The mystery of capillary root formation
Root systems absorb nutrients and anchor plants in the soil − two crucial functions for a plant's growth and further development. The formation of capillary roots is vital to the root system and determines how much water and minerals a plant can absorb. As early as 1937, scientists knew that it takes only 4 months for a single rye plant to produce some 13 million individual roots! But up to now, the genetic basis of this complex process has remained unexplained.
The production of new roots is a complex combination of cell division, growth and differentiation. A specialized layer of cells in the root − the pericycle cells − must be activated to start dividing again. Therefore, it is also crucial that the cell cycle − the process that directs cell division − be under optimal control. Although the precise factors that underlie these processes and how they work together are virtually unknown, it has been quite clear that an enormous number of factors are involved.
Tom Beeckman and his team in the VIB Department of Plant Systems Biology took on the challenge of identifying all the genes that are involved in the process of capillary root formation. They used a simple model plant for this study: the Mouse-ear Cress or Arabidopsis thaliana.
Large-scale research identifies genes involved in capillary root formation
First of all, the researchers developed a special method − the Lateral Root-Inducible System (LRIS) − with which they are able to have capillary roots grow in a controlled manner. They studied all the genes that are connected with the formation of capillary roots and compared them with the complete genome of a plant that is unable to form capillary roots. By analyzing these large data sets in detail, the Ghent team discovered which genes are crucial for the formation of new capillary roots. For this part of the project, they used micro-array technology, with which thousands of samples can be studied simultaneously.
The development of capillary roots is important for sustainable agriculture
Capillary root formation is controlled by both internal and external signals. This ensures that the root system adapts itself to changes in the soil − a very heterogeneous and changeable environment. From the agricultural point of view, the branching of the root is essential because roots are responsible for helping plants adapt to adverse environmental conditions. A better understanding of capillary root formation will enable the cultivation of crops that absorb water and minerals more efficiently. An important step toward a more environment-friendly, sustainable agriculture in a world whose population is growing while the land available for agriculture is diminishing.
Tom Beeckman is in charge of the root development group in the VIB Department of Plant Systems Biology, which is under the direction of Dirk Inzé (for more info, see: www.vib.be/Research/EN/Research+Departments/Department+of+Plant+Systems+Biology/Tom+Beeckman)
Journal
The Plant Cell