Myo-inositol was reported and believed to play a role in cell division. See the attached two papers (yellow highlights). And, it makes sense because callus is a group of undifferentiated cells derived from many runs of cell division.
Myo-inositol is a sugar-like carbohydrate produced by most plants. It has a taste which has been assayed at half the sweetness of table sugar (sucrose). Myo-inositol (inositol) is an added ingredient in various ROOTs products because it is important for normal plant growth and development. Myo-inositol is important for phosphate storage, cell wall biosynthesis, the production of stress related molecules, cell-to-cell communication, storage and transport of plant hormones.
Inositol is also an essential molecule for the production of the plant cell wall. Plant cell walls are made primarily of sugar chains called polysaccharides. An oxidized form of inositol is the most common and important sugar involved in polysaccharide production for cell walls. In addition to cell wall biosynthesis, these inositol-derived sugars provide components for other vital pathways involved in storage, transport, and development.