[SCAN] Searching for molecular regulators of cork cambium in a cork non-producing model tree

SCAN

Title: Searching for molecular regulators of cork cambium in a cork non-producing model tree

Speaker: Célia Miguel, ITQB NOVA & iBET

Affiliation: Forest Biotech Lab

Abstract:

During plant secondary growth, the epidermis is replaced in the stems and roots by the periderm. This protective tissue is derived from the activity of the phellogen or cork cambium that forms a continuous ring of meristematic cells around the stem and roots. In a few plant species, of which the cork oak is an extreme example, the activity of the phellogen contributes to a significant enlargement of the trunk, producing a thick layer of phellem or cork. Despite its critical importance in protecting the plant, little is known about the functioning of the phellogen.

The SHORT-ROOT (SHR) transcription factor, belonging to the GRAS family of plant-specific proteins, has been well characterized in Arabidopsis, being a key regulator of radial patterning and stem cell niche specification in the roots. PtSHR2B, a SHORT-ROOT like gene identified in the Populus genome, was investigated to better understand its role in meristem function in Populus. We showed that PtSHR2B is expressed in the phellogen, pointing to a regulatory role in this meristem during secondary growth. Overexpression of PtSHR2B in Populus not only affected overall plant growth, but altered the ratio between the amounts of wood and bark tissues in the stem. We further present experiments that indicate that PtSHR2B may act, at least partially, through the regulation of cytokinin homeostasis.