Researchers at the University of California have shown for the first time a molecule on which plant development depends.
This is the auxin molecule. The word auxin comes from the Greek word auxin, which means to grow. There are two main pathways that auxin uses to control plant growth, and one of them was first documented by scientists.
Plant cells are located in cell walls, their main layer consists of three components: cellulose, hemicellulose and pectin.
Pulp works like reinforcement in a high-rise building and provides strength. It is also made stronger by the hemicellulose chains.
Zhenbiao Yang, professor of botany and research team leader
These components determine the shape of plant cells, they can turn out to be leaves or needles. These shapes help to make the cells dense and keep the plants stable.
One theory states that when plants are ready to grow, auxin induces cell oxidation, which weakens the bonds between the components and allows the walls to soften and expand. This theory was proposed half a century ago, but how auxin activates oxidation is still a mystery.
The authors of the new work found that this happens because auxin causes the penetration of protons into the cell walls, thereby lowering their pH level. The lower pH activates a protein, expansin, which breaks down the bonds between cellulose and hemicellulose, allowing cells to expand.
There are two known mechanisms by which auxin regulates growth. One is the drop in pH, described in a new study. Another is the ability of auxin to turn on gene expression in the nucleus of plant cells.
The authors summarized and stated that auxin is important for almost every aspect of plant growth and development, in particular for fruits, seeds and roots. Therefore, the new discovery, they are sure, will help in maintaining agriculture, as well as for understanding the basic principles of biology.