Cell Walls | wasteneyslab

Cell Wall Formation

Cellulose microfibrils are vital components of plant cell walls, playing a key role in providing structural integrity and influencing the direction and extent of cell expansion. These microfibrils are synthesized by cellulose synthase complexes (CSCs), which are dynamic protein assemblies that move along microtubule tracks to deposit cellulose in an organized pattern. This highly coordinated process determines the mechanical properties of the cell wall and its ability to guide anisotropic growth, allowing plants to achieve their characteristic shapes and sizes.

In Arabidopsis thaliana, the COBRA protein has emerged as a critical regulator of cellulose biosynthesis, acting at the intersection of CSC activity and the proper assembly of microfibrils. COBRA is believed to interact with cellulose or its intermediates, potentially facilitating the crystallization or alignment of cellulose microfibrils during deposition. The spatial and temporal regulation of COBRA, alongside its interactions with CSCs, is central to ensuring the strength and integrity of the cell wall.

Near-TIRF image of cortical microtubules Cellulose-synthase-complexes (CSCs) at plasma membrane move along the cortical microtubules aligned perpendicular to the cell growth axis. Scale bar = 5 um. Image by Miki Fujita.
Cryo-planed Arabidopsis stem Cryo-planed Arabidopsis stem was used to remove cytoplasmic content and to view the innermost layer of the cell wall. Scale bar = 150 um. Image by Miki Fujita.
Cryo-planed epidermis of Arabidopsis stem 50 um The top region of inflorescence stems contain recently devided cells and we often observe the cell plate. Scale bar = 50 um. Image by Miki Fujita.
Cellulose microfibrils The most recently deposited cellulose microfibrils are aligned perpendicular to the cell growth axis. Scale bar = 200 nm. Image by Miki Fujita.
Golgi localization of cellulose-synthase-complexes in rsw1-1 mutant at restrictive temperature Donut-shaped structure are fluorescently-labelled cellulose-synthase-complexes (CSCs) localized in Golgi. At restrictive temperature, CSCs are absent from plasma membrane in the rsw1-1 (CesA1) mutant. Scale bar = 5 um. Image by Miki Fujita.

Our lab is particularly intrigued by the role of microtubules in guiding CSC movement and how their interaction with COBRA and other cell wall-associated proteins contributes to cell wall quality and function. By exploring the complex interplay between these molecular players, we aim to uncover the mechanisms underlying the precise organization of cellulose microfibrils and their contribution to cell expansion and plant development.

Cell Wall Formation

Near-TIRF image of cortical microtubules

Cellulose-synthase-complexes (CSCs) at plasma membrane move along the cortical microtubules aligned perpendicular to the cell growth axis. Scale bar = 5 um. Image by Miki Fujita.

Cryo-planed Arabidopsis stem

Cryo-planed Arabidopsis stem was used to remove cytoplasmic content and to view the innermost layer of the cell wall. Scale bar = 150 um. Image by Miki Fujita.

Cryo-planed epidermis of Arabidopsis stem 50 um

The top region of inflorescence stems contain recently devided cells and we often observe the cell plate. Scale bar = 50 um. Image by Miki Fujita.

Cellulose microfibrils

The most recently deposited cellulose microfibrils are aligned perpendicular to the cell growth axis. Scale bar = 200 nm. Image by Miki Fujita.

Golgi localization of cellulose-synthase-complexes in rsw1-1 mutant at restrictive temperature

Donut-shaped structure are fluorescently-labelled cellulose-synthase-complexes (CSCs) localized in Golgi. At restrictive temperature, CSCs are absent from plasma membrane in the rsw1-1 (CesA1) mutant. Scale bar = 5 um. Image by Miki Fujita.