A Mechanism for Sustained Cellulose Synthesis during Salt Stress

Abiotic stress, such as salinity, drought, and cold, causes detrimental yield losses for all major plant crop species. Understanding mechanisms that improve plants’ ability to produce biomass, which largely is constituted by the plant cell wall, is therefore of upmost importance for agricultural activities. Cellulose is a principal component of the cell wall and is synthesized by microtubule-guided cellulose synthase enzymes at the plasma membrane. Here, we identified two components of the cellulose synthase complex, which we call companion of cellulose synthase (CC) proteins. The cytoplasmic tails of these membrane proteins bind to microtubules and promote microtubule dynamics. This activity supports microtubule organization, cellulose synthase localization at the plasma membrane, and renders seedlings less sensitive to stress. Our findings offer a mechanistic model for how two molecular components, the CC proteins, sustain microtubule organization and cellulose synthase localization and thus aid plant biomass production during salt stress. [Display omitted] [Display omitted] •Identification of two components (CC1 and 2) of the cellulose synthase complex•The CCs directly interact with microtubules and promote their dynamics•The CCs support microtubule and cellulose synthase activity during salt stress•A mechanistic model for how plant biomass is sustained during salt stress Plant biomass provides us with many essential products and an understanding for how it is synthesized is therefore important to support human activities. A central element to plant biomass is the cell wall; a cellular exoskeleton in which the glucan-based polymer cellulose is a prominent component. This paper identifies a protein family whose members are components of the cellulose synthesizing machinery in plants and reveals a mechanism for how plants maintain their biomass producing capacity during saline conditions.