Simulation of marked root hair curling in Rhizobium‐legume symbiosis

Abstract

The soil bacterium Rhizobium infects its leguminous host plants in temperate regions of the world mostly by way of the growing root hairs. Root hair curling is a prerequisite for root hair infection, although sidelong root hair infections occasionally have been observed. The processes underlying Rhizobium‐induced root hair curling are unknown.Computer simulation of root hair growth indicates that one‐sided tip growth inhibition by Rhizobium can result in root hair curling when three conditions are simultaneously fulfilled: 1) rhizobial growth inhibition is strong enough to prevent removal out of the tip growth range: 2) root hair surface growth between the attached Rhizobium and the root hair top is inhibited; 3) rhizobial growth inhibition is limited to one side of the root hair.The results predict that root hair curling by stimulation of tip growth is improbable. This study accentuates the need for information about the growth processes contributing to tip growth in leguminous root hairs.