Comparative Transcriptome Analysis of Two Contrasting Soybean Varieties in Response to Aluminum Toxicity.

Lijuan Zhao,Junyi Gai,Yan Li,Juge Liu,Jingjing Cui,Wei Wang,Zhubing Hu,Songnan Yang,Yuanyuan Cai

doi:10.3390/ijms21124316

Lijuan Zhao, Junyi Gai + Show 7 more

Open Access

https://doi.org/10.3390/ijms21124316

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Abstract

Aluminum (Al) toxicity is a major factor limiting crop productivity on acid soils. Soybean (Glycine max) is an important oil crop and there is great variation in Al tolerance in soybean germplasms. However, only a few Al-tolerance genes have been reported in soybean. Therefore, the purpose of this study was to identify candidate Al tolerance genes by comparative transcriptome analysis of two contrasting soybean varieties in response to Al stress. Two soybean varieties, M90-24 (M) and Pella (P), which showed significant difference in Al tolerance, were used for RNA-seq analysis. We identified a total of 354 Al-tolerance related genes, which showed up-regulated expression by Al in the Al-tolerant soybean variety M and higher transcript levels in M than P under Al stress. These genes were enriched in the Gene Ontology (GO) terms of cellular glucan metabolic process and regulation of transcription. Five out of 11 genes in the enriched GO term of cellular glucan metabolic process encode cellulose synthases, and one cellulose synthase gene (Glyma.02G205800) was identified as the key hub gene by co-expression network analysis. Furthermore, treatment of soybean roots with a cellulose biosynthesis inhibitor decreased the Al tolerance, indicating an important role of cellulose production in soybean tolerance to Al toxicity. This study provides a list of candidate genes for further investigation on Al tolerance mechanisms in soybean.

Highlights

Acid soils comprise up to 50% of the potentially arable land in the world [1,2] and about 21% of total arable land in China [3]
M90-24 (M) and Pella (P), were chosen for this study due to their difference in Al tolerance, as shown by their relative root growth (RRG) under Al stress compared with control conditions
The root growth of P was severely inhibited (RRG = 0.30) after 24 h of Al stress, and we chose 6 and 12 h as the time points to perform the comparative transcriptome analysis using the roots of these two soybean varieties under Al stress and control by RNA-seq

Summary

Introduction

Acid soils comprise up to 50% of the potentially arable land in the world [1,2] and about 21% of total arable land in China [3]. Al toxicity can damage and restrain the growth of plant roots, and affect the absorption of nutrients and water, leading to the reduction in crop yield [2,7,8]. Studies have suggested that the cell wall is the first barrier when plant roots interact with Al in acid soil, and the major pool of Al in plants. Al-induced inhibition of cell elongation in the hypocotyl of Abelmoschus esculentus was mainly due to the Al-binding in epidermis, and 95% of the Al in epidermis was in the cell wall [13]. Many studies showed that the main Al-binding sites in cell wall are polysaccharides [15,16,17]. In addition to the direct Al-binding, the plant cell wall is associated with ectopic lignin deposition, and activation of jasmonate and ethylene signalling pathways [19,20]

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