Assays of Protonemal Growth Responses in Physcomitrella patens Under Blue- and Red-Light Stimuli

: The non-seed land plant Physcomitrella patens is a model species for developmental, cellular, and molecular biology studies in mosses and also for performing genetic analyses. Previously, it was shown that wild-type P. patens displays a unique photomorphogenetic behavior, in which chloronemal filaments grow in the opposite direction to a blue-light source. Here, we describe bioassay systems that can be used to study light avoidance responses as well as other aspects of photomorphogenetic regulation in P. patens grown under red- and blue-light sources.