A preliminary report on the characteristics of Ginkgo biloba

A preliminary report on the characteristics of Ginkgo biloba

There is only one genus and one species in the family Ginkgoaceae, which is a relict plant left over from the Quaternary Ice Age [1]. It is a specialty of China and is called plant "living fossil". It has many uses, such as edible, medicinal, timber, ornamental and so on. it is an important deciduous tree species for special economic forest production and garden cultivation. Anlu City, located in the northeast of Hubei Province, is located in the confluence zone between the remaining veins of Dahong Mountain and the northern edge of Jianghan Plain. There are not only natural distribution of ginkgo biloba (Ginkgo biloba Linn) community, but also rich secondary ginkgo woodland. There are 29000 ginkgo trees, 59 ancient ginkgo biloba over a thousand years old, 1468 ancient ginkgo biloba over 500 years old, and 4683 ancient ginkgo biloba over 100 years old, which is known as the "hometown of ginkgo biloba". In November 2009, the first national forest park named after a single tree species was established in Anlu City. In 1987, it was found that the leaves of a ginkgo biloba with roots and big branches were yellowish-yellow-light green-yellow during the growing period, while the leaves of other branches were light green-green-yellow. According to the continuous follow-up investigation for many years, it was found that the leaves of the branch were yellow from sprouting and spreading leaves until the end of May. After June, the newly germinated leaves were light yellow, and the mature leaves gradually turned light green, and then turned yellow after mid-October. This character is stable and can be propagated and popularized as landscaping and leaf-picking varieties in production by making use of its golden leaves in spring and autumn, light yellow and light green in summer, and high content of total flavonoids.

1 materials and methods

1.1 Reproductive methods

The mother tree has a height of 16 m, a DBH of 110 cm, a crown width of 13 m, a yellow leaf variable branch length of 7 m and a base diameter of 19.5 cm. After 6 consecutive years of sprouting from this branch, 1-2-year-old branches were used for propagation. The rootstock used for grafting is 1-4-year-old ginkgo biloba seedlings. The seedlings are raised by strip sowing, row spacing is 25 cm, grafting operators are fixed, split grafting and skin grafting are used in spring, bud grafting is in autumn, nursery land is the old nursery, and there is no other special management and protection measures after grafting.

1.2 comparison of leaf chromaticity

From spring to early summer, leaf pigment photography samples of asexual 3-year-old trees and rootstock seedlings of the same year were taken once a week at 10:00, with a SONY P100 digital camera with an image distance of 60 cm and a fixed focus of 35 mm (equivalent to 60 mm of the full camera). According to the weather program-controlled exposure, the two sampling exposure parameters were the same, and the color images of ginkgo biloba leaves were recorded. According to the 524 color RGB value data, the leaf color map values of Ginkgo biloba and Ginkgo biloba leaves were converted into RGB values by Photoshop CS software, and the leaf colors at different times during the development of Ginkgo biloba leaves were described, and the differences between them were compared.

1.3 biochemical analysis and comparison

(1) determination of flavonoid content. The leaves of Ginkgo biloba were collected from Nanjing Forestry University, and the contents of total flavonoids in leaves were determined by liquid chromatography (HPLC) in the laboratory of Nanlin Dalin College. The data were compared with the contents of total flavonoids in local common ginkgo biloba [2-3] and Guangdong, Jiangxi, Gansu and other places [4-7]. The economy of cultivation of Ginkgo biloba as leaf-picking raw material was analyzed.

(2) Leaf pigment factor. Nanjing Forestry University was entrusted to collect the leaves of Ginkgo biloba and Ginkgo biloba planted in the subordinate forest farm, and the contents of carotenoids and chlorophyll of Ginkgo biloba and Ginkgo biloba were analyzed by the laboratory of Nanlin Dalin College. Acetone-ethanol mixture spectrophotometry was used to compare the difference of yellowing factor between ginkgo biloba leaves and common ginkgo biloba leaves.

(3) DNA detection. Nanjing Forestry University was entrusted to collect the leaves of Ginkgo biloba and Ginkgo biloba, which were planted in the forest farm of Nanjing Forestry University. Bioer life gradient PCR instrument, TOMY MX-160 freeze centrifuge, DYY-6C electrophoresis instrument, DYC-34A electrophoresis tank, TAKARA taq enzyme, TAKATA DNA extraction kit and SYNGENE GENEGenios imaging system were used in the laboratory of Nanlin Dalin College. The detection methods were SSR gene analysis and 8%PAGE gel detection. The reaction system is shown in Table 1. The sequence of samples is starting from marker, and the genetic differences between common ginkgo, golden ginkgo, common ginkgo, golden ginkgo and common ginkgo are compared.

Table 1 Detection reaction system

(4) phenotypic observation of yellow leaves. The asexual propagated seedlings were planted in 2 hm24 980,0.4 hm2996, 1 hm22 490 and 0.33 hm2 822 seedlings in Wangyizhen Town, Xundian Town, Xiaonan District and Geputan Town, Yunmeng County, respectively. After planting, the phenotypic stability of yellow leaves was observed regularly every month for 4 years from sprouting and developing leaves in spring to falling leaves in late autumn.

2 results and analysis

2.1 grafting propagation

After 7 consecutive years, the shoot growth of the seedlings propagated by bud grafting method was 3050 cm. The shoot growth of the seedlings propagated by branch grafting method was 20-40 cm in the same year. The leaves of grafted seedlings were thicker than those of common ginkgo biloba seedlings, with a width of 7 cm, a leaf length of 5 cm and a petiole length of 4 cm. The largest leaf has a width of 13 cm, a leaf length of 10 cm and a petiole length of 5 cm. The effect of grafting propagation of yellow leaf ginkgo biloba is shown in Table 2, and most of the seedlings survived by skin grafting and bud grafting. The leaves of grafted seedlings remain yellow after full leaf expansion and yellowish in summer as shown in Fig. 1 and 2. In the follow-up promotion and production, all the seedlings of asexual reproduction were used to maintain the characteristics of yellow leaves.

Fig. 1 characteristics of yellow leaves of grafted seedlings

Table 2 Table of grafting seedlings of Ginkgo biloba L.

Fig. 2 characteristics of yellowish leaves of grafted seedlings in summer

2.2 chromaticity comparison

Through the fixed-point observation of 1-year-old and 4-year-old young trees for 4 years in a row, it can be seen that the new buds of Ginkgo biloba are light yellow every year, the leaves are orange to golden yellow in April, gradually turn to light yellowish green in May, and yellowish green from June to October. The green component increased and gradually turned to yellow after the middle of October. The comparison of chromatographic values from March to June is shown in figure 3.

2.3 biochemical analysis

(1) the main components of leaves. The analysis results of leaf pigment samples are shown in Table 3. It can be seen from the table that the total chlorophyll of yellow leaf plants is significantly lower than that of green leaf plants, in which chlorophyll α is 6.5 times lower and chlorophyll β 6.3 times, but carotenoids are only 2.4 times lower. The carotenoid / chlorophyll ratio of yellow leaf plants is 2.6 times higher than that of green leaf plants, that is, the relative content of carotenoids in yellow leaf plants is higher than that of green leaf plants. At the same time, the content of total flavonoids in yellow leaf type was 1.7 times higher than that in green leaf type.

Fig. 3 Color map of two kinds of ginkgo biloba leaves

Table 3 comparison of pigment content and total flavonoid content

Table 4 comparison of total flavonoids content

(2) content of total flavonoids. The content of flavonoids fluctuates greatly due to the difference of growth region, tree age, variety and picking year, as shown in Table 4. However, the content of total flavonoids in yellow leaf ginkgo biloba was 1.77 times higher than that of common ginkgo biloba in the same year. Ginkgo biloba is used as the medicinal raw material of flavonoids, and the economic recovery index of its content in the international market is ≥ 2.4%. If the yellow leaf ginkgo biloba is used in the production of leaf-picking raw materials, the economic benefit is significant.

(3) the results of 8%PAGE detection. The DNA sequence analysis of polymerase chain reaction is shown in Table 5 and figure 4. In the test, 8 pairs of 10 pairs of primers were amplified effectively, but primers 54 and 64 could not be amplified. The results showed that the polymorphism of golden ginkgo biloba was different from that of common ginkgo biloba.

(4) comparison of the stability of yellow leaves in offspring. According to the observation results of each planting base, ginkgo biloba sprouted from late March to early April, shoots in the middle of April, and spring shoots only once a year. From the beginning of germination to the end of May, the color of leaves and petioles were yellow. After June, the new tender leaves were bright yellow, the mature leaves gradually turned to light green, and then turned yellow after mid-October. The fallen leaves entered dormancy from late October to mid-November, which accorded with the characteristics of yellow ginkgo biloba (Ginkgo biloba var.aurea Beiss) [8]. The periods of phenological changes at each point are shown in Table 6. After continuous observation for 4 years, the change of leaf color was consistent with that of the parent plant, and the phenological performance was also synchronized with that of the control Ginkgo biloba. The leaf color of grafted young ginkgo biloba trees was consistent with that of mother leaves and phenology, indicating that the offspring of asexual reproduction maintained genetic stability [Jishan Huayao].

Table 5 primer sequence table

Fig. 4 Electrophoretic bands of PAGE gel of two species of Ginkgo biloba

Table 6 phenological table of ginkgo biloba

3 conclusion

The main results are as follows: (1) the variety has stable characters and excellent characteristics. The results of observation for several years showed that the yellow-leaf ginkgo biloba trees with asexual reproduction grew vigorously, the annual shoot growth was about 80cm, the new shoots were brown-gray, the perennial branches were gray, the branch bark was smooth and the lenticels were not obvious. The standard leaf (the fourth leaf of short branch) determined by Nanjing Forestry University is fan-shaped, the angle is about 105 °, the leaf is large and thick, the leaf color is yellow or light yellow, and the depth of leaf crack is irregular. The leaf width is 9.04 cm, the leaf length is 5.83cm, the petiole is short, only 4.51cm. Considering that the function, size and character of leaves were basically finalized in the middle of April, the best ornamental period of Ginkgo biloba is in the late spring and early summer from April to May, coupled with the high content of flavonoids, it is an excellent greening variety with high ornamental value and leaf raw materials.

(2) passed the provincial variety examination and approval. After 11 years of systematic observation and experimental cultivation, the results showed that the mutated yellow leaf ginkgo biloba had the advantages of stable genetic characters, easy grafting and high content of total flavonoids. After reporting to the competent department, it was successfully examined and approved by Hubei Forest Variety approval Committee in April 2014, and named Ginkgobiloba'Anlu Jinye.

(3) increase the intensity of popularization and utilization. In order to make effective use of the excellent local ginkgo variety resources, in October 2017, Xiaogan Forestry Science and Technology extension Center won 1 million yuan from the central government's forestry science and technology extension demonstration project to popularize and plant this variety in ANLU City and Dawu County. The project plans to build a demonstration and extension base of 300mu by 2019 and spread 1000 mu around it. The implementation of the project will be in strict accordance with the design of the afforestation project, further speed up the breeding and planting of seedlings, deploy the management force, and implement the technical plan, so that the variety advantage of ANLU Golden Leaf Ginkgo biloba can be transformed into resource advantage as soon as possible, so as to generate income for forest farmers and add color to the ecological environment.