The Arabidopsis TETRATRICOPEPTIDE THIOREDOXIN-LIKE 1 Gene Is Involved in Anisotropic Root Growth during Osmotic Stress Adaptation.

María Belén Cuadrado-Pedetti,Miguel Angel Botella,María Martha Sainz,Inés Rauschert,Mariana Sotelo-Silveira,Vítor Amorim-Silva,Omar Borsani

doi:10.3390/genes12020236

Abstract

Mutations in the Arabidopsis TETRATRICOPEPTIDE THIOREDOXIN-LIKE 1 (TTL1) gene cause reduced tolerance to osmotic stress evidenced by an arrest in root growth and root swelling, which makes it an interesting model to explore how root growth is controlled under stress conditions. We found that osmotic stress reduced the growth rate of the primary root by inhibiting the cell elongation in the elongation zone followed by a reduction in the number of cortical cells in the proximal meristem. We then studied the stiffness of epidermal cell walls in the root elongation zone of ttl1 mutants under osmotic stress using atomic force microscopy. In plants grown in control conditions, the mean apparent elastic modulus was 448% higher for live Col-0 cell walls than for ttl1 (88.1 ± 2.8 vs. 16.08 ± 6.9 kPa). Seven days of osmotic stress caused an increase in the stiffness in the cell wall of the cells from the elongation zone of 87% and 84% for Col-0 and ttl1, respectively. These findings suggest that TTL1 may play a role controlling cell expansion orientation during root growth, necessary for osmotic stress adaptation.

Highlights

Drought is a significant constraint for crop production worldwide
We show that a mutation in TETRATRICOPEPTIDE THIOREDOXIN-LIKE 1 (TTL1) caused a deceleration in root growth rate compared to Col-0 with increasing osmotic potential
In this work we aim to investigate the role of TTL1 in maintaining primary root growth during osmotic stress adaptation

Summary

Introduction

A critical trait related with water deficit tolerance is the root adaptation capacity to keep growing and exploring the soil in a new hydric condition [1–4]. Even though it is critical for plant survival, root growth adaptation during this stressful condition is not well understood [5]. In the EZ, cells exponentially elongate, with large vacuoles and the nucleus displaced to the cell wall. In this zone, multiple changes occur at the cellular level, such as in microtubules reorientation, cellulose deposition, cell wall softening, and new cell wall synthesis [9]. Elongated cells are displaced to the DZ where terminally differentiate and no longer elongate [7,8]

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