Cell division patterns during early cork development in two Quercus spp.

Poster presented at the XX International Botanical Conference, Madrid, Spain, July 21–27, 2024.

Authors:

Davide Botticelli ^1,2,3,4, Carlos Vila-Viçosa^1,2,3,5, and Ana Campilho^1,2,3

Affiliations:

1. CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Vairão -Universidade do Porto (UP), Portugal
2. Departamento de Biologia, Faculdade de Ciências, UP, Portugal
3. BIOPOLIS Program in Genomics, Biodiversity and Land Planning, CIBIO, Vairão, Portugal
4. Department for Innovation in Biological, Agro-food and Forest system, University of Tuscia, Viterbo, Italy
5. MHNC-UP - Museu de História Natural e da Ciência da UP, Portugal.

Abstract:

More than 350 hundred years have passed since Hooke’s examination of a slice of cork under a microscope, and despite being the “first cells” to be called as such, little is known about the mechanisms regulating cork cells pattern formation.

The main objective of this study is to address a distinct feature of the cork oak (Quercus suber L.) phellogen (the lateral meristem that produces phellem/cork). This tree’s unique genetic program allows the same ring of meristematic cells to keep up with the inner trunk enlargement as long as the tree is alive. However, it is unknown how the same ring of phellogen cells is maintained and active for years. We hypothesize that cork oak's phellogen cells undergo frequent anticlinal divisions. As a strategy, early developmental stages of phellogen/cork tissue pattern are being compared between two oak tree species: the cork oak and the round-leaf oak (Quercus rotundifolia Lam.). Both species are iconic in Mediterranean landscapes, they are phylogenetically related (Eurasian Subgenus Quercus), but display contrasting periderms (triplet tissue composed from phelloderm- phellogen- phellem). The round-leaf oak produces a rhytidome (successive periderms) because the phellogen cell ring collapses periodically, as opposed to the single periderm of the cork oak.

Young branches of cork oak and round-leaf oak were collected for light microscopy observation and analysis. Image analysis methods were optimized for a robust comparative analysis of tissue pattern features (orientation of cell division, cell types, cell numbers and cell size) between the two oak tree species. This poster communication will present our results so far.