Editors: The color photograph that will appear on the cover of the journal Science is available. See details at end.
UC Davis biologists report the discovery of an important element in the complicated internal communication and transportation systems of plants: a previously unknown "movement protein" that carries information-bearing RNA from stems and leaves to faraway roots and flowers.
The findings should provide basic insight into the evolutionary processes underlying complex plants and could lead to better defenses against crop diseases.
The Davis team, led by professor of plant biology William Lucas, is one of only a few worldwide that are unraveling how plants transport many important internal cargoes, including genetic messages that govern growth and flowering.
"This new study is very important," says Richard Jorgensen, an associate professor of plant sciences at the University of Arizona and also an expert in the field. "What they've identified is probably a component in a radically new system for communication between cells and between organs of the plant."
The current picture of the plant's transportation, or phloem, system looks something like a bustling subway. The tube- shaped sieve elements of the phloem are the subway lines, the companion cells of the sieve elements are the stations, and connecting tunnels called plasmodesmata allow cargoes to move from the stations into the subway lines.
In the Jan. 1 issue of the journal Science, the UC Davis study introduces the new factor, the movement protein.
In the cells of leaves and stems, the movement protein binds
to an informative segment of genetic code called messenger
RNA (mRNA). Like a subway ticket, the movement protein lets
the mRNA enter the plasmodesmal tunnel to the subway line, or
phloem translocation stream. Once in the subway line, the
complex of movement protein and mRNA travels very rapidly to
distant stations located in roots and flo
Contact: William Lucas
University of California - Davis