Plants' root-shoot mechanism studied

LA JOLLA, Calif., March 2 (UPI) -- U.S. scientists say they've identified the genetic interactions plant embryos use to determine which end grows the shoot and which end puts down roots.

Researchers at the Salk Institute report on the conflict between two groups of antagonistic genetic master switches that set up a plant's polar axis with a root on one end and a shoot on the other.

"In what is arguably the most important decision for a plant -- setting up the root/shoot axis -- occurs during the early embryonic stages," said the study's lead author, Assistant Professor Jeffrey Long.

He said plant embryogenesis establishes a very simple structure that contains two stem cell populations: the shoot meristem, which will give rise to all the "above ground" organs such as the stem, leaves and flowers, and the root meristem that gives rise to the root system, which lies below the ground and provides water and nutrients to the plant.

"This work shows how genes interact in complex ways to establish organs along the root-shoot axis," said Susan Haynes of the National Institutes of Health, which partly funded the research. "The study reveals important parallels with the gene networks that coordinate organ formation in animal embryos, and helps us understand the critical mechanisms that guide normal development."

The findings are detailed in the early online edition of the journal Nature.