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Open Access Research article

Genome-wide transcriptome and functional analysis of two contrasting genotypes reveals key genes for cadmium tolerance in barley

Fangbin Cao1, Fei Chen1, Hongyan Sun1, Guoping Zhang1, Zhong-Hua Chen2* and Feibo Wu1*

Author Affiliations

1 College of Agriculture and Biotechnology, Zijingang Campus, Zhejiang University, Hangzhou 310058, P.R. China

2 School of Science and Health, Hawkesbury Campus, University of Western Sydney, Locked Bag 1797, Penrith NSW 2751, Australia

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BMC Genomics 2014, 15:611  doi:10.1186/1471-2164-15-611

Published: 19 July 2014

Abstract

Background

Cadmium (Cd) is a severe detrimental environmental pollutant. To adapt to Cd-induced deleterious effects, plants have evolved sophisticated defence mechanisms. In this study, a genome-wide transcriptome analysis was performed to identify the mechanisms of Cd tolerance using two barley genotypes with distinct Cd tolerance.

Results

Microarray expression profiling revealed that 91 genes were up-regulated by Cd in Cd-tolerant genotype Weisuobuzhi and simultaneously down-regulated or non-changed in Cd-sensitive Dong17, and 692 genes showed no change in Weisuobuzhi but down-regulated in Dong17. Novel genes that may play significant roles in Cd tolerance were mainly via generating protectants such as catalase against reactive oxygen species, Cd compartmentalization (e.g. phytochelatin-synthase and vacuolar ATPase), and defence response and DNA replication (e.g. chitinase and histones). Other 156 up-regulated genes in both genotypes also included those encoding proteins related to stress and defence responses, and metabolism-related genes involved in detoxification pathways. Meanwhile, biochemical and physiological analysis of enzyme (ATPase and chitinase), phytohormone (ethylene), ion distribution and transport (Cd, Na+, K+, Ca2+, ABC transporter) demonstrated that significantly larger Cd-induced increases of those components in Weisuobuzhi than those in Dong17. In addition, Cd-induced DNA damage was more pronounced in Dong17 than that in Weisuobuzhi.

Conclusions

Our findings suggest that combining microarray, physiological and biochemical analysis has provided valuable insights towards a novel integrated molecular mechanism of Cd tolerance in barley. The higher expression genes in Cd tolerant genotype could be used for transgenic overexpression in sensitive genotypes of barley or other cereal crops for elevating tolerance to Cd stress.

Keywords:
ATPase; Cadmium fluorescent indicator; Cadmium tolerance; Microarray; Hordeum vulgare L; Integrated molecular mechanism