Blaschek, Leonard - Wood Cell Wall Architecture

Research

Leonard Blaschek standing in front of a tree in a snowy forest landscape.Photo: Don Johnels

The formation and maintenance of secondary cell walls – i.e. wood – involves the biosynthesis and interaction of several complex biopolymers, including polysaccharides, proteins, and polyphenolics. They are assembled intracellularly, at the plasma membrane, or in the cell wall itself. During wood formation, these processes need to be coordinated with each other, with cell growth, and with environmental stresses, on time-scales between milliseconds and centuries. How this coordination is mechanistically achieved, and how it allows cells to coalesce into functional wood, is what we are trying to understand in the Wood Cell Wall Architecture Group at UPSC.

Identifying unknown cogs in the machinery of wood formation

The biosynthesis, transport, polymerisation and interactions of cell wall polymers are catalysed and modulated by countless gene families in all compartments of the plant cell. Our understanding of the initiation, quantitative coordination and nanometre-scale assembly of these polymers is primarily hampered by the size of many of the putatively involved gene families. These large, partially redundant gene families make pinpointing functions of single paralogs challenging. Additionally, much of what we currently know about wood formation has been pioneered in Arabidopsis—an annual herb. To pierce through the genetic redundancy shrouding wood formation, and discover gene functions specifically relevant for woody, perennial growth habits, we perform large scale, multi-target CRISPR screens in Populus. Such screens allow the generation of hundreds of novel higher-order mutants for phenotyping screening in the state-of-the-art tree phenotyping platform at UPSC.

Multi-modal protein interaction networks

Virtually all cellular processes are modulated by protein–protein interactions. Ubiquitous examples are enzyme–substrate interactions, co-receptors, peptide ligands, and effector proteins. All of these interactions do not occur independently from each other, but instead form a highly dynamic, interlinked protein–protein interaction landscape. These landscapes hold enormous amounts of information, covering development, homeostasis and defence mechanisms. To harness this information, we use a fully endogenous proximity labeling technique called PUP-IT, which allows us to pinpoint interactions as they occur in the plant. These in planta data can then be integrated with co-expression networks, in silico structure modelling and metabolic profiles, to paint a comprehensive picture of the cellular processes during wood formation.

Cell wall biochemsitry in situ

Biochemical changes in the cell wall of specific wood components – such as the middle lamella between adjacent cells, or newly forming cell walls – can have considerable consequences for tissue dynamics and plant growth. Yet, in traditional biochemical approaches, these changes often get lost, because they only occur in a (by mass) negligible fraction of bulk-extracted cell wall material. Because of this, we focus on analytical approaches in situ. These include histochemical stain (Wiesner, Mäule), microspectroscopy (Raman, FT-IR) and confocal microscopy (auto-fluorescence, exogenous probes). These techniques allow us to define biochemical changes directly where they occur, and link them directly to cellular and physiological phenotypes.

Key Publications

  • Zheng S, Blaschek L, Pottier D, Dijkhof LRH, Özmen B, Lim PK, Tan QW, Mutwil M, Hauser AS, Persson S (2025). Pupylation-based proximity labeling unravels a comprehensive protein and phosphoprotein interactome of the Arabidopsis TOR complex. Advanced Science; 12: 2414496
  • Low PM, Kong Q, Blaschek L, Ma Z, Lim PK, Yang Y, Quek T, Lim CJR, Singh SK, Crocoll C, Engquist E, Thorsen JS, Pattanaik S, Tee WT, Mutwil M, Miao Y, Yuan L, Xu D, Persson S, Ma W (2025). ZINC FINGER PROTEIN2 suppresses funiculus lignification to ensure seed loading efficiency in Arabidopsis. Developmental Cell; 60(12): 1719-1729.e6
  • Blaschek L, Serk H, Pesquet E (2024). Functional complexity on a cellular scale: why in situ analyses are indispensable for our understanding of lignified tissues. Journal of Agricultural and Food Chemistry 72:13552–13560.
  • Blaschek L, Murozuka E, Serk H, Ménard D, Pesquet E (2023). Different combinations of laccase paralogs nonredundantly control the amount and composition of lignin in specific cell types and cell wall layers in Arabidopsis. Plant Cell 35:889–909.
  • Ménard D, Blaschek L, Kriechbaum K, Lee CC, Serk H, Zhu C, Lyubartsev A, Nuoendagula, Bacsik Z, Bergström L, Mathew A, Kajita S, Pesquet E (2022). Plant biomechanics and resilience to environmental changes are controlled by specific lignin chemistries in each vascular cell type and morphotype. Plant Cell 34:4877–4896.