Overexpression of ANAC046 Promotes Suberin Biosynthesis in Roots of Arabidopsis thaliana.

Kashif Mahmood,Steven J Rothstein,Lukas Schreiber,Viktoria Valeska Zeisler-Diehl,Yong-Mei Bi,Kosala Ranathunge

doi:10.3390/ijms20246117

Abstract

NAC (NAM (no apical meristem), ATAF1/2, and CUC2 (cup-shaped cotyledon)) proteins are one of the largest families of plant-specific transcription factors, and this family is present in a wide range of land plants. Here, we have investigated the role of ANAC046 in the regulation of suberin biosynthesis and deposition in Arabidopsis. Subcellular localization and transcriptional activity assays showed that ANAC046 localizes in the nucleus, where it functions as a transcription activator. Analysis of the PANAC046:GUS lines revealed that ANAC046 is mainly expressed in the root endodermis and periderm, and is also induced in leaves by wounding. The transgenic lines overexpressing ANAC046 exhibited defective surfaces on the aerial plant parts compared to the wild-type (WT) as characterized by increased permeability for Toluidine blue stain and greater chlorophyll leaching. Quantitative RT-PCR analysis showed that the expression of suberin biosynthesis genes was significantly higher in the roots and leaves of overexpression lines compared to the WT. The biochemical analysis of leaf cuticular waxes showed that the overexpression lines accumulated 30% more waxes than the WT. Concurrently, overexpression lines also deposited almost twice the amount of suberin content in their roots compared with the WT. Taken together, these results showed that ANAC046 is an important transcription factor that promotes suberin biosynthesis in Arabidopsis thaliana roots.

Highlights

IntroductionPlants employ protective mechanisms to cope with environmental challenges in their surroundings
Given their sessile growth, plants employ protective mechanisms to cope with environmental challenges in their surroundings
Spatio-temporal expression of Arabidopsis transgenic lines expressing PANAC046:GUS cassette showed that ANAC046 is mainly expressed in the root endodermis (Figure 2A) and periderm (Figure 2B), floral organs and at the base of young developing siliques (Figure 2C)

Summary

Introduction

Plants employ protective mechanisms to cope with environmental challenges in their surroundings. The development of lipophilic apoplastic barriers, which are made of cutin and suberin, holds great significance [1]. These barriers provide protection against threats that plants face above- or below-ground during their life [2]. Cutin is the integral part of the plant cuticle and is constitutively produced by the epidermal cells of most the aerially developing plants tissues and functions as an interface between plants internal tissues or cell layers and the external environment [2]. Regardless of the sites and factors of its deposition, the primary function of suberin polymer is to regulate the movement of water and solutes across the cell/tissue layers and to restrict pathogen entry into tissues, thereby ensuring tissue integrity and plant survival

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