Do you know how Lian Xin develops?

July is the best time to appreciate the lotus. Lotus has been loved by people since ancient times. As early as 3000 years ago, the Book of Songs appeared such a poem "there is a Fusu, and there is Hewa", which is also the earliest written record about lotus. The breeze of summer brushed the lake gently, and a lotus lotus swayed in the wind, exuding a faint fragrance. From ancient times to the present, lotus is not only a symbol of beauty, but also the love of countless literati.

Picture source: Zhou Jiangtao

Nowadays, a group of scientists are still trying to decrypt the mystery of Lotus and contribute wisdom for the study of lotus. Facing this beautiful flower, let's learn more about the secret of Lian's unknown.

1. Classification and structure of lotus

Lotus, belongs to Lotuski, is an important aquatic economic plant. It is one of the oldest Gemini plants, and it is equivalent to the relics survived by Mizukoto, Ginkgo, and Chinese goose palm.

At present, the two existing species of lotus in the world are: Asian lotus (n.nucifera gartn.) And the American yellow lotus (zheng et al., 2022). Asian lotus is mainly distributed in northern Asia and northern Australia. There are many varieties and rich resources. The yellow lotus in the Americas is mainly distributed in North America, Caribbean, and Atlantic, which is basically wild.

The geographical distribution of Asian lotus and American yellow lotus (picture source: reference 2)

There are certain differences in the aspects of plant types, patterns, and colors. Asian lotus plants are tall, with a variety of flower types such as single petals, heavy petals, and heavy tables. The color changes between white and pink to red; the yellow lotus plants in the Americas are short and the flower is yellow. Although Asian lotus and American yellow lotus are separated by the Pacific Ocean in geographical distribution, and there are different phenotypes, there are no reproductive isolation, and they have eight pairs of chromosomes.

Lotus is mainly composed of the following parts: lotus, leaves, lotus puffs, lotus seeds, lotus root and root.

Lotus structure diagram (picture source: Yang Hui)

Lotus: Also known as the lotus, 菡萏, Fuyu, water hibiscus, etc., is one of the top ten famous flowers in China. Lotus is single, gender, consisting of calyx, stamen, pistil group, flower custard and petals. The size, color, form, and quantity of petals are different, forming a gorgeous flower state.

Lotus leaves: The lotus leaves are round -shaped, and the whole leaf margin is microwave -shaped. It is the main organs for the photosynthesis of the lotus. The surface of the lotus leaves has thick waxy layers and lipids, which can prevent water from penetrating. Therefore, we can see that lotus leaves wet water without dipping water. reason.

Lotus Puff: Developed from the lotus of the lotus flower, showing a flat -top shape. After the fertilization, the flower support is increasing with the development of the fruit and seeds, forming a lotus puff, which is yellow -green in the early stage. After mature, it is tan.

Lotus seeds: The fruit of the lotus is commonly known as "lotus seeds". Lotus seed leaves are rich in starch and can be eaten. In addition, lotus seeds are particularly longevity, and they can go to sleep for thousands of years.

Lotus root: Lotus root is the underground root of the lotus. It plays the role of nutrients and reproduction. It is an important ingredient. When the 藕 is broken, the white filament will be formed. The elasticity is large and the pump is not easy to break. Because the coriander contains tannins, it is easy to oxidize blue and black when encountering iron cutting.

Roots: There are two main roots of lotus, namely seed root and uncertain roots. Seed roots are the main roots formed by embryo roots during sowing. They are not developed and do not play the main role. It is impulsive to be born on the section of the underground stems, and there are many side roots on the top of it to fix the effects of plants and absorb moisture and nutrients.

Lotus is widely used and is used as landscape viewing, casual food and vegetables. According to the agronomy traits and cultivation, the lotus is generally divided into three categories, namely: Hualien, Zilian, and 藕 lotus.

The main classification of lotus (picture source: Xin Jia)

Second, why is the heart of lotus seeds bitter?

Lotus seeds are the mature seeds of lotus, slightly oval or spherical, 1.2 to 1.8cm long, 0.8 to 1.4cm diameter, consisting of four parts: peel, seed skin, cotyledon and lotus seeds. The mature lotus seed seeds are dark brown or tan, with hard texture and not easy to peel off. Two yellow -white child's leaves are thick and thick, and there are green lotus seeds in the middle.

Lotus seed anatomy (picture source: Xin Jia)

Starting from the fascination for 0 days, the lotus seeds gradually increased in shape, and the peel gradually changed from yellow to green, and then turned to dark brown. The complete development cycle of lotus seeds is about 30 days, which can be divided into four development stages, that is, the period of organ formation (1 to 3 days after pollination, 1-3 dap), cell swelling period (4-9 dap), nutrient accumulation period (10-25 DAP) and dehydration mature period (26-30 DAP) (Sun et al., 2020).

Lotus seed development dynamic changes (picture source: Sun Heng)

In summer, we taste fresh lotus seeds and enjoy the sweetness of the taste buds, but many friends will find that lotus seeds have bitter taste when eating. what about this?

It turns out that the eating time of lotus seeds will greatly affect its fresh food taste. Generally, we will choose the lotus seeds after the pollination. At this time, the lotus seeds have a high water content, which is sweet and delicious. When the lotus seeds developed to 18 days, the leaf accumulated high content of starch, and the water content was reduced, so the taste was poor.

In addition, the lotus seeds at this time have a bitter taste, which is caused by not removing the clean green lotus seed heart. Lotus seeds can synthesize a variety of alkaloids, mainly including lotus, alienine, and methane of methamphetamine. With the development of lotus seeds, the lotus heart alkali has continued to accumulate, and the bitter taste increases. Lotus Heart Biomangine Chemical Structure (Picture Source: Xin Jia)

Third, the photosynthesis of lotus seed heart needs light?

Lotus seeds are located inside the lotus seeds, and they are tightly wrapped in the outer leaves, seeds and peels. During the development of lotus seeds, the color of the lotus seed heart has gone through the transition from white, yellow -green to dark green, which is mainly caused by the accumulation of chlorophyll.

Generally speaking, the synthesis of quilt plant chlorophyll requires light. Lotus is one of the earliest species of the quilt plant. Why can lotus seeds synthesize chlorophyll in the "dark" environment? This peculiar phenomenon has aroused the interest and attention of many scholars at home and abroad. Researchers gave the lotus pontn aversion treatment during the development of lotus seeds, and found that the color of the lotus seed heart was obviously yellow, proved that the synthesis of chloride in the heart of lotus seeds needed light.

Zixin Deloma Experimental Figure (Picture Source: References 4)

Through the whole genome appraisal of the structure gene of chlorophyll biosynthesis in the lotus, it is found that the synthetic pathway of chlorophyll biological synthesis in the lotus is consistent with other quilt plants. It is significantly raised, consistent with the accumulation mode of chlorophyll.

In the chlorophyll synthesis pathway, the converting primary chlorophyll acid ester to chlorophyll acid ester to catalyze into catalytic chlorophyllization into chlorophyll acid ester is a key step. The generated chlorophyll acid is further transformed to form chlorophyll. Light -dependent primary chlorophyllite oxidation enzyme (LPOR) is a key enzyme to participate in this reaction in the quilt plant, and this process is the only reaction that requires light in the quilt plants to synthesize light. However, some naked plants and microorganisms can use this reaction with rayal chlorophyllized oxidase (DPOR) that does not depend on light.

Chlorophyll synthesis path (picture source: Xin Jia)

Researchers have found that there is no DPOR encoding gene in the lotus in the lotus research on nuclear -based and chloroplast genome, but it is identified to two LPOR encoding genes, and its expression mode is consistent with the accumulation of chlorophyll accumulation. Important molecular evidence.

Picture source: Zhou Jiangtao

As early as in ancient my country, Lotus became a plant that we were watching, eating and singing. Nowadays, in the context of my country's characteristic agricultural development, lotus plantation has become an important source of increasing farmers' income in some areas. As an ancient species, Lian has changed its research value far more than itself. In the accumulation of history, she exudes a unique charm.

However, there are still many unsolved mysteries in the lotus, such as: millennial lotus seeds germination, evolution of lotus, etc. The writing of these scientific chapters requires the joint efforts of generations of scientific researchers. We will solve more unknown secrets and let this beautiful flower bloom forever.

Produced: Popular Science China

Author: Xin Jia Sun Heng (Wuhan Botanical Garden of the Chinese Academy of Sciences)

Producer: China Science Popularization Expo

references:

1. Wang Qichao, Zhang Xingyan. Chinese lotus variety map [M]. China Forestry Publishing House, 2005.

2. Lin Z, zhang C, Cao D, et al., 2019. The Latest Studies on Lotus (NELUMBO NUCIFERA) -an Emerging Horticultural Model Plant. International of Molecular Sciences, 20: 3680.0.

3. Sun H, li j, song h, et al., 2020. Comprehensive analysis of agpase generals uncoVERS theIR POTENTIAL ROLES in Starch biosynthesis in lotus seed. BMC Plant Biology, 20: 457.7.

4. Sun H, song h, deng x, et al., 2022. Transcriptome-Wide Characterization of Alkaloids and Chlorophyll Biosynthesis in Lotus Plumule. Fronties in Plant Science, 13: 88553.

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