Rhizobium tropici biopolymer enhances lateral root formation in agar-grown Arabidopsis

Manipulation of natural plant growth matrix density is important for agricultural, environmental, and industrial applications. Extracellular biopolymeric material (EPM) is emerging as a potent biological compound capable of aggregating soil and sand matrices; yet the effects of EPM on the plant root system, the major organ that interacts with the growth matrix, remain unknown. Here, we began bridging this gap in our knowledge by demonstrating that EPM promotes a dramatic proliferation of lateral roots of Arabidopsis seedlings grown on agar matrix, mainly at the matrix-air interface. This biological effect of EPM positions it as a natural tool for developmental studies of root systems, as well as for its use to improve control of soil erosion by plant vegetation.