The survival secret of "old lichen"
We were washed up by the waves on a small island covered with lichen and moss. Legend has it that there is no rain on the island, and the land is almost always permafrost, lacking nutrients. In order to find the secret of the lichen's survival, we flew to an older lichen by the wind and asked it the story of the birth of the lichen.
Knowledge Link: The Birth of Lichen
In order to adapt to this environment, the "ancestors" of lichens, that is, some algae and fungi co-evolved to form a complex organism. In this complex, the algae perform photosynthesis to provide nutrients for the fungus; the fungus absorbs water and inorganic salts from the outside world, and coats the algae in it to prevent direct sunlight from causing the algae cells to dry out and die. The two ancestors are dependent on each other, and they have lived through those hard years together to survive to this day.
Lichen and moss on the rock
The elder lichen said, "Our appearance has given this barren land a turn for the better. The lichenic acid we keep secreting corrodes the rock surface we grow on, causing the rock surface to gradually crack and break, coupled with weathering, gradually A soil layer is formed on the surface of the rock. The soil creates conditions for the growth of other higher plants. Therefore, we are often referred to as "plant potentiators" or "pioneer plants"." Lichen proudly tells the story of the past, " I still remember that the moss brother next to me appeared shortly after we were born. Although it did not differentiate into roots, stems and leaves, it is different from me. It is already a real plant." At this time, the old lichen suddenly said to me: "That's right, I have seen some creatures that resemble you in this tundra before. I don't know if they are your relatives. Go and see." Then, it pointed to the back of its body.
Following the guidance of the old lichen, we found a group of photosynthetic bacteria basking on the rock surface. When we asked them where there was something to fill their stomachs, they said that just basking in the sun. We were very puzzled. At this time, a small photosynthetic bacteria jumped out and told us: "Although our photosynthetic bacteria are bacteria like you, we have one more baby in our body than you-photosynthetic pigment. With it, we can directly use the sun. The energy of yours has been synthesized into nutrients. It’s not like you wandering around looking for food. How about? I’m great, right?” We nodded one after another. The little bacterium smiled and said: "It's not easy to meet a'hometown' in the tundra. Let me tell you the principle of making photosynthetic pigments."
Encounter "The King of Pasture"
I don’t know how long it took, the monsoon suddenly blew on the island. We rode the monsoon deep inland all the way to reach the temperate grassland deep in the mainland, and slowly landed on a slender blade of grass. The grass sensed our arrival, greeted us enthusiastically, and told us about the situation in this area.
"The climate here is a typical grassland climate. Because it is far away from the ocean, it doesn't rain much. It rains only occasionally in summer. Because of the dry climate, tall trees cannot grow, only grasses like us that don't need much water. Plants and some drought-tolerant crops grow here. Introduce myself, I am Stipa, next to me is alfalfa. I am a perennial grass, a typical grassland plant. Because my roots are particularly developed, even underground I can drink the deep water, so I am not afraid of drought. Alfalfa is also a perennial herb, but it is a legume forage. It is abundant and rich in nutrients. It can also improve the soil and allow more growth here. Pasture, so it is hailed as the'king of pasture' by humans."
Photosynthetic pigments are pigments that participate in the absorption and transmission of light energy or cause primary photochemical reactions in photosynthesis. It mainly includes three categories: chlorophyll (including bacterial chlorophyll), carotenoids and phycobilidin. The photosynthetic pigment in photosynthetic bacteria is bacterial chlorophyll
Alfalfa is a legume forage, which can improve the soil, so it is hailed as the "king of forage" by humans.
Stipa is a perennial grass, a typical grassland plant
Stipa paused, and then said: "By the way, I seem to have seen you somewhere, it seems to be on the roots of legumes. Yes, are you also called rhizobia? You and the roots of legumes grow in symbiosis and form One by one tumor-like tissues, which are root nodules. Then the nitrogen in the atmosphere is converted into nitrogen fertilizer for our plants. At the same time, our plants will also deliver some nutrients to you through the roots, forming a wonderful symbiotic relationship. My brother alfalfa seems to be just like I know you very well, and I want to be as strong as it is. Would you like to settle down here?"
Nodules on plant roots
The green tropical rain forest hides the wisdom of survival everywhere
There are microorganisms that degrade lignin in the intestines of termites, helping it to convert the lignin in the trunk into nutrients
I quickly explained that we are not rhizobia. But after listening to its introduction, I am still very interested in this group of friends called Rhizobium. So we followed the roots of alfalfa and went underground to see the little buddies of Rhizobium. My little bacteria buddy gained the ability to fix nitrogen through plasmid transfer and gene exchange with rhizobia in the soil, and settled here. I still insist on the idea of wanting to travel around. However, in order to survive the cold and dry winter here, the nitrogen-fixing bacteria here formed circular dormant bodies-cysts, which are not heat-resistant but drought-resistant, and we have evolved more powerful dormant bodies because of the need for wandering. Spores. It has strong resistance to high temperature, ultraviolet light, dryness, ionizing radiation and many toxic chemicals.
A tropical rain forest with hidden survival wisdom
As winter has passed, we wake up from the spores, leave the grassland along the melting river in early spring, and enter a lush tropical rainforest.
Due to the rain erosion in the rain forest, a large amount of nutrients in the top soil of the rain forest are washed into the river with the precipitation. There are many saprophytic fungi that feed on dead wood and fallen leaves. It seems that we are going to have a satisfying meal with these plant corpses rich in lignin and cellulose.
There are a lot of vines living in tropical rain forests. They climb on the trunks of big trees and reach the sky. Some have even trapped the big trees alive. We followed the wind and fell on the leaves of a vine plant and asked it why their family thrived in the tropical rain forest. It tells us:
"There are many tropical rain forest plants. In order to survive, they must compete for sunlight and use the most efficient means to grow to the upper level with sufficient sunlight. For example, some big trees grow very tall. Although our family is not as strong as a big tree However, we attached to the trunk of the big tree and climbed up quickly. After reaching the upper layer, we began to expand horizontally, almost occupying the upper layer of the rainforest, so we soon occupied the advantage of survival in the tropical rainforest. And those who did not Plants that can get sunlight can only reduce their own nutrient consumption, become low and sparse, or they can only gradually die. There is no way, the competition for survival is so cruel."
At this time, I saw small white bugs. Crawling around in the trunk, as if gnawing at the trunk. The vine tells us that they are called termites and have existed on the earth for 200 million years. They feed on tree trunks, which not all bugs can do. Because there are a large number of microorganisms that can degrade lignin in the intestines of termites, which help termites convert the lignin in the trunk into usable nutrients. Out of curiosity, some of my friends have acquired the ability to degrade lignin through genetic exchange and evolution with the microorganisms in the intestines of termites in the tropical rainforest, so they decided not to drift and settle here. And I want to go to more places, meet more friends, and witness the appearance of this planet 30 million years after I was born.
Along the way, I saw colorful natural landscapes, flora and fauna, and even microbes like mine. Because of the difference in sunlight and temperature, combined with the influence of ocean currents, monsoons and precipitation, various regional environments have been formed on the earth. In order to adapt to this complex and changeable natural environment, creatures have also evolved their own ways of survival, playing the great song of life on the blue planet of the earth.
