Peripheral membrane TTL proteins safeguard cellulose synthesis under stress.

Abstract

Land plants provide around eighty percent of biomass on Earth and roughly one-third corresponds to cellulose (Bar-On et al 2018). Despite its biological and societal importance, many aspects of cellulose biosynthesis and regulation remain elusive. Controlled primary cell wall remodeling allows plant growth under stressful conditions, but how these changes are conveyed to adjust cellulose synthesis is not well understood (Colin et al 2023). In this work, we identify that Tetratricopeptide Thioredoxin-Like (TTL) proteins, which we previous describe as a scaffold of brassinosteroids signalling components, are also new members of the cellulose synthase complex (CSC) and we describe their unique and hitherto unknown dynamic association with the CSC under cellulose-deficient conditions (Amorim-Silva et al 2019 and Kesten, García-Moreno, Amorim-Silva et al 2022). We found out that TTLs are essential for maintaining cellulose synthesis under high salinity conditions, establishing a stress-resilient cortical microtubule array, and stabilizing CSCs at the plasma membrane. To fulfill these functions, TTLs interact with Cellulose Synthase1 (CESA1) and engage with cortical microtubules to promote their polymerization. We propose that TTLs function as bridges connecting stress perception with dynamic regulation of cellulose biosynthesis at the plasma membrane. In addition, we are currently working to identify and characterize new components involved in TTLs function and dynamics during cellulose biosynthesis under saline stress conditions.

References: Amorim-Silva et al. 2019 The Plant Cell Bar-On et al. 2018 Proc. Natl. Acad. Sci. Colin et al. 2023 The Plant Cell Kesten, García-Moreno, Amorim-Silva et al. 2022 Sci. Adv.