Minisymposium 21: Integrative Plant Biology

Abs # 35004: RNA-based Long-distance Communication Through Phloem

Presenter:	Yoo, Byung-Chun , byoo@ucdavis.edu
Authors	Yoo, Byung-Chun  (A)   Miura, Eriko M. (A)   Archer-Evans, Sarah  (A)   Hwang, Nien-Chen  (A)   Lucas, William J. (A)
Affiliations:	(A): University of California, Davis

A role for RNA as a non-cell-autonomous signaling macromolecule is emerging as a new paradigm in plant biology. Studies on higher plants have shown the operation of cell-to-cell and long-distance communication networks that mediate the transport of both endogenous RNA and viral RNA/DNA. Recent studies have established that the phloem sap of the angiosperms contains a unique population of RNA molecules. In addition, heterografting experiments revealed that delivery of specific RNA molecules into the scion could be correlated with a change in developmental phenotype. Plasmodesmata and the phloem have also been implicated in the spread of the sequence specific signal that underlies post-transcriptional gene silencing (PTGS) in plants. Currently, little is known with respect to how RNA molecules enter and exit the phloem translocation pathway. Our research goal is to develop a comprehensive understanding of the processes that underlie the operation of the phloem, both as a nutrient delivery system and as an information superhighway. To achieve this goal, we have investigated how non-cell-autonomous proteins and ribonucleoprotein complexes enter and exit the translocation stream by passage through the unique plasmodesmata that interconnect companion cells and sieve elements. These studies involve a range of experimental techniques and require an integration of objectives from the genetic and molecular to the cellular, physiological and whole-plant levels. The specific aims that we are currently pursuing are as follows: (1) Dissection of the molecular components involved in mediating RNA exchange between the CC-SE complex; (2) identification and characterization of the NCAPs involved in the phloem long-distance translocation of RNA; (3) determination of the cellular and molecular basis for the RNA surveillance field (SurF). Findings from these studies will be discussed in the context of the role played by plasmodesmal-mediated trafficking of long-distance information macromolecules in the integration of physiological and developmental processes that take place in distantly located organs of the plant.