Why is the lotus seeds I eat not sweet and delicious at all?Finally found the reason …

July is the best time to appreciate the lotus. Lotus has been loved by people since ancient times.As early as three thousand years ago, the Book of Songs appeared such a poem "There is a Fusu, and there is Hewa" in the mountains. This is also the earliest written record about the lotus.The breeze of summer brushed the lake gently, and a pond of 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 feelings 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.Lotus classification and structured lotus belong to Lotuskolian, and is an important aquatic economic plant.It is one of the oldest twins, and is equivalent to the relics that survived by Mizukoto, Ginkgo, and Chinese goose palm.At present, the two existing species of the 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 the yellow lotus of the Americas, picture sources: 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 plant in the Americas is short and yellow.Although Asian lotus and American yellow lotus are separated by the Pacific in geographical distribution and 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., it 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, shape, 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.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 tone 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 coriander is broken, the white filament will be formed. The elasticity is large and the pump is not easy to break. It is often called "藕 藕 当".Because the cricket 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 sections of the underground stems, and there are many side roots on the top of it, which plays a fixed plant and absorbs the effects of 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

Why is the heart of lotus seeds bitter?Lotus seeds are the mature seeds of lotus. They are slightly oval or spherical, 1.2 to 1.8 cm long, 0.8 to 1.4 cm diameter.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 the middle of the green lotus seeds.

Lotus seed anatomy, picture source: Xin Jia developed from the pollination for 0 days. Lotus seeds gradually became larger in shape. 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, namely the period of organ formation (1 to 3 days after pollination, 1-3 dap), cell swelling period (4-9 dap), and the accumulation period of nutrients accumulation period(10-25 DAP) and dehydration mature period (26-30 DAP) (Sun et al., 2020).

Lotus seed development dynamic changes, pictures 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.This is why?It turns out that the eating time of lotus seeds will greatly affect its fresh food taste.Generally, we will choose the lotus seeds 15 days after pollination. At this time, the lotus seeds have a high water content, which tastes 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 Bio -alkali Chemical Structure, Picture Source: Xin Jia

Does the photosynthesis of lotus seeds need 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 lotus seed hearts 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 seed heart synthesize chlorophyll in the "dark" environment?This strange phenomenon has aroused interest and attention of many scholars at home and abroad.Researchers gave the lotus puff avoid light treatment during the development of lotus seeds, and found that the color of the lotus seed heart was obviously yellowing, proving that the synthesis of chloride in the heart of lotus seeds needed light.

Lotus Seed Heart Delivery Experimental Picture, Picture Source: References 4

The whole genome identification was carried out through the structure genes 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, it is a key step to convert the primary chlorophyllite to chlorophyll acid acid into catalytic primary chlorophyllite into catalytic enzyme (POR).For quilted plants (almost all blooming plants), the primary chlorophyll acid ester oxidation enzyme (LPOR) that light dependencies can help them convert the primary chlorophyllized acid into chlorophyll acid, and then synthesize chlorophyll.And some naked plants (such as ginkgo) and microorganisms will use this reaction to use the primordial chlorophyll amurate oxidation enzyme (DPOR) that does not depend on light.

Chlorophyll synthesis path, picture source: Xin Jia

Through the study of nuclear -based and chloroplast genome, researchers found that there were two LPOR coding genes in the lotus without finding the DPOR encoding gene.This discovery provides important molecular evidence for the light dependence of chloride synthesis in the heart of the lotus.

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.References: [1] Wang Qichao, Zhang Xingyan. Chinese lotus varieties chart [m]. China Forestry Publishing House, 2005. [2] Lin Z, ZHANG C, Cao D, et al., 2019. The Latest Studies on LOTUS (Nelumbo nucifra) -an emerging horticultural model plants. International Journal of Molecular Sciences, 20: 3680. [3] SUN H, Li J, SONG H, ET Al., CompireheSive An Alysis of Agpase Genes UncoVers their Potential ROLES in Starch BiosynthesisIn Lotus Seed. BMC Plant Biology, 20: 457. [4] Sun H, Song H, Deng X, et al., 2022. Transcriptome-Wide Characterization of Alkaloids and Chlorophyll Biosynthenthe SIS in Lotus Plumule. Frontiers in Plant Science, 13:885503. [5] Zheng P, SUN H, LIU J, Et Al., 2022. Comparative Analyses of American and Asian Lotus Genomes Reveal Insights INTO PETAL COLOR, Carpel Thermogenesis AN domstication. The Plant Journal, 110: 1498-1515.

This article was produced by popular science China, produced by Xin Jia and Sun Heng (Wuhan Botanical Garden of the Chinese Academy of Sciences), and the regulation of the Chinese Popular Science Expo

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