Edinburgh, Scotland, United Kingdom - TAIR

Repression of apical HD-ZIP III homeobox
genes is required for Arabidopsis embryonic
root development
Development of seed plant embryos is polarized along the apical-basal axis.
This polarization occurs in the absence of cell migration and culminates in the
establishment of two distinct pluripotent cell populations; the shoot and root
apical meristems (SAM, RAM), which post embryonically give rise to the entire
shoot and root systems of the plant. The acquisition of genetic pathways that
delimit root from shoot during embryogenesis must have played a pivotal role
during land plant evolution because roots were likely derived from shoots of
ancestral vascular plants. However, such pathways are very poorly understood.
Here we show that RAM establishment in the model plant Arabidopsis thaliana
requires restriction of the Class III HOMEODOMAIN-LEUCINE ZIPPER (HD-ZIP
III) proteins PHABULOSA (PHB) and PHAVOLUTA (PHV), which direct both
SAM development and shoot lateral organ polarity. Failure to restrict PHB and
PHV expression via a microRNA (miRNA)-dependent pathway prevents correct
elaboration of the root development programme. As such, repression of a
fundamental shoot development process is essential for correct root
development.
74
C23
Wednesday 17:45 - 18:00
Development
Dr Carla Galinha1
Stephen Grigg1
Noortje Kornet2
Claudia Canales1
Ben Scheres2
Miltos Tsiantis1
1Dept. of Plant Sciences
Univ. of Oxford
Oxford
UK
2Dept. of Biology
Faculty of Science
Utrecht University
Utrecht
The Netherlands