The "rich and aristocratic family" in the plant world: Why does citrus have such a huge "family"?

There are thousands of fruits in our daily life, and there are some fruits that everyone must be familiar with, especially in the cold winter, they are definitely the "darlings" of the fruit world, that is, citrus fruits. But does anyone know how this huge system of them came about? The word "hybridization" is definitely unavoidable, today Pangke will take you to take a look!

The growing citrus family

Orange is the most common fruit in modern times. It is fresh, tender and juicy and suitable for people of all ages. It is not only delicious, but also the starting point for many fruits we often eat. For example, orange and lime are hybridized to produce lemon, and orange and tangerine are hybridized to produce tangerine...

Generally speaking, reproductive isolation exists in nature. Fruits like citrus rely on pollen to produce offspring. There are usually two ways to achieve reproductive isolation: one is to prevent one's own pollen from falling on the pistils of other plants; the other is to prevent foreign pollen from germinating on one's own pistils. But citrus doesn't mind at all, and the family relationship is very chaotic. Any two of them can produce new varieties, and their offspring can continue to combine with other citrus plants to produce more variations, and they can even evolve into new varieties through cell mutations.

Coupled with the continuous participation of nature's biggest "troublemaker" - humans, new technologies such as grafting, changing growing areas and other behaviors have prompted them to produce more changes.

Although the relationship between these fruits is complicated, and it can even be said that the hybridization of these plants is somewhat "unethical", they do have some common origins. They are all descendants of citron, wild pomelo and wild tangerine.

Grapefruit

Three "ancestors" of the genus Citrus

Pomelo is the seasonal fruit now. It is full of water, has a thick skin and is easy to store, so we are very familiar with it. Citron is not very common, because its skin is particularly thick, so very little can be eaten, and its growth habits are suitable for high temperature and humid environment. Buddha's hand and Yunnan citron are both its variants.

Wide-skinned tangerine is also a very common fruit. Although the peel is relatively loose, the flesh is very delicious. Ugly orange is a high-priced fruit because of its sweet taste.

Ugly orange

Many years ago, these three used the power of nature or used their fruits to attract wild animals and humans to sow them. After a long period of baptism, they ushered in an era of hybridization and prosperity in modern times. When two different plants are planted together, coupled with the large number of disseminators, the dissemination channels are very rich. Citrus fruits are isolated before zygotic. Through continuous cross-pollination and continuous accumulation of tiny variants, new varieties are constantly born. From appearance, taste to the color of the peel, a variety of new fruits are constantly mixed and matched. For example, oranges are hybridized from grapefruits and wide-skinned mandarins, sweet oranges and grapefruits are combined to form grapefruits, and sour oranges and citrons are combined to form lemons...

The citrus family continues to expand

After intra-genus hybridization developed to a certain extent, it could no longer meet humanity's ever-increasing demand for new delicacies, and the genera Citrus and Fortunella also joined the expansion of this family.

Although the three are from different genera, it does not affect their "combination" at all. As the offspring of orange and trifoliate orange, although it does not enter the market as a fruit, it is an extremely excellent citrus rootstock.

The citrus family is not the only one with a messy family system

Citrus has such a complicated family relationship, but Saccharum is not afraid! Because it is also a crop that grows in the chaos of family relationships. According to research, the earliest sugarcane varieties are tropical species (Saccharum officinale) and cut hand dense (Sweetroot grass), and the combination of the two gave birth to the bamboo cane that is now popular in China. However, the appearance of Saccharum is not as different as that of Citrus. People's planting of sugarcane is closely related to the increasing demand for sugar in modern development. Unlike Citrus, there is no greater demand, so its hybridization history is not as rich as that of Citrus.

The initial hybridization of sugarcane can be traced back to the early 20th century, when someone discovered that hybrid sugarcane seeds could germinate seedlings, and at the same time derived the "noble" breeding theory, which actually determined that tropical species were the origin of sugarcane development, that is, noble species. Other members of the genus Saccharum could be hybridized with it, and the constantly "noble" sugarcane gradually became a good product for modern sugar extraction. Today, almost all sugarcanes have genes from tropical species, just like "peach and plum trees all over the world"!

Interspecific hybridization is a common sight in the plant world. So far, there are more than 300,000 members of the plant world, and more than 70,000 plant species are hybrids. Although the structural properties of these hybrid fruits are basically the same, they have different tastes and characteristics. We have to admire the magic of nature.

Creative team: China Science and Technology Museum New Media Team

Review expert: Shi Jun, PhD in botany, well-known popular science writer

This article comes from: China Digital Science and Technology Museum