Method for increasing water resistance and yield of oil peony

Abstract

To provide a method for improving the water resistance of oil-based peony and increasing its production. [Solution] Using the FD variety of oil peony as the mother plant, the father plants DFG, YLC, YPH, and HFR with different affinities are selected and crossed to obtain the following hybrid combinations: (1) Close affinity: DFG x FD; (2) Medium affinity: YLC x FD; (3) Distant affinity: YPH x FD; (4) Distant affinity: HFR x FD. Furthermore, this method also includes a step of using coronatine to replace hydrophilic soaked seeds during seed germination. It has been confirmed that this method significantly improves the water resistance of oil peony and also improves the yield.

Description

[Technical field]

[0001] The present invention relates to a method for increasing the water tolerance of oil peony and at the same time increasing the yield, in particular through hybridization and seed soaking with crown ethylene (coronatine). [Background technology]

[0002] "Fengdan" is a variety of oil peony mainly cultivated in the Jiangnan region of China, and is attracting attention as a new woody oil crop. It has characteristics such as drought resistance, adaptability to poor soil, cold resistance, and shade resistance, but its root system is fleshy and sensitive to moisture, so it is classified as a plant with low water resistance. Because of the high amount of precipitation in the southern region, flooding occurs frequently and has a significant impact on the yield of "Fengdan". Every year, the yield of "Fengdan" is reduced by more than 40% due to precipitation. Especially in the Jiangnan region of China, the pod formation period of "Fengdan" overlaps with the rainy season, so the root system is submerged in water for a long period of time, which can lead to disease and even rot. In the above-ground parts, the leaves turn yellow or black, and mold develops before the fruit pods have matured. For this reason, as a fundamental solution, it is urgent to select a highly water-resistant oil peony variety and solve the problem of yield reduction due to lack of water resistance at the variety level. Developing a new water-resistant variety of "Fengdan" through crossbreeding and introducing it into production is of great significance to the development of the peony industry.

[0003] Hybridization is one of the traditional breeding methods, and because it is simple and effective, it is still used as the main method for developing new varieties. Many researchers have obtained new peony genetic resources through crossing oil peony with ornamental peony. The main breeding goals are to improve ornamental value, strengthen resistance to adverse conditions, and develop varieties for specific purposes such as cut flowers, bonsai, and oil. The breeding directions for strengthening resistance to adverse conditions are mainly heat resistance, cold resistance, drought resistance, salt resistance, heavy metal resistance, and disease and pest resistance, and there are few reports on water resistance as a breeding goal, and only evaluation of water resistance among peony varieties. Improving the water resistance of a weak variety by crossing a strong variety with a weak variety is the most effective and reliable method. However, there have been no reports of the creation of genetic resources for water resistance of "Fengdan" at home and abroad, and oil peony varieties with high water resistance are eagerly awaited in the production field.

[0004] In the present invention, through interspecific crossing between different ornamental peony varieties from the Jiangnan region of China and "Fengdan", the fruit set rate and germination rate of the hybrid seeds in different crossing combinations are verified, and a waterlogging test is carried out on the progeny and parent plants at the seedling stage. The morphological and physiological indexes of the seedlings are measured to select the progeny with excellent water resistance. The new water-resistant "Fengdan" variety obtained by this invention provides a variety resource, especially in the southern regions with high precipitation, especially in the Jiangnan region of China, solving the fundamental problems in the production of "Fengdan" and providing a resource guarantee favorable to the development of the oil peony industry.

[0005] Coronatine (COR), a compound isolated from a pseudomonosporangium derived from lilac, has a similar chemical structure to jasmonates (JAs) and many similar physiological functions. Studies have shown that COR has various physiological functions, such as regulating plant growth and development, inducing related secondary metabolites, and enhancing plant resistance to environmental stress (Xu Ruqiang, 1998; Ai Lin, 2008). For example, Qi Fuguo et al. (2006) reported that COR treatment increased the soluble protein content and reduced the relative electrical conductivity and MDA (malondialdehyde) content in wheat leaves under low temperature conditions. Ai Lin et al. (2008) found that COR treatment maintained the relative water content of rice leaves, promoted the accumulation of soluble proteins, reduced cell membrane permeability, and maintained cell membrane integrity under drought conditions.

[0006] Patent document CN201810769231 discloses a breeding method for improving the drought resistance of oil peony. In this method, an oil peony variety with excellent characteristics is selected as the mother plant, a variety with stable yield is selected as the father plant, crossed to harvest F1 seeds, and the F1 is cultivated and mixed harvested to obtain F2 seeds. The F2 individual is crossed with the mother plant to obtain BC1 seeds, and the BC1 individual is crossed with the mother plant again to obtain BC2 seeds. Finally, the BC2 seeds are planted, self-pollination is performed for 3 to 4 generations, and the best type is selected to become a new variety of oil peony. During this process, stress agents are used to perform moisture stress treatment and inhibit the germination of seeds that are not drought tolerant, thereby reducing the occurrence of false positive drought-resistant seeds, reducing the total sample amount for crossing, and reducing the amount of work to improve breeding efficiency.

[0007] Patent document CN202010947381 discloses a method for improving the drought resistance of oil peony using methyl jasmonate. Specifically, the method involves spraying methyl jasmonate on the leaves of oil peony during cultivation, which can significantly improve the net photosynthetic rate of the leaves of oil peony, reduce the damage caused by drought stress to the peony, and enhance the resistance of the peony to drought stress. However, the above prior art has still not solved the problem of water resistance of oil peony. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] China Patent Publication CN201810769231 [Patent Document 2] China Patent Publication CN202010947381 Summary of the Invention [Problem to be solved by the invention]

[0009] In view of the above problems, the technical problem that the present invention aims to solve is to develop a new water-resistant oil peony variety, and to provide a method for improving the water resistance of the new variety and increasing the yield. [Means for solving the problem]

[0010] The present invention provides a method for improving water resistance and increasing yield of oil peony, comprising the steps of: The oil peony cultivar "Houtan" FD was used as the female plant, and the male plants DFG, YLC, YPH, and HFR, which have different affinities, were selected and crossed to obtain the following cross combinations.

[0011] (1) Close affinity: DFG × FD (2) Medium affinity: YLC×FD (3) Distant affinity: YPH × FD (4) Distant affinity: HFR × FD The method of the present invention further includes an alternative treatment to hydrophilic soaking with coronatine during seed germination.

[0012] The concentration of the coronatine is 0.1 μmol / L to 0.5 μmol / L. The present invention also provides a use of coronatine for improving the water resistance of oil peony, wherein the concentration of coronatine is 0.1 μmol / L-0.5 μmol / L. Effect of the Invention

[0013] The new oil peony variety obtained by the method of the present invention exhibits water resistance during the rainy season and maintains a high yield when fruiting. [Brief description of the drawings]

[0014] [Figure 1] Phenotypic changes in tree peony following flooding treatment (from left to right: FD Fengdan seedlings, YPH×FD hybrid progeny, YLC×FD hybrid progeny). [Diagram 2] Measurement results of sucrose synthase (SS), a physiological index of peony hybrid progeny under flood stress. Different lowercase alphabets on a short grid indicate statistically significant differences at the P<0.05 level between different plantings within the same treatment time (n=3, same below). [Diagram 3] Measurement results of plant α-amylase, a physiological indicator of peony hybrid progeny, under flood stress. [Figure 4] Measurement results of plant alcohol dehydrogenase (ADH), a physiological indicator of peony hybrid progeny, under flood stress. [Diagram 5] Measurement results of plant pyruvate decarboxylase (PDC), a physiological indicator of peony hybrid progeny, under flood stress. [Figure 6] Measurement results of plant soluble protein (s-protein), a physiological indicator of peony hybrid progeny under flood stress. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The present invention will be further described below with reference to specific examples. Coronatine (hereafter abbreviated as "COR") is a compound isolated in 1977 from the culture medium of Psudomonas syringae pv. Atropurpurea, which causes disseminated yellows in many plants.

[0016] COR has a structure and function similar to jasmonic acid (JA), with a molecular formula of C18H25NO4 and a molecular weight of 319.4 Da. COR is composed of coronamic acid (CMA) containing α-amino acid and coronafasic acid (CFA) with a polyketone structure linked by an amide bond, and has an alkane structure similar to methyl jasmonate (hereinafter abbreviated as "JA-Me"), as shown in chemical formula 1. In addition, the activity of COR is much higher than that of JA. COR stimulates the secondary metabolism of plants, promotes the production of various plant toxins, and is involved in regulation under adverse conditions. Its mode of action is similar to that of JA. According to one invention, both JA and COR have the effect of improving the drought resistance of sorghum seedlings, and COR has been shown to be more effective than JA. It has been found that the regulating effect of COR has a certain dose effect, promoting plant growth at low concentrations and suppressing growth at high concentrations.

[0017] The structural formula of coronatine is: chemical formula 1 JPEG0007670918000002.jpg4999

[0018] Coronatine in the present invention can be obtained by industrial fermentation production (e.g., ZL200510011466.2; ZL200510085280.1; ZL200710099033.6; ZL200810119153.2). It can also be purchased directly from chemical manufacturers, for example, Sigma product number C8115, and stored in a freezer at -20°C. Before use, prepare a 1 mmol / L solution with double distilled water, and dilute with tap water or field water when in use.

[0019] The concentration of coronatine used in the present invention is suitably 0.05 to 1 μmol / L, and a concentration of 0.1 to 0.5 μmol / L provides particularly excellent effects.

[0020] Working Example 1. Materials and Methods 1.1 Test materials The test material, “Fengdan” (hereafter referred to as FD), is a 10-year-old sapling introduced from Tongling City, Anhui Province. The ornamental peonies “Yipinhong” (hereafter referred to as YPH), “Yulouchun” (hereafter referred to as YLC), “Hongfulong” (hereafter referred to as HFR) and “Dafugui” (hereafter referred to as DFG) from the Jiangnan region of China are varieties cultivated in Zhejiang Province, China, with pink and red flower colors and chrysanthemum, crown and pavilion flower shapes.

[0021] 1.2 Hybridization Based on the affinity between peony varieties in the Jiangnan region of China, the following hybrid combinations were selected. The main combinations are as follows:

[0022] (1) Close affinity: DFG × FD (2) Medium affinity: YLC×FD (3) Low affinity: YPH×FD, HFR×FD

[0023] 1.3 Method This is done between 9:00 and 11:00 a.m. on a sunny day. At the end of March, one or two days before flowering, the flower buds start to color and the petals start to open slightly. Select the mother plant in the first blooming stage, remove the stamens, and cover it with a bag. At the beginning of April, when the stamens of the father plant mature and the pollen starts to scatter, collect the pollen with tweezers and place it in a test tube containing a desiccant. Take a small amount of pollen with a cotton swab and apply it to the stigma of the mother plant, from which the stamens have already been removed, for artificial pollination. After pollination, cover it with the bag again and secure the bottom with a clip to prevent pollination by insects. Seven days after artificial pollination, remove the bag and expose it to natural light. Harvest the fruit pods when they change from green to crab yellow between July 30 and August 5. Dry the harvested fruit pods in a dark place indoors while ensuring ventilation for about a week, and after they have completely split open, remove the seeds by hand. The number, weight and fruit set rate (number of fruit pods / 100 number of pollinated seeds) of the seeds are recorded, the extracted seeds are soaked in water for 24 hours before sowing, the number of germinations for each combination is recorded and the germination rate (number of germinations / 100 number of seeds sown) is calculated.

[0024] Furthermore, to confirm whether seed soaking with different concentrations of methyl jasmonate and coronatine could induce water resistance, different concentrations of methyl jasmonate or coronatine were used to replace water soaking. The concentrations of methyl jasmonate and coronatine were 0.1 μmol / L, 0.5 μmol / L, and 1.0 μmol / L, and the test subjects were YLC×FD.

[0025] 1.4 Water resistance analysis Select the hybrid progeny with full seeds and the seeds of the parent plant, and sow them in 90 mm bicolor pots. When the seedlings develop two leaves, they are transplanted, one plant per pot, and cultivated outdoors for two months. Then, select seedlings with uniform growth conditions and conduct a submersion test. Place the potted seedlings in an aquarium, irrigate with water until the soil is submerged by 2 cm, and observe continuously for one week. Investigate morphological indicators such as plant height, root system length, and root crown ratio, and measure the relative chlorophyll content. In addition, collect the top leaves as test materials and use them to measure physiological indicators related to flood stress (sucrose synthase (SS), pyruvate decarboxylase (PDC), alcohol dehydrogenase (ADH), α-amylase (RAMY) activity, and soluble protein (PRO) content). Finally, collect each data, comprehensively evaluate the water resistance of the hybrid progeny and parent plant, and select the hybrid progeny with strong water resistance.

[0026] 1.5 Methods for measuring the above enzymes and proteins Sucrose synthase (SS): Measured using the Sucrose Synthase ELISA Detection Reagent Kit from Jianglai Biotechnology Co., Ltd.

[0027] Pyruvate decarboxylase (PDC): Measured using the plant pyruvate decarboxylase ELISA detection reagent kit from Jianglai Biotechnology Co., Ltd.

[0028] Alcohol dehydrogenase (ADH): Measured using Jianglai Biotechnology Co., Ltd.'s Plant Alcohol Dehydrogenase ELISA Detection Reagent Kit.

[0029] α-Amylase (RAMY): Measured using Jianglai Biotechnology Co., Ltd.'s plant α-amylase ELISA detection reagent kit.

[0030] Soluble protein (s-protein): Measured using Jianglai Biotechnology Co., Ltd.'s plant soluble protein ELISA detection reagent kit.

[0031] 1.6 Method for determining relative chlorophyll content Measure using a JC-YLC chlorophyll meter.

[0032] 2. Results and Analysis 2.1 Fruiting status of different hybrid combinations In order to understand the fruit set of different hybrid combinations, the number of fruit capsules and seeds harvested from each combination was investigated, and the fruit set rate was calculated in combination with the number of pollinations. The fruit set rates of all four hybrid combinations were over 70%, with the YLC×FD combination being the highest, reaching 85%. This was followed by the HFR×FD, YPH×FD, and DFG×FD combinations, which showed fruit set rates of 75%, 71.66%, and 70%, respectively. The seeds obtained from each combination were weighed, and the seed weight per grain was calculated based on the number of seeds. As shown in Table 1, the single grain weights of the seeds obtained from the four hybrid combinations were all in the range of 443.3 to 464.7 mg, with no significant differences observed.

[0033] Table 1. Fruiting status of different hybrid combinations JPEG0007670918000003.jpg32116

[0034] 2.2 Seed germination of different hybrid combinations To further clarify the seed germination status of different hybrid combinations, 150 seeds with fullness and uniform size were selected from each hybrid combination and germination status was statistically collected after sowing. As can be seen from Table 2, there were obvious differences in seed germination status among different hybrid combinations. The highest germination rate was achieved by the YLC×FD combination, followed by the YPH×FD combination. The lowest germination rates were achieved by the DFG×FD and HFR×FD combinations, with germination rates of 80.00%, 78.67%, 60.00%, and 59.33%, respectively. Overall, all four hybrid combinations had high germination rates, all of which were above 59%.

[0035] Seed soaking treatments with different concentrations of methyl jasmonate and coronatine had a slight effect on the germination rate of YLC × FD, specifically, 1.0 μmol / L of methyl jasmonate and coronatine reduced the germination rate.

[0036] Table 2 Seed germination rate of different hybrid combinations JPEG0007670918000004.jpg28116

[0037] Table 3. Germination rate of YLC×FD seeds after soaking treatment with different solutions. JPEG0007670918000005.jpg34116

[0038] 2.3 Water resistance of hybrid progeny Based on the test results in 2.2, two hybrid combinations with high germination rates, YPH×FD and YLC×FD, were selected and the water resistance of the hybrid progeny was further investigated using six groups soaked with different concentrations of methyl jasmonate and coronatine (shown in Table 3). The uncrossed "Houtan" was used as the control for the mother plant, and observations were made in terms of phenotype, morphology and physiology. After one week of observation, the following results were obtained.

[0039] 2.3.1 Phenotypic characteristics From the outside, the leaves of the control "Hōdan" seedlings are relatively thin and pale in color. On the other hand, the hybrid seedlings obtained from the hybrid combinations YPH×FD and YLC×FD have thick leaves and darker leaves. When the phenotypic changes were observed one week after flooding, as shown in Figure 1, the leaves of the control plants showed slight wilting and drooping, while the hybrid seedlings obtained by crossing were normal, with flat leaves and no wilting symptoms.

[0040] In addition, when the seeds of YLC × FD hybrid seedlings were soaked in six different concentrations of methyl jasmonate and coronatine (shown in Table 3), no differences were observed in any of the groups, and the leaves spread flat and showed no wilting symptoms (not shown).

[0041] 2.3.2 Morphological index measurement results Flooding was performed on hybrid seedlings and control seedlings, and their morphological indices were investigated. Comparing the flooding treatment group with the untreated control group, there was no change in plant height in the flooding treatment group, but the plant height in the untreated control group increased by about 0.2-0.3 cm. After flooding, the relative leaf chlorophyll content decreased by 8.1% in "Hōdan," while it increased by 12.5% ​​and 0.38% in YPH×FD and YLC×FD, respectively. The root system length and root cap ratio of the flooding treatment groups were both significantly lower than those of the control group, with the root system length of YPH×FD and YLC×FD decreasing by 27.08% and 24.42%, respectively, and the root cap ratio decreasing by 13.33% and 21.08%, respectively.

[0042] Comparing the hybrid seedlings with the control seedlings, the plant height, root length, and root crown ratio were all affected by the flooding treatment, with growth halting and root length and root crown ratio tending to decrease. In contrast, the relative chlorophyll content increased in the hybrid seedlings and decreased in the control seedlings. The decrease in the root crown ratio in the hybrid seedlings (13-21%) was smaller than that in the control seedlings (31.88%).

[0043] Furthermore, in the YLC×FD hybrid seedlings soaked in six different concentrations of methyl jasmonate and coronatine (shown in Table 3), the relative chlorophyll content increased significantly in the 0.5 μmol / L coronatine treatment group, and the reduction in the root cap ratio in this group was also significant. The specific values ​​are shown in Table 5.

[0044] Table 4. Morphological indices of peony hybrid progeny after flood treatment JPEG0007670918000006.jpg43116

[0045] Table 5 Morphological index measurements of water damage treatments in different soaking groups of peony hybrids after YLC × FD JPEG0007670918000007.jpg44115

[0046] 2.3.3 Physiological index measurement results Using FD as a control, physiological indicators related to flooding, such as sucrose synthase (SS), pyruvate decarboxylase (PDC), alcohol dehydrogenase (ADH), α-amylase (RAMY), and soluble protein (PRO), were measured to clarify the flooding tolerance of the hybrid progeny obtained from different hybrid combinations. As can be seen from Figure 3, when flooding treatment is not performed, the sucrose synthase (SS) activity of FD, YPH×FD, and YLC×FD is almost unchanged. With the extension of the flooding treatment time (0 to 7 days), the SS activity of the three combinations shows a tendency to first increase and then decrease, reaching the highest level on the 5th day of flooding treatment. During the first 3 days of flooding treatment, the SS activity of the hybrid combination YLC×FD is obviously higher than that of the control FD. On the 5th day, there is no difference between the three combinations, but on the 7th day, the SS activity of the hybrid combinations YPH×FD and YLC×FD is significantly higher than that of the control FD.

[0047] As can be seen from Figure 4, without flooding treatment, the α-amylase (RAMY) activities of the hybrid combinations YPH×FD and YLC×FD are significantly higher than that of the control FD. With the extension of the flooding treatment time (0-7 days), the RAMY activities of the three combinations show a tendency to first increase and then decrease. The hybrid combination YLC×FD reaches the highest level on the third day of flooding treatment, while YPH×FD and the control FD reach the highest level on the fifth day of flooding treatment. The RAMY activity of the control FD increases sharply one day after flooding treatment, and the change is larger than that of the hybrid combinations YPH×FD and YLC×FD. During the flooding treatment period, the RAMY activity of the hybrid combination YPH×FD is almost the same as that of the control FD, but YLC×FD is significantly higher than that of the control FD on the 0th, 3rd, and 7th days of flooding treatment.

[0048] As can be seen from Figure 5, without flooding treatment, the alcohol dehydrogenase (ADH) activity of the hybrid combinations YPH×FD and YLC×FD is significantly lower than that of the control FD, with YLC×FD being the lowest. With the extension of the flooding treatment time (0-7 days), the ADH activity of the control FD shows a tendency to increase and then decrease, reaching the highest level on the 5th day. The ADH activity of YPH×FD continues to increase until the 7th day, and on the 7th day it shows significantly higher ADH activity than YPH×FD and the control FD. At all treatment times, the ADH activity of YPH×FD is significantly lower than that of the control FD.

[0049] According to Figure 6, without flooding treatment, pyruvate decarboxylase (PDC) activity of YPH×FD and YLC×FD is significantly lower than that of the control FD. With the extension of flooding treatment time (0-7 days), the PDC activity of the control FD first increases and then shows a tendency to decrease, reaching the highest level on the 5th day. YPH×FD and YLC×FD first increase rapidly, then increase slowly, reaching the highest level on the 7th day. During the flooding treatment period, the PDC activities of YPH×FD and YLC×FD are significantly higher than that of the control FD, with little difference between the two hybrid combinations.

[0050] According to Figure 7, without flooding treatment, the soluble protein (PRO) contents of YPH×FD and YLC×FD are significantly higher than that of the control FD. With the extension of flooding treatment time (0-7 days), the PRO contents of the three combinations show a tendency to first increase and then decrease, reaching the highest level on the 5th day. One day after flooding treatment, the PRO contents of YPH×FD and the control FD increase rapidly and are higher than that of YLC×FD. The PRO content of YLC×FD increases rapidly from 1 to 3 days after flooding treatment, becoming almost equivalent to that of YPH×FD and significantly higher than that of the control FD. On the 5th and 7th days, the PRO content of YPH×FD is significantly higher than that of YLC×FD.

[0051] 2.4 Seed production of hybrid progeny The 11 sets of seedlings shown in Table 5 were obtained by dividing and raised, and were transplanted in March of the third year to the experimental field of the Zhejiang Provincial Institute of Garden Plants and Floriculture. The spacing between plants was set at 60cm, and the spacing between rows at 100cm. Fertilization and weeding were otherwise carried out in accordance with normal field management and pest control methods. The seedlings were harvested in October of the same year when the fruit pods turned from green to yellow and split open. After harvesting, the seeds were quickly threshed and dried, with the moisture content of the seeds kept at 10%-12%. The harvested seeds were weighed and converted to calculate the yield per mu. The results are shown in Table 6.

[0052] Table 6. Fruiting rate of oil-producing peony JPEG0007670918000008.jpg94116

[0053] In peony varieties with different seed sources, no phenomenon of cross incompatibility is observed in the cross between the Central Plains Peony and Feng Dan, the cross between the Japanese Peony and Feng Dan, or the cross between the Jiangnan Peony and Feng Dan, but there are obvious differences in the characteristics of the hybrid progeny obtained by crossing different varieties. The results of the present invention show that the fruit set rate of the hybrid seeds obtained by the cross combinations with different compatibility is different, but there is no direct relationship between the compatibility and the high or low fruit set rate. The fruit set rate of the hybrid seeds obtained by the different cross combinations is all above 70%, reaching a maximum of 85%, which is significantly higher than the fruit set rate of 40% by self-pollination of Feng Dan, so that the fruit set rate of Feng Dan can be improved by artificial pollination. This result is consistent with the literature report. Regarding the single grain weight of the seeds, there was no significant difference between the different cross combinations, but the single grain weight of the seeds obtained by the HFR x FD cross combination was slightly higher at 0.4647g. The single seed weight of the other cross combinations, DFG, YLC, and YPH with FD, was approximately 0.44 g, indicating that the size of the hybrid seeds obtained by crossing the selected Jiangnan Peony cultivar with Fengdan was relatively uniform.

[0054] The germination rate of hybrid seeds obtained from different crossing combinations is not uniform, which is not only related to the compatibility between the male and female plants, but also related to the harvest time of the seeds. According to the results of the present invention, the germination rate of seeds obtained from the crossing of "Gyokuroushun", "Ippinhong" and Fengdan is more than 78%, and the germination rate of seeds obtained from the crossing of "Daifuki", "Hongfuyou" and Fengdan is also more than 59%. According to the literature, the germination rate of seeds obtained from self-pollination of Fengdan is less than 50% unless special treatment is performed. Therefore, it can be seen that the germination rate of seeds of all crossing combinations obtained in the present invention is obviously higher than that of seeds obtained from self-pollination of Fengdan.

[0055] There are various methods for creating water-resistant seeds. Among them, the method of improving the water resistance of the progeny by crossing a male plant with high water resistance with a female plant is one of the relatively traditional and effective methods. Ornamental peony varieties from the Jiangnan region of China, such as "Yulou Chun", "Ippinhong", and "Hong Fulong", are highly water-resistant and very well adapted to the rainy climate of Jiangnan, making them ideal male plants. Feng Dan is the main cultivar of oil peony in the Jiangnan region of China, and is one of the best choices for a breeding mother plant because it has strong adaptability and excellent fruiting ability. By crossing a male plant with strong water resistance with a female plant with excellent adaptability and fruiting ability, it is expected that a progeny with high water resistance can be created. In the present invention, an ornamental peony variety from Jiangnan was crossed with Feng Dan, and the water resistance of the resulting hybrid progeny was analyzed. The water resistance of the seedlings of the hybrid progeny was evaluated from three aspects: phenotype, morphology, and physiology.

[0056] From the phenotypic characteristics, it can be seen that the hybrid progeny obtained by crossing "Gyokuroushun", "Ippinkou" and Fengdan has thicker leaves and is obviously more water-resistant than the parent "Fengdan". This indicates that the hybridization changes the leaf characteristics of the plant, and as a result, the plant's resistance to flood stress is improved. From the morphological index, it was confirmed that when Fengdan plants are subjected to flood stress, the relative chlorophyll content of the leaves decreases, but in the seedlings of the hybrid progeny, the relative chlorophyll content does not decrease but rather increases. This is consistent with the phenotypic results. When a plant is subjected to flood stress, the root system in the underground part stops growing or grows slowly due to lack of oxygen, and as a result, the aboveground part also stops growing due to lack of nutrition. From the results of the present invention, it was found that after flood treatment, the aboveground part of the plant stopped growing, the underground part of the plant was also inhibited, and the root crown ratio was also reduced compared to the untreated plant, but the reduction in the hybrid progeny was obviously smaller than that of the control. This indicates that the peony plants obtained through hybridization have improved adaptability to flood stress.

[0057] When plants are under flood stress, the lack of oxygen in the root system causes a large consumption of carbohydrates in the aboveground parts, resulting in metabolic disorders. To adapt to flood stress and reduce damage suffered by the plant, enzymes related to metabolism, such as sucrose synthase (SS), α-amylase (RAMY), alcohol dehydrogenase (ADH), and pyruvate decarboxylase (PDC), are activated and self-regulated. In this study, we analyzed the activities of four enzymes and the soluble protein content of the progeny of hybrids obtained from different crossing combinations.

[0058] As a result, overall, the physiological indices of water resistance of the hybrid progeny obtained by the cross combination YLC×FD were all significantly higher than the control FD, i.e., SS, RAMY, ADH, and PDC. The physiological indices of water resistance of the hybrid progeny obtained by the cross combination YPH×FD were also higher than the control FD, and especially the three indices SS, PDC, and PRO reached significant levels. During the flood treatment period, ADH and PDC reached their highest values ​​on the 7th day, while SS, RAMY, and PRO reached their highest values ​​on the 5th day. This result indicated that the progeny quality obtained by crossing promoted the activity of enzymes related to sugar metabolism and reduced the degree of water stress experienced by the plant. The results of the present invention further prove that a new quality with water resistance can be created by cross breeding a quality with water resistance and a quality with low water resistance.

Claims

1. A method for improving the water resistance of oil-based peony and increasing its production, comprising the steps of: The oil peony variety FD was used as the female plant, and the male plants DFG, YLC, YPH, and HFR, which have different affinities, were selected and crossed to produce DFG x FD, YLC x FD, YPH x FD, HFR x FD, obtaining four or more hybrid combinations.

2. 2. The method of claim 1, wherein the hybrid combination is YLC x FD.

3. 3. The method of claim 2, wherein coronatine is used to replace soaked seeds during seed germination.

4. 4. The method of claim 3, wherein the concentration of coronatine is 0.1 μmol / L to 0.5 μmol / L.

5. 5. The method of claim 4, wherein the concentration of coronatine is 0.5 μmol / L.

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