Role of patterning factors in the shade avoidance response – Københavns Universitet

Role of patterning factors in the shade avoidance response

PhD defense for Esther Botterweg Paredes

Summary

Plants
are sessile organisms and as such, they have evolved mechanisms to sense and
respond to their environment. Different abiotic factors such as nutrient and
water availability, temperature, and perhaps most importantly, light, define
the final shape of plants. Light harvesting is performed by leaves, which arise
at the flanks of the shoot apical meristem (SAM), and grow into a planar lamina
showing dorso-ventral polarity. The adaxial (or upper) surface is specialized
in light capture for photosynthesis, whereas the abaxial (or lower) surface is
specialized in gas exchange. Two transcription factor families are responsible
for the polarization of leaves. In this context, class III Homeodomain Leucine
Zipper (HD-ZIPIII) proteins specify the adaxial domain of leaves, and KANADI
proteins the abaxial domain. REVOLUTA (REV) is one of the five HD-ZIPIII Class
proteins present in the genome of Arabidopsis thaliana and KAN1 belongs to the
KAN transcription factor family. Besides regulating factors involved in leaf
polarity establishment, the REV/KAN1 module is involved in vascular patterning,
and also directly and antagonistically regulates the expression of several
genes, encoding proteins involved in shade-induced growth. We have shown
binding of REV and KAN1 to the promoter regions of these genes using
ChIP-seq/q-PCR approaches, as well as their mis-regulation in rev and kan1
loss- and gain-of-function mutants, respectively. Specifically, our findings
show that the REV/KAN1 module regulates the expression of WOX4, encoding a
transcription factor that specifies the vascular cambium. We show that these
patterning factors are influenced by environmental responses (i.e. shade), ultimately unraveling a new function of shade-induced growth in vascular patterning.

Supervisor

Associate Professor Stephan Wenkel

Assesment Committee

Professor Ute Höcker, University of Cologne, Germany

Professor Jaime Martínez-García, CRAG, Barcelona, Spain

Associate Professor Mathias Pribil (chair)

Reception

Reception afterwards in CPSC hall