Getting To The Root Of Water Flow In Plants

An international team of researchers has discovered how a single plant peptide hormone controls the development of two different cell types central to water flow through plants.

AsianScientist (Jan. 31, 2019) – Scientists in Japan, China and Germany have identified a developmental process by which plants grow structures to control water flow through their roots, stems and leaves. Their findings are published in the journal Nature Plants.

Water flows within specialized structures from the roots, through the stem to the leaves, where its evaporation is regulated by microscopic pores called stomata. Without proper water flow, plants cannot carry out photosynthesis, grow or reliably produce flowers, fruit and seeds.

All the water-conducting structures are produced by tightly controlled developmental sequences: cells must divide to produce the necessary cell types, in the correct place and at the right time. But many details of how these complex developmental processes are regulated remain unclear.

In the present study, an international team of researchers led by Professor Tatsuo Kakimoto of Osaka University, Japan, has uncovered a peptide hormone that functions as a signaling molecule controlling the development of two completely different types of cells, both of which are involved in creating the cellular structures for water flow.

The team used the small plant Arabidopsis (Thale cress), which grows and reproduces rapidly and has a smaller, simpler genome than most crop plants. By studying the plant’s anatomy using fluorescent dyes and microscopy, and by producing mutant plants with gene editing, they found that the genes encoding the peptide hormone CLE9/10 are active in cells that lead to the development of stomata in the leaf, as well as precursor cells of water-conducting vessels known as xylem in the root.

“In the primordial cells in leaves, binding of CLE9/10 to a protein receptor controls the number of stomatal pores,” said study first author Assistant Professor Qian Pingping. “But in the roots, it binds to a different protein receptor, where it controls the production of xylem vessels.”

In addition to identifying these two different receptors, the team also revealed that a co-receptor protein is involved in the leaf signaling system.

“In animals, there are examples of signaling molecules that are received by multiple receptors,” said Kakimoto. “This study shows that the same types of signaling systems operate in plants. It is interesting that the two developmental processes, involving distinct receptors in different parts of the plant, generate completely different structures that are both essential for water flow. These results have implications for understanding how multiple processes in plant development are coordinated.”



The article can be found at: Qing et al. (2018) The CLE9/10 Secretory Peptide Regulates Stomatal and Vascular Development Through Distinct Receptors.

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Source: Osaka University; Photo: Shutterstock.
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