An Experimental System for Examining Phototropic Response of Gametophytic Shoots in the Moss Physcomitrella patens.

Shoot phototropism benefits growth and metabolism in land plants by enabling them to position their photosynthetic organs in favorable light conditions. Nonvascular land plants, like the ancestors of modern mosses, are believed to have been among the first plants to occupy the land. To understand the evolutional history of shoot phototropism in land plants, we have established a system for experimentally studying phototropism in gametophores of the moss Physcomitrella patens. Here we will describe the key points in our system, including obtaining etiolated gametophores, the light sources used for inducing bending, and the methods for evaluation of phototropic responses.