Plant Roots as Excellent Pathfinders: Root Navigation Based on Plant Specific Sensory Systems and Sensorimotor Circuits

Abstract

Roots are underground plant organs hidden in the soil and coping with many environmental challenges. The root system forms ultimately complex networks of roots with numerous root apices at the distal ends of all roots. All these root apices move away from the plant body, being pushed via the elongation region in which cells rapidly elongate. Each root apex acts as an autonomous sensory organ receiving information from numerous sensory systems feeding into the root apex transition zone. The latter is acting as command center navigating growing root apices through very complex underground environment. New root apices are formed continuously behind the growth zone in endogenous manner, initiated at the stele-cortex interface via cell divisions in the pericycle and endodermis. All this allows exploratory root systems to effectively explore and exploit large areas of heterogeneous soil. In order to find out the underlying biological mechanisms, root behavior can be observed and manipulated in laboratory. Roots use their plant-specific cognition and problem-solving apparatus which allows them to exploit heterogeneous soil for water and mineral nutrition. Plant-specific memory and processing of sensory information are discussed also from the perspective of plant-specific unconventional computing. We hope that our better understanding of root behavior will be relevant for the bioinspired robotics.