.

[0049] (2) After the seeds are disinfected, they are inoculated on MS solid culture medium to promote seed germination. After the seedlings have grown, they are transplanted to the nursery room for cultivation to obtain dragon fruit seedlings.

[0050] (3) The chromosome ploidy of the cotyledons of pitaya seedlings was measured by flow cytometry, and triploid, pentaploid, 3n+x, 4n+x, and 5n+x pitaya offspring were screened out.

[0051] (4) After the selected polyploid seedlings are strong, they are grafted onto mature old rootstocks of "Dahong" pitaya to promote rapid aging of branches. When the group blooms, the pollen activity and pollen quantity are detected by TTC staining. The lines with dead pollen are selected and pollinated with pollen from diploid pitaya "Wuxihong" to promote fruiting ( Figure 6 ).

[0052] (5) After fruiting, the quality of the fruits of each strain was measured, and the strains of dragon fruit with a center sweetness greater than 22% Brix, a distinctive color (orange-red with a little light brown) and a taste (pomegranate flavor) were obtained, and the yield reached more than 8,000 jin / mu.

[0053] Comparative Example 1 Pollination with the "bird's nest fruit" pitaya as the male and female parents can produce fruit, but cannot obtain a sterile line, and cannot obtain a new strain of pitaya with distinctive color and taste.

[0054] Comparative Example 2 Pollination with "Dahong" pitaya as the male and female parents can produce fruit, but cannot obtain sterile lines and new pitaya lines with distinctive color and taste.

[0055] Comparative Example 3 Hybridization using "Jindu" pitaya as the male parent and "Dahong" pitaya as the female parent can produce fruit, but cannot obtain a sterile line, and cannot obtain a new pitaya plant line with distinctive color and taste.

[0056] The above descriptions are only some embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made by those skilled in the art within the spirit and principles of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A method for breeding new varieties of pitaya sterile lines, characterized in that: The following steps are involved: (1) Using pitaya pollen with complex ploidy to pollinate the target female parent and harvest the fruit; The pitaya pollen with complex ploidy shows a complex polyploid system, and the pollen ploidy shows haploid, diploid and tetraploid at the same time; the pitaya with complex ploidy includes "bird's nest fruit" pitaya, "black dragon fruit" pitaya, and "thornless red" pitaya; (2) sowing the seeds and raising seedlings to obtain dragon fruit seedlings with changed fertility; (3) Measure the chromosome ploidy of the cotyledons of pitaya seedlings and select triploid, pentaploid, 3n+x, 4n+x, and 5n+x pitaya offspring; "n" represents a chromosome set, "x" represents the number of additional chromosomes, x ≠ 0 and x < n; (4) The selected polyploid seedlings are grafted onto mature old rootstocks after they have grown strong. When the group blooms, the pollen activity is tested to obtain the strain with dead pollen, which is the male sterile line of pitaya.

2. The method for breeding new varieties of pitaya sterile lines according to claim 1, wherein The male sterile pitaya line was pollinated with diploid pitaya pollen to induce fruiting.

3. The method for breeding new varieties of pitaya sterile lines according to claim 1, wherein The target female parent includes diploid and tetraploid pitaya.

4. The method for breeding new varieties of pitaya sterile lines according to claim 1, wherein The target mother plants include "Dahong" pitaya, "Spineless Red" pitaya, "Meilong" pitaya, "Guihonglong" pitaya, and Brazilian red-skinned bird's nest fruit.

5. The method for breeding new varieties of pitaya sterile lines according to claim 1, wherein The rootstocks include "Jindu" dragon fruit and "Dahong" dragon fruit.

Images