CHRISTIANSON, MICHAEL L. Department of Botany, University of Kansas, Lawrence, KS 66045. - The mosses Funaria hygrometrica and Ceratodon purpureus use different molecules to regulate growth of adjacent protonema.
In nature or in petri dishes, growth of moss protonema is regulated by
diffusible molecules produced by adjacent protonema. Work by Martin
Bopp and others has characterized the nature of the diffusible factor
produced by Funaria hygrometrica. "Factor H" is
dialyzable, heat stable, and begins to be produced at the time
caulonema appear. Experiments interacting several species of moss had
led to the conclusion that all mosses use this "Factor H." I
have examined the interactions of Funaria with
Physcomitrella patens and Ceratodon purpureus.
Funaria and Physcomitrella show intra- and
inter-specific regulation of growth exactly as the literature would
suggest. While Ceratodon shows intraspecific regulation of
growth, it neither regulates nor is regulated by adjacent colonies of
Funaria. Further experiments show that the Factor from
Ceratodon does not pass through a dialysis membrane: the
diffusible molecule used by Ceratodon to regulate protonemal
growth is chemically distinct from the dialyzable molecule used by
Funaria and many other mosses. As pointed out by Maxine Watson
some years ago, such diffusible morphogens have ecological as well as
developmental implications. The discovery of a second class of
diffusible signal means that juvenile interactions contributing to
structure and species diversity of moss communities are of two
distinct kinds. The interactions between species that share a
signalling molecule are qualitatively different from the interactions
between species that use different signalling molecules. Supported by
NSF OSR-9550487 and matching funds from the State of Kansas.
Key words: Ceratodon purpureus, chemical ecology, Funaria hygrometrica, moss, Physcomitrella patens, protonema