Plant hairy root cultures as plasmodium modulators of the slime mold emergent computing substrate Physarum polycephalum

Abstract

Roots of the medicinal plant Valeriana officinalis are well-studied for their various biological activities. We applied genetically transformed V. officinalis root biomass to exert control of Physarum polycephalum, an amoeba-based emergent computing substrate. The plasmodial stage of the P. polycephalum life cycle constitutes a single, multinucleate cell visible by unaided eye. The plasmodium modifies its network of oscillating protoplasm in response to spatial configurations of attractants and repellents, a behavior that is interpreted as biological computation. To program the computing behavior of P. polycephalum, a diverse and sustainable library of plasmodium modulators is required. Hairy roots produced by genetic transformation with Agrobacterium rhizogenes are a metabolically stable source of bioactive compounds. Adventitious roots were induced on in vitro V. officinalis plants following infection with A. rhizogenes. A single hairy root clone was selected for massive propagation and the biomass was characterized in P. polycephalum chemotaxis, maze-solving, and electrical activity assays. The Agrobacterium-derived roots of V. officinalis elicited a positive chemotactic response and augmented maze-solving behavior. In a simple plasmodium circuit, introduction of hairy root biomass stimulated the oscillation patterns of slime mold's surface electrical activity. We propose that manipulation of P. polycephalum with the plant root culture platform can be applied to the development of slime mold microfluidic devices as well as future models for engineering the plant rhizosphere.

Maze Solvers Demystified and Some Other Thoughts

“…Not only nutrients can be placed at the destination site but any volatile substances that attract the slime mould, e.g. roots of the medicinal plant Valeriana officinalis [31]. Note that in our experiments reported in [4] slime mould did not calculate the shortest path inside the maze but just one of the paths, while Oregonator based model always produces the shortest path.…”

A brief history of liquid computers

“…Not only sources of nutrients can be placed at the destination site but also non-nutritional yet aromatic substances, e.g. roots of the medicinal plant Valeriana officinalis [72].…”

Physical Maze Solvers. All Twelve Prototypes Implement 1961 Lee Algorithm

“…Not only nutrients can be placed at the destination site but any volatile substances that attract the slime mould, e.g. roots of the medicinal plant Valeriana officinalis [45].…”