Overexpression of the Aldehyde Dehydrogenase Gene ZmALDH Confers Aluminum Tolerance in Arabidopsis thaliana.

Han-Mei Du,Cheng-Feng Du,Shuai Luo,Wen-Zhu He,Yan Yu,Su-Zhi Zhang,Chan Liu,Xin-Wu Jin

doi:10.3390/ijms23010477

Abstract

Aluminum (Al) toxicity is the main factor limiting plant growth and the yield of cereal crops in acidic soils. Al-induced oxidative stress could lead to the excessive accumulation of reactive oxygen species (ROS) and aldehydes in plants. Aldehyde dehydrogenase (ALDH) genes, which play an important role in detoxification of aldehydes when exposed to abiotic stress, have been identified in most species. However, little is known about the function of this gene family in the response to Al stress. Here, we identified an ALDH gene in maize, ZmALDH, involved in protection against Al-induced oxidative stress. Al stress up-regulated ZmALDH expression in both the roots and leaves. The expression of ZmALDH only responded to Al toxicity but not to other stresses including low pH and other metals. The heterologous overexpression of ZmALDH in Arabidopsis increased Al tolerance by promoting the ascorbate-glutathione cycle, increasing the transcript levels of antioxidant enzyme genes as well as the activities of their products, reducing MDA, and increasing free proline synthesis. The overexpression of ZmALDH also reduced Al accumulation in roots. Taken together, these findings suggest that ZmALDH participates in Al-induced oxidative stress and Al accumulation in roots, conferring Al tolerance in transgenic Arabidopsis.

Highlights

Aluminum (Al) is one of the most abundant metal elements in the Earth’s crust and can be solubilized to the toxic species Al3+ in acidic soils [1]
The deduced protein sequence showed sequences identified at 70.16% and 72.28% with rice aldehyde dehydrogenases OsALDH3-1 and OsALDH3-2, respectively (Figure 1A)
To determine whether ZmALDH overexpression could enhance Al tolerance in transgenic Arabidopsis, we examined the growth of the two transgenic lines (L4 and L6) and WT plants treated with 0, 50, and 100 μM AlCl3

Summary

Introduction

Aluminum (Al) is one of the most abundant metal elements in the Earth’s crust and can be solubilized to the toxic species Al3+ in acidic soils (pH < 5.0) [1]. Al stress, which can rapidly inhibit root elongation even at a micromolar concentration, is one of themajor factors limiting crop yield in acidic soils [2]. Two kinds of aluminum tolerance mechanisms, organic acid extradition for external detoxification and Al sequestration into vacuoles for internal tolerance, have been adopted by plants [3,4,5]. Al stress induces oxidative stress, which causes the overproduction of reactive oxygen species (ROS) and aldehydes in plants [8,9,10].

Methods

Results

Conclusion