According to BBC) 14, why do flowering plants catch up with ferns and become the most important terrestrial plants all over the world? This question once troubled Darwin. Now, American microbiologists call it "genome slimming" or "secret weapon" of flowering plants around the world.
1898, Darwin put forward a question that puzzled him in the book Origin of Species. He said that if the species evolved gradually, why didn't flowering plants appear for billions of years, but in the Cretaceous (about 65.438 billion years ago, after the extinction of dinosaurs), flowering plants suddenly appeared in large numbers? Today, flowering plants account for 90% of all existing plant species in the world.
Scientists have been arguing about this problem for many years. Now, Kevin Simonin of the University of California, San Francisco and Adam Roddy of Yale University have found the answer: flowering plants "rule" the plant kingdom because their genomes have become thinner.
The researchers analyzed the genome data of hundreds of plants in the Royal Botanical Garden in London, including flowering plants, conifers and ferns, and compared their genome size, stomatal abundance and other structural characteristics. Later, they said that the "conclusive evidence" provided by these materials led them to reach the above conclusion.
They explained that because each cell must contain a copy of the plant genome, a smaller genome can make the cell smaller. If cells become smaller, more cells (such as those devoted to photosynthesis and water and nutrient transport) can be packed into a given volume of space. In addition, by reducing the size of each cell, water and nutrients can be transported more effectively, thus maximizing its growth rate.
They say that genome slimming only occurs in angiosperms, which is "a prerequisite for the rapid growth of terrestrial plants". Of course, the latest research also raises many other questions, such as why flowering plants can shrink their genomes more than other plant groups? Why do ferns and conifers with larger genomes and cells still exist? These questions need further study and answer.