Professor Marja Timmermans and a team of scientists at Cold Spring Harbor Laboratory (CSHL) have discovered the purpose of one genetic tool that is present in both mosses and flowering plants. The tool, called small RNA, has been used to make plants more sensitive to environmental cues and facilitate responses to those cues.

Small RNAs regulate gene activity via RNA interference (RNAi). One set of small RNAs, called tasiARF, has been conserved throughout the evolution of plants. tasiARF regulates the expression of proteins called auxin response factors (ARFs). Together, the tasiARF/ARF gene network plays a role in the development of the sexual organs, roots, and leaves of flowering plants. Surprisingly, this gene network is also found in mosses, which possess none of these plant parts.

To reveal why the tasiARF gene network is conserved, researchers examined its function in the moss species Physcomitrella patens response to auxin. The researchers discovered that tasiARF makes the moss more sensitive to auxin and makes the expression of genes that are stimulated by auxin more stable. Auxin affects plant development in a range of different ways, making regulation of the response to this hormone a key priority for plants.

The research group also discovered that some cells of the moss have high levels of tasiARF, and are more responsive to auxin, while some do not, and are less responsive to the hormone. This ability of tasiARF to promote a sensitive and robust auxin response, as well as to spatially regulate this response within the plant, made it such an indispensable tool over 450 million years of plant evolution.

Read the full article in CSHL News.