Abstract
Positional information is crucial to determine cell fate, underlying a basis of plant morphogenesis. Plasmodesmata constitute one of the pathways of such information, especially for transport of macromolecules. It is widely believed that plasmodesmata adjust their own size exclusion limit (SEL) to control intercellular movement of the large and informational signals, and accordingly play important roles for plant development. To date, although spatio-temporal regulation of SEL depending on developmental stages and environmental signals has been proposed at a tissue level in several angiosperms, it remains largely unknown how the SEL is regulated at a single cell level.
We, therefore, took advantage of a simple body plan of protonemata of the moss, Physcomitrella patens to approach this issue. We made the transformant that constitutively express the photoswitchable fluorescent protein Dendra2 to observe the protein movement. On the basis of this analysis, we found that the SEL in protonema is altered by the treatment of a phytohormone, abscisic acid. Our results suggested that the SEL in mosses as well as angiosperms is dynamically regulated in response to environmental stresses.
