Cellulose biosynthesis inhibitor isoxaben causes nutrient-dependent and tissue-specific Arabidopsis phenotypes

Dear Editor,

The plant cell wall is a sugar-rich matrix that surrounds every plant cell, providing structural support and acting as a first line of defense against pests and pathogens. As cell walls comprise the bulk of plant biomass, they are a major carbon sink and the source of many essential commodities, such as food, shelter, fuel, and clothing. Therefore, it is no surprise that cell walls are a major research topic, as knowledge gained can be harnessed to engineer plants with improved or tailored cell walls.

Cellulose is the major cell wall polysaccharide, made of long chains of glucose that act as the main load-bearing cell wall component. Cellulose is synthesized by plasma membrane–localized cellulose synthase (CESA) complexes, comprised of 18 CESA subunits and various accessory proteins (Pedersen et al. 2023). Cellulose biosynthesis inhibitors (CBIs) have been used for decades as important agricultural herbicides and also as invaluable molecular tools for studying cellulose regulation, as it is widely hypothesized that CBIs specifically target CESAs to inhibit cellulose synthesis (Tateno et al. 2016). Furthermore, CBIs are commonly used to induce cell wall weakening to characterize cell wall integrity sensing and damage response pathways (Denness et al. 2011; Engelsdorf et al. 2018). Despite being a focal tool for cell wall research, reports exist in the literature to suggest that CBIs may not function the way that we think they do...