Cell-to-cell communication plays an important role in coordinating development and specifying cell fate in all multicellular organisms.In plants,wherein cells are immobilized and trapped within a bodice of cellulosic cell walls,exchange of positional information required for normal organogenesis has recently become the object of a growing area of research.The branching of roots through progressive formation of lateral roots is a major determinant of root systems architecture to assist plants in water uptake,acquisition of nutrients,and anchorage.During the exploration of the soil,a sequential specification of lateral root founder cells occurs in the pericycle,followed by a regular sequence of cell divisions culminating in the growth of a primordia through the overlying tissues.To cope with environmental stresses,the entire process has to be tightly controlled and heavily relies on correct communication between cells that transport and exchange signals from the environment or other tissues in the plant.Over recent decades,plant hormones such as auxin and cytokinin have been studied as important messengers to coordinate lateral root formation.Only recently,an increasing number of studies reported on the potential involvement of cell communication systems for this developmental process (Figure 1).