Transcriptome Analysis of Cadmium-Treated Roots in Maize (Zea mays L.).

Runqing Yue,Haiyan Yin,Xiaolei Fu,Shuanggui Tie,Lu Liu,Xiaohua Han,Nana Chen,Haifeng Chi,Shufeng Yan,Jianshuang Qi,Shulei Guo,Caixia Lu

doi:10.3389/fpls.2016.01298

Runqing Yue, Haiyan Yin + Show 10 more

Open Access

https://doi.org/10.3389/fpls.2016.01298

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Abstract

Cadmium (Cd) is a heavy metal and is highly toxic to all plant species. However, the underlying molecular mechanism controlling the effects of auxin on the Cd stress response in maize is largely unknown. In this study, the transcriptome produced by maize ‘Zheng 58’ root responses to Cd stress was sequenced using Illumina sequencing technology. In our study, six RNA-seq libraries yielded a total of 244 million clean short reads and 30.37 Gb of sequence data. A total of 6342 differentially expressed genes (DEGs) were grouped into 908 Gene Ontology (GO) categories and 198 Kyoto Encyclopedia of Genes and Genomes terms. GO term enrichment analysis indicated that various auxin signaling pathway-related GO terms were significantly enriched in DEGs. Comparison of the transcript abundances for auxin biosynthesis, transport, and downstream response genes revealed a universal expression response under Cd treatment. Furthermore, our data showed that free indole-3-acetic acid (IAA) levels were significantly reduced; but IAA oxidase activity was up-regulated after Cd treatment in maize roots. The analysis of Cd activity in maize roots under different Cd and auxin conditions confirmed that auxin affected Cd accumulation in maize seedlings. These results will improve our understanding of the complex molecular mechanisms underlying the response to Cd stress in maize roots.

Highlights

Cadmium (Cd) is a highly toxic, non-essential element
Gibberellic acid (GA), an important phytohormone involved in plant responses to abiotic stresses, alleviates Cd toxicity by reducing Cd-dependent NO accumulation and Cd2+ uptake related gene expression in Arabidopsis (Zhu et al, 2012), whereas exogenous methyl jasmonate inhibits the uptake of Cd to the aboveground part of Kandelia obovata seedlings (Chen et al, 2014)
Ethylene is a regulator of multiple plant processes and Cd induces the biosynthesis of ethylene in Arabidopsis mainly via the increased expression of ACS2 and ACS6 (Schellingen et al, 2014)

Summary

Introduction

Cadmium (Cd) is a highly toxic, non-essential element It inhibits plant growth and development through its effect on physiological and metabolic processes, including growth reduction, leaf roll and chlorosis, respiration, photosynthesis, uptake competition, plant antioxidant defenses, generation of oxidative stress and lipid peroxidation, damage to the cell membrane, and enzyme inhibition (Hasan et al, 2009; DalCorso et al, 2010; Andresen and Kupper, 2013). Gibberellic acid (GA), an important phytohormone involved in plant responses to abiotic stresses, alleviates Cd toxicity by reducing Cd-dependent NO accumulation and Cd2+ uptake related gene expression in Arabidopsis (Zhu et al, 2012), whereas exogenous methyl jasmonate inhibits the uptake of Cd to the aboveground part of Kandelia obovata seedlings (Chen et al, 2014). Ethylene is a regulator of multiple plant processes and Cd induces the biosynthesis of ethylene in Arabidopsis mainly via the increased expression of ACS2 and ACS6 (Schellingen et al, 2014)

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