Functional Characterization of Aluminum (Al)-Responsive Membrane-Bound NAC Transcription Factors in Soybean Roots.

Yan Lin,Yingbing Xue,Jiang Tian,Yaoliang Pan,Xueqiong Guo,Cuiyue Liang,Jikai Luo,Guoxuan Liu,Kang Chen

doi:10.3390/ijms222312854

Abstract

The membrane-bound NAC transcription (NTL) factors have been demonstrated to participate in the regulation of plant development and the responses to multiple environmental stresses. This study is aimed to functionally characterize soybean NTL transcription factors in response to Al-toxicity, which is largely uncharacterized. The qRT-PCR assays in the present study found that thirteen out of fifteen GmNTL genes in the soybean genome were up-regulated by Al toxicity. However, among the Al-up-regulated GmNTLs selected from six duplicate gene pairs, only overexpressing GmNTL1, GmNTL4, and GmNTL10 could confer Arabidopsis Al resistance. Further comprehensive functional characterization of GmNTL4 showed that the expression of this gene in response to Al stress depended on root tissues, as well as the Al concentration and period of Al treatment. Overexpression of GmNTL4 conferred Al tolerance of transgenic Arabidopsis in long-term (48 and 72 h) Al treatments. Moreover, RNA-seq assay identified 517 DEGs regulated by GmNTL4 in Arabidopsis responsive to Al stress, which included MATEs, ALMTs, PMEs, and XTHs. These results suggest that the function of GmNTLs in Al responses is divergent, and GmNTL4 might confer Al resistance partially by regulating the expression of genes involved in organic acid efflux and cell wall modification.

Highlights

In soils with pH values below 5.0, Aluminum (Al) is solubilized as highly phytotoxic Al3+, which is able to interact with various cell components, leading to the disruption of signal transduction, the plasma membrane, the cytoskeleton, and DNA in the nuclei [1]
Our results suggest that soybean GmNTL members have a divergent function in Al tolerance, and GmNTL4 might confer Al resistance partially by regulating genes that are involved in organic acid efflux and cell wall modification
The function of NTLs in plant development and resistance to environmental stresses have been widely studied, little attention has been paid to consider the involvement of NTLs in plant Al responses

Summary

Introduction

In soils with pH values below 5.0, Aluminum (Al) is solubilized as highly phytotoxic Al3+, which is able to interact with various cell components, leading to the disruption of signal transduction, the plasma membrane, the cytoskeleton, and DNA in the nuclei [1]. The lost function of both XTH17and XTH31 reduced the accumulation of cell wall xyloglucan and the Al binding capacity in Arabidopsis, suggesting that XTHs play important roles in Al resistance [9,10]. Pectins are another group of complex polysaccharides being targeted by Al [11]. Understanding the molecular regulatory pathways of the genes involved in organic acid exudation, as well as modification of cell wall components (e.g., pectin and hemicellulose), would largely expand the understanding of plant Al tolerance mechanisms

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Results

Conclusion