EB1 contributes to microtubule bundling and organization, along with root growth, in Arabidopsis thaliana

Abstract

Microtubules are involved in plant development and adaptation to their environment, but the sustaining molecular mechanisms remain elusive. Microtubule-end-binding 1 (EB1) proteins participate in directional root growth in Arabidopsis thaliana. However, a connection to the underlying microtubule array has not been established yet. We show here that EB1 proteins contribute to the organization of cortical microtubules in growing epidermal plant cells, without significant modulation of microtubule dynamics. Using super-resolution stimulated emission depletion (STED) microscopy and an original quantification approach, we also demonstrate a significant reduction of apparent microtubule bundling in cytoplasmic-EB1-deficient plants, suggesting a function for EB1 in the interaction between adjacent microtubules. Furthermore, we observed root growth defects in EB1-deficient plants, which are not related to cell division impairment. Altogether, our results support a role for EB1 proteins in root development, in part by maintaining the organization of cortical microtubules..

A versatile microfluidic device for highly inclined thin illumination microscopy in the mossPhyscomitrella patens

“…As a proof-of-concept, we imaged microtubule reorganisation associated with regeneration of excised gametophore cells 15 in the microdevice. It is possible that the gametophore excision or injection in the microdevice transiently disrupts the microtubule arrays, based on low anisotropy values ( Figure 3E); however, the anisotropy score was eventually recovered to expected values for cortical microtubules [26][27][28] . Previous study demonstrated that gametophore cells regenerating as protonema produce certain signals, inhibiting protonema regeneration of the surrounding cells 15 .…”

“…Anisotropy score ( Figure 3E) ranging from 0 (purely isotropic arrays) to 1 (purely anisotropic arrays) reflects the alignment of microtubules. For instance, anisotropy values for parallel microtubule arrays, such as cortical microtubules, typically range between 0.2-0.3 [26][27][28] . In our experiments, the initial values for anisotropy were lower than expected (0.09 ± 0.04 at time 0) and recovered in 3 h (0.2 ± 0.11).…”

Root Development and Stress Tolerance in rice: The Key to Improving Stress Tolerance without Yield Penalties

“…Root growth is also regulated by other developmental processes including cell wall development. Plant cells are encased by cell walls mostly made of three types of polysaccharides: cellulose, hemicelluloses, and pectins, and cortical microtubules regulate development of cell walls by guiding cellulose deposition [55,56]. Plant cell walls are flexible and diverse, and cell wall development is involved in the growth of roots because roots are composed of a variety type of cells with different functions and developmental stages [55].…”

Plant and mouse EB1 proteins have opposite intrinsic properties on the dynamic instability of microtubules.

“…In this work, we decided to purify and use EB1-b, among the three orthologs identi ed in Arabidopsis, because it is the one showing the strongest phenotypes in plants when knocked-out or mutated [11], [13] and the most similar one to its mammalian counterpart [4] [8] [9]. Knowing the dissimilarity in sequence between EB1-b and EB1-a or EB1-c, continuing this work by comparing EB1-a, EB1-b and EB1-c to the mammalian EB1 would give more information regarding the conservation of the intrinsic functions of those proteins.…”

“…The mammalian version of EB1 has been puri ed and its effect on microtubule dynamics extensively studied both in vivo and in vitro [10]. In contrast, the plant EB1 roles in development and microtubule network organization have been explored using knock-out mutants and loss-of-function mutants, revealing functions in touch sensing and microtubule bundling [11], [12], [13] but its intrinsic properties have not been extensively studied in vitro yet.…”