Expression analysis of cell wall assembly and remodelling-related genes in Arabidopsis roots subjected to boron stress and brassinosteroid at different developmental stages

Rabia İşkil,Yonca Surgun-Acar

doi:10.1590/0102-33062018abb0023

Abstract

ABSTRACT Plant cell walls are affected by many biotic and abiotic stress conditions. The aim of this study is to determine the effects of 24-Epibrassinolide (EBL) on some cell wall-related genes in root tissue of five- and ten-week-old Arabidopsis thaliana plants exposed to boron (B) deficiency (0 µM) or toxicity (3000 µM) at the transcriptional level. Expressions of the genes that encode cellulose synthase (CESA1, CESA4, CESA6 and CESA8), cellulose synthase-like (CSLB5), expansin (EXPA5, EXPA8 and EXPA14) and cell wall protein (SEB1) decreased under conditions of B deficiency and toxicity. EBL treatments, in general, led the expressions of these genes to reduce significantly. Expressions of xyloglucan endotransglucosylase/hydrolase genes (XTH21 and XTH23) changed only under conditions of B toxicity. Boron stress and/or EBL treatments caused different responses in expression of pectin methylesterase (PME2 and PME41) genes. As a result of B stress, the expression levels of investigated genes changed more in roots of five-week-old plants than in roots of ten-week-old plants. Results of the present study include new findings that support the ability of BRs to increase molecular aspects of tolerance to stress in plants.

Highlights

Plant cell walls are one of the main barriers to abiotic and biotic stresses (Han et al 2012)
Boron toxicity (3000 μM) and EBL hormone co-applied with 3000 μM boric acid (BA) reduced the expression of CESA1 gene in a statistically significant way (Fig. 1A)
Boron deficiency and toxicity in root tissues of tenweek-old plants did not change the expression of CESA1 gene, while 3000 μM BA + EBL application resulted in a 2-fold reduction in expression (Fig. 1B)

Summary

Introduction

Plant cell walls are one of the main barriers to abiotic and biotic stresses (Han et al 2012). It can be suggested that the genes which can synthesize or hydrolize plant cell wall components may promote stress tolerance by means of changes in composition of the cell wall since they show different expressions under different stress conditions (Houston et al 2016). Boron (B), which is essential for plants, is taken up from soil in the form of boric acid (BA) (Brown et al 2002). Primary function of B in higher plants is to form borate esters with rhamnogalacturonan II (RGII) (Kobayashi et al 1996). Construction of this structure is critical for cell wall composition and function, and the complex controls cell wall porosity and strength (CamachoCristobal et al 2011). Boron deficiency (Camacho-Cristobal et al 2011) and B toxicity (Kasajima & Fujiwara 2007) cause expressions of the genes involved in numerous physiological processes to change

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