Unraveling the genetic controls of the growth of the roots of plants

11/01/2015

The stems and roots are formed around the xylem, formed in turn by hollow and long cells that act as channels - to transport water and minerals in the plant - and as a structural material. The structural strength of the xylem comes from a secondary cell wall that is inside the outermost cell wall, which is made either of helical fibers or of perforated layers. This secondary cell wall is made from three molecules: cellulose, hemicellulose (which are essentially sugars), and lignin, which provides strength.

UC Davis graduate student Mallorie Taylor-Teeples, working in conjunction with Siobhan Brady, assistant professor of plant biology at UC Davis, Sam Hazem of the U. of Massachusetts Amherst and others, cloned 50 genes involved in cellulose production , hemicellulose and lignin from the Arabidopsis plant and monitored their interactions with more than 460 transcription factors, or genes that activate or deactivate other genes.

With the help of UC Davis computer scientist Ilias Tagkopoulos and colleagues at the UC Davis Genomic Center, the researchers were able to build a network that shows how different genes and transcription factors connect with each other. The results were published online in the 24 December of the 2014 in the magazine Nature.

"EThis is the first time that such a network has been developed at this level in a plant"Said Brady. "It helps us think about how these networks can be controlled and manipulated".

Remarkably, the network contains a large number of "cfeedback ircuitos"Said Brady. An example of a feedback loop: the transcription factor X acts on the Y factor, which in turn acts on the Z gene. Such systems are well known in other control networks, reducing random "noise" and allowing coordination precise of the different steps without a regulatory center.

The researchers were also able to study how the system reacts to different types of environmental changes. For example, depriving the cells of iron roots, promotes the production of lignin, which increases the uptake of iron. But exposing the cells to salt causes a different response in which xylem cells proliferate to increase water transport.

Understanding the network of controls that influences the content of lignin, cellulose and hemicellulose can eventually help plant breeders to create varieties that are better suited for biofuel production, Brady said.

Source: Eurekalert.org