The knowledge about plant growth is a subject of considerable agricultural and ecological interest. The knowledge of factors controlling biomass increase in the below-ground compartment it is important not only to understand how plant biomass develops in roots but it could be used also for agriculture biotechnological applications.

For instance, new mutants of crop plants could be produced with a higher tolerance to constraining environmental conditions which often spots specific climates where agriculture needs to be developed for food production.

 

The plant growth depends on cell division taking place in shoot and root tissues , but still much work remains to be done in order to achieve a full knowledge of all factors controlling cell division. In addition, it is necessary to highlight that all the existing literature accumulated in regard of this topic refers mainly to shoot whereas very few are the studies published to date referring to cell division in roots.

 

The root system is important for acquisition of soil resources (water and nutrients) and therefore is reasonable to assert that spatial deployment of the root system in the soil determines, in the large measure, the ability of a plant to exploit those resources (Lynch, 1995).

Elongation of a root depends on activity of apical meristems whereas its diametral growth (in woody plants) depends mainly upon vascular cambium activity. Both root apical meristems and vascular cambium are constituted by initials (stem cells) and derivative cells (i.e., the first daughter cells obtained from initials) (Chiatante and Scippa, 2006). The rapid division of derivative cells is responsible for formation of all other different tissues which characterize a root.

The activity of the vascular cambium starts immediately at a distance of 2-3 mm from the root apex and it remains active until plant death when the root system has achieved a total length of several hundred meters. Therefore the activity of vascular cambium in the roots is the main factor responsible for biomass increase of a root system. Participation of cork cambium (Esau, 1965; Mauseth, 1988) activity in diametral growth in roots is strongly reduced in respect to cork cambium in the shoot and this is the reason why its importance for biomass production in the roots is considered negligible.

 

In recent years the extensive research, focused on cambium activity, has revealed the complexity of cambium initials regulation. Arabidopsis thaliana and Populus nigra, respectively annual and perennial, are the two species used as “model plants” for molecular study of the cambium as their genome has been sequenced. In this study, we will use mainly Populus and we will focus on searching for similarities and differences (if any) between factors regulating the vascular cambium activity present in shoots and roots.