A fibrous scaffold for in vitro culture and experimental studies of Physcomitrium patens

The model moss, Physcomitrium patens, is routinely cultured on cellophane placed over a solid nutrient medium. While this culture method is convenient for moss propagation, it is not suitable for studying how topographical features and mechanical cues from the environment influence the growth and development of moss. Here, we show that P. patens can be grown on fibrous scaffolds consisting of nanoscale, randomly oriented fibers composed of polyvinylidene tri-fluoroethylene (NRP). The moss adheres tightly to NRP in contrast to the lack of adhesion to cellophane. Adhesion to the scaffold is associated with slower tip growth of moss protonema for some time, followed by an increase in tip growth rate that is equivalent to that on cellophane. In addition, the orientation of the first subapical cell division plane differs between NRP-grown and cellophane-grown protonema. Nonetheless, moss colonies grown on NRP did not show signs of nutrient or photosynthetic stress and developed normal gametophores. Together, these data establish NRP as a suitable substrate for the culture of P. patens and to probe the influence of mechanical forces on tip growth and cell division of moss.