This article is from the WeChat public account: principle (ID: principia1687) , author: Bowles, Photo by Louis Maniquet on Unsplash
一 、
If you have the opportunity to travel back to the earth 500 million years ago, you will find that the earth was very different from today. At that time, there were no plants on the land, only some bacteria, fungi, and algae could survive on the land. All other living things lived in the ocean. Of course, you’d better remember to bring breathing equipment, because the composition of the earth’s atmosphere at that time was also very different.
However, after a “landing” drama on plants, that world changed almost completely. The emergence of plants brought soil, rivers, and an atmosphere rich in oxygen, allowing animals to eventually survive here. Among all the animals, a species called Homo sapiens appeared. Among all Homo sapiens, another group of “smartest” botanists have used complex computer simulation technology to “return” to the earth 470 million years ago. New genes emerged from evolution from water to land. The latest study, published in Contemporary Biology, found that the explosive emergence of new genes helped plants move from water to land.
二 、
Like today ’s plants, the first land plants contained many differently functioning cells that are regulated by thousands of genes. Researchers compared the genomes of 207 existing plant species and discovered the genes that first allowed plants to land, the key to changing Earth’s biology forever.
During the transition from plant to land, the origin of land plants was related to two outbreaks of the new gene. These two explosionsHair brings unprecedented genetic innovation. The first outbreak occurred before the origin of the terrestrial plant, that is, before the plant left the aquatic environment. This outbreak contained genes that could explain why the plant is multicellular. The second outbreak coincided with the origin of terrestrial plants, and it involved genes involved in adapting to challenges in terrestrial environments.
○ Picture source: Current Biology
This means that the evolution of terrestrial plants was driven by the emergence of new genes, which were not previously found in close relatives. We know this because natural selection removes genes that are not important to the functioning of the organism, so if these genes do not play an important role, they will be lost.
Interestingly, these new genes were found in all the land plants involved in the study, including the flowering plant (tomato, rice, and orchid) < / span> and non-flowering plants (cedar, ginkgo, and moss) This shows that these genes are essential for plants to survive on land, but how can genes help land plant ancestors adapt to the new environment?
○ As land plants evolved, many new genes appeared in plants. | Picture comesSource: Alexander Bowles
三 、
Green algae was one of the first relatives of the terrestrial plants, mainly in aquatic ecosystems such as oceans and rivers. They can absorb moisture and nutrients from the surrounding environment. When plants first occupied land, they needed a new way to get nutrients and water without having to soak it in the water all the time.
Researchers have discovered that genes help early land plants accomplish this task by developing pseudoroots. This root-like structure helps them stay fixed on the ground, getting moisture and nutrients. They also found genes related to gravitational (Earthward) , which is why the root system is growing in the right direction. After all, living without water means knowing where to go. These new genes help coordinate the plant ’s pseudoroot growth down and ensure stem growth to maximize the light they can absorb.
The transformation of plants from water to land occurs in environments with light and extreme heat and little water. The genes they discovered enabled early land plants to adapt to the stress of living outside the water, ensuring that they could stand on foot and endure these harsh environments.
A big difference between land plants and their close relatives, green algae, is that land plants develop embryos. In moss and ferns, this embryo appears as spores, while in many other plants it is a seed. They identified genes that enabled the first land plants to produce and protect these embryos with specialized tissues that reduce damage from UV and heat.
By protecting embryos, plants increase their chances of passing their genes to the next generation, making them easier to scatter and survive, and allowing land plants to settle on barren lands.
The transformation of plants from water to land is one of the most important changes in the life history of the planet. With the evolution of land plants, the number of new genes has far exceeded any period in the history of plant evolution, and even more than the number of genes brought about by flowering plants.
○ Various land plants. | Image credit: Alexander Bowles
The explosion of this new gene marks the most important evolution in plant life history. Previously, scientists believed that gradual changes in gene levels were the basis for the emergence of plants on land. Now we know that through the explosion of genetic innovation, the first land plants were able to produce embryos, endure a series of environmental pressures, and anchor themselves on land. These new genes enable plants to dominate drylands, enrich them to more than 374,000 species, and shape the modern ecosystems we see today around the world.
Reference source:
https://www.bristol.ac.uk/news/2020/january/land-plants.html
https://doi.org/10.1016/j.cub.2019.11.090
This article comes from WeChat public account: principle (ID: principia1687) author: Bowles