Seminar with Edouard Pesquet from Stockholm University
Cell cooperation during plant vascular tissue formation:
a tale of life and death
The colonization and survival of plants on land were enabled by the development of a vascular system which both conducts water and minerals throughout the plant body but also reinforces the plant organs mechanically for upright growth . The sap conducting cells, called tracheary elements (TEs), form a complex vascular plumbing system distributing the hydro-mineral sap to all the tissues of the organism.
The basic engineering design behind TE formation and function is achieved by (1) emptying the cell content by programmed cell death (PCD), (2) reinforcing the cell sides with a patterned secondary cell wall alternating thickened and unthickened areas regularly and (3) waterproofing the thickened cell sides with lignin [1,2,3]. Thus a corrugated partially waterproofed hollow cylinder is formed which can resist the pressure associated with the rising of the sap but also allows the sap content to be laterally distributed through TE unthickened areas.
he interplay between PCD, cell wall thickening and lignification during TE formation was studied at the cellular level using in vitro xylogenic cultures of Arabidopsis and real-time live cell imaging [4,5], at the genome level using transcriptomics, proteomics and metabolomics  and at the whole plant level by analyzing multiple transgenic and insertional mutants in newly identified genes differentially regulated during TE formation .
Pharmacological/genetic inhibitions coupled to chemical/genetic complementations in both xylogenic cell cultures and whole plants reveled that TEs lignify post-mortem by cooperative process with xylem parenchyma [7,8]. Altogether, our results highlight the tight cellular cooperation required for the full maturation and function of the hydro-mineral vascular system in plants.
 Ménard D. and Pesquet E. (2015) Cellular interactions during tracheary elements formation and function. Current Opinion in Plant Biology, 23, 109-115.
 Ménard D., Escamez S., Tuominen H. and Pesquet E. (2015) Life beyond death: the formation of xylem sap conduits. In Springer Books: Plant Programmed Cell Death, Edited by Arunika Gunawardena, Advances in Plant Biology, chapter 3, 55-76.
 Barros-Rios J., Serk H. and Pesquet E. (2015) The Cell Biology of Lignification in Higher Plants. Annals of Botany, 115, 1053-74.
 Kunz S, Pesquet E, Kleczkowski L. (2014) Functional Dissection of Sugar Signals Affecting Gene Expression in Arabidopsis thaliana. PLOS One, 9, e100312
 Ménard D, Serk H, Decou R, Pesquet E. (2017) Establishment and Utilization of Habituated Cell Suspension Cultures for Hormone-Inducible Xylogenesis. Methods Molecular Biology, 1544:37-57.
 Derbyshire,P., Ménard D. Green P., Saalbach G., Lloyd CW. and Pesquet E. (2015) Proteomic Analysis of Microtubule Interacting Proteins over the Course of Xylem Tracheary Element Formation in Arabidopsis. Plant Cell, 27, 2709-26.
 Pesquet E, Zhang B, Gorzsás A, Puhakainen T, Serk H, Escamez S, Barbier O, Gerber L, Courtois-Moreau C, Alatalo E, Paulin L, Kangasjärvi J, Sundberg B, Goffner D, and Tuominen H (2013) Non-cell autonomous post-mortem lignification of tracheary elements in Zinnia elegans. Plant Cell, 25, 1314-28.
 Van de Wouwer D, Vanholme R, Decou R, Goeminne G, Audenaert D, Nguyen L, Höfer R, Pesquet E, Vanholme B, Boerjan W. (2016) Chemical Genetics Uncovers Novel Inhibitors of Lignification, Including p-Iodobenzoic Acid Targeting CINNAMATE-4-HYDROXYLASE. Plant Physiology, 172, 198-220.
Edouard Pesquet is Principal Investigator of "Cell differentiation and coordination in tissues" research team at the Department of Ecology, Environment and Plant Sciences, University of Stockholm.