Edinburgh, Scotland, United Kingdom - TAIR

A systems biology approach to understanding
the root clock
In Arabidopsis, lateral roots are formed through the production of new meristems
from pericycle cells located at the xylem poles. Using an in vivo imaging system
we observed that positioning of these new meristems and the wave pattern
formed by the primary root follow a temporal periodic distribution with an
associated period of around 6 hours. However, the mechanisms that lie behind
the initiation of lateral root primordia and the selection of only some pericycle
cells to undergo dedifferentiation to form a new root are not known. Previous
reports have shown that expression of the auxin response reporter DR5 correlate
with lateral root initiation and that auxin production in pericycle cells is sufficient
to initiate a new lateral root. Our results indicate that DR5 expression in the basal
meristem oscillates following the pattern of a wave propagating along the
longitudinal axis of the primary root. To further understand this oscillatory
mechanism and lateral root positioning we performed microarray analyses of
two different root segments, the basal meristem and the adjacent upper region,
of 40 individual roots. Our results show two sets of genes oscillating in opposite
fashion. We hypothesize these genes are the basis of the molecular mechanism
determining lateral root positioning, and therefore make up a clock that
establishes lateral root initiation time. Other computational approaches as well
as analysis of several mutants, impaired in lateral root formation and other
developmental process, suggest that this clock might be also regulating other
periodic processes in the root, such as waving.
91
C40
Saturday 15:30 - 15:45
Systems Biology
Miguel Moreno-Risueno
Jaimie Van Norman
Philip Benfey
Duke University
Durham
NC
USA